The Hot Zone

Impacts of climate change felt way into future

Posted by Alison Hawkes on July 18, 2011
Category : The Oceans

The delay, or lag time, in the Earth’s climate system means that the full impacts of global warming will be felt long into the future. Well past our lifetimes, even. Atmospheric warming is followed by ocean warming is followed by a melting of polar ice sheets is followed by sea level rise.

Scientists are trying to predict this new, warmer state by looking into the record of past eras of climate change. In a study out of the University of Arizona, researchers found that melting ice sheets had a greater impact on sea level rise than the thermal expansion of the oceans during the previous interglacial period 125,000 years ago.

Photo: NASA

At that time, the sea level exceeded today’s by 26 feet. But only 1.5 feet could be attributed to thermal expansion of ocean water, the vast majority by melting sea ice.

Ocean temperatures were only 1.3 degrees Fahrenheit higher than today.

“This means that even small amounts of warming may have committed us to more ice sheet melting than we previously thought,” said  Nicholas McKay, a doctoral student at the UA’s department of geosciences and the paper’s lead author, in a press release.

The results, to be published in the journal Geophysical Research Letters, point to the danger of uncontrolled atmospheric warming. The researchers warn we are setting ourselves up for 3 feet per century of sea level rise, with most of it coming from the melting of polar ice sheets.

Using the last interglacial as an analog of today’s climate change is not certain science. Changes in the Earth’s orbit is thought to have tipped up global temperatures back then, while today it’s all about rising greenhouse gas concentrations.

Still, then as now, atmospheric warming triggers certain impacts, sea level rise being one of the major ones. For much of the world’s population living along the ocean shoreline, it hardly matters what causes the rise. The problem is they’ll be underwater.

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