The politics surrounding the science and policy of climate change is really, really nasty. Name-calling and ad hominem attacks are rampant. The recent wikileaks release of John Podesta's emails (Hillary Clinton's presidential campaign manager) uncovered a remarkable effort by minions at the Center for American Progress to silence University of Colorado political scientist Roger Pielke Jr. whose research suggested that climate change has not yet caused any discernible uptick in property damage. Pielke details his ordeal in an op-ed "My Unhappy Life as a Climate Heretic" over at the Wall Street Journal. As Pielke explains:
Much to my surprise, I showed up in the WikiLeaks releases before the election. In a 2014 email, a staffer at the Center for American Progress, founded by John Podesta in 2003, took credit for a campaign to have me eliminated as a writer for Nate Silver's FiveThirtyEight website. In the email, the editor of the think tank's climate blog bragged to one of its billionaire donors, Tom Steyer: "I think it's fair [to] say that, without Climate Progress, Pielke would still be writing on climate change for 538."
The only acceptable narrative for the activists over at the Center for American Progress is that climate is making the weather worse resulting in ever more property damage and anyone questioning the politically correct story must be drummed out of polite society.
So what did wikileaks reveal? Among other things, an email from ThinkProgress chief editor Judd Legum to major Democratic donor (and climate warrior) Tom Steyer bragging about how he had successfully trolled FiveThirtyEight statistical analysis website proprietor Nate Silver into getting rid of Pielke. Why go after Pielke? Because he had published an article at 538 based on his research daring to point out that so far climate change had not boosted "normalized" property damage. Normalized basically means taking into account the fact that as a result of economic and population growth there is more property and lives at risk from bad weather.
Pielke's conclusion elicited fury from activists and some climatologists. Silver published a rebuttal to Pielke by MIT hurricane expert Kerry Emanuel. Interestingly, Emanuel's rebuttal did not actually question Pielke's data showing that normalized damages had not been increasing. Instead, Emanuel cited studies in which climate models projected, among other things, that future warming would generate more powerful hurricanes that would cause more damage. Emanuel made an interesting distinction between trend detection and event risk assessment. He offered an illustration in which researchers report that the number of bears in a forest had just doubled. In this case, mauling statistics (trend detection) based on earlier bear populations would not be a reasonable guide to the mauling risks (event assessment) forest strollers would now face.
"When it comes to certain types of natural hazards, there are more bears in the woods," wrote Emanuel. "For example, there is a clear upward trend in overall North Atlantic hurricane activity by virtually all metrics, over the past 30 years or so, though the cause of this is still uncertain." Emanuel's claim was written in 2014. But are there in fact as a result of climate change more hurricanes lurking in the North Atlantic woods?
A recent analysis looking at historical changes in Atlantic hurricanes and tropical storms by researchers at NOAA's Geophysical Fluid Dynamics Laboratory finds that "the historical tropical storm count record does not provide compelling evidence for a greenhouse warming induced long-term increase" in the North Atlantic.
Emanuel and other modelers believe that warming will strengthen hurricanes. In other words, bigger bears will roam the woods. However, a September, 2015 study by researchers at NOAA's National Hurricane Center reported that "the global frequency of category 4 and 5 [more intense] hurricanes has shown a small, insignificant downward trend while the percentage of category 4 and 5 hurricanes has shown a small, insignificant upward trend between 1990 and 2014. Accumulated cyclone energy globally has experienced a large and significant downward trend during the same period." The bears are not yet getting bigger, but the models say they will soon.
So two years later what do we know about the loss trends that might be related to climate change? A study published in Nature Geoscience in October 2015 used a regression-based approach instead of normalization to analyze hurricane loss trends in the United States. The researchers reported:
Based on records of geophysical data, we identify an upward trend in both the number and intensity of hurricanes in the North Atlantic basin as well as in the number of loss-generating tropical cyclone records in the United States that is consistent with the smoothed global average rise in surface air temperature. We estimate that, in 2005, US$2 to US$14 billion of the recorded annual losses could be attributable to climate change, 2 to 12% of that year's normalized losses.
On the other hand, a November 2015 review article in Climatic Change noted that the recent Intergovernmental Panel on Climate Change's Special Report for Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (IPCC-SREX) report …
…demonstrated for the first time comprehensively that anthropogenic climate change is modifying weather and climate extremes. The report also documents, what has been long known, that losses from natural disasters, including those linked to weather, have increased strongly over the last decades. Responding to the debate regarding a contribution of anthropogenic climate change to the increased burden from weather-related disasters, the IPCC-SREX finds that such a link cannot be made today, and identifies the key driver behind increases in losses as exposure changes in terms of rising population and capital at risk.
And in a more recent analysis by reinsurer Munich Re's Head of Geo Risks Research Peter Hoeppe notes in a March 2016 article in Weather and Climate Extremes that …
…the number of loss relevant weather extremes has increased significantly. There is increasing evidence that at least part of these increases are driven by global warming. The increases in losses are driven predominantly by higher exposed values due to increasing wealth and population in many regions. The task to quantify the significantly smaller signal of climate change is very difficult as some more confounding parameters have to be considered for which data availability if confined.
Let's just say that the question of how much climate change contributes to current damages caused by weather extremes is still actively being debated. Just not by Pielke.
Disclosure: Pielke expressed some reservations about my book The End of Doom in his review. I rebut him. I do note that my book has a long section devoted to reporting the research on climate change and weather damages.