Should We Credit Global Warming When Disasters Don’t Happen?

Every time there is some sort of weather disaster somewhere, someone blames it on human-caused global warming. Maybe not directly, but the implication is clear. “While we can’t link individual events to global warming, the increase of this type of event is consistent with our expectations, blah, blah…”

Most recently this came in testimony from White House Science Adviser John Holdren before the Committee on Science, Space, and Technology of the U.S. House of Representatives:

In general, one cannot say with confidence that an individual extreme weather event (or weather-related event)—for example, a heat wave, drought, flood, powerful storm, or large wildfire—was caused by global climate change. Such events usually result from the convergence of multiple factors, and these kinds of events occurred with some frequency before the onset of the discernible, largely human-caused changes in global climate in the late 20th and early 21st centuries. But there is much evidence demonstrating that extreme weather events of many kinds are beginning to be influenced—in magnitude or frequency—by changes in climate.

Holdren then goes to list a bunch of types of extreme weather whose characteristics have changed (remarkably, all becoming worse), adding that:

There are good scientific explanations, moreover, supported by measurements, of the mechanisms by which the overall changes in climate resulting from the human-caused build-up of heat-trapping substances are leading to the observed changes in weather-related extremes.

Holdren’s implication is pretty clear—human-caused global warming is leading to changes in extreme weather. And just for good measure, he added this zinger:

[I]t is reasonable to say that most weather in most places is being influenced in modest to significant ways by the changes in climate that have occurred as a result of human activities.

If this were the case, then there is a lot of good news to be found here, for by and large the weather is pretty good, with rare examples to the contrary.

Take, for instance, what has been all abuzz this week in Washington, D.C.: how great the weather has been. The Washington Post’s Capital Weather Gang, which keeps close tabs on the pulse of D.C. weather, has commented repeatedly on how remarkable and enjoyable it has been. According to Holdren’s logic, we have global warming to thank, and yet I have not seen one news story that links the pleasant weather to human-caused climate change.

Across the country in Tucson, Ariz. (where I reside), the news this week has been dominated by the threat of the passage of the remnants of Hurricane Odile, which were forecast to move into the region from out of the Gulf of California. The predictions were for record-breaking rainfall amounts with the potential for widespread damage from flooding. The outlook stirred up memories of the passage of Tropical Storm Octave in 1983, which resulted in over $500 million (in 1983 dollars) of damage to the region. Thankfully, this did not come to pass. Instead, the heavy rains associated with Odile passed well east of the city, over much more sparsely populated country. Since apparently all weather is influenced by anthropogenic global warming, we have it to thank for averting what could have been a very costly and hugely disruptive situation affecting upwards of a million people.

And speaking of hurricanes, the first major hurricane (category 3 or greater) in almost two years formed in the Atlantic Ocean. But, in encountering conditions arguably consistent with human-caused climate change, Hurricane Edouard quickly weakened and remained far out in the open Atlantic, steering well clear of the U.S. mainland. Major disaster averted. It has now been nearly nine years since the last major hurricane made landfall in the United States, the longest such occurrence going back at least to the year 1900. Thanks, global warming!

I could go on, because there are a lot more cases of non-extreme weather than there are of extreme weather, and as many or more cases to be made for weather catastrophes averted by conditions “consistent with global warming” than caused by it.

So if you want to play the all-weather-is-influenced-by-global-warming game, you are going to lose.

Best bet would be to stick with the science, which for most types of extreme weather events and for most places indicates that a definitive link between event characteristics and human-caused climate change has not been established. Either talk about that situation or leave the attribution issue alone.