Appendix
In the pages that follow, we present descriptive statistics of the data used in our analysis.
Participation in congressional hearings on climate change
We begin by analyzing the types of actors who made statements during the climate change hearings in our sample. In contrast to what one might expect regarding hearings on the issue of climate change, most of the statements were not prepared by scientists (about 8% in the 109th and 11% in the 110th Congress). The majority of the speakers in both sessions of the Congress came from different branches of the US government. Although the hearings in both sessions of the Congress were dominated by government actors, there are a number of differences between these two sessions that are worth noting. First, there are striking differences between the government actors participating in the climate change hearings in these different sessions of the Congress. Even though the rules of the US Congress stipulate that the minority party is given the opportunity to call witnesses at Congressional hearings,Footnote 13 participation in these hearings was very different in the two sessions of Congress. In the 109th Session of Congress, which had a Republican majority, almost a quarter of the statements (24%) were provided by Republican members of the Congress. During the 110th Session of the Congress, which had a Democratic majority, in contrast, only 5 % of people making statements were Republican members of the Congress. Although the level of Republican participation changed significantly during these two Congressional Sessions, Democratic participation remained relatively stable (24% and 20% respectively). At the same time, participation by the Bush Administration increased significantly between the 109th and 110th Sessions (10% and 22% respectively). Table A1 presents these results. There are also noteworthy differences among non-governmental actors. Participation by representatives of businesses and business or trade associations decreased between the 109th and 110th sessions of Congress (20% to 14%). However, environmental group participation went up between these two sessions of the US Congress (about 9% to almost 15% respectively).
Table A1 Organizational affiliations of witnesses at congressional hearings on climate change (2005—2008)
How are actor types related to different concepts in the 109th and in the 110th Congress?
Although these results show that there are interesting patterns of participation during these two sessions of the US Congress, they do not tell us anything about the content of the Hearings. Accordingly, we now look at the distribution of issue stances among actor types in the 109th and 110th Congress for each of the three categories. Table A2 presents the number of statements per actor group and by time period and stance for each of the categories included in this analysis.
Table A2 Number of statements per actor group and by time period and stance
Legislation should regulate carbon dioxide emissions
There is a high level of polarization around the question of whether legislation should regulate carbon dioxide in both sessions of the Congress. In the 109th Congress, 26 policy actors spoke in support of the category and 12 spoke against it. There was only one policy actor who presented a moderate position, speaking on both sides of this issue—both for and against emissions legislation that includes the regulation of carbon dioxide. In this session of Congress, the policy actors against this category were all Republicans, representatives of the Bush Administration, and representatives of businesses or trade associations. Those in support of this category, in contrast, were mostly Democrats in the Congress and environmental groups.
In the 110th Congress, there were far fewer actors speaking against the category and many more actors supporting it: only eight spoke against this category and 40 policy actors spoke in support of it. Actors against this issue continued to come from the same social groups. There was one environmental group—the Natural Resources Stewardship Project, which is a Canadian non-profit organization that is known to include a number of leading climate change skeptics.Footnote 14
At the same time, there were also businesses and Republicans in Congress who supported this position. Although this issue continued to be polarized in the 110th Congress, there was less opposition and more support for legislation to regulate carbon dioxide by a broader range of actors.
Legislation that regulates carbon dioxide emissions will not hurt the economy
Statements during Congressional hearings on climate change frequently discussed the economic implications of regulating carbon dioxide. In the 109th Congress, there was a very high level of polarization around this issue. In fact, the debate was relatively balanced and there were almost an equal number of speakers for and against this category (22 versus 23 accordingly). Here again, those actors against the issue were predominantly Republicans in the Congress and businesses. Also like the first category, most of those actors who supported this statement were Democrats in the Congress and environmental groups. However, business and trade associations also supported this category.
In the 110th Congress, there was much less polarization: three different policy actors presented a moderate position, speaking on both sides of this category. Like the first category, support for the issue grew in this Congress and 38 actors spoke in support of the issue while 13 spoke against it in the later session. The increase in support also resulted in a broader diversity of actors supporting this category, including scientists.
Legislation should establish a market for carbon emissions through cap-and-trade
This subject was not a main topic of discussion during Congressional hearings in the 109th Congress. In this session, only 21 people spoke about it in their statements: 13 policy actors spoke in support of this category and eight spoke against it. Supporters were mainly from environmental groups. Like the previous two categories, those actors against the issue were mostly Republicans in the Congress and businesses.
In the 110th Congress, there was a lot more discussion about this issue. Thirty-seven actors spoke in support of it and 11 spoke against it. Supporters in this Congress included Democrats and Republicans in the Congress, along with environmental groups and business groups. Opposition was made up almost entirely of Republicans in the Congress. It is worth noting that there was one environmental group that spoke in opposition to the establishment of a cap-and-trade system in the United States: the American Council for an Energy- Efficient Economy.
Figure 6 shows a graphical representation of the data from Table A2. The number of positive statements is increased between the 109th and 110th Sessions of Congress in all three cases, while the number of negative statements is generally decreased, with the exception of the cap-and-trade issue. Most importantly, however, the diagrams demonstrate that this pattern holds, and is even more pronounced, for both Democrats and Republicans in the US Congress. The increase of negative cap-and-trade statements can be largely attributed to Republicans, but their marginal increase in positive cap-and-trade statements even exceeds their marginal increase in negative statements of this kind.
Correlation between issues
Table A3 reports correlations between issue stances based on the raw number of statements of a certain kind per actor. It is noteworthy that the correlation between different issues is fairly high, while the correlation between positive and negative pairs of issue stances is low in all cases, as expected. Interestingly, the cap-and-trade issue is correlated with the other issues to a lesser extent, which is also reflected by the network analysis.
Table A3 Correlations between issue stances
It is worth noting that the methods employed in this article do not require orthogonality of issues. The network analysis techniques presented in the article are rather a tool to analyze the dimensionality of the ideological space without being confined to two dimensions. The correlations are an interesting feature of the data, rather than an obstacle to the analysis.
Distribution of statements across time
Figure 7 shows the number of statements per month for all three issues. While most months are populated by a moderate number of statements, an extraordinarily high number of statements were made at the beginning of each of the two sessions of the US Congress that are included in this analysis.