Greenhouse gases are warming up our oceans, changing their chemistry, scientists say.

The gases that cause global warming are sometimes given as factors in problems ranging from the strength of hurricanes to altered wildlife habitats. But in what may be the most comprehensive look yet at the oceans, researchers say that the marine effect is just as severe.

“In terms of global warming, the oceans are where the action is,” said Tim Barnett, an oceanographer at the Scripps Institution of Oceanography. “The oceans are sort of a canary in the coal mine.”

Scientists have expanded their network of ocean detectors, dropping sensitive probes in seas where they sink up to 6,000 feet and rise automatically to transmit by satellite the temperatures, salt content and oxygen levels at various depths.

The first of 1,600 such profiling floats began collecting data a few years ago, said Sydney Levitus, director of the National Oceanic and Atmospheric Administration’s ocean climate laboratory.

Researchers say the detectors are confirming what computer models have predicted: that man-made greenhouse gases are warming the seas.

Greenhouse gases are trapping heat in the atmosphere, experts say. The result is a warmer planet, with melting glaciers and arctic ice sheets sending a flow of fresh water into fragile saltwater habitats.

The upper two miles of the oceans have warmed by about 0.11 degrees Fahrenheit since the 1950s and a total of 1.2 degrees in the past 100 years, according to NOAA.