Energy

New Satellite Data Still Shows Less Global Warming Than Climate Models

Satellite temperature data still shows about 40 percent less warming than the average climate model trend, despite more warming being added to the satellite record after researchers corrected for decaying satellite orbits.

The new updates, published in a recent study, increased the post-1998 warming trend 140 percent for the Remote Sensing System (RSS) satellite temperature database. Now, RSS shows more global warming than surface temperature records.

RSS still shows less warming than the average climate model predictions, according to a climate scientist who operates a competing satellite temperature data set.

“Our globally-averaged trend is now about +0.12 C/decade, while the new RSS trend has increased to about +0.17 C/decade,” Dr. Roy Spencer wrote on his blog Thursday.

“Note these trends are still well below the average climate model trend for [the lower troposphere (LT)], which is +0.27 C/decade,” wrote Spencer, who co-manages satellite-derived temperature data out of the University of Alabama-Huntsville.

Spencer’s colleague Dr. John Christy’s research found climate models show 2.5 times more warming in the bulk atmosphere than satellites and weather balloons have observed.

RSS data is now closer to the climate model trend, but the models still run warmer for the lowest few miles of the atmosphere.

In recent years, prominent climate scientists have had to reconcile with a growing mismatch between climate model predictions and the observational temperature record.

“Over most of the early twenty-first century, however, model tropospheric warming is substantially larger than observed,” reads a recent study led by climate scientist Ben Santer from Lawrence Livermore National Laboratory.

While some scientists, like Christy, say the mismatch shows a fundamental flaw with the climate theory, Santer argues the mismatch is caused by “systematic deficiencies in some of the post-2000 external forcings used in the model simulations.”

Scientists Carl Mears and Frank Wentz, who manage RSS data, were part of Santer’s study, and have now updated their satellite data bring. Their updates bring the observed warming trend closer to the models.

Mears and Wentz used models tuned to empirical measurements to correct for the decaying satellites orbits, which can influence temperature readings. Mears said “the new satellite data are in better agreement with the surface data,” Carbon Brief reported in late June.

Before the updates, RSS showed virtually no warming after 2002 — a period known as the “hiatus” — and was often used by man-made global warming skeptics as a counterpoint to the warmer surface temperature record.

New RSS data also shows more warming than Spencer’s UAH dataset. Spencer’s blog post details the differences between RSS and UAH data, including how each handles diurnal drift differently.

“We have a paper in peer review with extensive satellite dataset comparisons to many balloon datasets and reanalyses,” Spencer wrote. “These show that RSS diverges from these and from UAH, showing more warming than the other datasets between 1990 and 2002 – a key period with two older MSU sensors both of which showed signs of spurious warming not yet addressed by RSS. I suspect the next chapter in this saga is that the remaining radiosonde datasets that still do not show substantial warming will be the next to be ‘adjusted’ upward.”

“The bottom line is that we still trust our methodology,” Spencer wrote. “But no satellite dataset is perfect, there are uncertainties in all of the adjustments, as well as legitimate differences of opinion regarding how they should be handled.”

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