Satellite Data Show Global Warming Worse Than Thought

Climate change deniers have long pointed to satellite data showing lower temperatures than those recorded on the ground.

However, new research has found an explanation for this apparent discrepancy, The Independent reported.

The orbit of satellites around the Earth gradually decays over time due to friction in the Earth’s atmosphere and this gradually changes the time they pass over any one spot and this obviously has a significant effect on the temperature.

Using information from the satellites, the scientists, Carl Mears and Frank Wentz, of Remote Sensing Systems, a California-based research company, developed a new method of correcting for the changes. And what they found was startling.

The rate of warming was about a third higher at 0.174 degrees Celsius per decade between 1976 and 2016, compared to 0.134°C per decade.

Writing in the Journal of Climate, the scientists said: “The changes result in global-scale warming … about 30% larger than our previous version of the dataset.

“This change is primarily due to the changes in the adjustment for drifting local measurement time. The new dataset shows more warming than most similar datasets constructed from satellites or radiosonde [weather balloon] data.”

In an article on the Carbon Brief website about the new research, data scientist Zeke Hausfather said it showed an even faster rate of warming since 1998–at nearly 140%–than previous satellite-based studies.

“Climate skeptics have long claimed that satellite data show global warming to be less pronounced that observational data collected on the Earth’s surface,” he said.

“This new correction to the … data substantially undermines that argument. The new data actually show more warming than has been observed on the surface, though still slightly less than predicted in most climate models.”

Hausfather explained the problem with interpreting climate data from satellites due to their subtly changing orbit.

“As these satellites circle the Earth, their orbits slowly decay over time due to drag from the upper atmosphere,” he said.

“While the satellites are designed to fly over the same spot on the Earth at the same time every day–a precondition to accurately estimating changes in temperatures over time–this orbital decay causes their flyover time to change.

Hausfather noted that some satellites have fairly large orbital drifts, going from measuring temperatures at 2 p.m. to 6 p.m. or 8 p.m.

“Since the temperature changes since 1979 are on the order of 0.6 degrees Celsius or so, it is relatively easy for bias, due to changing observation times, to swamp the underlying climate signal,” he said.