Climate Experts Say the Two Hurricanes “should kill any doubt that climate change is real”

September 7, 2017 | Revolution Newspaper | revcom.us

As people in Texas are still suffering from devastation from Hurricane Harvey and as Hurricane Irma blasts through the Caribbean region, three climate experts are raising the question: “What is the role of human-induced climate change in these events, and how else have our own actions increased our risks?” Their article, titled “Harvey and Irma should kill any doubt that climate change is real,” appeared today at the Washington Post’s online feature PostEverything.

The authors—Michael Mann, professor of atmospheric science and director of Earth System Science Center at Penn State University; Susan J. Hassol, director of Climate Communication LLC; and Thomas C. Peterson, president of the Commission for Climatology of the World Meteorological Organization—note that “Fundamental physical principles and observed weather trends mean we already know some of the answers—and we have for a long time.”

They go on to sketch some of these scientific answers:

Hurricanes get their energy from warm ocean waters, and the oceans are warming because of the human-caused buildup of heat-trapping gases in the atmosphere, primarily from the burning of coal, oil and gas. The strongest hurricanes have gotten stronger because of global warming. Over the past two years, we have witnessed the most intense hurricanes on record for the globe, both hemispheres, the Pacific and now, with Irma, the Atlantic.

We also know that warmer air holds more moisture, and the amount of water vapor in the atmosphere has increased because of human-induced global warming. We’ve measured this increase, and it has been unequivocally attributed to human-caused warming. That extra moisture causes heavier rainfall, which has also been observed and attributed to our influence on climate. We know that rainfall rates in hurricanes are expected to increase in a warmer world, and now we’re living that reality.

And global warming also means higher sea levels, both because ocean water expands as it warms and because ice in the mountains and at the poles melts and makes its way into oceans. Sea level rise is accelerating, and storm surge from hurricanes rides on top of higher seas to infiltrate further into our coastal cities.

Heavier rain and higher sea levels can combine to compound flooding in major hurricanes, as the deluges cause flooding that must drain to the sea but can’t do so as quickly because of storm surges. Sadly, we saw this effect in play in the catastrophic flooding from Harvey.

As the authors point out, not everything is known yet, and there are “scientific linkages” still being worked on. One question that scientists are looking at, for example, is how the slow speed of Hurricane Harvey—almost stalling at points—that resulted in record rainfalls and catastrophic flooding may be related to climate change. The authors write:

Cutting-edge climate science suggests that such stalled weather patterns could result from a slowed jet stream, itself a consequence—through principles of atmospheric science—of the accelerated warming of the Arctic. This is a reminder of how climate changes in far-off regions such as the North Pole can have very real effects on extreme weather faced here in the Lower 48.

These linkages are preliminary, and scientists are still actively studying them. But they are a reminder that surprises may be in store—and not welcome ones—when it comes to the unfolding effects of climate change.

The authors point out the seriousness of the situation—and the urgency to act:

The effects of climate change are no longer subtle. We are seeing them play out before us here and now. And they will only worsen if we fail to act.

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