Hottest decade, warming ‘unmistakable’
Pat Brennan, science, environment editor, The Orange County Register
The past decade is the warmest ever recorded, and the powerful signals of global warming — from sea ice to glaciers, temperatures to sea level — are “unmistakable,” according to a new report from the nation’s climate agency.
The 2009 State of the Climate report, released Wednesday by the National Oceanic and Atmospheric Administration, says measurements of 10 different indicators shows the planet has been heating up for the past 50 years.
And the warming appears to be accelerating.
“Since the 70s, globally speaking, we have warmed at an unprecedented rate in the historical record, the last 100 or 150 years or so,” said Deke Arndt, the report’s co-editor and the chief of NOAA’s National Climatic Data Center Climate Monitoring Branch.
To get a full picture of the Earth’s changing climate, the report brought together measurements of seven “indicators” that are on the rise: air temperature over land and oceans, sea-surface temperature, sea level, ocean heat, humidity and the temperature in the layer of the atmosphere closest to the surface where weather is most active.
It also examines three indicators on their way down: Arctic sea ice, glaciers and spring snow in the northern hemisphere.
All 10 point to an intense global warming episode.
“It was striking to see all of these different climate indicators side by side, standing there together,” Arndt said. “To see them all on the same page, singing the same song — I won’t say that’s suprising or shocking, (but) it was emphatic. It definitely jumped out of the page at us.”
The decade-to-decade changes are the key to understanding the shift in climate, he said. And those trends are stark: the 1980s were the warmest decade measured to that point, every year of the 90s was warmer than the previous decades’ average, and the 2000s have been even warmer.
While the report did not address the issue of human influence on climate — which has been established by other scientific work, Arndt said — it also shows that greenhouse gas levels are rising as well, based on measurements in several places around the globe.
A large majority of climate scientists agree that human activity appears to be the main cause of planetary warming, although a small number, along with a strong contingent of climate “skeptics” among the public, question the science behind the assertion.
The NOAA report draws from the work of 300 scientists in 48 countries, using data collected from satellites, weather balloons, weather stations, ships, bouys and field surveys.
“Human activity has clearly changed the energy balance of the planet,” said Michael Prather, a climate scientist at UC Irvine who specializes in climate modeling and has been an author of climate reports from the Intergovernmental Panel on Climate Change. “We’ve clearly done that by pumping this stuff (greenhouse gases) out. It’s all basic physics.”
