That’s One Small Step for the IPCC; One Giant Leap for Understanding Our Climate Risk

The Intergovernmental Panel on Climate Change (IPCC) released a “special report” (that’s what they call topical reports they publish in between their better known comprehensive assessments) today that is worth a close look for anyone who wants to start getting ready for a future with weirder and often harsher weather.

About a year ago I published an opinion editorial taking the Intergovernmental Panel on Climate Change (IPCC) to task for neglecting risk-based information to help decision makers cope with inevitable uncertainties about the future impacts of climate change:

Since uncertainty is endemic to the future, when the second IPCC assessment concluded in 1995 that ‘The balance of evidence suggests a discernable human influence on the global climate’, the IPCC should have reconvened around the risk implications of this probable human influence. Instead, it redoubled its effort to reduce physical science uncertainties [which will not be resolved before action is required].

Happily, that changed today with the release of Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. While the title may be yawner, the official IPCC nickname for it is pretty cool – “SREX” (reminds me of T-Rex). And this title isn’t just a tip of the hat to the right way of thinking; the report actually lives up to its billing, with just one chapter focused entirely on physical science and 8 others focused on highly interdisciplinary topics directed at developing a risk-based understanding of how society can respond to the climate threat. In the IPCC’s own words, the report:

“…addresses, for the first time, how integrating expertise in climate science, disaster risk management, and adaptation can inform discussions on how to reduce and manage the risks of extreme events and disasters in a changing climate. The report evaluates the role of climate change in altering characteristics of extreme events. It assesses experience with a wide range of options used by institutions, organizations, and communities to reduce exposure and vulnerability, and improve resilience, to climate extremes.”

Without obsessing over futile attempts to eliminate uncertainties in the weather—if you don’t like it just wait a minute, right?— the SREX reviews the physical science basis for extreme weather risk and finds that several types of extreme events, like heat waves and heavy downpours, have become more frequent or severe. Moreover, it finds compelling evidence that manmade greenhouse gases have contributed to some of these trends. At the same time, damages and costs from extreme weather events have been increasing in recent decades. That trend is due in large part to socioeconomic trends – like more people and wealth concentrating along coastlines where storms sweep them away. But from a risk-management perspective, it is common sense to realize that when two trends are both moving in the direction of greater risk, it’s time to do something about it for BOTH reasons.

The SREX appropriately devotes much more text to social risk factors, such as trends in settlement patterns, sub-population vulnerability, and uneven capacity to adapt to changing weather patterns. It finishes with what we know and don’t know about how society can/should respond to changing weather extremes, focusing on “low-regret” strategies that have improved health and safety already and that simply make the world a better place to live, such as early warning systems, insurance innovations, and infrastructure improvements.

Since so many experts (more than 200 authors) were involved in preparing it, the SREX offers an important check on our own work here at C2ES. We released a paper back in June (when we were still the Pew Center on Global Climate Change) called Extreme Weather and Climate Change: Understanding the Link, Managing the Risk. In that paper, we contend that there is already sufficient evidence to understand that climate change is increasing the risk of extreme heat, heavy precipitation, and (in some places) drought and related wildfires. In contrast, there is less evidence that the risk from hurricanes has increased, but probably will in the future, and we really know nothing about how the risk of tornadoes relates to climate change now or in the future. Our assessment is in general accord with the SREX, which finds:

  • “It is likely (> 2:3 odds) that anthropogenic influences have led to warming of extreme daily minimum and maximum temperatures on the global scale.”
  • “There is medium confidence that anthropogenic influences have contributed to intensification of extreme precipitation on the global scale.”
  • “There is medium confidence that some regions of the world have experienced more intense and longer droughts.”
  • “It is likely that there has been an anthropogenic influence on increasing extreme coastal high water due to increase in mean sea level.” (our paper does not address sea level effects)
  • "There is low confidence in any observed long-term (i.e., 40 years or more) increases in tropical cyclone activity (i.e. hurricanes)."
  • "There is low confidence in observed trends in small spatial-scale phenomena such as tornadoes and hail."

The SREX doesn’t really go into wildfires, but it comments that “drought, coupled with extreme heat and low humidity, can increase the risk of wildfire.” That relationship is well established in the western United States, where large wildfires have increased dramatically in recent decades. While our paper is in no way a replacement for the SREX, it helps set the stage for non-technical readers.

Unfortunately, the SREX punts on the question of how feasible adaptation will be if the (human) world doesn’t reduce its greenhouse gas emissions to limit the ultimate extent of climate change, saying simply: “Although mitigation of climate change is not the focus of this report, adaptation and mitigation can complement each other and together can significantly reduce the risks of climate change.”

With manmade greenhouse gas emissions increasing by a record amount last year, common sense tells us that the risks of climate change are only marching upward – it’s basic physics! Clearly we will have to adapt to the changes that are underway, but I hope we will get our act together in time to reduce emissions before adaptation to future changes becomes intractable.

I suspect most people will find the SREX report slow reading. Fortunately, there is a handy 3-page fact sheet that boils it down neatly. Anyone who is serious about how to think about adapting to climate change – and the value of limiting its extent by reducing greenhouse emissions – should read the full report. (Note that only the summary for policymakers is available at this point. The full report is scheduled for release in February.)

Jay Gulledge is the Senior Scientist and Director of the Science and Impacts Program at C2ES.