Guest essay by Eric Worrall

A new study claims that while the US West will feel the impact of Climate Change by 2028, Southern Great [Plains] region won’t notice Climate Change until 2074.

When will the US feel the heat of global warming?

For the Great Plains, natural variability will dominate until late this century.

JOHN TIMMER – 3/21/2018, 6:55 AM

By increasing the energy stored in our atmosphere, climate change is expected to generate more severe storms and heat waves. Severe storms and heat waves, however, also happen naturally. As a result, it’s tough to figure out whether any given event is a product of climate change.

A corollary to that is that detecting a signal of climate change using weather events is a serious challenge. Are three nor’easters in quick succession, as the East Coast is now experiencing, a sign of a changing climate? Or is it simply a matter of natural variability?

A team of researchers has now looked at heat waves in the US, trying to determine when a warming-driven signal will stand out above the natural variability. And the answer is that it depends. In the West, the answer is “soon,” with climate-driven heat waves becoming the majority in the 2020s. But for the Great Plains, the researchers show that a specific weather pattern will push back the appearance of a warming signal until the 2070s.

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To quantify this difference, the authors developed a simple measure: the year in which half of the heat waves wouldn’t have qualified as heat waves if it weren’t for the influence of climate change. For the US West, that point was crossed in 2028. The West was followed by the Great Lakes, which crossed the threshold a decade later in 2037. But the Great Plains were on a completely different schedule. In the Northern Plains, the 50-percent threshold wasn’t crossed until 2056, while the Southern Plains didn’t have a clear signal of climate change until 2074.

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So why is internal variability so significant in the Great Plains? The researchers suggest two potential causes of these regional differences. One is a difference in the flow of air across the continental US, something that may be changing with our warming climate. If the prevailing winds become more erratic, then it’s possible that they would bring cooler air across the Plains more often. The alternative is soil moisture. This takes up heat from the air and ground as it evaporates, which would counteract some of the heating caused by greenhouse gases.

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