'Global warming is undeniable,' and it's happening fast, a new U.S. government report says.

The retreating Iceberg Glacier in Chile's Bernardo O'Higgins National Park (file).

Christine Dell'Amore
National Geographic News
Published July 28, 2010

"Global warming is undeniable," and it's happening fast, a new U.S. government report says.

An in-depth analysis of ten climate indicators all point to a marked warming over the past three decades, with the most recent decade being the hottest on record, according to the latest of the U.S. National Atmospheric and Oceanic Administration's annual "State of the Climate" reports, which was released Wednesday. Reliable global climate record-keeping began in the 1880s.

The report focused on climate changes measured in 2009 in the context of newly available data on long-term developments.

(See "Heat Wave: 2010 to Be One of Hottest Years on Record.") For instance, surface air temperatures recorded from more than 7,000 weather stations around the world over the past few decades confirm an "unmistakable upward trend," the study says.

And for the first time, scientists put data from climate indicators—such as ocean temperature and sea-ice cover—together in one place. Their consistency "jumps off the page at you," report co-author Derek Arndt said.

"This is like going to the doctor and getting your respiratory test and circulatory test and your neurosystem test," said Arndt, head of the Climate Monitoring Branch of NOAA's National Climatic Data Center.

"It's testing all the parts, and they're all in agreement that the same thing's going on."

Global Warming Sparked Extreme Weather in 2009?

Three hundred scientists analyzed data on 37 climate indicators, but homed in on 10 that the study says are especially revealing.

Those indicators include:

• humidity,
• sea-surface temperature,
• sea ice cover,
• snow cover,
• ocean heat content,
• glacier cover,
• air temperature in the lower atmosphere,
• sea level,
• temperature over land,
• and temperature over oceans.

(Original here.)