Michael Mann, originator of the hockey stick graph that shook world science in the 2001 IPCC Third Assessment Report and contributed to the 2007 Nobel Peace Prize, posted some thoughts today about the final IPCC climate synthesis report released by the UN on Sunday.
Mann’s take on the key points of the report, which calls for zero fossil fuel emissions by 2100:
“The world’s scientists are more confident than ever that climate change is not only real and caused by us, but that it is already taking a toll: on our health, on our economy, on our security, and on the health of our environment. The good news is that it it still possible to solve the problem cheaply. But if we delay acting, it will be far more expensive, and the damages will be far greater.”
He finds this latest IPCC synthesis report more definitive than the past reports in terms of its tone of certainty. He hears in it a higher level of confidence that human activity (fossil fuel burning) is responsible for warming. “The report is far more definitive that climate change isn’t some nebulous, far-off threat—it is negatively impacting us already, where we live.” He cites the influence of climate change in the US, such as increasing impacts of extreme droughts, floods, and massive wildfires.
What’s missing? Mann feels that the potential threat of low-probability—but potentially catastrophic—events gets short shrift in the new IPCC synthesis report. The potential damages associated with such events makes connsideration of them critical in any assessment of climate change risk. For example, Mann says:
“There is an emerging body of evidence in the peer-reviewed literature, for example, that we may have already crossed a tipping point in ice sheet behavior that commits us to more than 10 feet of sea level rise. There is quite a bit of uncertainty about the timescale on which this will unfold, but timescales as short as a century or two cannot confidently be ruled out.”
He also cites a body of evidence emerging in the peer-reviewed scientific literature that extreme events like the current wicked California drought might be associated with the northern hemisphere’s jet stream response to disappearing Arctic sea ice. “If so,” Mann says, “this would imply that climate change is already taking an even greater toll than the IPCC assessments imply.”
The urgency of today’s IPCC synthesis report findings should translate to a heightened sense of urgency at the upcoming negotiations in Lima (December 2014) and Paris (December 2015). “A sober reading of the synthesis report makes clear that we need to act now if we are to avert potentially catastrophic impacts of climate change on us and our planet.”
For more on the Synthesis Report itself, visit: