Coastlines in Danger: The Rate of Global Sea Level Rise is Accelerating

A new NASA study published just yesterday confirms long-held warnings about rising oceans from IPCC and other climate change watch dog bodies. What it found, looking back over the last 25 years, was not only that seas were rising, but that they were rising at an ever-increasing annual rate.

If we took a snap shot of the present day, we’d find that oceans are rising at a rate of around 3.3 mm per year. If that rate were to hold steady, it would translate to a 33 centimeter rise per century. Or about 1.1 feet. This is global average rise, of course. In more vulnerable places like Tidewater, VA, or New Orleans, or Miami, such a larger swelling of the world’s ocean could translate to 2-3 feet due to local conditions like subsidence or ocean current change.

That’s bad enough. But it’s not the whole story.

(NASA study shows that sea level rise rates are accelerating due to the melting of large glaciers in Greenland and Antarctica. The key driver of this melt is human fossil fuel burning and related accumulation of heat-trapping carbon dioxide in the Earth’s atmosphere. Carbon dioxide levels this year will hit near 412 ppm in April-May, a level not seen in 10-15 million years. Video Source: NASA.)

According to NASA, that annual rate of sea level rise is also rising. In other words, it’s accelerating like a car when you slowly but inexorably increase pressure on the peddle.

The present annual increase measured by NASA’s satellites shows a 0.08 mm rate of acceleration averaged over the past 25 years. What this means is that if the rate of increase remains steady, next year seas will rise by 3.38 mm, and the following year seas will rise by 3.46 mm. Extrapolate that to the end of this Century and you’d get an annual rate of rise of around 10 mm per year — or about 3.3 feet every 100 years.

This translates to roughly 26 inches of additional sea level rise from now to 2100 globally — or about 3-5 feet in more locally vulnerable places like Tidewater, New Orleans, and Miami.

(Over the past 25 years, the rate of sea level rise has been accelerating by 0.08 mm per year. A backwards extrapolation by NASA of satellite data is a broad confirmation of sea level observations and predictions by IPCC. However, increasing ice sheet instability in Greenland and Antarctica could further spike rates of acceleration, endangering coastal cities even more. This serious global risk is amplified by continued fossil fuel burning, and moderated by more rapid transitions to clean energy. Image source: AVISO.)

Of course, given the fact that we continue to burn fossil fuels, that the necessary renewable energy transition continues to be delayed by predatory industries and their proxy politicians (primarily republicans like Trump in the United States), there is no guarantee that the rate of annual increase in sea level won’t accelerate faster than it already is. So, for this reason, the new NASA, IPCC-confirming, report should be viewed under a caveat (Dr Eric Rignot points toward sea level rise of greater than 1 meter by 2100).

In other words, if we don’t respond soon, the glaciers in Greenland and Antarctica that are already speeding the rate of global sea level rise could start to really let loose and get us into even more trouble than we already are.


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