Cape Town - The world has got warmer over the past 100 years – but not at an even rate and some areas have even cooled, according to research published by climate scientists.
And to their surprise they found the largest accumulated warming has been in the mid-latitudes of the northern hemisphere.
The research group is from Florida State University in the US and Lanzhou University in China. According to a media release, their work is the first detailed look at global land-surface warming trends over the past 100 years that illustrates precisely when and where parts of the world started to warm or cool.
Previous work on global warming could not provide information of non-uniform warming in space and time because of the limitations of earlier climate research methods.
But this group used a new method of analysis developed by team leader Zhaohua Wu, an assistant professor of meteorology at Florida State, and they examined land surface temperature trends from 1900 onward for the entire globe, apart from Antarctica.
While the results, not unexpectedly, confirmed the world is indeed warming, they also showed it hasn’t happened everywhere at the same rate, which surprised the scientists.
“This warming is spatially and temporally non-uniform, and one needs to understand its evolution to better evaluate its potential societal and economic impact,” reads the abstract to their paper in this week’s edition of the journal Nature Climate Change.
The researchers reported “the global climate has been experiencing significant warming at an unprecedented pace in the past century”.
They found “noticeable warming” had started sporadically over the global land and accelerated until around 1980 but both the warming rate and spatial structure had changed little since.
Noticeable warming first occurred in the sub-tropical and sub-polar regions of the northern hemisphere, followed by sub-tropical warming in the southern hemisphere. The two bands of warming in the northern hemisphere had expanded from 1950 to 1985 and merged to cover the entire northern hemisphere.
The fastest warming in recent decades was in northern mid-latitudes.
From about 1910 to 1980, some areas near the Andes in South America were cooling down, and then had no change at all until the mid 1990s, and other areas near and south of the equator hadn’t seen significant changes comparable to the rest of the world.
Wu was quoted in the media release as saying: “Global warming was not as understood as we thought.” - Cape Argus