The massive layer of ice covering Greenland melted at a faster rate in July than at any other time in recorded history, with 97% of the entire ice sheet showing signs of significant thaw. The unprecedented rapid melting, which was captured in images taken from several satellites and released by NASA, alarmed scientists and deepened fears about the immediate consequences of climate change. Water once safely anchored in glacial ice is now surging into the sea at an alarming rate. Within a just a few decades, the flow could become a deluge, with millions of people living near coastlines in danger of inundation.
But scientists don’t yet know how fast this ice will melt, or how high our seas could rise as a result. In an effort to find out, a team of renowned and quirky geologists took a 4,000-mile road trip across Western Australia. They collected fossils and rocks from ancient shorelines and accumulated new evidence that ancient sea levels were frighteningly high during epochs when average global temperatures were barely higher than today.
In the new TED Book Deep Water: As Polar Ice Melts, Scientists Debate How High Our Oceans Will Rise, veteran environmental journalist, radio producer and documentary filmmaker Daniel Grossman explores the new and fascinating science — and scientists — of sea-level rise. His investigation turns up both startling and worrisome evidence that humans are upsetting a delicate natural equilibrium. If knocked off balance, it could hastily melt the planet’s ice and send sea level soaring.
We talked with Grossman about what inspired his new book.
The recent news of the Greenland ice melt is very troubling. Polar ice seems to be melting at an increasing rate. How worried should we be?
Very worried. There is good evidence that two of the three polar ice sheets — the Greenland and West Antarctic ice sheets — are beginning to shrink. While the amount they lose each year is small compared to the volume of the ocean, nobody knows how much the loss could accelerate in the future. Researchers of past climates have discovered natural incidents where sea level rose abruptly. Could the unprecedented warming and rate of warming of the 20th and 21st century catalyze a catastrophic collapse of the ice sheets? Nobody can say yet. According to some researchers I’ve spoken to, it could be that such a collapse is already under way and we just can’t see it yet.
Your book details the debate, even among scientists, of the rate of the melt. Why is it so hard to predict this precisely?
It is very difficult to figure out what’s happening with something as big as the Greenland or Antarctic ice sheets. If they were a country, the East and West Antarctic ice sheets would together be second in size only to Russia. They occupy the most forbidding and distant part of the planet. Also, despite the importance of studying polar ice, the scientific community is not provided with the resources it needs. Just to take one example: NASA doesn’t have a functioning icebreaker to clear a path for fuel and supplies to McMurdo Station, the largest and most important base in Antarctica. One of the two NASA breakers that used to service McMurdo has been mothballed. The other is dry-docked for repairs. Several years ago, I sailed on one of the world’s most powerful icebreakers, the Swedish ship Oden. The US has been leasing such ships for several years as a stopgap.
Scientists can observe what’s happening at the poles by satellite. But the satellite record only goes back several decades. Moreover, some important satellites have failed or retired early and haven’t been replaced. For instance, NASA’s ICESAT satellite monitored the ice sheets between 2003 and 2010, before failing. It had made more than a billion measurements of the elevation of the ice sheets. Due to budgetary restrictions, a replacement isn’t scheduled to be lofted until 2016. In the meantime, NASA flies a specially equipped aircraft in passes over Greenland and the Antarctic. (See Grossman’s interview on Living on Earth about Operation Ice Bridge.)
Scientists try to use computer models of ice sheets, informed by estimates of future warming, to predict melting. But not enough is known about how ice sheets behave to anticipate with certainty what will happen in the future. Today’s warming is like a global experimental trial that will only be run once. Some scientists believe that the best way to anticipate the results is to look back in time to see how Earth’s various parts responded to warming in the past. The approach makes sense, but it’s imperfect
Why is there so much difference in opinion amongst the scientists in this field?
Trying to understand what will happen to the ice sheets in the future is a difficult, cutting-edge scientific and technical challenge. As with any question on the ragged edge of scientific understanding, there are a variety of opinions and hypotheses. In contrast to many areas of scientific inquiry, the answer to this question is of grave consequence to the United States and the rest of the world. Unfortunately, the research is not funded as if it were an urgent national priority rather than simply an interesting curiosity. If Americans appreciated the seriousness of the potential that polar ice sheets could melt dramatically in the future, I believe they would demand that appropriate scientific studies be given higher priority.
Is the game already over? Can we slow polar ice melt?
The most worrisome indication that we might have started circling the drain concerns not ice sheets, but the floating sea ice in the Arctic. The sea ice there responds faster than glaciers to warming conditions, because it is never more than about 15 feet thick, and generally only 3 to 6 feet thick. Each year the sea ice expands to fill most of the Arctic Ocean in the winter and then contracts to about half its area in the summer. (Here’s a cool NASA visualization of the annual process.) The minimum size of the ice cap has been declining precipitously in the last 40 years. The rate increased substantially around 2000. In 2007, the minimum size reached the smallest ever observed, 37 percent smaller than the average size between 1979 and 2000. The size of the Arctic sea ice has no impact on sea level, since it is floating. (For the same reason, a full glass of soda doesn’t overflow when its ice cubes melt.) But brilliant white ice reflects much more solar energy than dark ocean water. Researchers say it is likely that within a matter of decades the Arctic will be ice-free in summers. That will vastly increase the amount of heat absorbed in the Arctic. The Greenland Ice Sheet nearby will warm faster, accelerating its loss of ice to the sea.
For all anyone knows, the insulating blanket of carbon dioxide that humans beings have spewed into the air has already set in motion an unstoppable process that will unleash the polar ice sheets, causing catastrophic sea level rise. But we might not know for decades. In the meantime, the sensible course of action would be to act as if it is not too late do do anything.
Your new book is not only a scientific story, it’s an adventure story. What’s the strangest place you’ve ever been while reporting on climate change?
I’ve been to many unusual places. In 2009, I reported on concern about decreased rainfall in parts of South Africa and Mozambique. Among the places I visited was the small kingdom of the Balobedu people of South Africa. There the Rain Queen, or Modjadji, is supposed to bless the region with abundant precipitation in otherwise-dry Limpopo Province. The most recent queen had recently died and nobody had yet succeeded her. However, an ancient attendant received me in a royal courtyard, a circle of heavily trodden earth surrounded by a tall stick fence. In Mozambique I visited a bat guano mine, which a project of CARE was reviving as a way to help increase agricultural productivity.
My most fun trip I’ve taken was to Palmer Station, the smallest US base in Antarctica, on the Antarctic Peninsula. I spent a month there with a small crew of quirky researchers and support staff. While the scientific research there was serious — I reported on research showing that the dramatic decline of Adélie penguins was caused by melting sea ice — the base sometimes reminded me of a summer camp for adults. The inhabitants organized activities like tie-dying to keep from going stir crazy. They played practical jokes on each other and sometimes jumped into their inflatable Zodiac boats to get closeup looks at whales that happened by.
Deep Water: As Polar Ice Melts, Scientists Debate How High Our Oceans Will Rise is part of the TED Books series.