’Missing’ Heat May Affect Future Climate Change
Current observational tools cannot account for roughly half of the heat that is believed to have built up on Earth in recent years, according to a "Perspectives" article in this week’s issue of Science. Scientists at the National Center for Atmospheric Research (NCAR) warn in the new study that satellite sensors, ocean floats, and other instruments are inadequate to track this "missing" heat, which may be building up in the deep oceans or elsewhere in the climate system.The heat will come back to haunt us sooner or later," says NCAR scientist Kevin Trenberth, the lead author. "The reprieve we’ve had from warming temperatures in the last few years will not continue. It is critical to track the build-up of energy in our climate system so we can understand what is happening and predict our future climate.The authors suggest that last year’s rapid onset of El Niño, the periodic event in which upper ocean waters across much of the tropical Pacific Ocean become significantly warmer, may be one way in which the solar energy has reappeared.The research was funded by the National Science Foundation, NCAR’s sponsor, and by NASA. A Science Perspectives piece is not formally peer-reviewed, but it is extensively reviewed by editors of the journal. Science had invited Trenberth to submit the article after an editor heard him discuss the research at a scientific conference.Trenberth and his co-author, NCAR scientist John Fasullo, focused on a central mystery of climate change. Whereas satellite instruments indicate that greenhouse gases are continuing to trap more solar energy, or heat, scientists since 2003 have been unable to determine where much of that heat is going.Either the satellite observations are incorrect, says Trenberth, or, more likely, large amounts of heat are penetrating to regions that are not adequately measured, such as the deepest parts of the oceans. Compounding the problem, Earth’s surface temperatures have largely leveled off in recent years. Yet melting glaciers and Arctic sea ice, along with rising sea levels, indicate that heat is continuing to have profound effects on the planet.In their Perspectives article, Trenberth and Fasullo explain that it is imperative to better measure the flow of energy through Earth’s climate system. For example, any geoengineering plan to artificially alter the world’s climate to counter global warming could have inadvertent consequences, which may be difficult to analyze unless scientists can track heat around the globe. Improved analysis of energy in the atmosphere and oceans can also help researchers better understand and possibly even anticipate unusual weather patterns, such as the cold outbreaks across much of the United States, Europe, and Asia over the past winter.