The Earth is Okay with a 400-Foot Sea-Level Rise

Whether or not Goklany is OK with a 250-foot sea level rise (SLR) — thank you, Mr. Romm, for putting words in my mouth! — the earth is OK despite a 400-foot rise since the last ice age. This translates into an average SLR of 22 feet per 1,000 years. The peak rate of SLR was undoubtedly much greater. So one must ask: What were the consequences of such a rapid rate of rise, and what do they tell us about the resilience of the rest of nature?

Mr. Romm says sea level could rise by 250 feet. But instead of being terrified by climate change (to use his word), let’s try some rational risk analysis.  What is this estimate based upon? Over what period of time is this rise supposed to take place? It makes a difference whether it’s decades, centuries, or millennia. He also confuses a possible geological catastrophe (such as melting of ice sheets) with a real socioeconomic catastrophe.  But a geological catastrophe does not necessarily imply a socioeconomic catastrophe, unless society is immobilized.

This is what the IPCC’s WG I SPM (p. 17) says about the Greenland Ice Sheet, “If a negative surface mass balance were sustained for millennia, that would lead to virtually complete elimination of the Greenland Ice Sheet and a resulting contribution to sea level rise of about 7 m.” [Emphasis added.] Presumably the same applies to other ice sheets.

But where is the showing that a negative surface mass balance will, in fact, be sustained for millennia? Even if climate models were perfect — and we know they are not, which is why they are called “models” — one would have to question the validity of any such exercise. What socioeconomic scenario is it based upon? What is assumed regarding the sum total of fossil fuels available to humanity? How long are we assumed to stay primarily reliant on fossil fuels, considering that cheaper renewables are supposedly around the corner, if not here already? How likely is it that such scenarios can be forecast with any confidence beyond a few years, let alone millennia?

Second, if it’s millennia, as the IPCC says, or even centuries, that gives us ample time to adjust, albeit at substantial socieconomic costs. But it need not be prohibitive or dangerous to life and limb if: (1) the total amount of SLR and, perhaps more importantly, the rate of SLR can be forecast with some confidence; (2) the rate of SLR is slow relative to how fast populations can strengthen coastal defenses and/or relocate; and (3) there are no insurmountable barriers to migration.

Consider, for example, that Lowe, et al. [in Avoiding Dangerous Climate Change, H.J. Schellnhuber et al. (eds), Cambridge University Press, Cambridge, 2006, p. 32-33], based on a “pessimistic, but plausible, scenario in which atmospheric carbon dioxide concentrations were stabilised at four times pre-industrial levels,” estimated that a collapse of the Greenland Ice Sheet would over the next 1,000 years raise sea level by 2.3 meters (with a peak rate of 0.5 mm/yr). If one were to arbitrarily double that to account for potential melting of the West Antarctic Ice Sheet, that would mean a SLR of ~5 meters in 1,000 years (with a peak rate assuming the peaks coincide) of 1 meter per century.

Human beings, unless terrified into immobility, can certainly get out of the way of such a sea level rise, especially if they have centuries or a millennium to do so.  In fact, if they can get early warning of such an event they could probably get out of the way in a matter of decades, if not years.

Can a relocation of such a magnitude be accomplished?

Consider that the global population increased from 2.5 billion in 1950 to 6.7 billion this year. Among other things, this meant creating the infrastructure for an extra 4.2 billion people in the intervening 58 years (as well as improving the infrastructure for the 2.5 billion counted in the baseline, many of whom barely had any infrastructure in 1950). These improvements occurred at a time when everyone was significantly poorer. Therefore, while relocation will be costly, in theory today’s — and, more to the point, tomorrow’s — wealthier world ought to be able to relocate billions of people to higher ground over the next few centuries, if need be. In fact, once a decision is made to relocate, the cost differential of relocating, say, 10 meters higher rather than a meter higher is probably marginal.  [Oh, I almost forgot – if a restructuring of the U.S. energy infrastructure can create 5 million jobs, imagine how many more jobs such a relocation would create.  Perhaps we should count such a massive effort as a benefit rather than a cost!]

What about the rest of nature?

As noted, the sea level has risen 400 feet in the past 18,000 years, and the rest of nature doesn’t seem any worse for wear.

So on sea level rise, I’d recommend rational risk analysis to Mr. Romm, because we have nothing to fear but fear itself.

Second, Romm makes assertions and rhetorical flourishes but doesn’t furnish any proof showing that 450 ppm is necessarily better than 750 ppm.  He says that

Notwithstanding a few papers that Goklany has dug up, the overwhelming majority of climate scientists recognize such warming as an unmitigated disaster for humanity — and indeed for all species — for generations to come.

Romm doesn’t have even a few papers to support either his explicit claim that 450 ppm will be better than 750 ppm or his implicit claim that climate change is more urgent than other potential problems. In fact the only studies that have looked at this issue — the Copenhagen Consensus and my own work — show that climate change is, for the foreseeable future, not even a close second in terms of either impacts on human well-being or policies to advance human well-being.  Even if unmitigated climate change is an unmitigated disaster, the analyses that exist indicate that there are other disasters that are larger in scope, more imminent than climate change, and more solvable. As always, we should address first things first, and that does not include mitigation that extends beyond “no regrets.” (For more on this, see my recent paper for Cato.)

While on this topic, I reproduce below a couple of tables that indicate that malaria and hunger could be worse under 550 ppm than 750 ppm out to the 2080s, assuming one has any confidence in the results out to that date. I also provide the source and affiliation of authors, highlighting the names of authors who were drafters of the IPCC WG II’s latest Summary for Policy Makers, so that Mr. Romm recognizes that they are not “skeptics,” are in good standing with the IPCC, and are associated with institutions that Mr. Romm should find acceptable.

Source:  Martin Parry,1 Cynthia Rosenzweig,2 and Matthew Livermore3 (2005). “Climate change, global food supply and risk of hunger.” Philosophical Transactions of the Royal Society B 360: 2125-2138.

1 Hadley Centre, UK Meteorological Office, Fitzroy Road, Exeter EX1 3PB, UK;2 Goddard Institute for Space Studies, 2880 Broadway, New York NY 10025, USA;3 Climatic Research Unit, University of East Anglia, Norwich NR4 7TJ, UK.

Source: N. W. Arnell,1 M. G. R. Cannell,2 M. Hulme,3 R. S. Kovats,4 J. F. B. Mitchell,5 R. J. Nicholls,6 M. L. Parry,7 M. T. J. Livermore,8 and A. White9 (2002). “The consequences of CO2 stabilisation for the impacts of climate change.” Climatic Change 53: 413-446.

1Department of Geography, University of Southampton, U.K.; 2NERC Centre for Ecology and Hydrology, Edinburgh, U.K.; 3Tyndall Centre for Climate Change Research, University of East Anglia, U.K.; 4Centre on Globalisation, Environmental Change, and Health, London School of Hygiene and Tropical Medicine, U.K.; 5 Hadley Centre for Climate Prediction and Research, U.K.; 6Flood Hazard Research Centre, Middlesex University, U.K.; 7Jackson Environment Institute, University of East Anglia, U.K.; 8Climatic Research Unit, University of East Anglia, U.K.; 9Department of Mathematics, Heriot-Watt University, U.K.

(For those who are convinced that nothing is more important than climate change, look at the “no climate change” and “unmitigated” columns, and note that impacts of unmitigated climate change are overshadowed by the impacts of other factors.)

So if 550 ppm isn’t necessarily better than 750 ppm, how can we be confident 450 will be better than 550, or 750?  Mr. Romm, show us your analysis that indicates 750 ppm is indeed worse than 450 ppm.  Or is this a matter of faith?

Let’s also look at the specific IPCC quote that Mr. Romm furnishes us with: “As global average temperature increase exceeds about 3.5°C [relative to 1980 to 1999], model projections suggest significant extinctions (40-70% of species assessed) around the globe.” Note that it doesn’t say “predictions” but “model projections.”  That itself speaks volumes. Also note that it doesn’t say “prove” but “suggest.” So Mr. Romm, tell us how good are these model projections? What are the uncertainties associated with the models? Have the model results been verified and validated in the real world using “out of sample” data? And how did they perform?

In fact, a close reading of the IPCC’s WG II Chapter 4 (on ecosystems) indicates that model projections are fraught with uncertainties, particularly if one considers that: (a) biophysical models use as inputs uncertain results from climate models, which become even more uncertain at the relatively small geographical scales needed to model effects on vegetation, habitat and species, and (2) biophysical models themselves are incomplete and imperfect. See also (Botkin et al. 2007 [pdf]).

Fourth, Mr. Romm provides us with a figure which purports to show us the “optimum” temperature window.  But this figure doesn’t show us anything of the sort.  Even assuming that the figure is valid — it has no error bars, or any real provenance other than it comes from a source that Romm trusts — all it shows is that temperature may have stayed within a relatively narrow range.  But we don’t know that this range is optimal for humanity.  In fact, combining our knowledge of human history with this figure suggests that humanity is better off when things are warmer!  Things were good during the warmth of the Holocene Optimum when Mesopotamia flourished, they were good during the Medieval Warm Period when Vikings inhabited Greenland, and things have never been better than they are today, even though today is warmer than the norm. (The last point is documented in my book, The Improving State of the World: Why We’re Living Longer, Healthier, More Comfortable Lives on a Cleaner Planet.)  Now, although correlation isn’t causation, what in this figure gives Romm the notion that some additional warmth will necessarily be worse?

In fact, the Yohe paper that Romm cites suggests that additional warming of up to 2°C, may be on the whole a net benefit to humanity, even though, like others, it seems that study doesn’t fully consider the increases in adaptive capacity and secular technological change, consideration of which would reduce future damages from climate change, effectively increasing the temperature beyond which climate change would result in net losses globally, and reduce the benefit-cost ratio for mitigation.

Also from This Issue

Lead Essay

  • Keeping Our Cool: What to Do about Global Warming by Jim Manzi

    The prospect of potentially catastrophic global warming forces us to make decisions under extreme uncertainty. Yet, Jim Manzi writes, “Despite the rhetoric, the best available estimate of the damage we face from unconstrained global warming is not ‘global destruction,’ but is instead costs on the order of 3 percent of global GDP in a much wealthier world well over a hundred years from now.” Manzi explores how best to evaluate the costs of greenhouse gas abatement on the present-day economy when compared to the long-term benefits of avoiding global warming. He concludes that there are very few benefits from these steps.

Response Essays

  • A Small Cost Will Avoid a Catastrophe by Joseph Romm

    American Progress Senior Fellow Joseph Romm argues that atmospheric CO2 has already reached an unacceptable level, and that urgent action is needed in the next few years. Fortunately, this action need not involve prohibitive costs. Indeed, many possible options for greenhouse gas abatement will result in economic benefits.

    These changes are desperately needed, too, before global warming reaches a tipping point beyond which the carbon sequestered in permafrost is also released into the atmosphere, aggravating the problem. Should we fail to act, widespread desertification, massive species extinction, and other catastrophic events are predicted, even by authorities whom Jim Manzi also accepts.

  • Reducing Vulnerability to Climate-Sensitive Risks is the Best Insurance Policy by Indur Goklany

    Indur Goklany argues, in response to Jim Manzi and Joseph Romm, that solving the likely problems resulting from global warming will be both cheaper and more effective than any global response aimed at stabilizing or changing the climate itself. Harm reduction will also pay important dividends regardless of the degree of global warming, since it will include the development of new treatments for diseases, better flood protection, improved crops, and general economic advancements for the developing world. When taken together, these factors will help us to face any global warming scenario effectively, and they will also offer even larger benefits outside any considerations of climate.

  • The New Climate Center: How Technology Could Create a Political Breakthrough by Michael Shellenberger and Ted Nordhaus

    Michael Shellenberger and Ted Nordhaus describe what they see as a significant political realignment: Both left and right, they claim, are converging on a state-sponsored and technology-based solution to global warming, one that will emphasize clean energy and/or carbon sequestration technologies. They argue that the debate about climate modeling is largely irrelevant and/or unproductive, because these technologies are generally agreed to be important in their own right and to have positive economic effects regardless of the degree of severity of global warming. They call on policymakers to embrace a large-scale, state-funded effort to achieve these breakthrough technologies and argue that state sponsorship for technological advancement is, historically speaking, the engine of much progress and innovation. This, they argue, is a reason to embrace the same approach with regard to global warming.

The Conversation