By Dr. Robert Thorson
When it’s cold, you can argue that global warming isn’t so bad after all. But global drowning? Now that’s a climate-change problem of a different color, a universally negative concept for creatures with lungs like us. That’s what’s now underway, thanks to irreversible trends in ice sheet decay.
When you’re looking at a globe, it’s easy to count the seven seas. Each of these is nothing more than a geographic district within a world ocean. Add water to the ocean anywhere, and, like pouring water into a bathtub, its level will rise everywhere.
For years, the major focus of public attention to global warming has been on weather-related concerns and ecological transitions for signature species. Rising sea level was seen as a concern for the distant future. Also, glaciologists were equivocating about the timing of the sea level rise because they couldn’t determine how stable or sluggish the ice sheets were, how fast they could disappear, and by what mechanisms.
Recently, however, they discovered some bad news. Two of the world’s three large ice sheets — Greenland and West Antarctica — are accelerating toward what is likely an irreversible meltdown into the sea. A new estimate for the total volume of ice being lost to the sea each year is 350 cubic kilometers. This translates to living space for half a billion average homes or the meeting space for a quarter-million convention centers.
If these trends continue, sea level will rise anywhere between 5 and 10 meters within a few centuries, with an unknown amount by the end of the 21st century, based on comparisons with the last interglacial ear. At maximum, this is enough to submerge the roof of your favorite seaside restaurant or marina. At the best guess of 6 meters, it’s enough to flood only the first floor. In either case, there would be no choice but to move higher, as half a billion people would be forced to do.
This is not fiction. For centuries, ship-bound explorers have watched icebergs calve into the sea. Later, newspapers published satellite photos of icebergs the size of Rhode Island breaking off from ice shelves.
Now, scientists have a new satellite tool for ice sheet monitoring. They’ve found GRACE, otherwise known as the Gravity Recovery and Climate Experiment. This imaging system allows technophiles to measure the gain or loss of weight from ice sheets. Results reported in the March 24 Science indicate that Greenland and West Antarctica are each losing billions of pounds of ice to the sea, while gaining back far less water in the form of snow. Other studies indicate that the principal mechanism of weight loss is the recent acceleration of outlet glaciers draining to the world ocean.
Basically, the polar ice sheets are slimming down. Their loss is the ocean’s gain. The ocean’s gain is a loss for individuals who are near sea level, and for the residents of states and nations with a coastline where homes, businesses, railroad lines and highways will have to be moved. This includes most countries, especially their port cities. In the United States, the list includes Boston, New York, Philadelphia, Miami, New Orleans, Los Angeles, San Francisco and Seattle.
The best thing about the scary new predictions is that it will end the political debate regarding New Orleans, which will almost certainly be an underwater archaeology site in the not-so-distant future. This case is just the metaphorical tip of the melted iceberg.
If you are an owner of shoreline property, I recommend you give some thought to what your insurance will cost a few decades from now. If you are an “anti-global-warming” activist, I recommend you accept the fact that it can’t be stopped, even if we zeroed all greenhouse gas emissions.
If you like global change statistics, consider the Kangerdlugssuaq Glacier in east Greenland, which has more than doubled its speed to 8 miles per year within the past five years.
Finally, if you are a global warming skeptic, I recommend you keep your head in the sand until the rise of the coastal water table convinces you to move.