But it’s still hard to pin down what, where and how bad
Climate change is likely driving some of the extreme weather events we’ve been seeing and more such weather is on the way, according to a much-anticipated report from the Intergovernmental Panel on Climate Change (IPCC).
“This is a pretty hard-hitting report,” says Chris Field, a Stanford climatologist and one of the co-chairs for the report. “What we can say is that some kinds of extremes are occurring more frequently,”
Some kinds. The UN panel carefully couches all of its findings in terms of probabilities and confidence levels, which vary widely depending on the type of weather event. Hence (italics are mine):
Sea Level Rise: “It is very likely (90-100% probability) that mean sea level rise will contribute to upward trends in extreme coastal high water levels in the future.”
Intense Rainfall: “It is likely (66-100%) that the frequency of heavy precipitation or the proportion of total rainfall from heavy falls will increase in the 21st century over many areas of the globe. This is particularly the case in the high latitudes and tropical regions, and in winter in the northern mid-latitudes. Heavy rainfalls associated with tropical cyclones are likely to increase with continued warming.”
Drought: “There is medium confidence that droughts will intensify in the 21st century in some seasons and areas, due to reduced precipitation and/or increased evapotranspiration (the movement of water through plants).
On the other hand, the IPCC reports “low confidence in any observed long-term (i.e., 40 years or more) increases in tropical cyclone activity (i.e., intensity, frequency, duration), after accounting for past changes in observing capabilities,” and “low confidence in observed trends in small spatial-scale phenomena such as tornadoes and hail because of data inhomogeneities and inadequacies in monitoring systems.”
“The thing that makes climate extremes difficult to analyze is that they’re extreme,” says Field, meaning they don’t happen often enough to provide a lot of data. “We’ve only been doing careful drought monitoring for a few decades.” Speaking to me by phone from Kampala, Uganda, where today’s report was released, he said “We shouldn’t be looking for absolute certainty of a certain disaster at a certain time. We should be looking for smart things to do that prepare us for a range of outcomes.”
One thing is sure: People are paying more attention lately. Extreme weather has become the most visible hallmark of climate change.
“We’re seeing a more acute sensitivity to the weather and to the climate,” says David Friedberg, CEO of the San Francisco-based Climate Corp. Friedberg’s start-up offers insurance against catastrophic climate events, to farmers and businesses. “When you speak to farmers, for example,” says Friedberg, “they speak about the fact that the last couple of years’ weather isn’t anything like they’ve experienced or any of the generations past have experienced in farming their land.”
“It was only three years ago when we saw a billion dollars worth of crop loss in the citrus industry, here in the Central Valley of California, as the result of an unusually prolonged freeze event,” says Friedberg. “And that sort of a freeze event we nearly hit again a year later.”
“We’re starting to see those effects,” Friedberg told me in an interview, just before the report was released. “We just happen to be a much more diversified agricultural economy here in California. So it doesn’t take just one weather event to wipe out all of the farmers.”
Friedberg says the UN has already attributed rising prices of some commodities to increasing weather volatility around the world. “As you’re getting more volatile weather, farmers need to charge more for their crops because we’re having more losses globally, than we had before.”
Today’s report is the first in which the IPCC has taken on the question of extreme weather events linked to climate change. It’s been a focus of speculation lately because, as Field says, “That’s where the impacts pile up.” An insurance industry survey recently tallied $14 billion in losses in the US this year alone, from catastrophic weather events.