We are living in the Anthropocene, the geological era in which humanity has altered the planet. Geochemical manifestations include air pollution and climate change due to exponential use of fossil fuels, and massive distribution of manufactured materials, such as plastic, concrete, pesticides, fertilizers and aluminum [1]. All of these changes harm people’s health and quality of life, and are interconnected with the daily practice of intensive care medicine.

A central ethical issue is how we should weigh the short-term benefits and the rights of doctors and hospitals to have a relatively large carbon footprint (from use of fossil fuel energy, plastics, etc.), against the longer term harms of such a footprint (increased climate change, with its devastating consequences for planetary and human health), the longer term benefits of reducing this footprint (e.g., having healthier patients), the rights of countless patients to have healthy lives, and justice concerns (since climate change disproportionately harms poorer individuals and countries). We argue that the latter considerations outweigh the former, and that intensivists should thus work to reduce this footprint.

It is estimated that the health care sector contributes to climate change with ~ 2Gt (Giga tons) CO2-equivalent (CO2-e) per year—5.2% of the world’s CO2-e emissions [2]. The level of the CO2-e emissions depends mainly on the energy source (coal, gas, wind, solar) and to a lesser extent on the implementation of energy saving strategies [3]. Intensive care units (ICU) are amongst the highest energy and resource intensive services [4]. Yet the energy needs of large hospitals could potentially be fulfilled by 100% renewable sources (see supplementary material). Indirect healthcare-related greenhouse gas emissions come from traffic and transportation (patients and employee commuting, business traffic), purchased medical and instrument equipment, downstream waste management and construction.

Fossil fuel energy use not only drives climate change, but also causes air pollution. Every year, 4.2 million deaths result from ambient air pollution, which exceeds the 6.5 million deaths due to coronavirus disease 2019 (COVID-19) registered during the past 3 years (see supplementary material). Exposure to fossil fuel-related ambient air pollutants cause oxidative stress, endothelial dysfunction and systemic inflammation, exacerbating cardiovascular and respiratory diseases [5], and risks of stroke, myocardial infarct, lung cancer, and acute respiratory distress syndrome (ARDS) [6]. Ambient air pollution also increases COVID-19 incidence, morbidity and mortality [7].

Heat stress caused by fossil fuels impedes health, too. Today, anthropogenic climate change account for 37% (range 20.5–76.3%) of warm-season heat-related deaths [8]. During heat waves, intensivists will confront rising numbers of patients suffering heat strokes, cardiovascular diseases, electrolyte imbalances and acute renal failure. The mortality rate among heat stroke patients is 21–63% [9]. Without consequent climate change mitigation, by 2100 global warming will exceed 3–4 °C, which is rated as a catastrophic warming scenario to humankind [10]. Humans are physiologically limited in their ability to adapt to a warming climate that involves both increasing temperature and humidity. Humans maintain a body core temperature at ~ 37 °C. Hence, in higher ambient temperature, we cannot emit heat to the environment, and sweating in high humidity becomes ineffective. The wet-bulb temperature (Tw) is the temperature measured by covering a standard thermometer bulb with a wetted cloth and fully ventilating it. For humans, Tw of 35 °C is the critical limit, at which point we cannot lose heat, no matter how wet or well ventilated we are. Today, deadly heat conditions occur only in tropical countries for about 11 days per year, but by 2100, ~ 74% of the global population will be exposed to more than 20 days per year of this deadly climate condition, if business-as-usual fossil fuel emissions continue (see supplementary material).

ICUs discard huge amounts of single-use plastics daily [4]. Human-made plastic mass has exceeded 8Gt worldwide, which is double the living biomass of animals on earth [11]. Global plastic production has increased from 2Mt (million tons) in 1950 to 380Mt in 2015, with 99% produced from fossil fuels. Plastic causes long-lasting problems, since it accumulates on beaches, in rivers and oceans, and in the air as macro-, micro- or nanoplastics, which enter the human body via inhalation, ingestion and skin contact. Plastic production worldwide is increasing as is human exposure, and the health impacts of plastic throughout its lifecycle are overwhelming [12]. Plastics are associated with breast cancer, ovarian, prostate, cervical and lung cancer, and trigger cardiovascular diseases, endometriosis, obesity, diabetes, attention deficit hyperactivity disorder and Alzheimer’s disease [12]. The COVID-19 pandemic has highlighted how much the health care sector depends on plastic disposable, single-use medical tools and packaging [13]. Until August 2021, the medical system generated more than 8Mt of pandemic-associated plastic waste, mostly related to personal protective equipment (73%) [13]. Hospital waste must be divided into infectious waste (~ 15% of which needs to be incinerated by 1000 °C), and general waste (~ 85%), from which parts can be recycled (~ 45%). However, most plastic waste should be avoided by reducing and reusing materials [14].

In 2019, 55.4 million all-cause deaths occurred worldwide, of which ~ 13.9 million were related to environmental pollution and global warming. The healthcare sector contributes to global warming, air and plastic pollution, and thus to these avoidable deaths every year (Fig. 1, upper panel).

Fig. 1
figure 1

a Health impacts from fossil fuel use in the health care sector. ADHD attention deficit hyperactivity disorder. b Planetary health aspects for intensivists

Intensivists will be facing rising patient numbers related to heat stress, extreme weather events, environmental pollution and increasing numbers of infectious diseases (Fig. 1, lower panel). These changes will take place concurrently with aging societies, leading to more vulnerable patients. Climate change-induced water and food shortages due to increasing droughts, wildfires and flooding will further destabilize societies. These long-term harms to human health outweigh the short-term benefits of using non-renewable energy sources and non-reusable plastic supplies. Intensivists should switch to use renewable energies, reduce our energy needs and avoid single-use plastics, as far as possible [15].

The future is now—we should be part of the solution rather than part of the problem.