Geoengineering Earth's Climate: Resetting the Thermostat

Geoengineering Earth's Climate: Resetting the Thermostat — page 5 — to remain covered in ice and snow year-round has changed Warmer temperatures in Earth’s atmosphere are melting the top of the glacier sending rivulets of ice water into the ocean Warming waters of the North Atlantic Ocean are melting the glacier from the bottom as well The melting glacier on the Evigheds Fjord is part of a much larger formation called an ice sheet Earth has two major ice sheets one on Greenland and one on Antarctica Measuring more than 660,000 square miles 1 7 million square kilometers Greenland’s ice sheet is approximately the size of Texas On average the ice sheet is 1 mile 1 6 km deep Its greatest depth is 3 miles 4 8 km If it were to melt entirely the total amount of water it contains would raise the oceans by about 23 feet 7 meters The rising waters would flood the coasts of every country on the planet and submerge many inhabited islands While the probability of the entire Greenland ice sheet melting is slim climatologists scientists who study Earth’s climate note that Greenland is shedding more ice during summer than it regains from snowfall in winter The US National Aeronautics and Space Administration NASA reports that Greenland’s ice sheet is losing about 31 billion tons 28 billion metric tons of ice annually Some of the melting ice evaporates turns into water vapor or stays on the land but most of it goes directly into the ocean And studies show that the melting on Greenland is increasing every year NASA uses satellites to measure the depth of Earth’s oceans The agency has noticed a definite rise in ocean levels over the last century with an average yearly rise of about 0 13 inches 3 3 millimeters While that may seem small it adds up to a 4 to 8-inch 10 to 20-centimeter rise over the past one hundred years If that water were lying in the street it could flow over curbs and into houses If you were standing next to the ocean the rising water would cover your legs to mid-calf Imagine that much water flooding the entire world And if the ice sheets continue to melt the water levels will only get higher NASA climate scientist Jay Zwally says that the melting of 8 G e o e nGi n e e r i nG e a r t h s c l i m a t e

Geoengineering Earth's Climate: Resetting the Thermostat — page 7 — ICELAND RISING The country of Iceland is rising out of the North Atlantic Ocean No this scene is not something from a science fiction movie The land is rising due to climate change Iceland’s rocky terrain is home to many glaciers The warming waters of the Atlantic Ocean and increasing air temperatures are beginning to melt some of the glaciers As the glaciers melt the land below them rises a little a phenomenon known as uplift Imagine a heavy person lying on a mattress pressing it down When the person gets up the mattress bounces up a bit That’s what’s happening to the land below Iceland’s glaciers Geologists say that in some places the uplift rate is 1 2 inches 30 mm per year the melting of either sheet would spell trouble As Greenland warms and sheds its ice so do other parts of the Arctic including Alaska Many climatologists think that the melted ice streaming into the Arctic Ocean and other northern waters is a signal that the canary has stopped singing They say that climate change has reached a dire tipping point Why is this occurring The answer is related to Earth’s atmosphere A DELICATE BALANCE Earth’s atmosphere is composed of 78 percent nitrogen and 21 percent oxygen The remaining 1 percent consists of argon and small amounts of greenhouse gases methane nitrous oxide carbon dioxide water vapor water in gas form and ozone Greenhouse gases in the atmosphere act like a blanket holding in heat and shielding Earth from certain kinds of radiation from the sun When solar energy reaches Earth’s atmosphere about 29 percent of it immediately bounces off clouds and gases and travels back into space The atmosphere absorbs 10 GeoenGineerinGearth’sclimate

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