The resulting rapid warming of both the atmosphere and the ocean, which Kolbert notes has absorbed about one-third of the carbon dioxide we have produced, is wreaking havoc on earth’s delicately balanced ecosystems. It threatens both the web of living species with which we share the planet and the future viability of civilization. “By disrupting these systems,” Kolbert writes, “we’re putting our own survival in danger.”
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The earth’s water cycle is being dangerously disturbed, as warmer oceans evaporate more water vapor into the air. Warmer air holds more moisture (there has been an astonishing 4 percent increase in global humidity in just the last 30 years) and funnels it toward landmasses, where it is released in much larger downpours, causing larger and more frequent floods and mudslides.
The extra heat is also absorbed in the top layer of the seas, which makes ocean-based storms more destructive. Just before Hurricane Sandy, the area of the Atlantic immediately windward from New York City and New Jersey was up to nine degrees warmer than normal. And just before Typhoon Haiyan hit the Philippines, the area of the Pacific from which it drew its energy was about 5.4 degrees above average.
Our oceans, a crucial food source for billions, have become not only warmer but also more acidic than they have been in millions of years. They struggle to absorb excess heat and carbon pollution — which is why, as Kolbert points out, coral reefs might be the first entire ecosystem to go extinct in the modern era.
The same extra heat pulls moisture from soil in drought-prone regions, causing deeper and longer-lasting droughts. The drying of trees and other vegetation leads also to an increase in the frequency and average size of fires.
Food crops are threatened not only by more pests and the disruption of long-predictable rainy season-dry season patterns, but also by the growing impact of heat stress itself on corn, wheat, rice and other staples.
Earth’s ice-covered regions are melting. The vanishing of the Arctic ice cap is changing the heat absorption at the top of the world, and may be affecting the location of the Northern Hemisphere jet stream and storm tracks and slowing down the movement of storm systems. Meanwhile, the growing loss of ice in Antarctica and Greenland is accelerating sea level rise and threatening low-lying coastal cities and regions.
Viruses, bacteria, disease-carrying species like mosquitoes and ticks, and pest species like bark beetles are now being pushed far beyond their native ranges. Everywhere the intricate interconnections crucial to sustaining life are increasingly being pulled apart.
via ‘The Sixth Extinction,’ by Elizabeth Kolbert – NYTimes.com.
