Hill Heat

The first post by Roger Pielke Jr., the contributing writer on climate for Nate Silver’s new FiveThirtyEight venture, is premised on a factually incorrect assertion. Pielke’s thesis is that “[a]ll the apocalyptic ‘climate porn’ in your Facebook feed is solely a function of perception,” premised on this claim:

In fact, today’s climate models suggest that future changes in extremes that cause the most damage won’t be detectable in the statistics of weather (or damage) for many decades.

This claim is false, even under Pielke’s terms. Pielke defines “extremes that cause the most damage” as “floods, droughts, hurricanes and tornadoes,” excluding “heat waves and intense precipitation,” because “these phenomena are not significant drivers of disaster costs.” (That exclusion is made without a supporting reference.)

In fact, climate models, checked against observations, have already detected changes in the most damaging extremes in the statistics of weather, even under Pielke’s carefully chosen terms:

• Anthropogenic greenhouse gas contribution to flood risk in England and Wales in autumn 2000, Pall et al, Nature 2011
• Atlantic hurricanes and natural variability in 2005, Trenberth and Shea, Geophysical Research Letters 2006
• Global warming increases flood risk in mountainous areas, Allamano, Claps, and Laio, Geophysical Research Letters, 2009
• Increasing drought under global warming in observations and models, Dai, Nature Climate Change 2012

Although there is an observed increase in frequency and intensity of tornadic activity in the United States, the observational record is insufficiently reliable as to make the trend certain. Similarly there is uncertainty in how global warming-driven changes will influence tornadic activity, though there is no question that global warming is changing the factors that determine tornadic development.

Given a sensible policy toward risk, that uncertainty should increase our concern about the continued pollution of our weather system, not decrease it.