2012高考二轮复习英语专题训练（江苏专用）专题2 阅读理解25_高考复习指南

2012高考二轮复习英语专题训练（江苏专用）专题2 阅读理解25

　　A brake on global warming—for now

　　One of the ocean’s most important climate functions is absorbing heat and carbon dioxide (CO2), one of the gases that cause global warming. Acting as a heat sponge (海绵), the oceans have absorbed huge amounts of heat and CO2 in the last forty years.

　　Fujita explains that “the oceans are saving us from faster climate change—they are a big flywheel that delays rapid overheating of the earth, putting a brake on the climate system.”

　　“That’s the good news,” he adds. “The bad news is that the oceans only slow the atmospheric warming. Once the oceans come to balance with a greenhouse-gas warmed earth, the extreme heat will remain in the atmosphere and things will get much hotter.” But where and how the oceans release this accumulated (积累) heat is uncertain. And as the ocean stores heat, fragile underwater ecosystems are struggling.

　　The most recent scientific report from the Intergovernmental Panel on Climate Change (IPCC) also notes with concern that the ocean is acidifying because of increased absorption of atmospheric CO2, and thus causing a threat for shell-forming species. Sharp increases in carbon dioxide levels will cause further acidification of the ocean.

　　Currents distributing heat

　　Another important role the oceans play is that of distributor. Oceans deliver heat and life-sustaining nutrients around the globe. Just as blood vessels bring oxygen and nutrients to cells in the human body, the ocean’s currents carry oxygen, nutrients and heat throughout the Earth. The ocean distributes 25 to 50 percent of the energy the planet receives from the sun. For example, the Gulf Stream carries heat across the Atlantic. This warm current gives northwestern Europe a milder climate than it would normally have so far north. A change to the ocean’s circulation (循环) patterns could throw Europe into a colder period, even as the rest of world experiences warmer temperatures.