A new study has created the first detailed look at global land surface warming trends over the last 100 years, illustrating precisely when and where different areas of the world started to warm up or cool down.
Result: the world is indeed getting warmer but not everywhere and not at the same rate.
This probably took a few scientists by surprise and many journalists, but outside the IPCC this is exactly what was known to be happening..
"Global warming was not as understood as we thought," said Zhaohua Wu, an assistant professor of meteorology at Florida State University, who led a team of climate researchers that used an analysis method newly developed to examine land surface temperature trends from 1900 onward for the entire globe, minus Antarctica.
Previous work by scientists on global warming could not provide information of non-uniform warming in space and time due to limitations of previous analysis methods in climate research.
The research team found that noticeable warming first started around the regions circling the Arctic and subtropical regions in both hemispheres. But the largest accumulated warming to date is actually at the northern midlatitudes. They also found that in some areas of the world, cooling had actually occurred.
"The global warming is not uniform," Chassignet said. "You have areas that have cooled and areas that have warmed."
For example, from about 1910 to 1980, while the rest of the world was warming up, some areas south of the equator — near the Andes — were actually cooling down, and then had no change at all until the mid 1990s. Other areas near and south of the equator didn't see significant changes comparable to the rest of the world at all.
The team's work is featured in the May 4 edition of the journal Nature Climate Change.
The detailed picture of when and where the world has warmed or cooled will provide a greater context to global warming research overall, Wu said.