Ice at the top and bottom of the planet - on Greenland and Antarctica - is melting faster than scientists previously thought, thanks to warming temperatures. This freshwater ice will pour into the ocean, causing sea levels to rise as much as three feet by the end of the century, and 20 feet or more after that. These are the alarming conclusions of a group of top climate researchers, including Dr. Bette Otto-Bliesner, a climate change scientist at the National Center for Atmospheric Research, in Boulder, Colo.

It's not new news that the ice sheets are melting and will cause sea level to rise - submerging coastal areas around the world. But Otto-Bliesner and her colleagues found that the rate at which the ice melts could accelerate, leading to more rapid rising of the oceans. There's still time to stem the tide of ice melt. But unless we do something soon to reduce greenhouse gas emissions, the scientists say, the melting process will become irreversible.

The research combines data from ice cores, coral records, and other geologic records of past climate, with computer simulations of climate. LIME talked with Dr. Bliesner about melting ice and rising sea levels.

LIME: You recently published two papers in Science that found that ice at the poles could be melting more quickly than previous research had predicted, and that this could contribute to significant - and rapid - sea level rise. What sort of time-frame are we talking about, and how much will sea levels rise?

DR. OTTO-BLIESNER: Over the next 100 years, sea level will likely rise by 0.5 to one meter (one to three feet) due to thermal expansion of the ocean as it warms and some melting of glaciers and ice sheets. Our results indicate that if Arctic summers warm to the levels of the Last Interglaciation [the melting period after the penultimate ice age, about 120,000 years ago] then Greenland and Antarctica will contribute increasing amounts of water to sea level rise. Evidence including ancient corals dated to the Last Interglaciation suggests that sea level may have risen at rates possibly exceeding one meter (three feet) per century.

LIME: What other events could or will be set in motion when this happens? Are there feedbacks we need to worry about? How concerned should we be?

DR. OTTO-BLIESNER: Sea level rise will affect low-lying areas and also areas prone to storm surges.

LIME: What would you say is the most significant research on climate change to emerge over the last year or two, and why?

DR. OTTO-BLIESNER: I wouldn't pinpoint just one study. It is the body of evidence building up that the climate system is changing - accelerating glaciers along the edges of Greenland and Antarctica [breaking off into the ocean at a faster rate], thawing permafrost [frozen ground in the Arctic], etc; evidence of dramatic changes in sea level during warmer periods in the past; and climate model results that project a warmer future Earth, not that much warmer than in the past when dramatic changes occurred.

LIME: What popular climate misconception would you most like to clear up?

DR. OTTO-BLIESNER: The misconception that there isn't a broad consensus among climate scientists that global warming is real and that human-induced changes are a major contributor.

LIME: As a scientist who studies the climate, you are likely confronted with disturbing facts about climate change on a daily basis. Has this led you to make any changes in your own lifestyle to reduce your impact?

DR. OTTO-BLIESNER: We are currently looking at various models of hybrid cars to replace my old car. I also try to drive less, combining many errands into one trip.

Image credit: Bette Otto-Bliesner, National Center for Atmospheric Research