How High the Seas?

Living as I do in San Francisco, along the coast, I remain deeply curious how high the sea rise is likely to be, between now and 2100. I have a cousin who recently bought a house in our Marina district. I kid that he may have to move to higher ground before too many years pass. Reading a new book by Peter Ward, Biology and Earth and Space Science Professor at the University of Washington in Seattle (The Flooded Earth: Our Future in a World Without Ice Caps), I learned, for the first time, that there is already in place a Bay Area Planning Commission which set out goals, in 2008, to plan for a likely three foot sea level rise. Unlike in Venice, Bangkok and other threatened cities, the planning commission has set in place plans to manage the rising waters. It readily acknowledges how unpleasant, sometimes dicey, such planning can be.

The bay area commission calls for plans to engage, if necessary, in triage: what to save and what to surrender. As the 2008 plan reads: “The plan should determine the measures needed to adapt to projected sea level rise by identifying: (a) the most significant structural, environmental, aesthetic, social, cultural and historic resources that must be protected from inundation; (b) those areas that are inappropriate for protection from inundation; (c)strategies and techniques that will make future conservation and development projects more resilient to climate change.


As many know, The International Panel on Climate Change in its 2007 report—much to the delight of some observers—predicted sea rises of from 18mm to 59mm in the twenty-first century. The 59 mm maximum the IPCC predicted (around 2 feet) is lower than the Bay Area’s Commission’s projected 3 feet or cognate projections of  the Dutch Delta Commission, which is investing $144 billion on its plan to protect below sea-level areas of the Netherlands from sea level rises. The Dutch commission reckoned on a 4.25 foot rise by 2100 and, perhaps, a rise of 6.5 feet by 2200. Even the IPCC’ s more conservative estimate of .59 meters would devastate parts of Bangladesh, where a sea level rise of 400 mm at the Bay of Bengal would put 11%  (some 10 million) Bangladeshi citizens in peril. A sea level rise of 200 mm would cause 740,000 environmental refugees or homeless in Nigeria.

The question o how high the sea is likely to rise in the next ninety or so years is, partially, a question of scientific predictions; it is, equally, a question of planning and investment for the future. Clearly, even the more conservative estimates of sea rise might imperil (at the great cost in billions of re-building the airports elsewhere) the airports of San Francisco and Seattle. Even when the IPCC’s predicted sea level rise of a maximum of .59 meters appeared,  many scientists raised serious questions about the accuracy of its model. James Hansen, the NASA climatologist, in his recent book, Storms of My Grandchildren set his estimate of a minimum of 5 feet rise by the end of this century. Stefan Rahmstorf in a blog post on the influential scientific web site,, suggests that there were faulty assumptions in the IPCC’s predictive model for sea rise. He predicts a possible meter rise in sea levels.

The IPCC model assumed that the ice sheet melt rates of 1993-2000 would continue, along the same average measure, throughout the rest of the century. Even members of the IPCC (including Rahmsfort, representing Germany) thought  that assumption was much too optimistic, especially since the rates of 1993-2000 already showed a significant increase (a rise of sea level from 1.8 mm per year to 2.8 to 3.1 mm per year) over sea rise rates before 1993. Much depends, in projections about sea level rise, on two variables: how fast will the ice sheets around Greenland and Antarctica melt. Another important variable is global warming’s impact on ocean warming. Warmer water expands the oceans.  An important article in Science (Sept., 2008) by W.T. Pfefer "‘Kinematic Constraints on Glacier Contributions to 21st Century Sea Level Rise," projects rises of from 0.8 to 2 meters in this century. A one meter rise would have a major impact on 100 million people. In point of fact, based on IPCC projections, the recent ice melts are faster and more extensive than predicted.

There are, of course, uncertainties in every model of future global warming. In part, we have not experienced such impacts for a long time. No sane person or planner, however, would discount that global warming is happening and will increase and so, also, will sea level rise, due to melting ice sheets. It pays to read a book such as, The Flooded Earth, or connect with the Web site,, to get a tutored sense of what is uncertain and what is beyond doubt.

Some of the uncertainties about global warming involve how high it can go to be tolerable (yet, inevitably, at some true financial costs to contain its negative consequences): can we sustain 450 ppm of C02 or will that take us too close to a tipping point of feedbacks (such as the melting of the tundras and the belching release of buried methane) so that, following the advice of James Hansen and Bill McKibben, we should aim more toward stabilizing parts per million of CO2 at 350 (it presently stands at 390)?

How much more warming of the oceans can we sustain? Already, in 1957, scientists Roger Reville and Hans Seus noted that “the oceans could not absorb CO2 as rapidly as humanity was releasing it.” With the ocean "sinks" filling up with CO2, the oceans have also become more acidic, threatening all coral reefs worldwide and encrusted sea fish. Warmer oceans also further erode ice sheets.

Another set of uncertainties have to do with how fast the warming will occur and, thus, how much time we have. Some have already despaired that it is too late. Others think we still have a margin of opportunity. Again, there are both “forcings” toward climate change (not all of them man-made) and feedback mechanisms. The more the glacial ice or ice sheets melt, the less the albedo effect (being able to reflect the sunlight back into space rather than absorbing it). That feedback exacerbates global warming.

Sea rise also threatens to involve coastal flooding and even deep contamination of fresh water sources. The Flooded Earth brought issues closer to home, for me, as it discussed The California Federal Bay Delta System. Deltas can be wonderful agricultural areas. A delta involves the inter-section of inflowing rivers where salt water meets fresh. In California, a major effort has been made to export the fresh water from the Sacramento River as it flows into the San Francisco bay to down-state San Joaquin Valley farmers. But as Ward notes in his book, “When freshwater is withdrawn at a faster rate than it can be replenished, the water table lowers with a decrease in overall hydrostatic pressure. When this happens near an ocean coastal area, salt water from the ocean intrudes into the freshwater aquifers.” So sea level rise can have important ramifications for fresh water supplies for drinking water. Salt contaminated fresh water supplies devastates farming.

Much money has been spent by fossil fuel-fueled lobbyists to raise skepticism about global warming (cf. James Hoggan’s Climate Cover-Up). But insurers, national security planners or coastal planning commissions can not take such a nonchalantly skeptical view. Too much is at stake for them—and for us too!

John Coleman, S.J.


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Bill Collier
7 years ago
Computer models and predictions are already of little value to some of the low-lying island nations in the South Pacific (e.g., Kiribati and Tuvalu) and the Indian Ocean (e.g., the Maldives). It's a near certainty that by mid-century they will either be completely submerged or that their fresh-water supplies will have been destroyed by sea water.

The Bay of Bengal is mentioned in Fr. Coleman's timely and important post. Earlier this year, the once-inhabited New Moore Island in the Bay of Bengal became completely submerged. NMI was the focus of a decades-long territorial dispute between India and Bangladesh. Perhaps resolution of trans-national territorial disputes will be an unforeseen silving lining to the problem of the rising oceans. :(
7 years ago
"Much money has been spent by fossil fuel-fueled lobbyists to raise skepticism about global warming (cf. James Hoggan’s Climate Cover-Up)."

If I'm not mistaken, the only actual verifiable evidence of any group in this debate acting inappropriately is on YOUR side of the argument, i.e. the UN Commission and the well-documented problems with its conclusions being influenced by non-scientific factors (which somehow never got mentioned on this blog).  So it seems a bit of a stretch (not mention intellectually lazy and unfair) to characterize the other side of the argument (which includes a Nobel-prize winner) as emanating merely from some nefarious, if not immoral, (profit) motive. 

For the record, I am not a full-blown global warming skeptic, only the "fixes" scare me.
David Cruz-Uribe
7 years ago
Actually, James Hogan's book provides exhaustive detail about the lies, obfuscations and irrelevancies that climate skeptics routinely use to confuse the discussion and deny the science that lies behind the study of global warming.  Further, the cash trail between many such skeptics and the fossil fuel industry (e.g. Big Oil and Big Coal) is equally well documented.  As the old comic strip said, "Cherchez le femme!"  A good example of this policy of lies and obfuscation has been the heated attacks on the IPCC and on the climate scientists involved in "ClimateGate."  In every case, outside evaluations have cleared them any wrongdoing. 

I would be vastly prefer non-statist solutions to global warming.  But we would first have to get everyone to agree that there is a serious problem, which the climate skeptics are devoted to preventing from happening.
7 years ago
"the heated attacks on the IPCC and on the climate scientists involved in "ClimateGate."  In every case, outside evaluations have cleared them any wrongdoing."

This is totally inaccurate.  The IPCC has faced documented international opprobrium for its shabby policices and rushed conclusions.

Again, dismissing people on the other side as merely manipulated by profit, or some other nefarious motive, is intellectually lazy and unfair.
Stanley Kopacz
7 years ago
I'll go with the consensus of the climatologists.  But I doubt we will change anything sufficiently.  Too many are making a buck off the status quo.  And the average american doesn't really want to change his or her lifestyle.  They'd rather blissfully sleepwalk.  THey can't even carpool enough to dissipate their traffic jams and get to work without a hassle.  So the disaster will happen in one form or another.  I'm pretty sure the human population will crash by the end of the century.  I donate to al these environmental groups but, in the back of my mind, I'm afraid original selfishness will win out.
Tom Maher
7 years ago
The ice sheet have been melting for 11,000 years amd jave casued millions of square miles of low-lying coastal lands to be submerged hundreds of feet below the surface of the ocean around the world.  Underwater archielogy hs found hundeds of intact cities a hundred feet underwater and amny miles offshore.  Since most of these underwate cities were discoveries within the last twently years it is obvious many more will be found. 

A mere 11,000 years to melt an ice sheet whcih was a mile thick and covered about a quarter of the earth surface is by itself a very accelerated process.  These massive ice sheets were formed  over hundreds of thoussands of years but were melted in a fractional part of time of only 11,000 years.  The warming of theearth climate is by itself a very agressive prcess that would naturally accellerate on its own the same a a pot of water absorb energy at an accelatated rate with a constant heat source.   The acceration of global warming is a natural outcome that is the overwhelming cause of climate change.  Human msut adapt to the overwhelming force of nature.   
David Cruz-Uribe
7 years ago
@Jeff Landry

The WSJ is well known for its bias against the science of climate change.  Reading the linked article carefully, it begins by giving credence to ClimateGate which was a non-issue:  see the report by Penn State completely exonerating the scientists involved:

As for the IPCC, again, the report seems determined to take molehills and blow them into mountains.  I refer you to the the report of the InterAcademy Council which says very few bad things (certainly not "international opobrium")  and makes recommendations for making its reports (already regarded as good) better.

 The whole flap over the IPCC was discussed in depth on the RealClimate blog:

And I never "dismissed the other side as merely manipulated by profit, or some other nefarious motive":  you are misreading me.  Nevertheless, when confronted with large quantities of money flowing from corporations with a vested interest in denying or downplaying the reality of global warming, I think it is legitimate to call this out.  When people such as "Lord" Monckton continue to spout demonstrable falsehoods and belittle science they clearly do not understand, then I think I can question their motives without being "intellectually lazy or unfair."

@Tom Maher

While the discoveries of underwater archeology are fascinating, they are mostly irrelevant.  The data show that the earth is warming at an accelerating rate and there are no natural forces which could cause this:  all the evidence points to anthropogenic CO2 as the cause of global warming.  A natural process would not   "accellerate on its own the same a a pot of water absorb energy at an accelatated rate with a constant heat source"  this is incorrect physics.  The rate at which water aborbs heat (more accurately, its specific heat) is essentially constant.  If you put a pot the stove with a constant flame, the time to raise it one degree is the same when it is room temperature as when it is almost boiling.
COline Doherty
5 years 11 months ago
Environmental change has a multiplier effect on other drivers of migration, such as economic hardship and crop failure. Yet terms such as “environmental refugees” and “climate refugees” may cause more problems than they solve. Neither category has status under international law. In the case of small island nations, there is an additional obstacle: If a whole state becomes submerged or uninhabitable, and there is no prospect of return, temporary refuge will not be enough. Bogumil Terminski argued in “Environmentally Induced Migrations” that there is a huge conceptual difference between “environmental migrants” and “environmental refugees”. According to this author environmental migrant is a persons making a short-lived, cyclical, or longerterm change of residence, of a voluntary or forced character, due to specific environmental factors. Environmental refugees, therefore, are people compelled to spontaneous, short-lived, cyclical, or longer-term changes of residence due to sudden or gradually worsening changes in environmental factors important to their living, which may be of either a short-term or an irreversible character. As the evidence for global environmental change has accumulated over the past decade, academics, policymakers, and the media have given more attention to the issue of “environmental refugees.” A major concern is whether environmental change will displace large numbers of vulnerable people in the developing world, particularly from rural areas where livelihoods are especially dependent on climate and natural resources. A widely cited article estimated that more than 25 million people were displaced by environmental factors in 1995. Myers argued that the causes of environmental displacement would include desertification, lack of water, salination of irrigated lands and the depletion of bio-diversity. He also hypothesised that displacement would amount to 30m in China, 30m in India, 15m in Bangladesh, 14m in Egypt, 10m in other delta areas and coastal zones, 1m in island states, and with otherwise agriculturally displaced people totalling 50m (Myers & Kent 1995) by 2050.


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