An international team of climate researchers says the world’s climate has warmed at an unparalleled rate over the past century, but has also found that this warming hasn’t occurred everywhere at the same rate.
Their research also indicates that some parts of the world actually cooled during the 100-year time period.
The new study, published in Nature Climate Change, is the first to provide a detailed look at trends in global land warming for the last 100 years, according to the researchers Florida State University and the College of Atmospheric Sciences at Lanzhou University in China.
The paper also provides details on exactly when and where different areas of the world started to either warm up or cool down.
To make their findings, the researchers developed an analysis method that reviewed historical records of land surface temperatures from 1900 through the present for the entire world, except Antarctica.
“Global warming was not as understood as we thought,” said Zhaohua Wu, an assistant professor of meteorology at Florida State University, who led the research team.
With their new data analysis method, scientists were able to provide the kind of details that had been missing from previous climate studies.
They said due to limitations of previous analysis methods in climate research, past studies on global warming didn’t provide information on non-uniform warming in space and time.
Their analytical review of historical records showed noticeable warming first started in and around the areas that encircled the Arctic and also the subtropical regions – the area between the 35th parallel in the Northern and Southern Hemispheres and the Tropics of Cancer and Capricorn, which includes parts of North and South Africa, the Middle East, Southern Europe, North and South America, Asia and Australia.
But the area of the world where they found the largest buildup of warming taking place through present times has been in the mid-latitudes of the northern hemisphere such as the US and Canada in North America, most European countries and Asian countries such as parts of China and Russia.
Along with the warming trends, they found cooling had actually occurred in some parts of the world.
“The global warming is not uniform,” said research team member Eric Chassignet, director of Florida State University’s Center for Ocean-Atmospheric Prediction Studies. “You have areas that have cooled and areas that have warmed.”
As most of the world was warming up between 1910 and 1980, some areas south of the equator near the Andes were actually cooling down, and then afterwards had no change at all until the middle 1990s.
Wu said that the detailed representation of when and where the world has warmed or cooled made possible by their analysis should provide a greater context to global warming research overall.
Animation of researchers findings.