'Irreversible' warming to raise sea levels

European researchers are saying irreversible warming triggered by greenhouse gases will cause sea levels to rise for thousands of years to come. Writing in the journal Environmental Research Letters, published by the Institute of Physics in London, scientists said as a result of greenhouse gas emissions up to now the world is committed to a sea-level rise of 3.6 feet by the year 3000. The study is the first to include glaciers, ice caps and the Greenland and Antarctic ice sheets in a projection of sea-level rises, the researchers said. In their analysis the Greenland ice sheet will be responsible for more than half of the sea level rises, they said, and that impact can cover huge time spans. "Ice sheets are very slow components in the climate system; they respond on time scales of thousands of years," study co-author Philippe Huybrechts said. "Together with the long life-time of greenhouse gases in the atmosphere, this inertia is the real poison on the climate system: Anything we do now that changes the forcing in the climate system will necessarily have long consequences for the ice sheets and sea level." The eventual severity of the problem could depend on the route the world takes to mitigate emissions, Huybrechts said. "Mankind should limit the concentration of greenhouse gases at the lowest possible level as soon as possible," he said. "The only realistic option is a drastic reduction of the emissions. "The lower the ultimate warming will be, the less severe the ultimate consequences will be."