Accra, July 20, (UPI/GNA) – New analysis of
satellite data has revealed the atmospheric signature of seasonal shifts caused
by climate change.
Previous studies have revealed seasonal
changes on the ground. As the planet has warmed, animal migrations have shifted
— birds are flying south and flowers are blooming earlier and earlier. Sea ice
patterns have changed, and both the hurricane and wildfire seasons have grown
longer.
For the new study, scientists set out to find
similar shifts several miles above Earth’s surface. Their effort, which
included the analysis of satellite temperature data collected between 1979 and
2016, marked the first time scientists have detected seasonal changes in the
atmosphere.
According to their calculations, detailed this
week in the journal Science, the chance of such shifts being the product of
natural variation — as opposed to manmade climate change — is approximately
five in a million.
“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,” lead study author Benjamin Santer, an atmospheric
scientist at the Lawrence Livermore National Laboratory in California, told
Nature. “What we see is profound evidence of the human impact on climate,
not only in the annual temperatures but also in the seasonal cycle.”
To pinpoint season atmospheric shifts,
scientists used computer models to simulate thousands of years of climate behaviour,
with and without rising greenhouse gas emissions. Researchers then compared the
simulations’ predictions with the satellite temperature data collected after
1979.
The satellite data was most similar to the
predictions of simulations that included rising greenhouse gas emissions. The
most striking difference was found among satellite data recorded above
landmasses. Scientists found the difference between summer and winter
temperatures have grown by an average of 0.4 degrees Celsius over the last four
decades.
“The changing seasonal cycle provide
powerful and novel evidence for a significant human effect on Earth’s
climate,” Santer said in a news release.
More than anything, the findings confirm what
climate scientists already knew. But Santer hopes the findings will silence
climate skeptics who argue evidence of climate change is over-reliant on
ground-based measurements.
“I don’t think this solves a major
problem in atmospheric sciences, nor does it change anything that I think about
the climate system,” Dessler said. “But it does provide even more
evidence that humans are altering the climate.”
GNA