Before today, sea level rise and flooding were already forecast to wreak havoc for millions now and in the coming decades. Now, the story looks much worse three times worse, to be precise. According to new research, hundreds of millions more people are already at risk from climate breakdown-caused coastal flooding and sea level rise than previously thought. And by the end of the century, large swathes of the coastal land we live on today could be unihabitable even with immediate and deep emissions cuts.
Existing estimates of risk from sea-level rise taken from NASA’s Shuttle Radar Topography Mission didn’t exactly paint a rosy picture for coastal communities. But in using space-based satellite imagery to measures the elevations of surfaces closest to the sky, much of the data actually reported the elevation of treetops and rooftops, rather than the ground itself. As a result, it overestimates coastal elevations by more than two metres on average, and more than four metres in urban areas.
This may not sound like much, but for millions of people two or three metres is the difference between safety or loss of livelihood and forced relocation. Thankfully, a handful of nations have now scanned coastal elevation using airborne laser-based radar equipment, and the new research, published in Nature Communications, uses the difference between these much more precise data and previously existing figures to recalibrate global estimates for land at risk of sea-level rise and flooding.
Based on the new model, the authors estimate not 28m but 110m people are already living below the current high tide line. And instead of 68m people living below annual flood levels, the figure is now 250m the same number that live less than one metre above sea level. That’s the equivalent of the UK, Russia, and Spain combined.
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