The planet's deep oceans at times may absorb enough heat to flatten the rate of global warming for periods of as long as a decade even in the midst of longer-term warming. According to a new analysis led by the National Center for Atmospheric Research (NCAR), based on computer simulations of global climate, ocean layers deeper than 1,000 feet are the main location of the “missing heat” during periods such as the past decade when global air temperatures showed little warming. Their findings also suggest that several more intervals like this can be expected over the next century, even as the trend toward overall warming continues.
NCAR's Gerald Meehl says, "We will see global warming go through hiatus periods in the future. However, these periods would likely last only about a decade or so, and warming would then resume. This study illustrates one reason why global temperatures do not simply rise in a straight line."
The trouble is, while the oceans save us--for a time, anyway--this also gives climate change skeptics a chance to say that climate change is not really happening. But it IS: The 2000s were Earth's warmest decade in more than a century of weather records. However, thanks to the oceans, the single-year mark for warmest global temperature, which had been set in 1998, remained unmatched until 2010, despite the fact that emissions of greenhouse gases continued to climb during that time. Satellite measurements during this period showed that the discrepancy between incoming sunshine and outgoing radiation from Earth actually increased. This implied that heat was building up somewhere on Earth--but where?
In 2010, NCAR researchers Kevin Trenberth and John Fasullo suggested that the oceans might be storing some of the heat that would otherwise go toward other processes, such as warming the atmosphere or land, or melting more ice and snow. Observations from a global network of buoys showed some warming in the upper ocean, but not enough to account for the global build-up of heat. Now atmospheric scientists say that the deep oceans are absorbing our extra heat--saving us for now. But how long can this last?
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