Satellite data confirms globe is warming rapidly

NASA's global temperature data set, which has found that the past 5 years have been the warmest on record, has received new and independent validation of its readings, per a new study.

Why it matters: The research bolsters confidence in NASA's data set, which climate change doubters have been trying to poke holes in for years, in part because it tends to find greater Arctic warming than NOAA. The study also signals how global observations might be conducted in the future.

What they did: Researchers took 2 global surface temperature data sets generated from independent instruments — based on land and in space — and compared them for the first time.

• One included readings from AIRS, an infrared instrument on NASA's Aqua satellite.
• The other was comprised of surface temperature measurements from NASA Goddard Institute for Space Studies' land-based weather observing stations and ocean buoys, collectively known as GISTEMP.

What they found: AIRS data closely matched the Goddard observations during the period of overlap, from 2003 through 2018, except for one key detail. The satellite data shows greater warming in the Arctic, particularly across the data-sparse Arctic Ocean, suggesting GISTEMP may be underestimating global warming there.

• The underestimate may be as large as 50% in some places, study co-author and director of NASA GISS Gavin Schmidt tells Axios, noting that the GISTEMP data set relies on interpolating Arctic regional temperatures from readings at far-flung land-based stations. This could cause a blind spot, of sorts, over the Arctic Ocean itself.
• Scientists have already concluded the Arctic is warming at more than twice the rate of the rest of the world.

What they're saying: “These findings should help put to rest any lingering concerns that modern warming is somehow due to the location of sensors in urban heat islands or other measurement errors at the surface,” Zeke Hausfather, a researcher at the University of California, Berkeley who was not involved in the new study, told the Washington Post.

• Schmidt said in the future surface station readings could be combined with satellite-inferred temperatures and other sources for more complete global temperature monitoring.