A bibliometric analysis on climate finance: current status and future directions

Since the adoption of the Paris Agreement in 2015, different countries have implemented various measures to achieve climate governance. This has attracted significant attention from the academic community, resulting in a rapid increase in climate finance literature. This study conducts bibliometric analysis and systematic review to identify the development trends and research hotspots in the field of climate finance. The empirical findings reveal that climate finance research primarily focuses on environmental science, energy fuels, economics, and finance. However, there is limited coverage of climate finance content in finance journals. Moreover, scholars in developing countries show less interest in climate finance compared to them in developed countries, and there is limited cross-regional collaboration among scholars from developing countries. Finally, this paper analyzes clustering results to identify and categorize the focal areas dispersed across research articles, and provides future directions for the advancement of climate finance.


Introduction
Climate change is a pressing concern for the international community.The impacts of climate change, such as natural disasters and extreme weather caused by climate change, have irreversible consequences for ecosystems, the economy, and society (Batten et al. 2016;Zhao et al. 2022).The world is currently facing a climate emergency.The burning of fossil fuels has significantly contributed to the increase in greenhouse gas emissions, altering the composition of gases in the atmosphere.As a result, global temperatures have risen by 1.1 °C compared to pre-industrial levels (UNEP 2023).The concentration of greenhouse gas emissions in the atmosphere is causing widespread damage and posing threats to lives, health, and food security.In December 2015, 196 parties to the United Nations Framework Convention on Climate Change (UNFCCC) reached the Paris Agreement.The agreement aims to limit the global temperature increase to 2 °C over pre-industrial levels in this century, with further efforts to limit the increase to 1.5°.To achieve the goals of the Paris Agreement, it is essential for every country to reduce greenhouse gas emissions by 30 Gt annually by 2030.One of the main challenges faced by countries today is securing the necessary funds for climate change mitigation and adaptation.In order to address this challenge, the World Bank has provided $31.7 billion in financing to assist countries in mitigating climate change in FY2022.Additionally, the IBRD and IDA have contributed $26.2 billion in climate finance, with almost half of this amount allocated to support countries in adapting to climate change and facilitating construction restoration (World Bank 2022).
Climate finance refers to "local, national, or transnational financing, which may be drawn from public, private, and alternative sources of financing, seeks to support mitigation and adaptation actions that will address climate change" by UNFCCC.Climate finance is critical to addressing climate change because large-scale investments are required to significantly reduce emissions and exploit renewable energy in order that the speed of climate change is slower than expected.Additionally, Hong et al. (2020) show in their special issue how finance contributes to mitigation and adaptation actions that will deal with climate change, including the fact that economists adopt asset pricing methods and decision theory to calculate social cost of carbon (Gollier 2013; Barnett et al. 2020), how to hedge climate risks (Engle et al. 2020), and that investors' awareness and attitudes towards climate change have influence on their own investment decisions as well as firm performance (Alok et al. 2020;Krueger et al. 2020).The reason why scholars have attached increasing importance to climate finance is that related natural disasters will cause volatility of financial market and further have tremendous impact on real economy and banking system.Therefore, in order to prevent external factors such as climate change and environment pollution from damaging the financial system by means of affecting real assets and investor sentiment, making investors suffer higher risks due to changes in the overall market environment, such as decline in corporate profitability, increase in the rate of default losses and volatility of stock and bond prices.More and more researchers have turned their attention to the emerging field of climate change to study the significant role of "finance" in climate action from many aspects.
However, as mentioned above, the field of climate finance has a broad scope, and many studies intersect with this subject, yet there is no unified research framework.In other words, during our literature retrieval and analysis process, we found that most of the literature related to climate finance spans scientific fields such as the environment and climate, as well as social science fields like policy, law, financing products, and risks.This makes it challenging for scholars interested in conducting research in this area to establish a comprehensive research framework.Moreover, there are few review papers on this topic, and almost no literature provides recommendations for future research directions based on analysis results.Therefore, this paper offers some extensions to the above content in the form of bibliometric review.
As the development of knowledge is a dynamic process, it may be difficult for researchers to capture the current research hotspots and research gaps in the field from a huge number of papers only relying on non-visualization technology, which is not conducive to a deep understanding of knowledge in this field and conduct future research (Darko et al. 2019).The systematic review classifies the theory, research methods, and perspectives of climate finance according to a certain organizational method, and can effectively use visualization technology to express the theoretical support and growing trend of climate finance.In recent years, bibliometric tools such as VOS viewer and Cit-eSpace have become popular for scholars to complete systematic reviews.Compared with other software, CiteSpace has more comprehensive functions and simpler operation methods.At the same time, this software can extract relevant information from a large number of journals, perform classified and visual analysis on multiple contents, and objectively reveal the quantitative relationship between different studies in this field (Li et al. 2017).VOSviewer, on the other hand, can provide a visual representation of cooperation and co-occurrence relationships between countries or regions, which greatly assists in studying geographical distribution and cross-collaboration patterns.Moreover, VOSviewer can offer citations and total link strength for the literature from various countries, providing a data-driven approach to track literature trends.Therefore, to help readers better focus on climate finance policies and development trends and to assist researchers in this field in obtaining relevant knowledge more quickly, this paper obtained a substantial amount of climate finance literature through a literature retrieval platform.After selection, a series of quantitative and qualitative analyses were conducted using bibliometric tools to provide a more intuitive understanding of the interdisciplinary nature, geographical distribution, cross-regional cooperation, research hotspots, and areas for further study in climate finance.This approach effectively compensates for the fragmentation and extensive scope of this emerging field, allowing scholars interested in this area to quickly concentrate on specific topics and make more significant contributions.
The results of the study show that although climate finance has attracted more and more attention and the concept of climate finance is widely cited in academic circles, financing projects are not an integral part of climate finance, and this topic rarely appears in the financial journals.Consequently, this paper concludes by illustrating the problems of current research and pointing out some research directions, which can serve as a reference guide for integrating climate change and financing methods in the future.The rest of the paper is organized as follows: the "Literature review" section introduces the literature review part of this paper, the "Materials and methods" section explains the research methodology, the "Synthesis analysis" section presents our findings and provides an in-depth analysis, the "Avenues for future directions" section describes the current research existing problems and future research directions, and the "Conclusions and limitations" section illustrates the conclusion and limitations.

Literature review
One of the goals of climate finance actions is to make funds flow to countries or regions that need to reduce carbon emissions, mitigate, and adapt to climate change.As measured in the Global Landscape of Climate Finance 2021 report, total climate finance has steadily increased over the last decade, reaching USD 632 billion in 2019/2020 (CPI 2021).However, this financing is far from enough to achieve the goal of "fighting to limit the temperature rise to 1.5 °C" in the Paris Agreement.Since all sectors that affect climate change -energy, transportation, water resources, industry, etc. -need funding to reform scientifically, the Climate Policy Initiative predicts that climate finance must increase by at least 590% -to USD 4.35 trillion annually by 2030to meet climate objectives.As the negative impact of climate change continues to expand, climate finance has become a major topic in climate negotiations among countries.The basic commitment reached in the negotiations is that the funds needed for climate finance will flow from developed countries to developing countries.However, apart from UNFCCC's broad classification of climate finance -climate finance is generally divided into public and privateacademic community does not have a unified definition of the topic, and climate financing, green finance, and sustainable finance are often referred to as confusion (Zhang et al. 2019;Debrah et al. 2023;Shishlov and Censkowsky 2022).Zhang et al. (2019) believe that green finance is a financial investment that can provide environmental benefits, which is not the same as the definition of climate finance, but the core characteristics of both are financing tools that solve environmental problems.Debrah et al. (2023) pointed out that the focus of climate finance is a series of measures to mitigate and adapt to climate change; sustainable finance is used to provide the required funds for socially inclusive green projects.And green finance is a relatively broad concept, including sustainable finance, environmental finance, carbon finance, and climate finance.It is kind of financial service aimed at improving the environment, mitigating climate change, and improving resource utilization efficiency.Shishlov and Censkowsky (2022) regard climate finance as a subset of green finance, which in turn belongs to the category of sustainable finance.They argue that sustainable finance has wider sustainable development goals -including environmental and social goals.For example, the 17 SDGs were mentioned in the 2030 Agenda for Sustainable Development.Green finance and climate finance have no generally accepted concepts.Generally, green finance is considered to only support environmental goals (excluding social goals), including climate change, greenhouse gas emissions, water or air pollution, and biodiversity protection.Although the concepts of these three are different, in general, climate finance, green finance, and sustainable finance all use financial instruments and various financing channels to improve environment, mitigate and adapt to climate change, and ultimately achieve global sustainable development goals.
For a long time, climate finance has been regarded as an action that the public sector needs to attach great importance to, but there are some problems in the financing mechanism of the public sector to mitigation and adaptation of climate change.For example, issues related to the Global Environment Facility (GEF) include (1) limited sources of funding to achieve the Convention's objectives and to provide environmental technology to developing countries; (2) inefficiencies due to long project decision-making and approval time; and (3) the implementation process that may not conform to the policies and cultures of different countries or regions (Zhang and Maruyama 2001;Stoll et al. 2021).In the face of the deepening climate crisis, the challenge of adapting to climate change is becoming severer and severer.According to the 2021 Annual Report of the United Nations Environment Program (UNEP), it is estimated that by 2030, the cost of adaptation in developing countries will increase to 140-300 billion US dollars per year.It is not enough to rely on financial support from public sector alone confronted with a huge amount of funding.As a result, private sector investment is gaining attention in the context of United Nations negotiations.The private sector includes the financial sector and private sector participants in the real economy.Its contribution to climate financing actions can not only adapt its own assets and operations to climate change, but also obtain commercial value in investment activities, which is in line with the interests of private companies (Pauw and Pegels 2013;Druce et al. 2016;Fayolle et al. 2019;Goldstein et al. 2019).In the 2010 Cancun Agreement, public and private sector financing are both considered as sources of climate finance.In February 2010, the "United Nations' Advisory Group on Climate Change Financing" released the "Report of the secretary -general's high-level advisory group on climate change financing."With this report as a watershed, the focus of global climate financing began to shift to the establishment of an independent climate financing mechanism, seeking new sources of funding and mobilizing funds from the private sector (Liu et al. 2018).However, since private sector investment projects need to consider their own interests, most of them will choose traditional projects with relatively mature technologies, and pay less attention to emerging energy and carbon capture technologies.Therefore, the private sector's participation in climate finance is a supplementary means rather than a substitute for the public sector (Pauw 2015), and it cooperates with the development sector as well as the international financial sector to jointly find long-term solutions to climate change (Pauw et al. 2016;Hsu et al. 2020;Stoll et al. 2021).
From a public sector perspective, a common understanding of climate finance responsibility will be essential to the successful mitigation of and adaptation to climate change (Egli and Stünzi 2019).Climate finance is a mobilization of resources aiming to contribute to governing climate change and looks incredibly similar: it is an emergent set of loose things and practices joined by governing nodes in a system of correlation (Bracking 2019).For the private sector, green bonds, as an emerging financial instrument, are a product of the economic transition towards green sustainability.The adoption of green bonds is vital for Asian countries in achieving sustainable energy efficiency and economic transformation.Research results from Zhao and Duan (2023) indicate that by 2050, China will strive to transition to more energy-efficient sources and finance this transition through the green bond market.Additionally, China has initiated a carbon trading market pilot program that integrates financial institutions with carbon emissions, creating numerous financing channels and introducing innovative products in climate finance (Zhou and Li 2019).Other scholars incorporate climate change risks into financial pricing models to determine loss distributions and yields.They also discuss how investors can build portfolios to hedge climate risks, minimizing the impact of external factors (Hong et al. 2020;Giglio et al. 2021).Presently, the climate policies of RECP countries are uncertain, and investor confidence in specialized investments is limited, resulting in restricted potential for green investments (Wang and Xu 2023).In India, financial professionals have a weaker awareness of ESG, climate change, and greenhouse gas risks.They seldom consider incorporating this data into credit risk assessment or loan product pricing, leading to significant risks in the lowcarbon transition (Colenbrander et al. 2023).To unlock the greater potential of climate finance, collaboration between the public and private sectors is necessary.Emerging and developing economies should focus on climate finance regulation and standards, implement specific green financial and fiscal policies (such as carbon taxes and green subsidies), and ensure the smooth and effective progress of climate finance actions.

Materials and methods
The method used in this paper is bibliometric analysis, a popular and rigorous method for exploring and analyzing large volumes of scientific data.It allows us to figure out the evolutionary nuances of specific domains while illuminating emerging areas in the field (Donthu et al. 2021).This method can conduct co-occurrence analysis of different research methods and contents of climate finance according to their relationship, and visualize the connection in terms of keywords, authors, countries or regions, and included journals or fields, so as to quickly discover the development trend in this direction and find research hotspots.

Identification of data resources
In academia, the number of citations is a commonly employed metric for assessing scholarly impact.As a result, citation analysis can reveal influential authors, articles, and journals within a knowledge domain.However, citation analysis is constrained by the scope of the database.This limitation signifies that citation analysis can only quantify citations from the same indexing sources, while citations from sources outside the index are not recognized.First, this paper chooses the SCI and SSCI databases in the core collection of Web of Science (WoS) as the literature retrieval source.Similar to Scopus, the WoS database incorporates a wide range of academic disciplines, including numerous publications in the social sciences, and the indexing coverage is quite comparable.However, WoS has a longer history, resulting in the inclusion of more early literature.Given that research and policies related to climate have attracted widespread attention for quite some time, the search results from WoS are likely to be more accurate and widely recognized in the literature (Zheng et al. 2020;Zhou et al. 2021).Furthermore, since co-citation analysis explores the knowledge structure of a field by using reference lists from articles within a database, it covers a significantly larger set of literature than the databases used for reviews, extending even beyond the coverage of the WoS index.Given that cocitation analysis has the capability to transcend the scope of the citation database it utilizes, it complements traditional citation analysis and offers a more comprehensive understanding of the knowledge domain.Among them, Science Citation Index (SCI), Social Sciences Citation Index (SSCI), and Arts & Humanities Citation Index (AHCI) are the three main sources of literature knowledge base, so it has the characteristics of massiveness and authority (Yang et al. 2021).Science Citation Index (SCI) and Social Sciences Citation Index (SSCI) collect a large number of literatures in the field of social sciences, which is in line with the research content of this paper; while AHCI collects literature in the field of humanities and art, which is different from the research content.In addition, most of the literature in AHCI will also be included in SCI and SSCI; that is, there are overlapping parts in the content.Therefore, this paper mainly selects SCI and SCI in WoS as the retrieval database.
To ensure the rationality and accuracy of the data selection method, we adopted PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) according to previous bibliometric experience (Kouwenberg and Zheng 2023;Chu et al. 2023), the data search process for Systematic Reviews and Meta-Analyses.It enables a clear overview of the steps involved in identifying and extracting documents for bibliometric analysis (Page et al. 2021).The specific process is shown in Fig. 1.
First of all, this article used the SCI and SSCI databases in the core database of WoS as the search basis, and we typed the keyword of "climate finance" in the subject column.We could obtain 3366 results (July 17, 2023).Second, we set the time range of retrieved journals as 2001-2022 (because the data in 2023 is incomplete), and excluded 366 non-English literatures, acquiring 3000 articles.In addition, in order to ensure the accuracy of the selected sample documents, this paper eliminated some noise documents, such as publication advertisements, letters, and submission guides and set the types of documents as journal articles and reviews.Hence, we obtained 2883 journal papers.In order to improve the validity of the research, we manually checked the titles, abstracts, and keywords of the search results, and excluded 572 journals that were not related to the topic of climate finance.Eventually, we saved the selected 2311 sample literatures in the form of full records associated with the content of this research and standardized them.The full record of each article in WoS contains the following basic information: author, title, abstract, keywords, publication year, and references.Therefore, this similar basic information can be used as the basis for finding the inner connection of the article and laying the foundation for the analysis of the results of the article.

Data analysis
After getting 2114 journal articles, we downloaded them to CiteSpace and VOSviewer in plain text format for visual analysis.The bibliometric analysis is divided into two parts.The first part is descriptive statistics.In this part, data is processed and categorized based on indicators extracted from the exported literature information, including annual publication counts, the research field to which the research content belongs, publication types, and the countries/regions of article authors.This categorization results in various visual charts.After importing the data, we first use Excel and to perform descriptive statistics, and make an intuitive interpretation of the growing trend of the literature by year, ranks in research fields, geographical distribution, and crosssectional collaboration in the form of charts.The second part is Science Mapping.In this part, data clustering is primarily based on indicators such as keywords, abstracts, and timespans from the literature.A single article often contains multiple keywords, and co-occurrence analysis links these keywords together.Keywords that co-occur more frequently result in larger nodes in the network, indicating their higher centrality.Additionally, by incorporating time into the network, it becomes possible to observe evolving trends over time.By combining different keywords and applying Cit-eSpace algorithms to select the most effective features from the initial set of features, they are stored in vectors, and by Fig. 1 PRISMA flow diagram demonstrates the four steps of the systemic review process (Moher 2009) transforming these selected features, new prominent features are formed, creating distinct categories.This allows us to identify corresponding topics based on these different categories.In this part, this article uses CiteSpace to conduct keyword co-occurrence analysis and clustering analysis based on the nodes and associations between documents, trying to (1) find out the hot topics and research directions of the latest research, and provide help for future research content by observing the evolution of different topics and keywords in the map; (2) discover scholars' attention to the topic of climate finance, and how to link climate change to finance so as to lead a better implementation outcome by listing highly cited papers and the cluster analysis results of climate finance.In addition, this paper also analyzes the limitations of current research and future research directions based on the above content, hoping to be helpful for future climate finance.

Descriptive statistics
This part includes the annual publication volume, the field of the articles, geographical distribution, and highly cited literature to analyze the basic status of climate finance research.

Publications per year
Figure 2 shows the trend in the number of publications over time in climate finance.It can be seen from the figure that before 2016, the annual growth rate of climate finance articles was relatively small, and this field did not receive much attention from scholars.However, the number of climate finance articles has increased by more than five times since 2016, from 95 articles published each year to 504 articles published in 2022.This may because the "Paris Agreement" signed in 2015 stipulates that countries must take "finance flows consistent with a pathway towards low greenhouse gas emissions in order to strengthen the global response to the threat of climate change in order to achieve sustainable development and eradicate poverty and climate-resilient development" (Kouwenberg and Zheng 2023).The signing of this agreement has attracted widespread attention of researchers on climate mitigation and adaptation financing, which has shown an exponential upward trend.In addition, we can also see from the figure that the growth rates in 2021 and 2022 are significantly greater than those in previous years.The possible reason is the reaffirmation of the objectives of the Paris Agreement at the United Nations Climate Change Conference (COP26) in Glasgow in 2021, and the Glasgow Climate Pact calls for a doubling of finance to support developing countries in adapting to the impacts of climate change and building resilience, which only accounts for about 25% of all climate finance (with 75% going towards green technologies to mitigate greenhouse gas emissions).

Research areas
Figure 3 suggests that the research field of climate finance is mainly concentrated in environmental science, with a total of 1690 documents, accounting for 73% of the total number of this topic.There are also a large number of related articles in the field of economics, mainly including renewable energy policy and investment in renewable energy technologies (Frondel et al. 2010;Paramati et al. 2017;Geddes et al. 2018;Zhang et al. 2022), green bond issues to finance climate-friendly projects (Nanayakkara and Colombage 2019;Flammer 2021;Sartzetakis 2021), and the role of carbon markets (Marron and Toder 2014;Tan et al. 2020).
In addition, we can also see from Fig. 3 that the number of literatures in the field of finance research is relatively small, accounting for only about 3% of the total number of climate finance articles screened in this paper.This shows that in

Geographic distribution of publications
This section analyzes the geographical distribution area of selected samples, which helps to recognize the differences of geographical and policy in climate finance, and promotes the integration of cross-regional research.It is worth noting that the geographical distribution of articles is divided according to the location of the author's institution at the time of publication.Figure 4 is obtained from the screening of the WoS database, and it shows the top 15 countries and regions with the largest number of publications and the corresponding number of documents.
Figure 4 presents that American scholars rank first, followed by British and Chinese scholars.As the largest developed economies in the world, scholars of the USA and the United Kingdom are more concerned about climate change than other countries.In 2018, the USA was one of the countries with the highest per capita greenhouse gas emissions at 62.19 tons.In addition, the president of the USA launched an initiative at the United Nations Climate Change Conference in 2022 (COP27) to back up his pledge to reduce greenhouse gas emissions with action, including doubling donation to the Climate Adaptation Fund, reaching $100 million.Since the UK is one of the key roles in global climate governance, its contributions to climate change after "Brexit" have also attracted much attention.In 2019, the newly revised "Climate Change Act" came into effect, officially establishing Fig. 4 Geographic distribution of journal articles on climate finance the UK's goal of achieving "net zero emissions" of greenhouse gases by 2050.In addition, the British government established the world's first carbon emission trading market, so carbon trading activities in response to climate change have also drawn attention of scholars.As the largest developing country in the world, China is also one of the largest greenhouse gas emitters, accounting for 27.79% of global emissions.As China gradually shifts from high-speed development to high-quality development, China implements a national strategy to actively address climate change, and strives to peak carbon dioxide emissions before 2030 and achieve carbon neutrality before 2060.The USA and the United Kingdom are typical representatives of developed countries, and China is a big country actively responding to climate change.Their research results will have an important impact on world climate change and economic development.Due to the globalization of the world economy, climate financing is not a matter within one country, but is mutual responsibility of countries all over the world.The development of climate finance cannot be achieved by only one or two countries, and it is the result of joint efforts of all countries in the world.Scholars in many countries have also carried out a series of related studies (e.g., Germany, Australia, Sweden) according to their regional and cultural backgrounds, respectively, and put forward some insights.These studies are indeed of great significance to both theoretical and practical development in the field of climate finance.However, as shown in Fig. 5, developed countries account for a relatively large proportion of research in the field of climate finance.This may be because the economy of developed countries has tended to be high quality, and the importance of climate governance has been widely recognized and they have carried out more activities related to climate finance.Under the impetus of practice, scholars have made more in-depth research on it.However, the practice of economic development in many developing countries is still in its infancy, so the consequences of climate change are not paid enough attention, and investment in clean technology is insufficient.As a result, the theoretical research related to this field has not been sufficiently received enough attention by researchers.
Based on the above analysis, climate finance researchers come from different countries or regions.In order to further analyze the status of cross-regional cooperative research by scholars, this paper uses VOSviewer software to visually display the co-occurrence network and collaboration strength of countries or regions, and the results are shown in Fig. 5 and Table 1.In addition, the weighted degree of a node is like the degree.It is also called total link strength which represents the total number of co-occurrences of a country or region with other nodes.It is based on the number of edges for a node, but ponderated by the weight of each edge.It is doing the sum of the weight of the edges.
It can be seen from Fig. 5 that scholars from the first four countries in Fig. 4 have strong cooperation with each other and are at the core of the leadership of the co-occurrence network.Table 1 graphically reveals that the higher the weighted degree value is, the more the cross-regional collaboration with others is.We can see that in the research field of climate finance, researchers from strong countries such as the USA, China, and the United Kingdom and Germany have more cooperation with other countries.In this context, the yellow portion represents the collaborative network of American scholars or institutions with other countries, revealing that the USA engages in widespread cross-regional cooperation.This is also well-supported by the weighted degree value for the USA in Table 1.This broad collaboration can be attributed to the presence of global institutions such as the World Bank and the United Nations headquartered in the USA, which greatly encourage policy research and implementation.The green and red portions represent the collaborative relationships of researchers from Germany and the United Kingdom with other countries.It is evident that there is close research exchange among European countries.The extensive collaborative network among European countries may be due to the European Union's climate change policy, specifically the European Union Emissions Trading System, which has garnered significant scholarly attention.Additionally, Europe's focus on renewable energy development, prompted by past energy crises, aims to ensure the stable functioning of nations.As the world's largest developing country, China actively fulfills its corresponding responsibilities and takes measures to improve the climate environment to achieve sustainable development.However, India, Pakistan, Brazil, Vietnam, and other countries are located at the edge of the co-occurrence network, and the connection with other countries is not close enough, which also shows that developing countries and developed countries have less cooperation in the field of climate finance.This is likely attributed to the uneven economic development in developing countries, which often results in prioritizing one aspect over another.While enhancing various aspects of management, factors with weaker ties to economic growth are easily overlooked, leading to inadequate investment in climate improvement.This mindset is prevalent in most countries, highlighting the need for a long-term balance between development and governance.Therefore, in the future, it is necessary to strengthen the connection between countries with different economic conditions and cultural backgrounds in climate finance, and promote cooperation and communication among countries on climate change actions, so as to achieve the target of global governance.

Influential journals and research areas
Table 2 ranks journals based on the total number of citations using node statistics from CiteSpace, including citations exclusively from articles in the climate finance database.The most cited journals in climate finance literature reflect the connections between climate change, energy policy, finance, economics, sustainability, and management.To date, the most cited journal is Energy Policy (2898 citations), originating from the United Kingdom, with a primary focus on energy utilization and new energy development.Following that is Climate Policy (2548 citations), which further underscores the significance of financing the transition to renewable energy in the literature.Third place goes to the environmental science journal Nature Climate Change (2305 citations), highlighting the interdisciplinary nature of this knowledge domain.Fourth and fifth positions are held by interdisciplinary journals related to energy, namely, Science (1783 citations) and Renewable & Sustainable Energy Reviews (1744 citations).Other types of journals predominantly cover areas such as environmental science, economics, and finance, aligning with the findings in Fig. 3.This suggests that content related to climate finance extends beyond traditional finance journals and is more prominently cited in the realms of environmental science and energyrelated literature, with a wide-reaching impact.
Three high-impact finance journals also appear in Table 2, namely, Finance Research Letters (659 citations), Journal of Financial Economics (269 citations), and Review of Financial Studies (66 citations), at ranks 13, 18, and 19, respectively.It is worth noting that out of the 2311 articles in our climate finance database, these top-tier finance journals have only published 16 articles.Surprisingly, even Journal of Finance, widely recognized as a premier finance journal, has not contributed a single article to our database.This points to a relatively limited focus on climate finance within mainstream finance journals, leaving a notable gap.Ecological Economics (29 articles, 1090 citations) and Energy Economics (19 articles, 605 citations) have stepped in to address this deficiency.In conclusion, we find that climate finance is a multidisciplinary field, prominently featured in journals specializing in energy policy, environmental science, climate change, economics, and finance.It also finds representation in interdisciplinary journals like Journal of Cleaner Production and Environmental Science and Pollution Research.One possible explanation for the limited publication in top-tier journals is that finance, as a discipline, often tends to neglect practical issues with foresight and interdisciplinary relevance.It tends to focus on deducing and validating theoretical models to provide a basis for investment or economic policy formulation.Climate finance, being an emerging field, presents numerous unresolved issues, leading to a research gap.Furthermore, looking at the region of journal affiliations, the top 20 most influential journals publishing climate finance articles predominantly come from Western and developed countries, with a significant presence from the United Kingdom and the USA.This reinforces the conclusion from the previous section that Western nations have a denser network of collaboration in climate finance.

High-cited literature
The citations of an article can reflect the contribution and influence of the article on the basis of existing theories.Generally speaking, articles with high citations are more influential than articles with low or no citations (Culnan 1986).Table 3 shows the 10 most cited articles, among which the most cited is the study of Malhi et al. (2008) on the threat of climate change and deforestation faced by the Amazon rainforest and the resulting thought on climate change.At the same time, the article also proposes to pay for the reduction of emissions caused by deforestation through the international carbon market or voluntary funds, so as to provide the necessary financial support for the promotion of rainforest and climate restoration.The other nine articles mainly discuss that (1) it can bring great benefits to finance for the development and utilization of renewable and clean energy (Wüstenhagen and Menichetti 2012;Paramati et al. 2017), (2) profit from green bonds and municipal bonds can be used to support climate-friendly projects as a source of climate finance (Karpf and Mandel 2018;Gianfrate and Peri 2019;Flammer 2021), (3) it is significant to explore optimal emission reduction methods consistent with the goals of the Paris Agreement (Robiou du Pont et al. 2017), and (4) there are some emerging areas such as blue carbon projects and low-carbon economy, and central banks in various countries incorporate green financing goals into practical policies (Wylie et al. 2016;Owen et al. 2018;Dikau and Volz 2021).The content of the above highly cited papers is mostly macro-policy theory, while there are few applied and empirical articles.Scholars need to conduct more in-depth research in this direction in the future.

Science mapping
This part visually presents the keywords of the selected documents and their correlations, keyword with citation bursts, and topic clustering analysis results, and conduct an in-depth analysis of their hidden content and trends.Central banks, climate-related risks, green finance, sustainability analysis.When a keyword is used by two or more articles, the number of uses constitutes the frequency of the keyword, and this keyword forms a node.And when two or more keywords are used in the same paper, they represent the correlation between the concept and the research object, so the corresponding connection will be founded between two nodes.In addition, we can also see the growing trends and shifts in research topics within knowledge domains by observing the occurrence of keywords by date (Zhang et al. 2012).
Figure 6 presents the co-occurrence network map of keywords in the field of climate finance generated by CiteSpace with a total of 181 nodes and 211 connections.After obtaining the required graph, we also need to set the frequency threshold of keywords.Unfortunately, the academic community has not given a definite calculation standard for the threshold.Therefore, this paper determines the threshold as 13 times through repeated calculations and experiments, and obtains 83 keywords (Yang et al. 2023).If the threshold is higher than 13 times, a lot of key information will be lost, and if it is lower than 13 times, there will be too many keywords, and accurate co-occurrence results cannot be obtained.This kind of keyword co-occurrence analysis can get more research hotspots in the field of climate finance.
The nodes in Fig. 6 represent keywords, and the connection lines represent the connections between keywords.The size of nodes is proportional to the number of times keywords appear, and the width of connection lines represents the correlation strength.The centrality is an important indicator to measure the strength and influence of keywords in this field.The greater the centrality is, the more articles there are in this topic and the greater the influence is.In addition, if a keyword has larger nodes and has more connection points with other keywords, it is likely to become the focus of research topics and attract widespread attention in this field.It can be seen from Fig. 6 that climate change, policy, climate finance, and renewable energy are located at the center of the map, so climate change is still the hottest topic in the current climate research field.Renewable energy will greatly reduce carbon emissions and help mitigate climate change because it has great contributions to replace heavily polluting coal, natural gas, and oil to generate electricity (Lewis 2010).Therefore, most scholars will turn their attention to investment in renewable energy to mitigate and adapt to climate change.Policy is the decision made by various countries to deal with climate threats after the Paris Agreement.Researchers will make theoretical contributions to the content of climate financing based on the climate policies and relevant laws as well as regulations of various countries.CO 2 and sustainable development, have become new breakthrough points and future development goals that all member countries are actively exploring in climate finance projects.As mentioned in the literature review, Asian countries are currently establishing carbon taxes and carbon trading markets, giving rise to numerous green investment products aimed at mitigating and adapting to climate change while achieving sustainability.Although other keywords are on the edge of the co-occurrence map, they still receive much attention and may be a hot topic in the future.Therefore, in the next section of this paper, through the analysis of knowledge evolution, we will further observe the research frontiers and research hotspot changes of climate finance.Finally, the network density is 0.013 (> 0.01), indicating that the links between nodes are relatively close, indicating that cross-research on different topics is definitely significant.

Evolution of research hotspots
The development of scientific research can be obtained from the keywords of published articles and changes in literature hotspots, so as to find the research content and influence intensity that have jumped over time.Keyword bursts can indicate hot topics that the scientific community has paid attention to or is currently paying attention to and their duration and intensity (Kim and Chen 2015).This paper uses the CiteSpace developed by Chen (2006) to conduct a visual analysis of the literature, so as to identify the emerging trends and continuous time points in the field of climate finance.According to the existing functions of CiteSpace, there are two ways to sort keywords with citation bursts: one is for the start time of burst and the other is for the strength of burst.In order to study the evolution of hotspots in climate finance, we choose to sort out by the former.Figure 7 shows the results of top 20 keywords with the strongest citation bursts.The relevant keywords started in 2001 and have lasted for a maximum of 15 years, and sustainable finance and financial development became hot spots in the last 2 years.Through further summarization, it is found that climate finance has the following dynamic evolution trends.
First of all, we can see from Fig. 7 that the citation burst of clean development mechanism and Kyoto protocol both started in 2001, and clean development mechanism lasted the longest (from 2001 to 2015).This indicates that in climate finance literature, researchers consider the relationship between policy formulation and the progress of financing projects to assess whether countries will fulfill their commitments after signing relevant agreements, which shows that it occupies an important position in the field of climate finance (Phillips et al. 2013;Hultman et al. 2020).This is because, since the Kyoto Protocol took effect in 2005, the Clean Development Mechanism (CDM) project has also attracted much attention.The core content of CDM is that developed countries provide capital and technology, and developing countries implement projects with greenhouse gas emission reduction effects.The Fig. 7 Top 20 keywords with the strongest citation bursts greenhouse gas emission reductions obtained by the projects can be included in the fulfillment of commitments in the Kyoto Protocol by developed countries.Therefore, this project can not only enable enterprises to adopt advanced technologies to reduce carbon emissions, but also obtain certain economic benefits.At the same time, it can also mitigate climate change, which plays a significant role in the field of climate finance (Bakker and Huizenga 2010).In addition, the burst intensity of climate change is the highest, which shows that most of the literature on climate finance revolves around the topic of climate change, and the connection is also extremely close (Bouwer and Aerts 2006;Malhi et al. 2007;Haites 2011;Timilsina 2021;Calvet et al. 2022).Although the citation burst of "Policy" has a relatively short duration, government policies still play an important role in promoting the allocation of public and private investment to climate mitigation and adaptation actions (Zhang and Maruyama 2001).Finally, we can clearly see from the figure that sustainable finance and financial development are frontier topics in the field of climate finance.This is because climate finance is generally understood as the scope of sustainable finance, and mitigation and adaptation to climate change and reduction of carbon dioxide emissions are also required to achieve the 17 Sustainable Development Goals (SDGs) stipulated in the 2030 Agenda for Sustainable Development (Shishlov and Censkowsky 2022).The risks brought about by climate change will also cause the loss of real assets and investment profit, and it is difficult to predict, leading to a drop in related stock prices, a drop in the price of bulk commodities, an increase in the default rate of enterprises, and an increase in the loss of bank credit business as well as an increase in insurance claims, which has greatly affected the stable development of the financial system (Dietz et al. 2016;Hong et al. 2020).Therefore, financial development has recently become one of the much popular research directions in climate finance.
In summary, similar to other areas, the research focus in this field tends to evolve with the development of major financing projects in various countries and influential international trends.Currently, the research hotspots driving the advancement of climate finance theory revolve around sustainable development, financial policies, and tools.These two broad directions encompass numerous subcategories.Therefore, in the next section, we will further segment the content above to assist scholars interested in this field in gaining a better understanding of the relevant topic.

Clustering analysis and explanation
CiteSpace has a keyword clustering function, which can extract noun phrases from the title, keywords, and abstract of a document according to the logarithmic likelihood ratio (LLR) method to get their properties and categories, so as to combine similar content to get multiple clustering results.In this analysis, it is the structure of the clusters rather than the content that matters (Chen 2006;Debrah et al. 2022).After filtering out categories with less relationship strength and less content, we get 8 clustering results, among which each one represents a basic research topic and field, which can help us better identify and summarize research hotspots as well as feasible research directions in the future.Visual results are shown in Fig. 8.
It can be seen from Fig. 8 that the clustering results are divided into eight modules, namely, climate finance, climate change, climate change adaptation, climate policy, natural disasters, financial development, green bonds, and Kyoto protocol.The order of cluster ID is from 0 to 7, and the smaller the number is, the more keywords are contained in this category, and the more diversified information can be Fig. 8 Clustering structure for climate finance research extracted from it.In addition, we can see from the top left corner of Fig. 8 that CiteSpace also gives two basic indicators to represent the structural properties of clusters, namely, the cluster modularity value -Q value, and the mean silhouette value -S value.The value range of Q is between [0, 1), which reflects the connection between different clusters.The Q value in Fig. 8 is 0.392 (> 0.3), indicating that the divided cluster results are reasonable, and the node connections within the clusters are relatively close.Similarly, the node connections between different clusters are also very dense.The S value reveals which nodes fit into this cluster, and which nodes lie outside the cluster.The larger the S value is, the more similar the contents of the nodes are in the category and the closer the connection is.The mean silhouette value in Fig. 8 is 0.7373 (> 0.5), indicating that they have similar content, the nodes are highly homogeneous, and the clustering results are convincing (Chen et al. 2010).After analyzing the basic indicators and structure, we explain the specific content in the figure.The clustering framework is shown in Table 4.
Table 4 summarizes the keywords contained in each cluster and the focus of the cluster field.Among them, the frequency of the selected keywords is greater than 10 to ensure the conciseness of the content of the article; the focus of the research field is to summarize the clustering topics, so as to more clearly obtain the research direction of the field of interest.Cluster #0 mainly includes adaptive climate finance activities, in other words, adopting political means and inter-country climate fund assistance actions to provide certain financial support for projects such as new energy development and carbon emission reduction (Bouwer and Aerts 2006;Paramati et al. 2017;Reguero et al. 2020;Timilsina 2021), while Cluster #1 presents the risks and adverse effects of climate change (Jongman et al. 2014;Koks et al. 2015;Abid et al. 2016;Hepburn et al. 2020); the two can be combined to conduct a systematic analysis of the reasons for climate finance as well as how and to whom it is financed.The Cluster #2 category focuses on the opportunities and challenges of implementing climate improvement actions, including reducing pollutant emissions by promoting innovation in clean technologies, improving production efficiency and ecosystem resilience, and the challenges that the damaged ecosystem is difficult to repair and the cost is too high, which raises new problems for future climate improvement (Wüstenhagen 2012;Alam et al. 2017;Jordaan et al. 2017;Geddes et al. 2018).Cluster #3 and Cluster #7 focus on climate adaptation actions implemented by international Based on the cluster analysis presented above, it is evident that literature related to climate finance encompasses eight major categories.These eight categories can be further grouped into three dimensions: policy support and macrotools for climate finance, financial products and microregulation for climate finance, and the risks and challenges posed by climate change.These three dimensions closely align with the literature classification in the literature review, reaffirming the credibility of our research.Moreover, when analyzing from the first dimension, we can compare the policy implementation backgrounds and measures of different countries, analyze the achievements, and comprehensively assess the strengths and weaknesses of various measures, which holds significant importance for the development of the literature.When approaching the analysis from the second dimension, we can consider incorporating climate finance projects into the accounting systems of carbon emissions, transitioning between old and new energy sources, insurance projects, stocks, and fixed-income securities, among other products.This can help establish specific models and standards to expand the boundaries of the blue ocean market.In the analysis from the third dimension, we can contemplate macro-policies and business operation models regarding the risks stemming from climate disasters highly prevalent in different regions.This involves expanding the existing risk and loss distribution models to provide robust support for adapting to climate change and investment returns.

Avenues for future directions
From the above analysis, it can be seen that the empirical development content of climate finance is relatively insufficient, and most of the research contents overlap; research on the topic of climate financing is mainly concentrated in developed countries, and the output of articles in developing countries is very small.Moreover, there is less cooperation with researchers from other countries; in addition, the topics that scholars focus on are mainly related to climate change, and most of the financing support related to climate policy stays in public sector expenditures and international policy cooperation, while there is little real integration with financial mechanisms and products (Dietz et al. 2016;Carè and Weber 2023), which is reflected in the fact that few climate finance-related content is published in finance journals.Therefore, this paper proposes the following research directions for reference.
Most of the research on climate finance focus on theoretical analysis, but pay less attention to empirical analysis.This is mainly because climate finance is a relatively immature financial field (Christophers et al. 2020), its practical results have not been well organized and fed back, and there is no unified standard for data acquisition and calculation methods.Therefore, it is difficult to conduct an empirical analysis of climate finance.Currently, the climate funding allocation system set by the Global Environment Facility (GEF) is widely accepted.The system sets the amount and upper and lower limits of funding allocation, which serve as the basis for countries to obtain climate financing quotas.However, the source of data and the implementation amount vary with the policies of different countries, resulting in less empirical analysis.Therefore, with the continuous improvement of climate policy and mechanism design of multilateral development institutions, the implementation results of climate finance will be more powerful.
Currently, there is insufficient cross-regional research in the field of climate finance.The risk brought by climate change is a common challenge faced by the whole world.Climate finance actions aim to promote the construction of ecological environment, reduce greenhouse gas emissions, and achieve sustainable goals through improving technology.Therefore, climate finance is an important path to achieve sustainable economic-social-environmental development, and countries or regions with different levels of cultural and economic development should pay more attention to it.However, as shown in Figs. 4 and 5, most of the scholars or institutions in this field come from developed countries and regions, and they have more cooperation and close contact with each other.However, developing countries draw less attention to climate finance, and the amount of literature published is relatively insufficient.Therefore, cross-cultural research on climate finance has great development prospects.
Climate finance covers the whole process of capital accumulation, flow, and distribution in response to global climate change, but financial journals rarely publish climate-related content, and most of the financial literature related to climate finance stays at the theoretical level, while methods and mechanisms catch less attention.Therefore, future climate finance research directions can be carried out from three aspects: the first one is about using financial methods to predict and reduce climate risks (Andersson et al. 2016;Hong et al. 2020;Barnett et al. 2020;Bressan and Romagnoli 2021;Giglio et al. 2021;Cepni et al. 2022;Alekseev et al. 2022).For example, how can green or environmental assets be used to hedge against climate risk?How to calculate the return of climate derivative financial products and whether vigorous supervision is needed?The second is about the impact of climate change on financial stability.As we all know, natural disasters and social changes caused by climate change will directly lead to different losses to the real economy, and the deterioration of the real economy will also cause cash flow fluctuations in the financial sector and decrease in the efficiency of capital financing, resulting in an increase of credit risks, market risks, and operational risk, negatively worsening financial stability (Dafermos et al. 2018;Battiston et al. 2021;Giglio et al. 2021;Liu et al. 2021).For example, how does climate change affect financial stability through asset values?How do climate risks affect the stability of the financial system by affecting investment portfolios and interest rates in the banking sector?The third is about the volatility caused by climate change on housing prices and credit markets (Giglio et al. 2021).For example, has the increase in carbon emissions significantly affected local house prices and caused volatility in the mortgage market?How to use interest rate and credit derivatives to hedge credit market risks caused by climate change?
Apart from the issues identified during the research process, this study conspicuously observes that there is limited focus on the regulatory aspects of climate finance in the research conducted on this topic.However, the refinement and effective development of any emerging product or system necessitate regulatory reforms and the involvement of local governments.Climate finance is no exception to this, as it significantly supports the transformation of the financial system and the growth of climate finance (Bhatnagar and Sharma 2022; Debrah et al. 2022).Therefore, appropriate policies are required to provide environmental and financial benefits to green investors, ensuring their confidence in proceeding with the entire project under organized protection, implementing a hierarchical, categorized, and segmented approach at each stage.This is because climate finance can only thrive within a clear and sound legal framework (Sachs et al. 2019).In simple terms, is there strict implementation of public regulation in climate finance projects?Have different regions established explicit policies or enacted relevant laws for this purpose?Furthermore, in the international context, the implementation of climate finance actions by member countries needs to be combined with micro-level actors such as enterprises or multinational corporations to leverage the multiplier effect of these policies.Enterprises aim to maximize their interests through investment actions, so the question of how to maximize benefits within the policy environment is currently a subject of consideration.Green innovation by enterprises is one of the preferable approaches.Enterprise green innovation encompasses innovations in production processes, new energy development, management mode innovation, and product greening.These innovations place high demands on enterprises, making the transition to lowcarbon and green initiatives a pressing issue that requires collective efforts on a global scale.

Conclusions and limitations
Since the adoption of the Paris Agreement in December 2015, the topic of climate finance has received extensive attention from scholars from all walks of life and has become an important action to achieve the sustainable development goals (Kouwenberg and Zheng 2023).With the in-depth development of this theory, different research methods and perspectives have been extended to this topic.It is difficult for readers to understand the development status and current hot topics of climate finance in numerous literatures, and to find a suitable research direction.This paper adopts the bibliometric analysis and literature review method to extract samples of existing literature on climate finance for visual analysis and interpretation to meet this challenge.
This paper extracts 2311 climate finance-related documents from the core database of WoS, completes the data screening and preparation for bibliometric analysis, and lays the foundation for the subsequent comprehensive analysis.In the chapter of comprehensive analysis, this article is divided into two parts.The article first examines the number of papers published each year in this field, different disciplines in which climate finance is located, the distribution and cooperation of researchers in countries and regions, and most cited papers to perform descriptive analysis, so that we can understand the current status and general content of climate finance.The second part is science mapping by Cit-eSpace.First of all, this paper makes a visual presentation of the research hot topics in this field through the co-occurrence network of high-frequency keywords, so that the current hot spots and knowledge structure can be seen more intuitively.Then, this article shows the results of the strong citation bursts and selected top 20 keywords with the strongest citation bursts to further understand the dynamic development process of climate finance and emerging research topics.At the end of this part, we conduct descriptive analysis on the clustering results, sort out the focus of each category and the keywords contained in it, so as to discover the main topics of climate finance.Finally, based on the above analysis, this paper gives the future research direction of climate finance from three aspects.
In general, from the analysis of the above contents, this paper draws three important conclusions.
(1) Research field of climate finance mainly focuses on the environment and energy, but this topic is not common in economics and finance journals.Although the current source of finance for climate change is gradually shifting from the public sector to the private sector, it is still not as interesting to finance researchers as topics such as asset pricing, corporate finance, and investment as well as monetary policy (Flammer 2021; Carè and Weber 2023).One potential explanation is that finance, as an academic discipline, often tends to overlook forward-looking and interdisciplinary realworld issues, emphasizing the derivation and validation of explanatory theoretical models (Diaz-Rainey et al. 2017).This approach might lead to substantial returns during the application process.However, emerging fields typically require more time to develop comprehensive systems and realize investment returns in practice, involving higher initial costs.This slower progress in climate finance research can be attributed to these factors.Additionally, most senior editors of mainstream economics and finance journals are based in the USA, where views on climate policies tend to be more polarized (Kouwenberg and Zheng 2023).In contrast, European countries hold relatively neutral policies and have established the European Union Emission Trading System, along with numerous supportive laws for climate finance activities.Therefore, there exist several research gaps in the field of climate finance, warranting deeper investigation by scholars.(2) There is insufficient cross-regional research on climate finance.Most of the research scholars on this topic come from developed countries such as the USA and the United Kingdom, and there is more cooperation among scholars, and the number of publications is gradually increasing (Fig. 5 and Table 1).The collaboration between American scholars and institutions with researchers from other countries is most prominent in this field, and substantial connections exist between the European Union and European countries.This may be attributed to the European Union's pioneering role in climate change policies since the early 1990s.
Our research findings demonstrate that the authors of the most highly cited articles in climate finance literature primarily originate from Western and developed nations.However, institutions or researchers in developing countries pay less attention on this topic.This is possibly because developing countries lack the necessary funds to enhance and govern their climate environment.In situations where multiple aspects, such as population, politics, economy, and legal systems, are underdeveloped, it becomes challenging to allocate the financial resources required to address climate risks.Consequently, various elements, including technological innovations, regulatory frameworks, and policy measures related to climate finance, may struggle to establish effective coordination among themselves.This, in turn, hinders the progress of climate finance projects and the expansion of collaborative networks.
In contrast, China, as a major nation committed to climate governance responsibilities, collaborates with other countries to advance the "Belt and Road" initiative.China has also established financial institutions such as the Silk Road Fund and the Asian Infrastructure Investment Bank (AIIB) to ensure the steady development of infrastructure projects in partner nations.As a major country that insists on taking responsibility for climate governance, China has made positive contributions to the realization of the goals of the Paris Agreement.In the future, China needs more space for cross-regional study.
(3) At present, climate change and policy implementation are hot topics in the field of climate finance, and many literatures mainly focus on the analysis of climate finance policies adopted by countries to achieve sustainable development goals and the status of innovative investment in new energy technologies and other macro-climate economics (Jordaan et al. 2017;Tolliver et al. 2020c;Timilsina 2021;Zhang 2022).Most of the research related to finance focuses on the positive impact of green bonds as a tool on the climate (especially carbon emissions) and environment (Tolliver et al. 2020b(Tolliver et al. , 2020c;;Fatica and Panzica 2021;Flammer 2021;Sartzetakis 2021).However, there are few studies on the specific mechanism analysis of financial risks caused by climate change and the pricing of financial products.In the "Avenues for future directions" section of this paper, specific research directions that explore the intersection of climate change and financial development are introduced, which can be further analyzed in the future.
Like other studies, this paper still has some limitations.First of all, based on the sorting and classification of climate finance literature, this paper uses descriptive analysis and systematic review methods to conduct visual research on the development status and the correlation between literature.However, our search was limited to the keyword climate finance, which could result in overlooking relevant literature related to "climate change, climate risk, sustainable development," and financial aspects such as "bond markets, stock returns, risk hedging," and other keywords.Additionally, some literature on carbon emissions, carbon finance, energy utilization, and ESG investments may have been inadvertently excluded from our search scope.Nonetheless, as we demonstrate in the subsequent processing steps, our selection of "all fields" during the search process means that all articles related to climate finance in the database will be retrieved, covering some of the keywords mentioned above.However, a large volume of retrieved articles may potentially impact the effectiveness of our analysis.It is worth noting that sustainable finance and green finance encompass a broader range of research content, but our search was specifically focused on climate finance within the context of climate change, possibly resulting in the omission of other pertinent literature.Secondly, because CiteSpace is limited in the selection of databases, we only selected WoS for retrieval in order to obtain more comprehensive analysis results.The results obtained from our search may differ from those of more popular databases like Scopus and Google Scholar.These databases have variations in terms of literature coverage, impact factors, and other aspects.Scopus' coverage of academic journals has been expanding, particularly in the fields of social sciences and arts and humanities.This expansion could lead to differences in the results of our bibliometric analysis and potentially result in inconsistencies, affecting the accuracy of our findings.However, as of now, Scopus has relatively limited coverage of articles published before 1996, which poses certain limitations.This suggests that, for most renowned scholars in various scientific fields, Scopus' lifetime citation counts may be lower than those from Web of Science (WoS).WoS remains one of the oldest and most widely recognized databases, covering a broad range of fields.It is known for its authority and the quality of journals it includes, making it suitable for interdisciplinary research, such as the one presented in this paper.In the future, exploring different databases for analysis might be worthwhile.Moreover, the database on climate finance has been updating all the time; we only focus on the literature content before July 17, 2023, and did not include the updated literature into the scope of our search.Therefore, to address this issue, we added an analysis of highly cited articles, which is crucial for enhancing the robustness of our research.Last but not least, all the literature was obtained from WoS' SCI and SSCI databases and filtered according to the criteria mentioned earlier.However, it is important to note that the manual selection process involved subjective judgments, as we filtered literature based on relevance to our research focus while excluding entirely unrelated content.This subjectivity could introduce bias when attempting to replicate our analysis.
In general, the goal of this paper is to visualize and summarize the growing trends and emerging fields of climate finance on the basis of existing literature, and provide a complete outline of climate finance through literature review methods.Although the amount of literature on climate finance has grown exponentially in recent years, most of the research just focus on the interpretation of macro-economic policies and future development in general.There are few in-depth studies on how to promote private financial flows in developing countries that lack institutional investors and carbon market transaction mechanism.More exploration is needed in the future for undeveloped theories and methods.

Fig. 2
Fig.2The number of publications over time,

Fig. 3
Fig. 3 Different research areas in climate finance

Fig. 6
Fig. 6 Keyword co-occurrence network of climate finance (knowledge map)

Table 1
Top 25 collaborating countries in climate finance research

Table 4
The framework of clustering results in climate finance