With headlines like “Warmest spring heats up economy,” readers weary of bad economic news might be forgiven for thinking that a little global warming is not such a bad thing. But the warming we’ve experienced globally over the past 30 years is more than “a little.” And in the U.S., it’s likely contributing to drought and wildfires in the West and more extreme weather nationwide.
This past May came in as the second warmest on record globally, trailing only May of 2010. For land area only, it was the warmest on record, at 2.18 degrees F above average. It was also the 36th consecutive May, going back to 1976, with global temperatures above the 20th-century average.
Back in November the Intergovernmental Panel on Climate Change (IPCC) released the executive summary for a “special report” called Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation (SREX for shorthand). Today, the IPCC released the full technical report that underlies the executive summary. In addition to documenting the scientific evidence that extreme weather events are on the rise, the report provides a risk-based analysis of how society can best respond to the climate threat. In the words of Chris Field, co-chair of one of the two working groups that produced the report:
“The main message from the report is that we know enough to make good decisions about managing the risks of climate-related disasters. Sometimes we take advantage of this knowledge, but many times we do not. The challenge for the future has one dimension focused on improving the knowledge base and one on empowering good decisions, even for those situations where there is lots of uncertainty.”
If you live in the central or eastern United States and have been outside lately, you can attest to the downright summery weather we’ve been experiencing. In fact, this March weather is not just unusual; it is unprecedented. In Detroit, there has not been a comparable spring heat wave since 1886, and that warm spell occurred a full month later (April 16-24). In Chicago, last week’s high temperatures in the low 80’s are similar to Chicago’s average high in August (82°).
Daily record highs have been falling in droves across the region, with some remarkable occurrences. One weather station in Michigan hit 85°F, breaking the previous daily record high by an unheard of 32°, which is also 48° above average. Two stations recorded low temperatures that beat the previous record high, something that experienced weatherman Jeff Masters had never seen before. This record warmth is not confined to the United States. Several Canadian cities surpassed both their all-time March and April records this week, an amazing feat considering the vast differences between March and April during a normal spring.
NOAA recently declared this winter to be the 4th warmest on record for the contiguous United States. That sort of announcement might be expected in a warming world. But what about the relatively cold winters of 2009-2010 and 2010-2011, which featured historic blizzards in the Midwest and the East Coast? Florida had snow seven times in 2010! And while we Americans enjoyed a very mild winter this year, Europe endured its most frigid cold snap in decades. That sort of winter weather may seem counter-intuitive in a warming world; it’s the sort of weather columnist Thomas Freidman has in mind when he writes about “Global Weirding.”
NOAA reported today that this winter turned out to be the 4th warmest on record in the contiguous United States. That’s not surprising given how much the world has warmed over the past few decades. In fact, all of the seven warmest years in over 100 years of climate data have occurred since 1992, and over the past three decades, a warmer-than-average winter has been twice as likely as a cool one. These data are consistent with how scientists say global warming affects the weather. The risk of warm winters is increasing over time, but that doesn’t mean that cold winters disappear, similar to the way that loaded dice change the probability of a particular roll but don’t eliminate other possibilities.