Topic: Energy and Environment

Why Future Net Negative Impacts of Global Warming Are Overestimated: Response to Conor Clarke, Part IV

This post responds to the last of Conor Clarke’s comments on my study, “What to Do About Global Warming,” published by Cato. This series started with the imaginatively titled, Response to Conor Clarke Part I, and continued with Cherry Picking Climate Catastrophes and  Do Industrialized Countries Have a Responsibility for the Well-Being of Developing Nations?

CONOR said:

I think Goklany is a bit picky and choosey with the evidence. … I also like the Goklany paper a lot. [THANK YOU!! I’ll take whatever I get.] But in this case it’s hard to resist. [Emphasis in original.]

To take one example (of several), Goklany’s hunger estimates rely heavily on those published by Global Environmental Change (GEC), which he uses to make the argument that “the world will be better off in 2085 with respect to hunger than it was in 1990 despite any increase in population.” But the GEC produced two estimates of hunger and climate change – one that assumes the benefits of CO2 fertilization and one that does not. Goklany picks the former estimate (I have no idea why), despite the fact the GEC says the effects of climate change “will fall somewhere between” the two. … [I}f you embrace anything other than the most Pollyanish CO2 fertilization estimate – the one that Goklany uses in his Cato paper – we will be living in a world in which climate change puts tens of millions of additional people at risk of starvation by 2085.

My RESPONSE:

First, let me elaborate on my selection of the set of studies that I used in my paper.  Essentially, the selected set of studies (published in Global Environmental Change) was the only one that had estimated global impacts using detailed process models in conjunction with the IPCC’s latest scenarios, and were peer reviewed.  Moreover, they come with a provenance that people who may be unhappy with my results cannot impugn. [This is important only because many people arguing about global warming seem to be more concerned about who did the study and whether the results bolster their predilections, than how the study was done.]  Specifically, virtually all the authors were intimately connected with the IPCC. The senior author of the hunger study was also the co-chairman of the IPCC’s Work Group II, which was responsible for compiling the portion of the IPCC’s latest assessment that dealt with impacts, vulnerability and adaptation. The authors of the water resource and coastal flooding studies were the lead authors of corresponding chapters in that IPCC report. An earlier version of the same set of impact studies was the basis for the claim by Sir David King, erstwhile science advisor to Her Majesty’s Government, that global warming was a more serious threat than terrorism (see here). The Stern Review also drew quite heavily from these studies (see below).

Let’s now turn to Conor’s comments on the hunger study and why I assumed that the benefits of carbon fertilization would be realized in the future. Indeed, the hunger study (Parry et al.) produced two separate estimates — one assuming that carbon fertilization is a reality, and the other assuming zero carbon fertilization.  But the two estimates are not equally likely. There are literally hundreds, if not thousands of experimental studies that show carbon fertilization is a reality (see also here), that higher CO2 not only increases the rate of photosynthesis, but also increases the efficiency of water use by plants (i.e., it confers a degree of immunity to drought), among the many other benefits CO2 bestows on plants and other carbon based life, including all creatures – big and small – in the biosphere that depend directly or indirectly on photosynthesis.  The probability that direct CO2 effects on crop growth are zero or negative is virtually non-existent (IPCC, 2001b: 254–256). Second, the positive effect of carbon fertilization was based on the average of experimental studies; it’s not an upper bound estimate. On the other hand, the notion of “zero fertilization” is an assumption not supported by the vast majority of empirical data. So averaging results from the two estimates makes no sense and would understate the average benefits that would likely result from carbon fertilization.

Notably, the Stern Review, invoked a study by Long et al. (subscription required) to estimate future levels of hunger based on “zero fertilization” using precisely the same study (Parry et al.) that I  – and Conor, in his comments – used. But Long et al.’s results have been disputed by other scientists (also see here), including some contributors to the IPCC’s assessment.  More importantly, Long et al. only suggested that under field conditions, carbon fertilization may be a third to less than half of what is indicated by experiments using growth chambers, not that it would be zero. It also noted that fertilization may be stronger under drought conditions or if sufficient nitrogen is employed. But drought is one of the bogeymen of global warming, and increased use of nitrogen is precisely the kind of adaptation that would become more affordable in the future as countries become wealthier, as they should if the IPCC’s scenarios are to be given any credence.  Indeed, that is one of the adaptations allowed in Parry et al. Also, the fact that crop yields are higher in richer countries is partly because they can more easily afford nitrogen fertilizers (see here, p. 78). In fact, China’s nitrogen use per hectare is already among the world’s highest. For all these reasons, even if one accepts the Long et al. study as gospel, it is reasonable to assume that the effect of carbon fertilization will be closer to the “higher” estimate from the Parry et al. study than to the “zero fertilization” case.

But, more importantly, the uncertainties related to the magnitude of the CO2 fertilization effect is most likely swamped by a major source of overestimation of hunger in Parry et al.’s estimates.

Although Parry et al. allows for some secular (time-dependent) increases in agricultural productivity, increases in crop yield with economic growth due to greater application of fertilizer and irrigation in richer countries, decreases in hunger due to economic growth, and for some adaptive responses at the farm level to deal with global warming, Parry et al. itself acknowledged that these adaptive responses are based on the “current range” of available technologies, not on technologies that would be available in the future or any technologies developed to specifically cope with the negative impacts of global warming (Parry et al., p. 57).  The potential for future technologies to cope with global warming is large, especially if one considers bioengineered crops (see here, chapter 9), which Parry et al. admittedly didn’t consider. Moreover, an examination of the sources cited in Parry et al. indicates that the “current range” of technology is actually based on 1990s or earlier technology. That is, it is not quite current.

The approach used in Parry et al. to estimate the impacts of global warming decades from now is, in essence, tantamount to estimating today’s level of hunger (and agricultural production) based on the technology of 50 years ago. In fact, the major reason why Paul Ehrlich’s Population Bomb turned out to be a dud was that it underestimated or ignored future developments in agricultural technology.

As noted in Part I of this series of responses, ignoring technological change can, over decades, lead to overestimating adverse impacts by orders of magnitude. Notably, due to a combination of technological change and increasing affluence, U.S. death rates due to various water related diseases – dysentery, typhoid, paratyphoid, other gastrointestinal disease, and malaria – declined by 99%–100% from 1900 to 1970.  For the same reasons, during the twentieth century, global death rates from extreme weather events declined by over 95%.

This basic methodological shortcoming, however, is not unique to Parry et al. It is common to ALL global warming impact studies that I have read – and I have read plenty of them.

For all these reasons, the adverse impacts of global warming for hunger (as well as other aspects of human well-being, e.g., due to malaria and coastal flooding) that I used in my paper are, more likely than not, substantially overestimated. And by the same token, ignoring technological change (and not fully accounting for increases in wealth) also assures that the positive impacts of global warming are likely to be underestimated, further overestimating the net negative impacts of global warming.

Therefore, far from being Pollyanish, the estimates used in my paper most likely substantially exaggerate the net negative impacts of global warming. Despite that, those estimates cannot justify emissions cuts that go beyond no-regret actions at this time or through the foreseeable future.

The Post and Times Push for Cap and Trade

Since the June House vote on the Waxman-Markey “cap-and-trade” bill, lawmakers from both chambers have backed significantly away from the legislation. The first raucous “town hall” meetings occurred during the July 4 recess, before health care. Voters in swing districts were mad as heck then, and they’re even more angry now. Had the energy bill not all but disappeared from the Democrats’ fall agenda, imagine the decibel level if members were called to defend it and Obamacare.

But none of this has dissuaded the editorial boards of the The New York Times and Washington Post. Both newspapers featured uncharacteristically shrill editorials today demanding climate change legislation at any cost.

The Post, at least, notes the political realities facing cap-and-trade and resignedly confesses its favored approach to the warming menace: “Yes, we’re talking about a carbon tax.” The paper—motto: “If you don’t get it, you don’t get it”—argues that in contrast to the Boolean ball of twine that is cap-and-trade, a straight carbon tax will be less complicated to enforce, and that the cost to individuals and businesses “could be rebated…in a number of ways.”

Get it? While ostensibly tackling the all-encompassing peril of global warming, bureaucrats could rig the tax code in other ways to achieve a zero net loss in economic productivity or jobs. Right. Anyone who makes more than 50K, or any family at 100K who thinks they will get all their money back, please raise you hands.

The prescription offered by the Times, meanwhile, is chilling in its cynicism and extremity. It embraces the fringe—and heavily discredited—idea of “warning that global warming poses a serious threat to national security.” It bullies lawmakers with the threat that warming could induce resource shortages that would “unleash regional conflicts and draw in America’s armed forces.”

(Note to the Gray Lady: This is why we have markets. Not everyone produces everything, especially agriculturally. For example, it’s too cold in Canada to produce corn, so they buy it from us. They export their wheat to other places with different climates. Prices, supply, and demand change with weather, and will change with climate, too. Markets are always more efficient than Marines, and will doubtless work with or without climate change.)

Appallingly, the piece admits that “[t]his line of argument could also be pretty good politics — especially on Capitol Hill, where many politicians will do anything for the Pentagon. … One can only hope that these arguments turn the tide in the Senate.” In other words: the set of circumstances posited by the national-security strategy are not an object reality, but merely a winning political gambit.

There’s no way that people who see through cap-and-trade are going to buy the military card, but one must admire the Times’ stratagem for durability. Militarization of domestic issues is often the last refuge of the desperate. How many lives has this cost throughout history?

Nevertheless, one must wonder at the sudden and inexplicable urgency that underpins the positions of both these esteemed newspapers. Global surface temperatures haven’t budged significantly for 12 years, and it’s becoming obvious that the vaunted gloom-and-doom climate models are simply predicting too much warming.

Still, one must admire the Post and Times for their altruism. The economic distress caused by a carbon tax, militarization, or any other radical climatic policy certainly won’t be good for their already shaky finances, unless, of course, the price of their support is a bailout by the Obama Administration.

Now that’s cynical.

‘Cash for Clunkers’ Is a Lemon

Jerry Taylor and I published an op-ed criticizing the Cash for Clunkers program on Friday. We weren’t alone in our evaluation of the program.

Two interesting critical analyses of the Cash for Clunkers program were published over the weekend. The first by New York Times reporter Matt Wald examines the energy savings that would result from the program.  If a clunker traveling 12,000 miles at 16 miles per gallon (consuming 750 gallons per year) were traded in for a new car getting 25 mpg while traveling the same distance (480 gallons a year), the the trade-in would save the driver 270 gallons per year. Multiply that by the roughly 245,000 vehicles that had been traded in under the program as of last Friday, before Congress extended the program, and you get 1.6 million barrels  saved each year. That sounds great until you realize it’s only about two hours’ worth of our daily consumption, which is about 18.6 million barrels per day so far in 2009.  But the savings is probably much less than that because old cars are not driven 12,000 miles per year.

The second critical analysis, examining the program’s effect on carbon emissions, appeared as a figure in the Outlook section of this weekend’s Washington Post.  Over 10 years, the new cars will reduce emissions by 7 million metric tons, which is about 0.04% of the 16 billion metric tons that U.S. cars will produce over that time. That is, taxpayers will pay $147 per ton of CO2 reduction ($1.03 billion dollars divided by 7 million tons). In comparison, the economic literature estimates that the cost of the marginal damages of carbon emissions is between $15 and$50 per ton (see, e.g., this and this).

Do Industrialized Countries Have a Responsibility for the Well-Being of Developing Nations?

Conor Clarke’s second comment at The Atlantic blog on the study, “What to Do About Climate Change,” was that:

Goklany’s estimates are based on global aggregates that hide the unequal distribution of the climate change burden. Yes yes, I know Manzi will say that’s not decisive: As long as global GDP is higher, we can redistribute our way out of the problem more effectively tomorrow than we can today. I would be more comfortable with that debate if I thought vast international restributions of income in the name of global equity were more likely tomorrow than they are today.

RESPONSE:

Global greenhouse gas controls will also have uneven consequences. First, cost of controls will vary from country to country, and sector to sector. Second, because the impacts of climate change will also vary from area to area, the benefits of control will necessarily be uneven. They will also vary over time. In fact, for some sectors, some areas may benefit even under the IPCC’s warmest scenario, at least through the foreseeable future.  For example, through at least 2085, climate change would increase the global population at risk of water stress (see Figure 2, here).  Therefore controlling climate change would exacerbate the global population at risk of water stress. So both the costs and benefits of climate change controls will also be distributed unevenly. Third, as noted here, implementing climate change controls that go beyond no-regret actions requires that today’s poorer generations  delay solving the real problems they face here and now and instead put resources into solving the hypothetical problems that may (or may not) confront tomorrow’s far wealthier — and technologically better-endowed — populations. Nothing equitable about that.

Conor Clarke’s third comment was:

… I’m suspicious of the ethical calculus that says we should not focus on one large global problem because larger global problems might exist. [Emphasis in the original.] That kind of moral math rarely corresponds to the political reality. (Do you think the average congressperson opposed to Waxman-Markey has trouble sleeping at night over new cases of malaria or global hunger?) Nor does it correspond to the historical responsibility: Industrialized nations are more responsible for the global problems created by climate change than the problems of population growth.

RESPONSE:

I am puzzled as to why Conor suggests we should focus on one large global problem — presumably climate change — when larger global problems might exist. Why should we focus on any problem when other larger ones are unresolved?

Nevertheless, Conor is correct, political decisions are rarely based on ethical calculus — the more’s the pity.

In any case, my paper doesn’t advocate twiddling our thumbs when it comes to climate change. Yes, it doesn’t advocate aggressive action (going beyond no-regret actions) to control climate change in the near to medium term. Instead it focuses on increasing adaptive capacity, technological prowess, and sustainable economic development which would enable society to respond to whatever problems it may face in the future, including climate change. As the paper shows, aggressive mitigation would not be the best approach to advance human well-being and deal with today’s urgent problems while advancing the ability to address tomorrow’s problems (see Table 5, here).

Specifically, it would reduce vulnerability to today’s urgent climate-sensitive problems — e.g., malaria, hunger, water stress, flooding, and other extreme events — that might be exacerbated by climate change.  Second, it would strengthen or develop the institutions needed to advance and/or reduce barriers to economic growth, human capital, and the propensity for technological change. Together, these two elements would improve both adaptive and mitigative capacities, as well as the prospects for sustainable economic development. Third, my paper advocates implementing no-regret mitigation measures now, while expanding future no-regret options through research and development of mitigation technologies. Fourth, it would let the market pick winners and losers among the various no-regret options. Fifth, it would continue research into the science, impacts and policies related to climate change, and monitoring of impacts to provide early warning of any “dangerous” impacts were they to be manifested.

Although Conor is probably correct in suggesting that politicians rarely undertake any ethical calculus in arriving at their decisions, many have nevertheless asserted that reducing greenhouse gas emissions is a moral imperative. See, e.g., here. But what is the basis for this claim?

These claims are never accompanied by any analysis that compares the magnitude and urgency of climate change versus other problems that humanity faces today or in the foreseeable future. The only such comparative analyses that have been undertaken are those done as part of Lomborg’s Copenhagen Consensus exercise and my Cato paper [and their prior versions, see, e.g., “Potential Consequences of Increasing Atmospheric CO2 Concentration Compared to Other Environmental Problems.” Technology 7S (2000): 189-213 and Copenhagen Consensus 2004.].  And these provide no support for the oft-repeated but unsubstantiated claim that climate change is a moral imperative given the many other real problems that exist today.

Finally, Conor raises the issue of historical responsibility of industrialized nations for global warming.  As Henry Shue, an Oxford ethicist, notes, “Calls for historical responsibility in the context of climate change are mainly calls for the acceptance of accountability for the full consequences of industrialization that relied on fossil fuels.” [Emphasis added.] But a fundamental premise behind these calls is that the “full consequences of industrialization” are negative. This is one more unsubstantiated claim.

In fact, by virtually any objective measure of human well-being — e.g., life expectancy; infant, child and maternal mortality; prevalence of hunger and malnutrition; child labor; job opportunities for women; educational attainment; income — humanity is far better off today that it was before the start of industrialization, due to the cycle of progress and economic surpluses fueled for the most part by fossil fuels. In addition, hunger and child labor are as low — and job opportunities for women as high — as they are today partly due to the direct effect of fossil fuel powered labor saving technology.  This is clearly true for industrialized countries. Figure 1 shows that life expectancy — perhaps the single most important indicator of human well-being — increased for the U.S through the 20th century, even as CO2 emissions, population, affluence, and material, metals, and organic chemical use increased. Matters have also improved in developing countries. And global life expectancy increased from 31 years in 1900 to 47 years in the early 1950s to 69 years today.

Goklany 

Notably, much of the improvement of human well-being in developing countries is due to the transfer of technology (including knowledge) from industrialized countries to developing countries. Moreover, a substantial share of the income of many developing countries comes directly or indirectly from trade, tourism, aid, and remittances from industrialized countries.  Consequently, developing countries are far ahead of today’s industrialized countries at equivalent levels of economic development.

For instance, as noted here (pp. 20-21):

in 2006, when GDP per capita for low income countries in PPP-adjusted terms was $1,327, their life expectancy was 60.4 years, a level that the U.S. first reached in 1921, when its GDP per capita was $5,300. Surprisingly even Sub-Saharan Africa, the world’s developmental laggard, is today ahead of where the U.S. used to be. In 2006, its per capita GDP was at the same level as the U.S. in 1820 but the U.S. did not reach Sub-Saharan Africa’s current infant mortality level until 1917 when, and life expectancy until 1902, by which time the U.S. was far wealthier. [All GDP figures are in terms of real 1990 dollars, adjusted for purchasing power.]

Thus, empirical data do not support the underlying premise that industrialization of today’s developed countries has caused net harm to developing countries.

So what is it that industrialized countries have a “historical responsibility” for?  For the diffusion of knowledge and technology that they developed and which helped developing countries improve their well-being, and for helping increase incomes in the latter through trade, aid, remittances, and tourism?

As noted at Reason on-line: “Who knows, in accounting for both benefits and damages [associated with greenhouse gas emissions], Bangladesh would not end up owing the United States!”

Another Shot Fired in the Carbon Tariff Debate

I’ve written before about the “carbon tariff” debate, and will continue to do so as the Senate gears up to write a climate change bill. Indeed, I have a paper coming out in early September with a fuller analysis of the effects of slapping tariffs on countries in an effort to force them to sign up to international carbon-limiting agreements. [Spoiler alert: you’ll be shocked to know that I conclude that using trade measures in climate change policy is possibly illegal under world trade rules, definitely costly to the U.S. economy, and more than likely counterproductive in the efforts to forge a climate agreement (for what that’s worth).]

Seemingly unconcerned about the costs of green protectionism, ten Democratic senators crucial to the upcoming Senate vote (long-standing protectionists all, with the exception of newbie Al Franken) sent a letter to the White House yesterday, urging President Obama to rethink his (lukewarm) resistance to carbon tariffs. They argue that a dreaded “unlevel playing field” would result from saddling U.S. industries with higher carbon costs while, say, Chinese ones remain unencumbered.

You’ll have to wait for my paper for a full examination of those arguments, but in the meantime here’s some excellent analysis of the politics of it all by former Catoite, international trade lawyer, and friend of liberty Scott Lincicome. He assesses the scorecard as follows:

Pro carbon tariffs - Ten protectionist Senators, the US House of Representatives (in Waxman-Markey), France [link added], and Paul Krugman.

Anti carbon tariffs - the rest of the world.

Flood Insurance: Mend It or End It, But Don’t Just Extend It

Before leaving for the August recess, the House of Representatives passed a bill (HR3139) to extend the authority for the National Flood Insurance Program (NFIP) until March 2010.  The program was set to expire on Oct. 1, 2009.   The bill now goes to the Senate.  Instead of taking up HR3139, the Senate should insist on real reforms to the NFIP, rather then a blanket extension.

Since Hurricane Katrina, the NFIP has operated under a deficit of close to $17 billion, which had to be borrowed from the Treasury in order to pay claims.  Under the NFIP’s current structure, it cannot even make the interest payments on its borrowing; these losses will ultimately hit the taxpayer. 

The Senate last Congress passed a strong reform bill that would have eliminated almost half of the subsidies in the NFIP.  The House decided to instead seek an expansion of the broken program, adding wind coverage and raising the coverage levels (despite the availability of private flood insurance).

Many of the homes receiving subsidies under the NFIP are either vacation/second homes or properties where the government has paid repeated claims.  In one instance, a house in Houston this is valued at around $100,000 received over $800,000 in flood insurance claims over a 20-year period, before it was finally destroyed. 

Not only does the NFIP subsidize at taxpayer expense beach-front vacation homes, but there is growing evidence that the program causes substantial harm to the environment and local fisheries.  Just last year, the National Marine Fisheries Service issued a finding that the NFIP is pushing orcas and some runs of salmon to extinction.  Before the federal government forces significant costs on the private sector to protect the environment, perhaps it should take a close look at the damage its own activities inflict.

Cherry Picking Climate Catastrophes: Response to Conor Clarke, Part II

Conor Clarke at The Atlantic blog, raised several issues with my study, “What to Do About Climate Change,” which Cato published last year.

One of Conor Clarke’s comments was that my analysis did not extend beyond the 21st century. He found this problematic because, as Conor put it, climate change would extend beyond 2100, and even if GDP is higher in 2100 with unfettered global warming than without, it’s not obvious that this GDP would continue to be higher “in the year 2200 or 2300 or 3758”. I addressed this portion of his argument in Part I of my response. Here I will address the second part of this argument, that “the possibility of ‘catastrophic’ climate change events — those with low probability but extremely high cost — becomes real after 2100.”

The examples of potentially catastrophic events that could be caused by anthropogenic greenhouse gas induced global warming (AGW) that have been offered to date (e.g., melting of the Greenland or West Antarctic Ice Sheets, or the shutdown of the thermohaline circulation) contain a few drops of plausibility submerged in oceans of speculation. There are no scientifically justified estimates of the probability of their occurrence by any given date. Nor are there scientifically justified estimates of the magnitude of damages such events might cause, not just in biophysical terms but also in socioeconomic terms. Therefore, to call these events “low probability” — as Mr. Clarke does — is a misnomer. They are more appropriately termed as plausible but highly speculative events.

Consider, for example, the potential collapse of the Greenland Ice Sheet (GIS). According to the IPCC’s WG I Summary for Policy Makers (p. 17), “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 the West Antarctic Ice Sheet.

But what is the probability that a negative surface mass balance can, in fact, be sustained for millennia, particularly after considering the amount of fossil fuels that can be economically extracted and the likelihood that other energy sources will not displace fossil fuels in the interim? [Remember we are told that peak oil is nigh, that renewables are almost competitive with fossil fuels, and that wind, solar and biofuels will soon pay for themselves.]

Second, for an event to be classified as a catastrophe, it should occur relatively quickly precluding efforts by man or nature to adapt or otherwise deal with it. But if it occurs over millennia, as the IPCC says, or even centuries, that gives humanity ample time to adjust, albeit at a socioeconomic cost. But it need not be prohibitively dangerous to life, limb or property if: (1) the total amount of sea level rise (SLR) and, perhaps more importantly, the rate of SLR can be predicted with some confidence, as seems likely in the next few decades considering the resources being expended on such research; (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.

This would be true even had the so-called “tipping point” already been passed and ultimate disintegration of the ice sheet was inevitable, so long as it takes millennia for the disintegration to be realized. In other words, the issue isn’t just whether the tipping point is reached, rather it is how long does it actually take to tip over. Take, for example, if a hand grenade is tossed into a crowded room. Whether this results in tragedy — and the magnitude of that tragedy — depends upon how much time it takes for the grenade to go off, the reaction time of the occupants, and their ability to respond.

Lowe, et al. (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 cm/yr). If one were to arbitrarily double that to account for potential melting of the West Antarctic Ice Sheet, that means a SLR of ~5 meters in 1,000 years with a peak rate (assuming the peaks coincide) of 1 meter per century.

Such a rise would not be unprecedented. Sea level has risen 120 meters in the past 18,000 years — an average of 0.67 meters/century — and as much as 4 meters/century during meltwater pulse 1A episode 14,600 years ago (Weaver et al. 2003; subscription required). Neither humanity nor, from the perspective of millennial time scales (per the above quote from the IPCC), the rest of nature seem the worse for it. Coral reefs for example, evolved and their compositions changed over millennia as new reefs grew while older ones were submerged in deeper water (e.g., Cabioch et al. 2008). So while there have been ecological changes, it is unknown whether the changes were for better or worse. For a melting of the GIS (or WAIS) to qualify as a catastrophe, one has to show, rather than assume, that the ecological consequences would, in fact, be for the worse.

Human beings can certainly cope with sea level rise of such magnitudes if they have centuries or millennia to do so. In fact, if necessary 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 6.8 billion this year. Among other things, this meant creating the infrastructure for an extra 4.3 billion people in the intervening 59 years (as well as improving the infrastructure for the 2.5 billion counted in the baseline, many of whom barely had any infrastructure whatsoever in 1950). These improvements occurred at a time when everyone was significantly poorer. (Global per capita income today is more than 3.5 times greater today than it was in 1950). Therefore, while relocation will be costly, in theory, tomorrow’s much 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. It should also be noted that over millennia the world’s infrastructure will have to be renewed or replaced dozens of times – and the world will be better for it. [For example, the ancient city of Troy, once on the coast but now a few kilometers inland, was built and rebuilt at least 9 times in 3 millennia.]

Also, so long as we are concerned about potential geological catastrophes whose probability of occurrence and impacts have yet to be scientifically estimated, we should also consider equally low or higher probability events that might negate their impacts. Specifically, it is quite possible — in fact probable — that somewhere between now and 2100 or 2200, technologies will become available that will deal with climate change much more economically than currently available technologies for reducing GHG emissions. Such technologies may include ocean fertilization, carbon sequestration, geo-engineering options (e.g., deploying mirrors in space) or more efficient solar or photovoltaic technologies. Similarly, there is a finite, non-zero probability that new and improved adaptation technologies will become available that will substantially reduce the net adverse impacts of climate change.

The historical record shows that this has occurred over the past century for virtually every climate-sensitive sector that has been studied. For example, from 1900-1970, U.S. death rates due to various climate-sensitive water-related diseases — dysentery, typhoid, paratyphoid, other gastrointestinal disease, and malaria —declined by 99.6 to 100.0 percent. Similarly, poor agricultural productivity exacerbated by drought contributed to famines in India and China off and on through the 19th and 20th centuries killing millions of people, but such famines haven’t recurred since the 1970s despite any climate change and the fact that populations are several-fold higher today. And by the early 2000s, deaths and death rates due to extreme weather events had dropped worldwide by over 95% of their earlier 20th century peaks (Goklany 2006).

With respect to another global warming bogeyman — the shutdown of the thermohaline circulation (AKA the meridional overturning circulation), the basis for the deep freeze depicted in the movie, The Day After Tomorrow — the IPCC WG I SPM notes (p. 16), “Based on current model simulations, it is very likely that the meridional overturning circulation (MOC) of the Atlantic Ocean will slow down during the 21st century. The multi-model average reduction by 2100 is 25% (range from zero to about 50%) for SRES emission scenario A1B. Temperatures in the Atlantic region are projected to increase despite such changes due to the much larger warming associated with projected increases in greenhouse gases. It is very unlikely that the MOC will undergo a large abrupt transition during the 21st century. Longer-term changes in the MOC cannot be assessed with confidence.”

Not much has changed since then. A shut down of the MOC doesn’t look any more likely now than it did then. See here, here, and here (pp. 316-317).

If one wants to develop rational policies to address speculative catastrophic events that could conceivably occur over the next few centuries or millennia, as a start one should consider the universe of potential catastrophes and then develop criteria as to which should be addressed and which not. Rational analysis must necessarily be based on systematic analysis, and not on cherry picking one’s favorite catastrophes.

Just as one may speculate on global warming induced catastrophes, one may just as plausibly also speculate on catastrophes that may result absent global warming. Consider, for example, the possibility that absent global warming, the Little Ice Age might return. The consequences of another ice age, Little or not, could range from the severely negative to the positive (if that would buffer the negative consequences of warming). That such a recurrence is not unlikely is evident from the fact that the earth entered and, only a century and a half ago, retreated from a Little Ice Age, and that history may indeed repeat itself over centuries or millennia.

Yet another catastrophe that greenhouse gas controls may cause is that CO2 not only contributes to warming, it is also the key building block of life as we know it. All vegetation is created by the photosynthesis of CO2 in the atmosphere. In fact, according to the IPCC WG I report (2007, p. 106), net primary productivity of the global biosphere has increased in recent decades, partly due to greater warming, higher CO2 concentrations and nitrogen deposition. Thus , there is a finite probability that reducing CO2 emissions would, therefore, reduce the net primary productivity of the terrestrial biosphere with potentially severe negative consequences for the amount and diversity of wildlife that it could support, as well as agricultural and forest productivity with adverse knock on effects on hunger and health.

There is also a finite probability that costs of GHG reductions could reduce economic growth worldwide. Even if only industrialized countries sign up for emission reductions, the negative consequences could show up in developing countries because they derive a substantial share of their income from aid, trade, tourism, and remittances from the rest of the world. See, for example, Tol (2005), which examines this possibility, although the extent to which that study fully considered these factors (i.e., aid, trade, tourism, and remittances) is unclear.

Finally, one of the problems with the argument that society should address low probability high impact events (assuming a probability could be estimated rather than assumed or guessed) is that it necessarily means there is a high probability that resources expended on addressing such catastrophic events will have been squandered. This wouldn’t be a problem but for the fact that there are opportunity costs associated with this.

According to the 2007 IPCC Science Assessment’s Summary for Policy Makers (p. 10), “Most of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.” In plain language, this means that the IPCC believes there is at least a 90% likelihood that anthropogenic greenhouse gas emissions (AGHG) are responsible for 50-100% of the global warming since 1950. In other words, there is an up to 10% chance that anthropogenic GHGs are not responsible for most of that warming.

This means there is an up to 10% chance that resources expended in limiting climate change would have been squandered. Since any effort to significantly reduce climate change will cost trillions of dollars (see Nordhaus 2008, p. 82), that would be an unqualified disaster, particularly since those very resources could be devoted to reducing urgent problems humanity faces here and now (e.g., hunger, malaria, safer water and sanitation) — problems we know exist for sure unlike the bogeymen that we can’t be certain about.

Spending money on speculative, even if plausible, catastrophes instead of problems we know exist for sure is like a starving man giving up a fat juicy bird in hand while hoping that we’ll catch several other birds sometime in the next few centuries even though we know those birds don’t exist today and may never exist in the future.