Feb 18, 2014
Was the IPCC assessment too optimistic on sea-level rise?
The majority of respondents in Vision Prize’s latest poll, reckon it’s at least “about as likely as not” that sea-level rise this century will exceed 0.91 m, the highest value projected in the IPCC’s fifth assessment report. (Disclosure: environmentalresearchweb has entered a collaboration with Vision Prize).
In contrast, only 5% of those surveyed believe it’s likely or very likely that the rise will be less than the lowest level in the IPCC report, namely 0.25 m.
The IPCC’s Working Group 1 met back in September 2013 to approve the summary for policymakers of its “Climate Change: the Physical Science Basis” report. The full version was published at the end of January. The fifth assessment report increased projections for sea-level rise by around 60% compared with 2007’s fourth assessment.
The Vision Prize findings broadly agree with a survey carried out by scientists from the Potsdam Institute for Climate Impact Research, Germany, and Rutgers University, University of Rhode Island and Tufts University in the US. In this, 90 researchers who’d published on sea level in the last five years concluded that sea-level rise by 2100 is likely to be 0.7–1.2 m if greenhouse gas emissions are not mitigated. Two-thirds (65%) of the respondents reckoned that sea level would rise more than the upper end of the IPCC’s projected range by 2100. If greenhouse gas emissions are reduced strongly, these experts expected sea-level rise to be 0.4–0.6 m by 2100.
“Complex problems often cannot simply be answered with computer models,” wrote Stefan Rahmstorf of the Potsdam Institute for Climate Impact Research at RealClimate, in an article about this earlier survey. “Experts form their views on a topic from the totality of their expertise – which includes knowledge of observational findings and model results, as well as their understanding of the methodological strengths and weaknesses of the various studies. Such expertise results from years of study of a topic, through one’s own research, through following the scientific literature and through the on-going critical discussion process with colleagues at conferences.”
In terms of climate solutions, the latest Vision Prize poll reveals that carbon capture and storage (CCS) is not thought likely to have a short-term impact. Just 16% of those surveyed believe the technology will measurably affect the global climate by 2050. And only 3% would choose CCS as a top priority for large private investment attempting to avoid dangerous levels of global warming. When it came to this type of spending, distributed renewables were the most popular choice, closely followed by energy efficiency. In third place was next-generation nuclear power. Nanotechnology was the least preferred option, receiving zero votes, while solar radiation management just missed the wooden spoon.
As with previous Vision Prize polls, the experts surveyed agreed with each other more than they thought they would, with the most common views tending to be even more common than expected. Vision Prize asks respondents for their answer to each question as well as how they believe their peers will react. Poll participants are pre-screened to ensure they have relevant expertise.
For more from the poll, including views on the chances of atmospheric carbon dioxide concentrations reaching double pre-industrial levels by 2100 and whether the overall effect of climate change could be positive, head to Vision Prize.
• This article was amended on 19 February 2014 to update the "Investment Priorities" figure with the responses to the "None of the above is needed (no dangerous global warming is likely to occur this century)" option.
- Expert assessment: sea-level rise could exceed one meter in this century
- IPCC: changes unprecedented over decades to millennia
- IPCC publishes full report Climate Change 2013: The Physical Science Basis
- Climate experts agree with each other more than they think
- RealClimate on Sea-level rise: What the experts expect