New study links human impact on climate with changing seasons

Published by Charline Fernandez on July 23, 2018

July 23rd, 2018

Human effect on the Earth’s climate has had a “significant” impact on the seasonal cycle of temperatures, a new study has found.

A recent study published in Science and led by Lawrence Livermore National Laboratory in California focused on the lowest layer of the atmosphere, the troposphere, where weather conditions take place and analysed the contrast between the warmest and coldest months of the year at different locations.

The researchers used satellite data which shows an annual average warming of 1.25 degrees from 1979 to 2016. They crossed the data with a fingerprint method to separate anthropogenic and natural influences on seasons.

The pattern match between the human influence fingerprint and the satellite patterns of seasonal cycle change was highly significant, the report finds.

“Our results suggest that attribution studies with the changing seasonal cycle provide powerful and novel evidence for a significant human effect on Earth’s climate,” said the lead author, Benjamin Santer.

The researchers found that away from the moderating effects of oceans, the mid-latitude regions in the Northern Hemisphere have a “large seasonal cycle of atmospheric temperature” with frigid winter and hot summers which could be attributable to continental drying.

This seasonal heartbeat, however, is becoming stronger as a result of emissions from human activity, the study found.

The researchers also observed small changes in the tropical seasonal temperature cycle and “a decrease in the size of the seasonal cycle” in the Antarctic region.

The study is the first of its kind as no formal fingerprint study had been performed with the changing seasonal cycle of tropospheric temperature.

“We hope that this finding will stimulate more detailed exploration of the seasonal signals caused by anthropogenic forcing,” the researchers concluded in the paper in Science.

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