Survey confirms scientific consensus on human-caused global warming

11-08-2014 | News item

A survey among climate scientists in 2012 shows that there is widespread agreement regarding a dominant influence of anthropogenic greenhouse gases on recent global warming. This agreement is stronger among respondents with more peer-reviewed publications. Respondents who characterized the human influence on climate as insignificant, reported having the most frequent media coverage regarding their views on climate change.

The survey was conducted by PBL Netherlands Environmental Assessment Agency, in collaboration with researchers from the Netherlands and Australia. More than 1800 international scientists studying various aspects of climate change, including physical climate, climate impacts and mitigation, responded to the questionnaire.

Level of consensus regarding attribution

The researchers found that, as the level of expertise in climate science grew, so too did the level of agreement on the contribution of greenhouse gases to global warming. 90% of respondents with more than 10 climate-related peer-reviewed publications (about half of all respondents), agreed that anthropogenic greenhouse gases (GHG) are the dominant cause of recent global warming. This is consistent with other research. Analyses of the literature generally find a stronger consensus than opinion surveys such as ours, because of a stronger consensus among highly published – and arguably the most expert – climate scientists.

The more publications the respondents report to have written, the more important they consider the contribution of greenhouse gases to global warming. Responses are shown as a percentage of the number of respondents (n) in each subgroup, segregated according to self-declared number of peer-reviewed publications.
The more publications the respondents report to have written, the more important they consider the contribution of greenhouse gases to global warming. Responses are shown as a percentage of the number of respondents (n) in each subgroup, segregated according to self-declared number of peer-reviewed publications.

Media exposure

Respondents were also asked about the frequency of being featured in the media regarding their views on climate change. Respondents who thought climate sensitivity was low (less than 1.75 degrees C per doubling of CO2) reported the most frequent media coverage. Likewise, those who thought greenhouse gases  had made an insignificant contribution to observed warming reported the most frequent media coverage. This shows that contrarian opinions are amplified in the media in relation to their prevalence in the scientific community, which probably contributes to the divergence between public and scientific opinion regarding climate change.

Percentage of respondents who reported “very frequent” media coverage is largest for those who estimate climate sensitivity to be low (<1.75 degrees for a doubling of CO2 concentration). n is the number of respondents for each range of climate sensitivity estimates.
Percentage of respondents who reported “very frequent” media coverage is largest for those who estimate climate sensitivity to be low (<1.75 degrees for a doubling of CO2 concentration). n is the number of respondents for each range of climate sensitivity estimates.