RISING SEAS
As the planet warms, the sea rises. Coastlines flood. What will we protect? What will we abandon?
How will we face the danger of rising seas?
A seawall now protects Maale, capital of the Maldives, an Indian Ocean archipelago that is the lowest, flattest country on Earth.
By the time Hurricane Sandy veered toward the Northeast coast of the United States last October 29, it had mauled several countries in the Caribbean and left dozens dead. Faced with the largest storm ever spawned over the Atlantic, New York and other cities ordered mandatory evacuations of low-lying areas. Not everyone complied. Those who chose to ride out Sandy got a preview of the future, in which a warmer world will lead to inexorably rising seas.
A profoundly altered planet is what our fossil-fuel-driven civilization is creating, a planet where Sandy-scale flooding will become more common and more destructive for the world’s coastal cities. By releasing carbon dioxide and other heat-trapping gases into the atmosphere, we have warmed the Earth by more than a full degree Fahrenheit over the past century and raised sea level by about eight inches. Even if we stopped burning all fossil fuels tomorrow, the existing greenhouse gases would continue to warm the Earth for centuries. We have irreversibly committed future generations to a hotter world and rising seas. (…)
Global warming affects sea level in two ways. About a third of its current rise comes from thermal expansion – from the fact that water grows in volume as it warms. The rest comes from the melting of ice on land. So far it’s been mostly mountain glaciers, but the big concern for the future is the giant ice sheets in Greenland and Antarctica. Six years ago the Intergovernmental Panel on Climate Change (IPCC) issued a report predicting a maximum of 23 inches of sea-level rise by the end of this century. (…) However, that report intentionally omitted the possibility that the ice sheets might flow more rapidly into the sea, on the grounds that the physics of that process was poorly understood. But climate scientists now estimate that Greenland and Antarctica combined have lost on average about 50 cubic miles of ice each year since 1992 – roughly 200 billion metric tons of ice annually. Many think sea level will be at least three higher than today by 2100.
(National Geographic magazine. Vol. 224, nº 3, September 2013. Adaptado.)
No 2º parágrafo, as ocorrências do pronome we estabelecem referência com
