WASHINGTON – Doubters of climate change may have lost one of their key talking points: a set of satellite temperature data that had seemed to show no warming for the past 18 years.
The Remote Sensing System temperature data, promoted by many who reject mainstream climate science and most recently by Republican presidential candidate Sen. Ted Cruz, now show a slight warming since 1998. Ground temperature measurements, which many scientists call more accurate, all show warming in the past 18 years.
“There are people that like to claim there was no warming; they really can’t claim that anymore,” said Carl Mears, the scientist who runs the Remote Sensing System.
The change resulted from an adjustment Mears made to the fix a nagging discrepancy in the data from 15 satellites.
The satellites are in polar orbits, so they are supposed to go over the same place at about the same time as they circle from north to south. Some of them drift a bit, which changes their afternoon and evening measurements slightly. Some satellites had drift that made temperatures warmer, others cooler. Three satellites had thrusters and stayed in the proper orbit, so they provided guidance for adjustments.
Mears said he was “motivated by fixing these differences between the satellites. If the differences hadn’t been there, I wouldn’t have done the upgrade.”
NASA chief climate scientist Gavin Schmidt and Texas A&M climate scientist Andrew Dessler said experts and studies had shown these problems that Mears adjusted. Both said the adjustments are well supported in a study in the American Meteorological Society’s Journal of Climate.
The study refutes the idea of a pause in global warming, “but frankly common sense and looking at how Earth was responding over the past 18 years kind of makes this finding a ‘duh’ moment,” wrote University of Georgia meteorology professor Marshall Shepherd.
The other major satellite temperature data set, run by University of Alabama Hunstville professor John Christy, shows slight warming after 1998. But if 1998 is included in the data, it sees no warming. But that should change with a warm 2016, Christy said.