Not only is Earth’s surface warming, but the troposphere — the lowest level of the atmosphere, where weather occurs — is heating up too, U.S. and British meteorologists reported on Monday.
In a review of four decades of data on troposphere temperatures, the scientists found that warming in this key atmospheric layer was occurring, just as many researchers expected it would as more greenhouse gases built up and trapped heat close to the Earth.
This study aims to put to rest a controversy that began 26 years ago, when a 1990 scientific report based on satellite observations raised questions about whether the troposphere was warming, even as Earth’s surface temperatures climbed.
The original discrepancy between what the climate models predicted and what satellites and weather balloons measured had to do with how the observations were made, according to Dian Seidel, research meteorologist for the U.S. National Oceanic and Atmospheric Administration.
It was relatively easy to track surface temperatures, since most weather stations sat on or close to the ground, Seidel said by telephone from NOAA’s Air Resources Laboratory in Silver Spring, Maryland, outside Washington.
Measuring temperature in the troposphere is more complicated. Starting in the late 1950s, scientists dangled weather instruments from big balloons, with the data sent back to researchers by radio transmission as the balloons rose through the six miles (10 km) of the troposphere.
BALLOONS AND SATELLITES
The first satellite data on troposphere temperature was gathered in 1979, but neither weather balloons nor these early satellite weather observations were accurate measures of climate change, Seidel said.
“They’re weather balloons and weather satellites, they’re not climate balloons and climate satellites,” she said. “They’re not calibrated precisely enough to monitor small changes in climate that we expect to see.”
When the 1990 study was published, showing a lack of warming in the troposphere especially in the tropics, it prompted some to question the reality of surface warming and whether climate models could be relied upon, NOAA said in a statement.
This latest paper reviewed 195 cited papers, climate model results and atmospheric data sets, and found no fundamental discrepancy between what was predicted and what is happening in the troposphere. It is warming, the study found.
This study is one of several published this year pushing back against those who doubt the reality of climate change and the role human activities play in it.
Scientists at NOAA, the United Kingdom Met Office and the University of Reading contributed to the paper, published on Monday in Wiley Interdisciplinary Reviews – Climate Change, a peer-reviewed journal.
International climate change talks are set to start on November 29 in Cancun, Mexico, but prospects for a global deal to curb greenhouse emissions are considered slim.