WASHINGTON (AP) — Scientists have witnessed carbon dioxide trapping heat in the atmosphere above the United States, chronicling human-made climate change in action, live in the wild.

A new study in the journal Nature demonstrates in real-time field measurements what scientists already knew from basic physics, lab tests, numerous simulations, temperature records and dozens of other climatic indicators. They say it confirms the science of climate change and the amount of heat-trapping previously blamed on carbon dioxide.

Researchers saw "the fingerprint of carbon dioxide" trapping heat, said study author Daniel Feldman of the Lawrence Berkeley National Laboratory in California. He said no one before had quite looked in the atmosphere for this type of specific proof of climate change.

Feldman and colleagues used a decade of measurements from instruments in Alaska and Oklahoma that looked straight up into the sky and matched what they saw with the precise chemical composition and heat fingerprints of carbon dioxide trapping heat. Scientists say carbon dioxide from the burning of coal, oil and gas is the chief cause of global warming.

In doing so, the data show clouds, water vapor or changes in sun's radiation are not responsible for warming the air, as some who doubt mainstream climate science claim, Feldman said. Nor could it be temperature data being tampered with, as some contrarians insist, Feldman said.

"The data say what the data say," Feldman said. "They are very clear that the rising carbon dioxide is actually contributing to an increased greenhouse effect at those sites."

The study is good technical work, said climate scientist Andrew Dessler of Texas A&M University, but it is expected — sort of like confirming gravity with a falling rock.

___

Online:

Nature: http://www.nature.com/nature

___

Seth Borenstein can be followed at http://twitter.com/borenbears