Al Gore on the Story of Rising Seas: From Antarctica to Bangladesh

Zee Evans, National Science Foundation

by Al Gore, reposted from the Climate Reality Project

After crossing the legendary Drake Passage, we came in sight of the Antarctic continent. It is a majestic, otherworldly place. The Antarctic Peninsula, which juts northward toward South America, is lined with ice-covered mountains and surrounded by abundant wildlife in the sea. But even on this continent that looks and feels pristine, a troubling process is underway because of global warming.

The ice on land is melting at a faster rate and large ice sheets are moving toward the ocean more rapidly. As a result, sea levels are rising worldwide. Most of the world’s ice is contained in Antarctica – more than 90 percent. The West Antarctic Ice Sheet, which lies south of the Peninsula, contains enough water to raise sea levels worldwide by more than 20 feet. Part of the ice sheet, the Pine Island Glacier ice shelf, is among the many in Antarctica that are shrinking at an accelerating rate. This has direct consequences for low-lying coastal and island communities all over the world – and for their inland neighbors.

In analyzing the relationship between melting ice and sea level rise, it is important to distinguish between two kinds of ice: the ice on land and the ice floating on top of the sea. When floating ice melts, sea level is not affected, because its weight has already pushed the sea level upward. But the melting of glaciers and ice sheets resting on land does increase sea level rise. So far, the melting of small mountain glaciers and portions of ice sheets in Antarctica and Greenland has been the main contributor to sea level rise from the loss of ice. (As the oceans warm up, their volume naturally expands, and this too has been a contributor to a small portion of the sea level rise that has occurred in the age of global warming).

Scientists aren’t yet sure precisely how much sea levels will rise over the next century. What we do know is that sea level rise is occurring already, with real consequences for human beings who live near the coasts. In the world’s largest port cities, 40 million people are now already at risk of severe coastal flooding. That number could well triple within the next half-century or so.

Even wealthier countries are not immune to the impacts. In the United States, for example, particularly vulnerable areas are: Miami Beach, the Chesapeake region, coastal Louisiana, and coastal Texas. In some of these areas, the land is sinking even as the oceans rise. This will have implications that extend right up to the steps of our nation’s Capitol. A recent study found that sea level rise of only a tenth of a meter would lead to $2 billion in property damage and affect almost 68,000 people in Washington, D.C. In addition, the enhanced threat of storm surges was illustrated last year when tropical storm Irene led to warnings that the New York City subway system and tunnels into the city could be flooded.

But the most vulnerable regions lie in developing countries, where populations are still rising fast and there is little money to shore up infrastructure. The cities most threatened by sea level rise are places like Calcutta and Mumbai in India; Guangzhou, China; and Ho Chi Minh City, Vietnam. And of course, there are more than a few low-lying island nations – like the Maldives – that are already in imminent danger.

Then there is Bangladesh. A one-meter sea level rise – which could happen as soon as 2050 according to some Antarctic specialists – could result in between 22 and 35 million people in Bangladesh relocating from the areas in which they now live and work. Two-thirds of this nation is less than five meters above sea level. For the nation’s 142 million people packed into a small space, climate change poses a nearly unimaginable challenge. The threat of sea level rise is not simply flooding, but saltwater intrusion that hurts the production of rice, the country’s staple crop. Increased damage to rice farmers could soon put 20 million farmers out of work and force them into crowded cities.

Here in Antarctica, it’s easy to feel isolated from the rest of the world. But as I look at this exquisite continent buried deep under the ice, it’s troubling to think about what will happen as this ice melts ever more rapidly.

— Al Gore, originally posted at the Climate Reality Project.

Related Post:

The Greenland and Antarctic ice sheets are losing mass at an accelerating pace, according to a new NASA-funded satellite study. The findings of the study — the longest to date of changes in polar ice sheet mass — suggest these ice sheets are overtaking ice loss from Earth’s mountain glaciers and ice caps to become the dominant contributor to global sea level rise, much sooner than model forecasts have predicted.

13 Responses to Al Gore on the Story of Rising Seas: From Antarctica to Bangladesh

  1. Steve Funk says:

    Seems like I read somewhere that melting sea ice does have an effect because it is mostly frozen from fresh water and, being less dense, would float higher in salt water. Might have been in one of potholer 54’s videos.

  2. Rabid Doomsayer says:

    Ice sheets are so very complex, with relatively few scientists studying them. Our understanding has changed so much even in the last ten years.

    Each outlet glacier is different in so many ways. Lessons learnt for one glacier have to be relearned for another. Even ice has differnt structures, up to sixteen different phases. Water can remain a liquid below -20 Celcius, if the pressure is just above 200mpa.

    I am not sure where I read it, but one glaciologist said that we do not know within a factor of ten how fast things will happen.

  3. Rabid Doomsayer says:

    OK we would not get anything like 200 mpa under the ice. So presumably all the ice ice ice 1, only at points when things are moving would we generate sufficient pressure. I also have no idea how the various clathrates would behave.

  4. Tim says:

    If I’m not mistaken, the density difference is small effect. However (again, if I’m not mistaken) I was under the impression that the thermal expansion of oceans (as they warm above) about 4 C has been the largest contribution to rising water levels. Moving forward, ice melt becomes the larger effect. Someone correct me if I’m wrong though.

  5. David Fox says:

    And this coming on the heels of the second hottest American summer on record. I don’t know where this winter ranks, but given the expanse of the warmer than normal conditions, I’d imagine we have a good shot at top ten warmest.

    I wonder what could be causing all of this warmth…

  6. David Fox says:

    Sorry, meant to post that to Joe’s blog about the LA Times article.

  7. prokaryotes says:

    Here you can see US ocean property at oceanside and what 1 m looks like

    You have to factor in, salt water groundwater intrusion and erosion, which both can have a huge impact on it’s own.

  8. Sime says:

    and you would be right, normally the change would be small but if you have large volumes of ice then it starts to become significant…

    Try this over at SKS

  9. prokaryotes says:

    There is possibly a positive feedback to sea level rise, and i think it is tied to the change of ocean currents

    and since 2002 the sea surface in the western Arctic has risen by around 15cm, and the volume of fresh water has swollen by roughly 8000 cubic kilometres. This is around ten per cent of all the fresh water in the Arctic Ocean

  10. rum says:

    oh noooooo. the second warmest summer in america….oh nooooooo. so was this temp determined to the thousandth decimal place to make sure that the 1930’s didnt come into play? it just amazes me how brilliant these guys are that they know that the temp in the US is ‘whatever’ to the one thousandth can they be so accurate? i know i am just a lowly geologist and could never figure something out like this so i am glad there are scientists so brilliant that they have the ability.

  11. rum says:

    yep, those darn positive feedbacks again. makes everything so darn unstable. these positive feedbacks are getting so much more common, aren’t they?

  12. Kermit says:

    Hi, rum. Perhaps you could be more specific – discuss one particular feedback loop that distresses you, and we can discuss it or link to an article that does.

    Are you confused that some feedbacks are producing changes when they weren’t before? Remember that greenhouse gas-induced global warming is happening – about 0.8°C warmer than the start of the industrial age, I believe – so many of these various processes are moving toward homeostatis for the new conditions. Previous climate changes known from the geological and other records often show a new stable condition which lasted for centuries or even millions of years.

  13. John McCormick says:

    Yep, I get positive feed backs from rum…not all good.