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Climate change’s dominos

Arctic sea ice melt starts the cascade

When I was young, I enjoyed setting dominos on end in complex branching rows. Then, by pushing one ever-so-slightly until it toppled over, I created a whole cascade of falling dominos rippling out across the floor. Humanity is playing the same game, but on a much grander scale.

The dominos are falling now!

With all the warm temperature records set during the summer of 2012, and attributed to anthropogenic global warming (us), it should come as no surprise that a new record was set in the Arctic. On Sept. 16, the Arctic sea ice melted to its lowest extent on record.

The National Snow and Ice Data Center reported Arctic sea ice covered just 24 percent of the surface of the Arctic Ocean, smashing the previous record low of 29 percent in 2007. In the 1970s, summer sea ice would usually cover about half of the Arctic Ocean.

Every summer in September, the melting of Arctic sea ice reaches its minimum extent for the year and then begins to rapidly refreeze. However, this new ice is thinner than the older ice and will melt more quickly the next summer.

The Intergovernmental Panel on Climate Change, in their 2007 Fourth Assessment Report, indicated that this low ice extent would not occur until the middle of the century or later. Now, scientists are suggesting the summer Arctic could be ice free by 2020.

For many this is great news. Big Oil interests can hardly wait to start drilling, mineral interests to start extracting, shipping interests to start shipping. But climate scientists are alarmed that we may have pushed over the first domino.

Melting sea ice doesn’t contribute directly to rising sea levels since it is already displacing the same amount of water it will after it melts. But, the melting Arctic sea ice can trigger a cascade of dire consequences, including melting land ice — which does raise sea levels, ones rising now!

Because white ice reflects most of the sun’s radiation and dark ocean water absorbs most of the sun’s radiation, a self-reinforcing cycle results. Melting sea ice exposes more ocean water which absorbs more of the sun’s heat energy, which melts more ice, which exposes more ocean … you get the idea. This is known as a self-reinforcing or positive feedback loop. The reflectivity of the Earth’s surface is called its albedo and when it changes from a mostly reflective surface to a mostly absorptive surface it is known as an albedo flip. Earth’s albedo is flipping now!

Thus begins a truly scary cascade of falling-domino events. The warming Arctic Ocean is now warming the surrounding continental shelves and the land masses of North America, Greenland, Northern Europe and Siberia.

Methane hydrates, a frozen form of methane also known as clathrates, rest on the shallow, warming, ocean floor. Methane from clathrates, which may be more abundant globally than all other fossil carbon sources combined, has 25 times the global warming potential of carbon dioxide. As shallow ocean waters warm and the methane hydrates melt, methane bubbles up to the surface, entering the atmosphere. Large areas of bubbling methane have been recently found in the East-Siberian Sea. Clathrates are melting now!

The release of methane is also occurring on land. North America and Siberia have large areas of permafrost, permanently frozen ground. The warming Arctic melts the permafrost and it, too, releases large quantities of methane. Next, the boreal forests, which grow on the permafrost and which contain more carbon than all Earth’s temperate forests combined, are collapsing and decaying, releasing their stored carbon as methane and carbon dioxide to the atmosphere. These methane and carbon releases are positive climate warming feedbacks. They add to the greenhouse effect, further warming Earth’s surface and lower atmosphere, cascading out ever faster. The permafrost is melting now!

Space does not allow me to discuss all the other ice melting, albedo flipping, carbon/methane releasing events around the globe and their impacts, but ice is melting nearly everywhere.

The dominos are falling and, if you have played this game, you know it is very hard to stop. An irreversible chain of events may already have been set in motion that will change Earth as we known it, for millennia.

We all need to wake up, open our eyes, and act to stop this madness. The time to act is now!

Bill Gran is an adjunct instructor in the field of Global Warming & Climate Change at Greenfield Community College. He lives in Heath.

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