Global warming has become perhaps the most complicated issue facing world leaders. On the one hand, warnings from the scientific community are becoming louder, as an increasing body of science points to rising dangers from the ongoing buildup of human-related greenhouse gases — produced mainly by the burning of fossil fuels and forests. On the other, the technological, economic and political issues that have to be resolved before a concerted worldwide effort to reduce emissions can begin have gotten no simpler, particularly in the face of a global economic slowdown.
World leaders gathered in Copenhagen in December 2009 for a session tha that had been years in the making but that fell short of even the lowered expectations with which it opened. The 192 nations in attendance at the end merely agreed to try to reach a binding accord before at a follow up meeting in Cancun, Mexico, in December 2010. By the summer, Ban-Ki Moon, the United Nations Secretary General, was saying that no sweeping accord was likely, and recommending that a better approach might consist of small steps in separate fields that built toward wider consensus.
At the heart of the international debate is a momentous tussle between rich and poor countries over who steps up first and who pays most for changed energy menus.
In the United States, Democratic leaders in the Senate in July 2010 gave up on reaching even a scaled-down climate bill, in the face of opposition from Republicans and some energy-state Democrats. The House had passed a broad cap-and-trade bill in 2009.
In the meantime, recent fluctuations in temperature have intensified the public debate over how urgently to respond. A string of large snowstorms in the Washington area and freezing weather in Florida in the winter of 2009-2010 were seized on by climate change skeptics. But the combination of flooding, heat waves and droughts in the summer were taken by most researchers trained in climate analysis as evidence to show that weather extremes are getting worse.
The long-term warming trend over the last century has been well-established, and scientists immersed in studying the climate are projecting substantial disruption in water supplies, agriculture, ecosystems and coastal communities. Passionate activists at both ends of the discourse are pushing ever harder for or against rapid action, while polls show the public locked durably in three camps — with roughly a fifth of American voters eager for action, a similar proportion aggressively rejecting projections of catastrophe and most people tuned out or confused.
Background
Scientists learned long ago that the earth's climate has powerfully shaped the history of the human species — biologically, culturally and geographically. But only in the last few decades has research revealed that humans can be a powerful influence on the climate as well.
A growing body of scientific evidence indicates that since 1950, the world's climate has been warming, primarily as a result of emissions from unfettered burning of fossil fuels and the razing of tropical forests. Such activity adds to the atmosphere's invisible blanket of carbon dioxide and other heat-trapping "greenhouse" gases. Recent research has shown that methane, which flows from landfills, livestock and oil and gas facilities, is a close second to carbon dioxide in impact on the atmosphere.
That conclusion has emerged through a broad body of analysis in fields as disparate as glaciology, the study of glacial formations, and palynology, the study of the distribution of pollen grains in lake mud. It is based on a host of assessments by the world's leadingorganizations of climate and earth scientists.
In the last several years, the scientific case that the rising human influence on climate could become disruptive has become particularly robust.
Some fluctuations in the Earth's temperature are inevitable regardless of human activity — because of decades-long ocean cycles, for example. But centuries of rising temperatures and seas lie ahead if the release of emissions from the burning of fossil fuels and deforestation continues unabated, according to theIntergovernmental Panel on Climate Change. The panel shared the2007 Nobel Peace Prize with former Vice President Al Gore for alerting the world to warming's risks.
Despite the scientific consensus on these basic conclusions, enormously important details remain murky. That reality has been seized upon by some groups and scientists disputing the overall consensus and opposing changes in energy policies.
For example, estimates of the amount of warming that would result from a doubling of greenhouse gas concentrations (compared to the level just before the Industrial Revolution got under way in the early 19th century) range from 3.6 degrees to 8 degrees Fahrenheit. The intergovernmental climate panel said it could not rule out even higher temperatures. While the low end could probably be tolerated, the high end would almost certainly result in calamitous, long-lasting disruptions of ecosystems and economies, a host of studies have concluded. A wide range of economists and earth scientists say that level of risk justifies an aggressive response.
Other questions have persisted despite a century-long accumulation of studies pointing to human-driven warming. The rate and extent at which sea levels will rise in this century as ice sheets erode remains highly uncertain, even as the long-term forecast ofcenturies of retreating shorelines remains intact. Scientists are struggling more than ever to disentangle how the heat building in the seas and atmosphere will affect the strength and number of tropical cyclones. The latest science suggests there will be more hurricanes and typhoons that reach the most dangerous categories of intensity, but fewer storms over all.
Steps Toward a Response
The debate over such climate questions pales next to the fight over what to do, or not do, in a world where fossil fuels still underpin both rich and emerging economies. With the completion of the United Nations Framework Convention on Climate Change at the Earth Summit in 1992, the world's nations pledged to avoid dangerously disrupting the climate through the buildup of greenhouse gases, but they never defined how much warming was too much.
Nonetheless, recognizing that the original climate treaty was proving ineffective, all of the world's industrialized countries except for the United States accepted binding restrictions on their greenhouse gas emissions under the Kyoto Protocol, which was negotiated in Japan in 1997. That accord took effect in 2005 and its gas restrictions expire in 2012. The United States signed the treaty, but it was never submitted for ratification, in the face of overwhelming opposition in the Senate because the pact required no steps by China or other fast-growing developing countries.
It took until 2009 for the leaders of the world's largest economic powers to agree on a dangerous climate threshold: an increase of 2 degrees Celsius (3.6 degrees Fahrenheit) from the average global temperature recorded just before the Industrial Revolution kicked into gear. (This translates into an increase of 1.3 degrees Fahrenheit above the Earth's current average temperature, about 59 degrees).
The Group of 8 industrial powers also agreed that year to a goal of reducing global emissions 50 percent by 2050, with the richest countries leading the way by cutting their emissions 80 percent. But they did not set a baseline from which to measure that reduction, and so far firm interim targets — which many climate scientists say would be more meaningful — have not been defined.
At the same time, fast-growing emerging economic powerhouses, led by China and India, still oppose taking on mandatory obligations to curb their emissions. They say they will do what they can to rein in growth in emissions — as long as their economies do not suffer. The world's poorest countries, in the meantime, are seeking payments to help make them less vulnerable to the impacts of climate change, given that the buildup in climate-warming gases so far has come mainly from richer nations. Such aid has been promised since the 1992 treaty and a fund was set up under the Kyoto Protocol. But while tens of billions of dollars are said to be needed, only millions have flowed so far.
In many ways, the debate over global climate policy is a result of aglobal "climate divide.'' Emissions of carbon dioxide per person range from less than 2 tons per year in India, where 400 million people lack access to electricity, to more than 20 in the United States. The richest countries are also best able to use wealth and technology to insulate themselves from climate hazards, while the poorest, which have done the least to cause the problem, are the most exposed.
In the meantime, a recent dip in emissions caused by the global economic slowdown is almost certain to be followed by a rise, scientists warn, and with population and appetites for energy projected to rise through mid-century, they say the entwined challenges of climate and energy will only intensify.
تعليقات
إرسال تعليق