Two New Reports

The first is from the Brookings Institution. The report (click here for PDF) quantifies transportation and residential carbon emissions for the 100 largest U.S. metropolitan areas. Not surprisingly, the report finds that the carbon footprint of the average city dweller is substantially lower than their rural compatriots. More surprisingly perhaps, the carbon footprint of city dwellers is also increasing more slowly than the national average, 7.5% between 2000 and 2005 compared to 9% nationally. The fact that it is still increasing rather than decreasing is depressing though.

The report also found that per capita emissions vary widely between cities, largely due to the availability of public transport and the fuels used for electricity generation. Each of the 10 metro areas with the lowest per capita electricity usage hailed from states with higher-than-average electricity prices. The report also made the following policy recommendations:

1. Promote more transportation choices to expand transit and compact development options
2. Introduce more energy-efficient freight operations with regional freight planning
   
3. Require home energy cost disclosure when selling and “on-bill” financing to stimulate and scale up energy-efficient retrofitting of residential housing
   
4. Use federal housing policy to create incentives for energy- and location-efficient decisions
5. Issue a metropolitan challenge to develop innovative solutions that integrate multiple policy areas
   

The second report was released reluctantly (in fact, in response to a court order) by the federal government and is a summary of recently published research on the effects of climate change on American life, including agriculture. Click here to download the full report, which is about 270 pages long. (I found the 2.75MB download very slow, perhaps because it is a popular download, or perhaps because the government deliberately put it on a slow server. The ability to download just the 17-page executive summary would be welcome.)

After reciting the evidence for climate change, the executive summary refers to the conclusions of previous government reports that “it is very likely that temperature increases, increasing carbon dioxide levels, and altered patterns of precipitation are already affecting U.S. water resources, agriculture, land resources, biodiversity, and human health, among other things” and that “it is very likely that climate change will continue to have significant effects on these resources over the next few decades and beyond.” It then goes into more detail about the effects on agriculture, health etc.

The report identifies benefits as well as costs and some of the conclusions are almost laughably obvious; for example the report predicts a decrease in energy used for heating and an increase in the energy used for cooling and that more people will die from the heat while fewer will die from the cold. (The point about energy use is not entirely trivial however, since while we use electricity for cooling we often use natural gas for heating.) While far from alarmist, the overall picture painted by the executive summary gives ample cause for alarm.

The body of the report is packed full of information for those interested in the details, including geographically detailed historical information about changes in precipitation, temperature etc. over the past century.

A Difficult Few Years Ahead for AGW?

I was not going to do much climate change science on this blog, but it has not been lost on me that my recent posting about a climate skeptic provoked more controversy than any other posting. So, I decided to delve a little more into some of the skeptics’ claims. I am not talking about the more mainstream skeptics who accept the science but believe there are better ways to spend our limited resources than on combating climate change, which is a defensible position. Rather I am talking about those who dispute that Anthropogenic Global Warming (AGW) is a reality.

The typical claim here is that global warming stopped in 1998, and more recently that January 2008 was actually colder than January 2007. I decided to try to get to the truth behind the truthiness. I think the first thing to point out is that while it is accepted by almost all scientists that greenhouse gases tend to increase the mean temperature of the earth, nobody has suggested that this is the only factor affecting the earth’s temperature. One well-known additional factor is the presence of CFCs and SO2 in the atmosphere, both of which tend to reflect some of the incoming radiation and make the earth cooler, and this tended to counter the effects of greenhouse gases until regulation reduced emissions of these gases in the 1990’s. (Indeed it has been suggested that we may need to create a similar effect deliberately if we fail to act soon enough on greenhouse gases.)

Two other factors are sun spots, and the “Southern Oscillation” between El Nino and La Nina ocean currents and winds. The latter may not seem relevant to the mean temperature of the earth, but it is; as well as I can understand it, La Nina forces more of the heat into the lower depths of the ocean and thus makes the surface temperature (which is what we measure) cooler than it would otherwise be.

The effect of sun spots is also somewhat unintuitive; since they are dark, one might expect then to reduce the irradiance of the sun, but in fact they do the opposite: more sun spots means more radiation from the sun. Sun spot activity is roughly cyclic, increasing for about 4 years and then declining for about 7, though it is not entirely predictable. Since about 2001 we have been in the declining phase of “cycle 23” and we are now just about at the bottom of the cycle. There has been some concern that the start of cycle 24 might be delayed. (But see http://science.nasa.gov/headlines/y2007/14dec_excitement.htm for the possible first evidence of cycle 24.)

Even if cycle 24 starts on schedule, there will be a couple of years of lower temperatures (than might otherwise pertain) because the earth’s temperature lags the sunspot activity by about 2 years. In addition, we are at the beginning of a La Nina period, which also tends to cool the earth’s surface. What we have is an upward trend due to greenhouse gases superimposed on two somewhat regular cycles both of which are approaching their low points, plus of course quite a bit of noise. The net result is that we probably will not see exceptional temperatures in the next year or so; the skeptics will have a field day and the faithful will be tested. (A good summary of where we are can be found at http://data.giss.nasa.gov/gistemp/2007.) We can be fairly sure however that by 2012 at the latest we will see new records broken. We must all hope that we don’t have to wait that long for more aggressive action.

Krysten Byrnes

I had thought that GW would be the last skeptic standing (see previous post), but they seem to be coming out of the woodwork lately. I reported yesterday about Nigel Lawson’s new book. This morning, NPR did a long piece (www.npr.org/templates/story/story.php?storyId=89619306) about 16-year-old Kristen Byrnes taking on Climate Scientists with her web site home.earthlink.net/~ponderthemaunder. It seems in part to be a way for her to collect donations to her college fund; let’s hope that succeeds because she might learn something. Right now her scientific credentials seem minimal. For example, she said on the show that CO2 does not reflect heat back to earth, which is quite correct but irrelevant; the mechanism of global warming, known since 1850 by the way, is that CO2 absorbs certain frequencies from the earth’s radiation and then radiates energy in all directions.

Dealing with Skeptics

The New York Times reported on Sunday that climate change skeptics are drawing attention to the recent cold weather in China and other places to cast doubt on climate change. (See http://select.nytimes.com/mem/tnt.html?_r=1&emc=tnt&tntget=2008/03/02/science/02cold.html&tntemail1=y&oref=slogin) I have not written on the science before, because I did not think it was necessary, but maybe this is an excuse to rehearse the argument I use on the increasingly rare occasions when I am faced with a skeptic.

Frequently I find there is a misunderstanding that scientists are somehow struggling to explain observed climate change. Nothing could be further than the truth. Climate change due to human activity -- anthropogenic climate change – was predicted by John Tyndall as early as 1860 (see http://www.tyndall.ac.uk/general/history/) and has been vigorously promoted by James Hansen of NASA (see for example http://en.wikipedia.org/wiki/James_Hansen) since the 1970’s. In other words the theory preceded the observed effect.

Because of this, the focus over the past decade or so on whether we are actually observing climate change has been a diversion which has had the effect of wasting a lot of time during which we could have been taking action. Of course, the scientific method requires that we test our theories by observation, but there are different kinds of scientific theories. Testing climate change by observation is not a defining moment for science, like for example demonstrating that light gets bent by gravity validating the general theory of relativity. It is more like watching a heated kettle of water in the expectation that steam will appear from the spout. If it does not, we have some serious rethinking to do, but nobody seriously doubts that it will. Arguing about whether we actually can see the first wisp of steam is not very productive.

In the case of climate change, if it did not happen then we would have to rethink a good deal of the physics we thought we have known for over a century. It is a simple energy imbalance due to the absorption spectra of greenhouse gases and the different spectra of incoming radiation from the sun and the outgoing radiation from the earth. More heat comes in than goes out, so the earth warms up until it reaches a new equilibrium. Except that right now we are adding to the greenhouse gases to this equilibrium temperature keeps rising.

(It is perhaps worth noting here the amount of inertia in the system. Even if we could stop all greenhouse gas emissions today, stablizing the current concentration of these gases at 380 ppm of carbon dioxide equivalent, the average temperature of the earth would still continue to rise for decades. And then of course there is inertia at the next level down, in that we cannot stop the emissions today. The goal of IPCC efforts is to stabilize the concentration at 450 ppm.)

The precise effects of climate change in specific regions are much less certain, and skeptics often seize on this uncertainty. The reason for the uncertainty is that the heat landing on the earth is concentrated towards the equator, whereas the radiation from the earth is more evenly spread. Heat gets transferred from the equator towards the poles by air and sea currents, and predicting how these will be affected by climate change is much more difficult than the simple energy-balance model which tells us that the average temperature of the earth has to increase. Some places may get wetter, others drier, some may even get colder. There are very complex computer models but they probably cannot be relied upon as definitive. What we can be pretty sure of is that there will be disruptive changes.

If all the above fails to convince a skeptic, one can always fall back on the last resort sometimes known as the precautionary principle. If there is even a significant chance of catastrophic effects of anthropogenic climate change is true, does it not make sense to act as if it is true? If we were in a car heading towards what looks like a concrete wall we would not delay braking because it might be a paper mock-up, still less because we could not predict exactly which bones we would break.

As I write this, NPR is running a story about one example of a possible local effect. The locks on the Panama Canal are being widened and deepened to take larger ships. Its operation is however threatened by climate change because it depends upon rainfall. The canal rises 85 feet above sea level and the water for the locks on both sides is gravity-fed fresh water from artificial lakes. Climate change could reduce rainfall and threaten its operation. Of course, by then the Northwest Passage may be a viable alternative.