You Can't Freeze Away Sea-Level Rise

Why don't we just take some of that melting ice and send it back inland? Turns out it's not that easy. Bernhard Staehli/Shutterstock

Yet another idea for dealing with the effects of global warming, rather than tackling the causes, isn't looking good. It seems no matter what we do, we won't be able to refreeze the melting glaciers in order to stop the rising oceans.

While political leaders put off the harder aspects of replacing fossil fuels, or deny we have a problem altogether, some people have pondered if there are ways to fight the problem that don't require taking on such powerful interests. Known as geoengineering, these ideas range from bolstering natural processes such as oceanic plankton to constructing vast shields in space to keep the sunlight off.

So far, these proposals always seem to cost more than shifting to solar and wind energy, and often carry dangers too, but the ideas don't stop. Dr. Katja Frieler of the Potsdam Institute for Climate Impact Research has gone for a slightly more modest approach – doing nothing about rising temperatures, but fighting one of its worst consequences: rising seas.

"We explored a way to at least delay the rise of sea level we can no longer avoid by even the strictest climate-change mitigation strategies. This is estimated to reach about 40 centimeters (16 inches) by the end of the century," Frieler said in a statement.

Frieler and her colleagues investigated the possibility of pumping sea water onto Antarctica, where it would freeze. It is a more drastic version of the idea to fill below-sea-level basins with water to take the edge off sea-level rise.

However, this modern-day King Canute act won't work, Frieler found. If the water was frozen around the edge of the continent, Frieler discovered it would quickly slide off again.

Frieler modeled what would be required to pump the water 700 kilometers (435 miles) inland, where it would take 1,000 years before returning to the sea. Pushing water that far would be a huge effort under any circumstances, but the existing ice sheet – 4,000 meters (13,000 feet) high – makes the challenge almost impossible. While Antarctica is very windy, it would take 850,000 wind turbines – a tenth of the current annual energy supply worldwide – to capture the energy required to force the water.

Inland Antarctica gets much higher than this, meaning water would need to be pumped up a long way. Denis Burden/Shutterstock

"The magnitude of sea-level rise is so enormous, it turns out it is unlikely that any engineering approach imaginable can mitigate it," said Professor Anders Levermann, co-author of the paper in Earth System Dynamics that explores the viability of the plan.

Given how unrealistic Frieler and Levermann's requirements turn out to be, it is easy to question why the work was done in the first place. However, Frieler argued, "Our approach is definitely extreme, but so is the challenge of sea-level rise." He added: "Local adaptation, for instance building dikes, will not be physically possible or economically feasible everywhere.”

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