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Дата добавления: 2015-09-15; просмотров: 760

A decade ago, the idea that the climate was warming up as a result of human activity was largely theoretical. We knew that since the Industrial Revolution began in the 18^th century, factories, power plants, automobiles and farms have been loading the atmosphere with heat-trapping gases, including carbon dioxide and methane. …(1)

Not any more. Two separate studies published in Science linked a significant increase in the temperature of the oceans with global warming caused by human activity. An authoritative report issued by the UN-sponsored Intergovernmental Panel on Climate Change also found that the trend to a warmer world has unquestionably begun. Worldwide temperatures have climbed more than .6ºC over the past century. After analyzing data going back at least two decades on everything from air and ocean temperatures to the spread and retreat of wildlife, the IPCC asserts that this slow but steady warming has had an impact on 420 physical processes and on animal and plant species on all continents.

Glaciers, including the legendary snows of Kilimanjaro, are disappearing from mountaintops around the globe. Coral reefs are dying off as the seas get too warm for comfort. Drought is the norm in parts of Asia and Africa. The Arctic permafrost is starting to melt. Lakes and rivers in the colder climates are freezing later and thawing earlier each year. Plants and animals are shifting their ranges poleward and to higher altitudes, and migration patterns of animals as diverse as polar bears and beluga whales are disrupted.

… (2). Nor are the changes over. Already, humans have increased the concentration of carbon dioxide, the most abundant heat-trapping gas in the atmosphere, to 30% above pre-industrial levels – and each year the rate of increase gets faster. The obvious conclusion: temperatures will keep going up.

Unfortunately, they may be rising faster and heading higher than anyone expected. By 2100, says the IPCC, average temperatures will increase between 1.4ºC and 5.8ºC – more than 50% higher than predictions of just a decade ago. … (3) Even at the low end, the changes could be problematic enough, with storms becoming more frequent and intense, droughts more pronounced, coastal areas even more severely eroded by rising seas and rainfall scarcer on agricultural land. But if the rise is significantly larger, the result could be disastrous. With seas rising as much as 88 cm, enormous areas of densely populated land – coastal Florida, much of Louisiana, the Nile Delta, the Maldives, Bangladesh – would become uninhabitable. … (4). Agriculture would be thrown in turmoil. Hundreds of millions of people would have to migrate out of unlivable regions.

Public health could suffer. Rising seas would contaminate water supplies with salt. Higher levels of urban ozone, the result of stronger sunlight and warmer temperatures, could worsen respiratory illnesses. … (5). Warmer temperatures could widen the range of disease-carrying rodents and bugs, such as mosquitoes and ticks, increasing the incidence of dengue fever, malaria, encephalitis, Lyme disease and other afflictions. … (6). Humans will have a hard time adjusting, especially in poorer countries, but for wildlife, the changes could be devastating.

As in any other area of science, the case of human-induced global warming has some uncertainties – and like many pro-business lobbyists, the US President has proclaimed those uncertainties a reason to study the problem further rather than act. But while the evidence is circumstantial, it is powerful, thanks to the IPCC painstaking research. … (7). Its mission: to sift through climate-related studies from a dozen different fields and integrate them into a coherent picture. “It isn’t just the work of a few green people,” says John Houghton, one of the early leaders who at the time ran the British Meteorological Office. “The IPCC scientists come from a wide range of backgrounds and countries.”

With the US essentially sidelining itself in the global-warming fight, it is possible that the battle may never be effectively engaged.

(From ‘Time’, abridged)