CSI Earth: Human 'fingerprints' detected in Earth's seasonal temperature changes

Doyle Rice | USA TODAY

Now there's proof we're messing around with the seasons.

For the first time, scientists have shown that human-caused climate change is affecting seasonal temperature cycles, a study released Thursday suggests.

The study shows that summers are warming more rapidly than the other three seasons as the planet's temperature rises, especially in portions of the Northern Hemisphere.

It concludes that there's no "natural" way the temperatures could have changed this way without the influence of rising atmospheric greenhouse-gas concentrations. Human-inflicted climate change is caused by the burning of fossil fuels such as coal, oil and gas, which release heat-trapping greenhouse gases such as carbon dioxide and methane into the atmosphere.

In fact, the study says the seasonal "heartbeat" of frigid winters and hot summers is becoming stronger with human emissions of greenhouse gases.

The study also represents the first time scientists have identified a human "fingerprint" on Earth's atmosphere in a new place: the troposphere, or the lowest region of the atmosphere where weather occurs.

The findings provide "powerful and novel evidence for a significant human effect on Earth’s climate,” said study lead author Benjamin Santer, a climate scientist at Lawrence Livermore National Laboratory.

“In the biological world, lots of people have been looking for and finding these changes, so we decided to take a look at the satellite data,” Santer told Nature magazine. “What we see is profound evidence of the human impact on climate, not only in the annual temperatures but also in the seasonal cycle.”

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The researchers used nearly 40 years of satellite temperature data to reach their conclusion. Satellite measurements from 1979 to 2016 provide a continuous and near-global record of temperatures.

The study is solid, but unsurprising, Andrew Dessler, an atmospheric scientist at Texas A&M University, told Nature. “I don’t think this solves a major problem in atmospheric sciences, nor does it change anything that I think about the climate system,” he said. “But it does provide even more evidence that humans are altering the climate.”

The study was published in the peer-reviewed journal Science, a publication of the American Association for the Advancement of Science.