January 30, 2008

What the Future Holds in Store

The American Geophysical Union (AGU) recently released its new and improved “position statement” on global warming. Andy Revkin of the New York Times featured the AGU’s release on this DotEarth blog site and asked AGU members to chime in on their opinions of the statement that was developed by the AGU’s ruling Council. While there were definitely members who expressed dismay at the position statement, a majority of commentors gave it their hearty endorsement. Apparently, most of the endorsers have not given a very in depth consideration of all that is contained in the AGU’s statement, for otherwise, (we would hope anyway) that they would have been a bit more reserved.

For instance, the AGU’s position statement includes the following sentence: “If this 2 degrees Celsius warming [above 19th century levels] is to be avoided, then our net annual emissions of carbon dioxide must be reduced by more than 50 percent within this century.” This is akin to stating “If pigs had wings, they could fly.” Sure, you could endorse the statement, but to do so would seem a bit foolish. First off, pigs don’t have wings, and it would take nothing short of a miracle for them to acquire them, and secondly, even if they had wings, it is not guaranteed that they could fly. The most pig-shaped bird we can think of—the penguin which is large and rotund and flopping around on its belly a lot of the time—has wings, but can’t fly. Thus even if the impossibility of pigs sporting wings was overcome, it wouldn’t insure a successful flight.

The same is true of the AGU’s statement about a 50% CO2 reduction this century and its impacts on global temperature. First off, it will take nothing short of a miracle for the 50% reduction to take place, and secondly, it probably wouldn’t stop the temperature from rising 2ºC above “natural” levels. Endorse it if you want, but it doesn’t reflect well on your scientific reasoning skills.

Here’s why the 50% emissions won’t happen. We’ll visit the why it probably won’t keep temperatures from topping out more than 2ºC above pre-industrial levels in a subsequent essay.

Figure 1 shows the evolution since the beginning of the 20th century of both total worldwide population (in red) and total worldwide emissions of carbon dioxide (in blue). The two data series are in virtual lock step with each other. Indicating, as we all know, that we are currently living in the “fossil fuels” era of human’s inhabitation of earth.

The inset in Figure 1 is another way of illustrating the strength of the relationship between global population and global CO2 emissions. There are periods of slight undulation about the strong linear relationship between the two, but by and large, worldwide population and worldwide CO2 emissions are pretty tightly and consistently linked.

Figure 1. Evolution of global population (red) and global carbon dioxide emissions (blue) since 1900. Inset shows the tight relationship between population and CO2 emissions. (Population data are from the U.S. Census Bureau, and CO2 emissions data are from the Carbon Dioxide Information Analysis Center (CDIAC).

To look ahead to the end of the century, we simply extend the x-axis to the year 2100 and plot the global population projections out to the year 2050 (which is as far as anyone, or at least the U.S. Census Bureau, is really willing to make any concerted guess) (Figure 2). Notice that by 2050, the global population is expected to be just over 9 billion people, up by about 2.5 billion from where we are in 2007.

Figure 2. Same as Figure 1, except that we include global population projections to the year 2050 and extend the time axis (x-axis) to the year 2100.

Currently, global CO2 emissions stand at about 8,600 million metric tons of carbon (MMTC). The horizontal black line is drawn through the value of 4,300 MMTC, which is one-half the current emissions and is a target that many people clamor (including the AGU Council and its supporters) is necessary to be reached this century to keep global average temperatures from rising more than 2ºC above the pre-industrial average (even this probably won’t achieve this goal, as we’ve mentioned, but that is another story).

There are only four ways to bring total global CO2 emissions (blue line) down below the target (black line) by the end of this century.

The first is to bring the world’s population back down under 4 billion—the population that produces about half as much CO2 as the population does now (ignoring of course, that the world’s most populous country is rapidly increasing per capita CO2 emissions as you read this). In other words, we must immediately begin to buck the current population growth rate and prove the projections wrong. Instead of the world’s population growing by 2.5 billion people, it must decline by at least that amount. Then, as is evidenced by the relationship in Figure 1, CO2 emissions (hopefully) will follow.

Since no one seems to putting forth this modest proposal, we’ll assume that this isn’t what people have in mind (or at least aren’t expressing it).

Which means that somehow, some way, we must try to break apart the blue and the red curves and send the blue one (CO2 emissions) downward, while the red one (population) continues upward.

There are three possible way to for this to happen. One is the immediate and massive build-out of nuclear fission power plants all around the world. The other two fall under the category “and then a miracle happens,” in other words, reliance on new technologies that are nowhere close to currently existing—the development of some highly efficient CO2 sequestration technique that doesn’t require much energy to run, or the development of a completely new method of producing energy that doesn’t emit greenhouse gases—something like nuclear fusion. Rest assured that each of these three solutions—widespread nuclear fission, CO2 sequestration, a new energy source—will be met with an outpouring of opposition like never seen before due to their inherent danger (on many fronts) and possible environmental impact.

And since there seems no sign of an explosive growth of nuclear fission plants around the world, and considering that they take about 20+ years from planning to power production, it looks like when and if we do decide that this is the preferred methodology (and overcome the opposition), we’ll have a lot of catching up to do. Remember that until a large number of new nuclear power plants are up and running, the blue line and the red line in Figure 2 are still going to be locked together, and growing higher all the time—which makes reaching the black target line sometime this century that much more difficult and increasingly unlikely via this route.

The lack of a plethora of nuclear power plants in the works means that we are putting all of our eggs in the hope-for-a-miracle basket. Obviously, mankind will someday have to rely on a different energy source than fossil fuels, after all, they are in finite supply. So in the long run, if not sooner, a new type of energy production will be developed. One of these eggs will hatch, it is just a matter of whether it will hatch in time to drive CO2 emissions below the target by the year 2100.

Notice the things that didn’t make the list of possible ways to separate the blue line from the red line, namely, expansion of solar or wind technologies, burning our food rather than eating it (i.e., ethanol production) and conservation measures. Ironically, these are the primary solutions being proffered. Check out any “10 things you can go to stop global warming” lists or read through proposed congressional legislation to see for yourself. Consider that if these “alternative energies” were widely feasible, they would currently supply more than 1.5% of the world’s total energy. And conservation is limited—after all, we can only roll energy usage back so far before we are unable to sustain our current lifestyle (and no government on earth is going to purposely role back the standard of living of its people—or at least they won’t be governing very long if they do—Update Jan. 31, 2008: Although apparently this is precisely what Bill Clinton proposes that we do!). For example, in order to keep CO2 emissions constant at current levels in the face of a growing population, we must reduce our CO2 emissions proportionate to population growth. For instance, the global population is currently growing at a rate of about 1.2% per year. So, we must reduce our CO2 emissions by 1.2% per year—not just around the home, but throughout society and around the world. By 2050 the reduction needs to be 30% just to keep things constant at today’s levels. Then, over the next 50 years (if the population stops growing) we need to reduce our CO2 emissions by an additional 50 percent! So that by the end of the century every person on earth is only responsible for 1/3rd of the CO2 emissions that we were producing at the beginning of the century. Unless new, non-CO2 producing energy sources are developed, this is a virtual impossibility.

Consider that since the beginning of the 21st century, the per capita CO2 emissions from virtually every nation on earth has either held steady or, as is most often the case, increased. In China, the per capita CO2 emissions have doubled. And the capita are rising as well. The notion of everyone producing only 33% as much CO2 emissions as we do now, by the end of the century, without a new energy source, i.e., primarily through conservation practices, is simply unrealistic and untenable.

But no one seems to care about these realities. Instead, they continue to push on, as if simply saying or mandating that we are going to achieve a 50% emissions reduction means that we will. Folks act as if outlawing incandescent light bulbs and raising fuel-efficiency standards for automobiles will have some meaningful effect. If they mean morally meaningful (i.e., it will make them feel better) then, perhaps they are correct, if they mean climatologically meaningful, then they couldn’t be more mistaken.

What we really need, if people are serious about reducing carbon dioxide emissions, is an all out effort to develop new energy technology—make the miracle occur. This could happen (perhaps preferably) through the free market, or if it is the general consensus that the government needs to be involved, then the clearly stated purpose of any proposed legislation should be to raise the money necessary to support energy research—not mandate emissions restrictions without any good way of making it happen. The ultimate solutions must be distributed globally as the efforts of individual countries are not enough to lower the blue line in Figure 2 to the target. The politics of this cooperation is staggering to consider, in that energy is power, economically and militarily. And a global power-sharing scheme seems a long way from where our current world is.

So what really will happen is business-as-usual. Legislation will be proposed both in the United States and in other countries around the world with the stated goal of reducing carbon dioxide emissions, and some of this legislation will pass. But the targets won’t come close to being met as a bits-and-pieces solution will not achieve the goal of halving current global CO2 emissions by the year 2100—much less any year before then. In fact, more than likely, these legislative efforts will not, to any noticeable degree, even begin to separate the blue and the red curves for a long time to come—far too long to avoid elevating global temperature 2 degrees above “natural” levels.

That’s what the future holds in store. Get used to it.


Carbon Dioxide Information Analysis Center (CDIAC). Global, Regional, and National Fossil Fuel CO2 Emissions. http://cdiac.ornl.gov/trends/emis/tre_glob.htm

U.S. Census Bureau. World Population Information. http://www.census.gov/ipc/www/idb/worldpopinfo.html

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