Climate change deniers and skeptics have long used satellite data to back up their arguments. This is because the data showed lower temperatures than those recorded on the ground.
However, new research may be knocking the wind out of climate skeptics’ sails.
Dr. Carl Mears and Frank Wentz of Remote Sensing Systems found that orbital decay—the fact that friction in the Earth’s atmosphere causes satellites to slow and decrease their altitude—changes the time that satellites pass over any given spot. This obviously would have a significant effect on the temperatures recorded by those satellites.
Some satellites have very significant orbital drifts. They may previously have measured temperatures at 2 p.n., but now they may be measuring temperatures as late as 6 p.m. or 8 p.m.
When they corrected for satellites’ orbital decay, the researchers found something alarming: global warming is 140 percent faster than previously estimated.
“Climate skeptics have long claimed that satellite data shows global warming to be less pronounced than observational data collected on the Earth’s surface,” wrote Dr. Zeke Hausfather in an article on the Carbon Brief website about the new research. “This new correction to the…data substantially undermines that argument. The new data actually shows more warming than has been observed on the surface, though still slightly less than predicted in most climate models.”
According to Dr. Hausfather, most of the difference between the old record and the new one occurs after the year 2000. While the old record showed a “hiatus” period in global warming after 1998, the new record shows that warming continued unabated during the entire measurement period (1979 through 2016).
To ensure that they had the most accurate data, the researchers used the presence of multiple satellites in recent years to test for what they refer to as “odd man out” behaviors—that is, if three or more satellites are available and one differs substantially from others, they excluded the anomalous satellite’s data.
Surface temperature readings tend to agree closely despite the fact that many different groups are using different data sets.
“Unlike the satellite temperature record, where only a few satellites are measuring temperatures at any given point of time, there is a large amount of redundancy in surface temperature observations, with multiple independent sets of data producing consistent results,” said Dr. Hausfather. “Therefore, it is not too surprising that corrections to problems with satellite data would move them closer to surface records.”