
English: 
John Cook, Dana Nuccitelli, Sarah A Green,
Mark Richardson, Barbel Winkler, Rob Painting,
Robert Way, Peter Jacobs and Andrew Skuce
2013 Quantifying the consensus on anthropogenic
global warming in the scientific literature
Environ. Res. Lett. 8 024024
http://iopscience.iop.org/1748-9326/8/2/024024/article
Hi. I'm John Cook, lead author of 'Quantifying
the consensus on anthropogenic global warming
in the scientific literature'. In our paper,
we measured the level of agreement that humans
are causing global warming in peer-reviewed
climate papers published between 1991 and
2011. In recent years, two studies have measured
the level of agreement of human-caused warming
in the scientific community.
Both papers found that among climate scientists
actively publishing climate research, 97%
agreed that humans are causing global warming.
But scientists have to back up their opinions
with evidence that survives the scrutiny of
experts in their field. In other words, peer-reviewed
research.
The first analysis of this type was by Naomi
Oreskes, who in 2004 analysed publications
in the Web of Science between 1993 and 2003
matching the search term 'global climate change'.

English: 
She found that out of 928 papers, none rejected
the consensus position that humans are causing
global warming. Our paper builds upon this
research.
We expanded the search to cover the 21 years
from 1991 to 2011. In addition to 'global
climate change' papers, we also included papers
matching the term 'global warming'. This expanded
the number of papers to over 12,000. We also
divided Oreskes' six categories into two sets:
the type of research and the level of endorsement
of human-caused global warming. Each abstract
was classified according to whether it explicitly
or implicitly endorsed or rejected human-caused
global warming, or whether it took no position
on the cause of warming. Out of the 12,000
papers, we identified just over 4,000 stating
a position on human-caused global warming.
Among these 4,000 papers, 97.1% endorsed the
consensus position that humans are causing

English: 
global warming. In the second phase of our
study, we asked the scientists who authored
the studies to rate their own papers. 1,200
scientists responded to our invitation, so
that just over 2,000 papers in total received
a self-rating. Among the papers that were
self-rated as stating a position on human-caused
warming, 97.2% endorsed the consensus. These
results are strikingly consistent with previous
surveys.
Between 1991 and 2011, the percentage of endorsements
among papers expressing a position on human-caused
global warming marginally increased over time.
In the abstract ratings, the consensus grew
at a rate of 0.1% per year. In the self-ratings,
it grew by 0.35% per year, in both cases reaching
about 98% consensus in 2011.
However, there is a significant gap between
public perception and the actual 97% consensus.

English: 
When a US representative sample was asked
how many scientists agree that humans are
causing global warming, the average answer
was around 50%. This misperception has real-world
consequences. When people correctly understand
that the scientists agree on human-caused
global warming, they're more likely to support
policy that mitigates climate change. This
consensus gap is directly linked to a lack
of public support for climate action. This
underscores the importance of clearly communicating
the consensus and closing the consensus gap.

English: 
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