Scripps Study Finds Greenhouse Gases Proximate Cause of Ocean Warming

February 21, 2005

Researchers at the Scripps Institution of Oceanography at the University of California, San Diego, and their colleagues have produced the first clear scientific evidence that human activity-and very little else- is warming the world’s oceans.

The Scripps’ report, coming from one of the world’s leading ocean research institutions, may turn out to be the “smoking gun” that finally establishes the link between greenhouse gases (carbon dioxide and other pollutants) and the increase in temperature worldwide, or global warming.

The authors contend that their results clearly indicate that the oceans’ warming is produced “anthropogenically,” i.e. by human activities. The study, conducted by Tim Barnett and David Pierce, along with colleagues at Lawrence Livermore National Laboratory’s Program for Climate Model Diagnosis and Intercomparison (PCMDI), used a combination of computer models and real-world “observed” data to capture signals of the penetration of greenhouse gas-influenced warming in the oceans, a Scripps bulletin stated.

The findings were reported at the annual conference of the American Association for the Advancement of Science (AAAS), held in Washington D.C. Dr. Barnett, a research marine physicist in the Climate Research Division at Scripps, stated: “This is perhaps the most compelling evidence yet that global warming is happening right now and it shows that we can successfully simulate its past and likely future evolution.” He admitted to being “stunned” by the results because the computer models reproduced the penetration of the warming signal in all the oceans. “The statistical significance of these results is far too strong to be merely dismissed and should wipe out much of the uncertainty about the reality of global warming,” he continued.

In an interview with the BBC Barnett noted that the world’s oceans cover around 71 percent of the earth’s surface, and that what happens in them therefore has significant consequences on the world’s weather and climate. The study used advanced computer models of climate “to calculate human-produced warming over the last 40 years in the world’s oceans,” said Scripps’ bulletin. “In all of the ocean basins, the warming signal found in the upper 700 meters predicted by the models corresponded to the measurements obtained at sea with confidence exceeding 95 percent. The correspondence was especially strong in the upper 500 meters of the water column.”

The bulletin noted that it is this “high degree of visual agreement and statistical significance that leads Barnett to conclude that the warming is the product of human influence. Efforts to explain the ocean changes through naturally occurring variations in the climate or external forces- such as solar or volcanic factors–did not come close to reproducing the observed warming.”

If the observations Barnett and his colleagues have identified continue, they will “produce broad-scale changes across the atmosphere and land.” Rapidly melting glaciers in South America and China could greatly reduce the amount of water available in the dry summer months. In the Western U.S. warmer conditions could fundamentally alter the snow pack upon which many Western States rely for water.

“The new ocean study, taken together with the numerous validations of the same models in the atmosphere, portends far broader changes,” Barnett stated. “Other parts of the world will face similar problems to those expected–and being observed now–in the western U.S. The skill demonstrated by the climate models in handling the changing planetary heat budget suggests that these scenarios have a high enough probability of actually happening that they need to be taken seriously by decision makers.”

While it may be an exaggeration to say that the world’s decision makers have been “dithering” over climate change, the only concrete result so far has been the Kyoto protocol, which went into force last week (See IJ Website Feb.17), at least for the countries that have signed up to it. The United States, Brazil and China are notably absent. If the Scripps report convinces those who are still unsure about the causes of global warming that it originates from greenhouse gases, the world will owe Dr. Barnett and his colleagues a great debt.

More details concerning the report and the effects of global warming can be obtained on the Scripps’ Website at:; or on the AAAS Website at: For general information, see also the United Nations Environment Program Web site at:, and the Intergovernmental Panel on Climate Change at:

Was this article valuable?

Here are more articles you may enjoy.