We must act to address Global Warming by Jeffrey D. Sachs 1:09pm 9th Mar, 2007   March 19, 2007    Action on warming could curb nightmare impacts, by Alister Doyle. (Reuters)    Cuts in emissions of greenhouse gases can mute the worst impacts of global warming, such as water shortages for billions of people or extinction of almost half of Amazonian tree species, a draft U.N. report shows. The report, due for release on April 6, foresees ever worsening damage to the planet as temperatures gain, including rising seas that could swamp low-lying Pacific island states or declining crop yields that could mean hunger for millions.    "The longer we go without action (to curb greenhouse gases) the more likely it is that some of the big feedbacks will kick in," Richard Betts, manager of the climate impacts research team at the British Met Office and Hadley Center.    "We can make a big difference by either choosing a low emissions scenario or a high emissions scenario," said Gunnar Myhre, of the Center for International Climate and Environmental Research in Oslo.    Both were among lead authors of a U.N. climate report in February, based on the work of 2,500 scientists, that laid out scenarios of temperature rises of 1.1-6.4 Celsius (2 to 11.5 Fahrenheit) by 2100 over 1990 levels.    In the scenarios, the biggest temperature gain comes if the world stays dependent on fossil fuels, with 70 percent of energy in 2100 from sources such as coal and gas, and sharply raises greenhouse gas emissions.    The scenario with the smallest temperature gain, below about 3 Celsius (5.4 F), assumes that carbon emissions will dip by 2100 by when the world will get about half its energy from renewable sources.    The draft report, due for release in Brussels, will build on the first part and lay out the regional impacts of climate change, such as a drying of the Amazon basin or a sharp contraction of vast Himalayan glaciers that feed rivers in Asia.    In the draft, a temperature rise above about 3C could mean a sharp expansion in water shortages, for 1.1 to 3.2 billion people.    At about that level potential crop yields would also start to fall in all parts of the world after briefly benefiting farmers in some regions away from the tropics.    And above about a 4 Celsius (7.2 F) gain, one scenario sees a potential extinction of about 45 percent of Amazonian tree species.    "The uncertainties in the emissions scenarios are as large, if not larger, than uncertainties about the response of the climate" to greenhouse gases, Betts said. Both Betts and Myhre declined comment on the regional impacts.    "The scenarios depend on the evolution of society, how population will grow, what technology will be used, how the economy will grow," he said.    Mar. 08, 2007    A Climate for Change, by Jeffrey D. Sachs. (Time Magazine)    When climate-change skeptics mock the fear about a rise of a "few degrees" in temperature, we should remind them of how it feels to have a 103° fever. A few degrees above normal can mean the difference between life and death, species survival and extinction. And a few actions on our part could make the difference between a healthy planet and one that falls into an environmental tailspin.    Many climate shocks have already become more common: powerful hurricanes, droughts, heat waves and blizzards. Much worse will come unless we stabilize the level of carbon dioxide, or CO2, in the atmosphere at safe levels. Before the industrial era, CO2 concentration was 280 parts per million (p.p.m.) in the atmosphere. If current trends continue, that could reach 560 p.p.m. by mid-century. Yet because our energy system is so deeply embedded in the world economy--in vehicles, power plants, factories, residences and office buildings--it will take decades to reamp it. So people who care about the future of the planet will need to push for businesses to produce electricity, concrete, steel and plastics in new ways.    Concerned citizens will also have to think globally. The U.S. is about to be overtaken by China as the world''s largest emitter of CO2 from energy use. For years we have brushed off the rest of the world as other countries have pleaded for the U.S. to get its house in order. Now as China''s CO2 output threatens more intense hurricanes and droughts in the U.S., the tables are turned, and we will certainly want China to control emissions. In fact, since CO2 mixes freely in the atmosphere, every country''s climate depends on the whole world''s actions. The good news is that global action, if timely and strong, could head off a doubling of CO2 at an annual cost of less than 1% of world income.    The timing for a global agreement is right. In December the U.S. and the rest of the world will begin negotiating a set of standards to follow the Kyoto Protocol, which expires in 2012. The new rules need to embody certain key realities: all countries must join; the world''s power plants, automobile fleets and buildings will have to shift to low-carbon technologies; a world "price" must be charged for emitting carbon into the atmosphere to provide a market incentive for companies and governments to make the changeover. And rich countries must help poor countries get on the low-carbon track by, for example, compensating them for ending the deforestation that leads to carbon emissions as well as a loss of biodiversity.    Earlier this month, the Global Roundtable on Climate Change, which is based at the Earth Institute at Columbia University and includes companies and organizations from all parts of the world, adopted a consensus statement that could serve as a template for an international agreement. Green-technology leaders like General Electric, insurance leaders like Swiss Re, automobile firms like Volvo and innovative Chinese and Indian firms all endorsed it, as did many of the world''s prominent scientists.    Now you can join as well. The roundtable invites you to add your signature to show that the citizens of the world yearn for a serious and global agreement, one based on the best science and the interests of our children. By signing you can send a powerful message to politicians and business leaders around the globe that climate change is a battle for our common future.    * Sachs, author of The End of Poverty, directs the Earth Institute at Columbia University Visit the related web page
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