February 10, 2005

Timetable of Doom

The UK newspaper The Independent grows less and less credible as its tales of global warming doom and gloom grow ever more outrageous. We have a name for this genre—science fiction.

The UK newspaper The Independent is doing everything it can to proclaim itself the world’s leading newspaper of environmental doom and gloom. Here are a sampling of headlines from just the past two weeks alone: “Apocalypse Now: how mankind is sleepwalking to the end of the Earth,” “Greenhouse gas ‘threatens marine life,” “Dramatic change in West Antarctic ice could produce 16ft rise in sea levels,” “Coral reefs may start to dissolve in 30 years,” “Global warming is ‘twice as bad as thought,’” “Countdown to global catastrophe,” and “Global warming approaching point of no return, warns leading climate expert.” All these articles seize upon the most extreme and outrageous claims made by like-minded scientists and politicians whose goal it is to scare the world back into the Dark Ages.

A case in point can be found in the latest of these incantations: “Global warming: scientists reveal timetable.” In that article, a timeline is laid out for our eventual destruction of the planet. According to The Independent, it goes something like this:

As present world temperatures are already 0.7ºC above the pre-industrial level, the process is well under way. In the near future—the next 25 years—as the temperature climbs to the 1ºC mark, some specialized ecosystems will start to feel stress, such as the tropical highland forests of Queensland, which contain a large number of Australia’s endemic plant species, and the succulent karoo plant region of South Africa. In some developing countries, food production will start to decline, water shortage problems will worsen and there will be net losses in GDP.

It is when the temperature moves up to 2ºC above the pre-industrial level, expected in the middle of this century—within the lifetime of many people alive today—that serious effects start to come thick and fast, studies suggest.

Substantial losses of Arctic sea ice will threaten species such as polar bears and walruses, while in tropical regions “bleaching” of coral reefs will become more frequent - when the animals that live in the coral are forced out by high temperatures and the reef may die. Mediterranean regions will be hit by more forest fires and insect pests, while in regions of the US such as the Rockies, rivers may become too warm for trout and salmon.

In South Africa, the Fynbos, the world’s most remarkable floral kingdom which has more than 8,000 endemic wild flowers, will start to lose its species, as will alpine areas from Europe to Australia; the broad-leaved forests of China will start to die. The numbers at risk from hunger will increase and another billion and a half people will face water shortages, and GDP losses in some developing countries will become significant.

But when the temperature moves up to the 3ºC level, expected in the early part of the second half of the century, these effects will become critical. There is likely to be irreversible damage to the Amazon rainforest, leading to its collapse, and the complete destruction of coral reefs is likely to be widespread.

The alpine flora of Europe, Australia and New Zealand will probably disappear completely, with increasing numbers of extinctions of other plant species. There will be severe losses of China’s broadleaved forests, and in South Africa the flora of the Succulent Karoo will be destroyed, and the flora of the Fynbos will be hugely damaged.

There will be a rapid increase in populations exposed to hunger, with up to 5.5 billion people living in regions with large losses in crop production, while another 3 billion people will have increased risk of water shortages.

Above the 3ºC raised level, which may be after 2070, the effects will be catastrophic: the Arctic sea ice will disappear, and species such as polar bears and walruses may disappear with it, while the main prey species of Arctic carnivores, such as wolves, Arctic foxes and the collared lemming, will have disappeared from 80 percent of their range.

In human terms there is likely to be catastrophe too, with water stress becoming even worse, and whole regions becoming unsuitable for producing food, while there will be substantial impacts on global GDP.

The only thing missing from this scenario is the alien invasion that occurs after our global defenses are down from the ecological and economical destruction. Perhaps they just haven’t thought that one up yet—although the specter of World War III breaking out for the same reasons (ecological destruction wrought by global warming, that is, not alien invasion) has visited on several occasions.

This apocalyptical view of the future contains the essential elements of environmental science fantasy—a world of tomorrow that is not so unlike the world of today, with the exception that scientifically unjustifiable events occur that inevitably lead to some sort of widespread (and spectacular) destruction. Where did all that water come from in Waterworld? Even a complete melting of the global ice caps doesn’t flood the entire planet. How did the cold air from the upper atmosphere get to the surface (ignoring the Ideal Gas Law) and flash freeze New York City in The Day After Tomorrow? An advanced alien species could only communicate with a single species on earth, the humpback whale in Star Trek IV: The voyage home? Humans will stop the centuries old practice of matching crops with the climate, and instead starve to death as temperatures warm according to The Independent? It’s all nonsense.

Here is just one of the major problems that pushes The Independent’s story from science fact to science fiction. Currently the average temperature of the surface of the earth is rising at a rate of about 0.17ºC (0.31ºF) per decade. It has been doing so, at a fairly constant rate (after accounting for temporary departures resulting from such episodes as El Nino events and volcanic eruptions) for about the past 30 to 35 years. If this rate were to persist into the future, the resulting global average temperature rise would be about 0.77ºC (1.4ºF) by the year 2050 and about 1.62ºC (2.91ºF) by the century’s end. This rate of increase is about half of that used to underlie The Independent’s scenario. This difference gives rise to a number of significant implications: (1) it doubles the amount of time that passes before each of the ‘crises’ occurs, (2) it allows for a greater time for which adaptation, both natural and technological, can take place, (3) it betters the chances that breakthrough advances are made in the field of energy production.

“Wait a minute,” someone might argue, “why are you assuming that the warming rate will remain constant in the future, given the growing demand for energy (and thus fossil fuel consumption)?”

We’ll answer this question with a lesson from the past, as well as with a look at what climate models tell us.

The history lesson is given in Figure 1. The top chart (Figure 1a) tracks the total global emissions of carbon dioxide from 1970 to 2000. There has been a relatively steady increase during these three decades as the world has grown—both in population and in GDP—that has led to current emissions being about two-thirds greater than emissions 35 year ago. The lower chart (Figure 1b) plots the year-over-year change in global average temperature against the total global carbon dioxide emissions. Notice that there is no relationship—while global carbon dioxide emissions have increased by nearly 66%, the rate of global temperature rise has not changed at all! There are likely a number of factors that have combined to produce this result, some of which are known and some of which are unknown, but in any case Figure 1 is a perfect integration of them all as these are actual observed data.

CO2 emissions
Figure 1a (top): Annual global emissions of carbon dioxide.
Figure 1b (bottom): Relationship between annual global carbon dioxide emissions and year-over-year change in annual average global surface temperatures.

The same, however, cannot be said about climate models. After all, computer climate models are only a product of what we put into building them. If our understanding of some processes is incomplete, or entirely lacking, then climate models will fail to produce accurate results. Nevertheless, let’s assume that climate models get the general concept right—an increase in atmospheric carbon dioxide concentration leads to an increase in global temperatures. We’ll rely on observations to fill in the details. What we get is illustrated in Figure 2 (taken from the last IPCC report). The spaghetti of colored lines is the projected global temperature increase from 19 different climate models when run with a 1 percent per year increase in carbon dioxide concentrations. Notice that the great majority of them (as well as the model mean) take the form of a straight line (ignoring all the short term year-to-year variations). In other words, even though atmospheric carbon dioxide concentrations become greater every year, the average year-over-year change in global temperature remains constant. If this sounds familiar, it is because this is precisely the same behavior that we saw in Figure 1b, using the actual observations. The only difference between the models and the observations is the rate of temperature change from one year to the next. In the models in Figure 2, the average rate of global temperature increase is about 0.25ºC (0.45ºF) per decade, while, you’ll recall, that the observations show the rise to be about 0.17ºC (0.31ºF) per decade.

The reason for this is obvious. The models are fed an increase in carbon dioxide of 1% per year. The real increase—after accounting for other greenhouse gases, such as methane, is much less, around a half a percent per year, and therefore the average of these climate models has to be considerably adjusted downwards.

Linear Rise
Figure 2. Change in average annual global temperatures as projected by 19 different climate models under a scenario of atmospheric carbon dioxide concentration increasing at 1 percent per year (a value that is about twice the current trend). (Source: Third Assessment Report of the Intergovernmental Panel on Climate Change).

The logical conclusion of all of this is that a coupling between climate models and observations indicates that a continuation of current temperature trends into the foreseeable future is a robust projection. As such, scary scenarios of a world devastated by ecological catastrophe brought about by rapidly rising temperatures is not supported by the best available science.

Of course, the future rate of temperature rise is but just one of the problems with The Independent’s timetable to the apocalypse. The other concerns the linkage between their economic/environmental catastrophe and their assigned levels of global temperature change. Suffice it say that the evidence in support of The Independent on that issue is equally lacking. But we’ll leave that rebuttal for another day.




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