What do scientists think about different climate policy? And why should we care?

Understanding scientists’ opinions about climate policy is important for at least two reasons.

Firstly, scientists advise policymakers through expert commissions such as the Intergovernmental Panel on Climate Change. Secondly, scientists from different fields partly shape public opinion about climate policy. In fact, a recent study shows that citizens in the United States and Germany expect scientists to be outspoken on climate policies and communicate their findings to policymakers and journalists.

To advance the debate on climate policy, Stefan Drews and Jeroen van der Bergh and I conducted a global survey of almost 800 scientists who recently published on climate policy in peer-reviewed journals. The aim was to elicit their views on climate policy criteria and instruments.

Researchers in our sample work in more than 70 developed and developing countries and a broad set of disciplines, including formal, social and natural sciences. We asked a large set of questions related to six types of climate policy instruments: direct regulation, e.g. quotas, standards, carbon taxation, cap-and-trade, e.g. the European Union’s emissions trading system, adoption subsidies; innovation support – such as research and development subsidies and information provision (ranging from education to eco-labels).

This survey produced a lot of results that have been recently published in Ecological Economics and Environmental Research Letters. Here, I want to highlight a few that I find most remarkable.

Consensus on some instruments, controversy on others

On average, all six instruments were rated by researchers as important (“value 3” on our Likert scale); however, the degree of consensus among disciplines on how important these instruments are in a policy mix varied widely, as per the figure below. In particular, direct regulation enjoys the greatest consensus, with only environmental and other economists being relatively more sceptical. These researchers predictably rated cap-and-trade and carbon tax high but researchers from other fields, notably political science and ecological economics, mostly disagreed.

To better elicit similarities and differences among disciplines on how important they consider the instruments, we clustered the 15 fields in our sample into five distinct groups. The result is demonstrated in the figure below, with the distance on the horizontal axis indicating the difference between fields in their views. As one can see, ecological economists and mathematicians or computer scientists are the most dissimilar groups from other discipline clusters. The remaining three groups are sociologists and psychologists; environmental and other economists plus law researchers; and a heterogeneous group consisting of various social and natural scientists.

Since carbon pricing instruments – carbon tax and cap-and-trade – have received contradictory appraisals on their capability to reduce carbon emissions in the recent literature, we examined researchers’ agreement with 10 statements about their functioning. The responses are displayed below. Among statements with the largest agreement are that consumers are more influenced by prices than environmental concerns – 80%, while there is more of a mixed response to whether carbon pricing can achieve zero carbon emissions.

We then statistically linked the importance of instruments in a climate policy mix with answers to these 10 statements. We found that two statements are positively and significantly associated with giving importance to both types of carbon pricing:

According to our results, one way to increase support for carbon pricing is to communicate the policy instrument’s advantages effectively.

Finally, we asked our expert scientists to indicate what they felt were the main strengths, weaknesses and knowledge gaps of carbon pricing compared with other policy instruments. Among the main strengths, the interviewed researchers named a clear price signal to both the producer and consumer, the financial sources the instrument provides to subsidize transformations towards zero-carbon economies and its flexibility in implementation. The perceived strengths of carbon pricing summarized above align with what economists have advocated for decades.

What appears less trivial is the perceived weaknesses of the instrument. In particular, researchers find it can increase inequalities by placing an unfair burden on the lower-income population, resulting in low political and public feasibility. Furthermore, the instrument appears to researchers as being vulnerable to manipulation and fraud.

As for perceived knowledge gaps, researchers cited policy synergy with other instruments, global implementation of carbon pricing and better empirically grounded models.

What’s striking is that some of the assessed perceptions and opinions are not in line with insights from the theoretical and empirical literature on carbon pricing. In a nutshell, there must be more communication about climate policy, particularly carbon pricing, between academic experts from distinct disciplines to ascertain the better climate policy instruments at play.