It seems to me you worry too much. The fact we think we have global warming is obviously due at least in part to the heat island effect.
Check out this web site. http://www.epa.gov/heatislands/
As someone who spent nearly 4 hours chewing on a Nerf football during last Sunday's Patriots-Chargers thriller, I'm in no position to address my anxiety. (Irrelevant Google-induced sidebar of the week: Nerf balls are apparently a must for sailing.)
The Urban Heat Island effect is popular because it makes sense. I know I've never questioned 
it. It's hotter on the pavement than on the grass. There's lots of pavement in the city. The weather people on TV are always saying it's a few degrees warmer at Reagan than it is in, say, Frederick. And there are lots of cartoons like this one that make a colorful (if not quite scientifically rigorous) case.
But after reading up on Urban Heat Islands, there seems to be only one thing everyone agrees on: It's really hard to objectively measure the temperature in a given place. If you take a temperature two feet off the pavement on a summer day, it's going to be much hotter than a temperature reading taken 100 feet above the pavement. Which is accurate? Unfortunately from a scientific standpoint, urban weather stations tend to be in/on/near buildings, while rural weather stations tend to be in/on/near dirt, so it's hard to make an accurate comparison. For details, scroll down to "Disadvantages of Surface and Air Temperature Measurements" at this site.
Because of all that disparity, there's some skepticism about whether the Urban Heat Island effect even exists, nevermind its effect on global warming. The UN's Intergovernmental Panel on Climate Change states, "Extensive tests have shown that the urban heat island effects are no more than about 0.05°C up to 1990 in the global temperature records used in this chapter to depict climate change."So it looks like the conventional wisdom about the effect of Urban Heat Islands is wrong on the global level, and a little shaky even on the local level. In fact, the very EPA website that Tom refers to discourages any direct connection between urban heat islands and global warming, and says that if anything, it's the byproducts of the heat island effect that could contribute to global warming ...
Heat islands describe local-scale temperature differences, generally between urban and rural areas. In contrast, global warming refers to a gradual rise of the earth's surface temperature.
While they are distinct phenomena, summertime heat islands may contribute to global warming by increasing demand for air conditioning, which results in additional power plant emissions of heat-trapping greenhouse gases. Strategies to reduce heat islands, therefore, can also reduce the emissions that contribute to global warming.
6 comments:
Miles -- I did not consider the possibility that you might think heat island cause Global Warming. In the 70’s, we did not have the computers and the programs that climatologists use today. Simulation models, whether they are accurate or not, do make predictions. That results in much of the difference in today’s global warming scare versus yesterday’s global cooling scare. With their climate models (that is, computer models of the worldwide weather), climatologists can make predictions. Fortunately, these predictions have not been accurate in predicting global warming.
As you should know, there are two substantial problems with any computer program. One is that you have to know what equations to put into it. The second is that you have to have good data for your computations.
Because the earth’s weather systems are so complex, we still have a lot to learn. So the equations are lacking. Consider that we did not discover the El Nino - La Nina effect in the Pacific Ocean until the 80’s. Supposedly, this effect on the world’s weather is only surpassed by the weather effects engendered by the tilt of the earth’s axis.
We also lack useful data because we did not begin collecting global data until recently. The time period over which we have been collecting global data did not begin until the launch of our first weather satellites. Given what the geologic and fossil data suggests about the length of the earth’s weather cycles, the time since the beginning of the space age is too small a period for us to have collected sufficient data.
There is also one other aspect of the Global Cooling scare that is worth considering. The suggestions that “we” were responsible for Global Cooling were muted. For the most part, the advocates did not presume to think we controlled the weather; no one was put to blame. So unlike the Global Warming scare, Global Cooling did not become a “cause” save the world from evil industrialists and global climate change deniers.
Fiddlesticks, I met to hit preview, but I got fouled up by the word verification. So the previous comment is a mess. Anyway, much of it I borrowed from a comment I made at this post, where it made mores sense. If nothing else, I suspect you will find the post on Waldo site interesting.
About heat islands. I did not mean to suggest heat islands cause global warming. The problem I was getting at comes from getting accurate data, which you also considered. What do you measure, where do you measure it and how? If you are trying measure the global temperature, the confusion created by things such as the heat island effect complicates this problem. How do you separate urbanization effects from global warming? Before the invention of weather satellites, we really did not have a solution for this problem.
Consider what global warming is. Global warming is essentially a prediction made by computer simulation modeling programs. These models project that we can produce CO2 significantly faster than the oceans can absorb it. Thus we put sufficient CO2 in the air to cause a temperature rise.
There are two substantial problems with any computer program. The first is that you have to know what equations to put into it. The second is that you have to have good data for your computations.
Because the earth’s weather systems are so complex, we still have a lot to learn. So the equations are lacking. Consider that we did not discover the El Nino - La Nina effect in the Pacific Ocean until the 80’s. Supposedly, this effect on the world’s weather is only surpassed by the weather effects engendered by the tilt of the earth’s axis.
We also lack useful data because we did not begin collecting data on a global scale until recently. The time period over which we have been collecting global data did not begin until the launch of our first weather satellites. Given what the geologic and fossil data suggests about the length of the earth’s weather cycles, the time since the beginning of the space age is too small a period for us to have collected sufficient data.
So while there actually may something to the Global Warming theory, whether the theory is true remains guesswork. The so-called consensus of the scientific community does not constitute scientific proof.
BTW - if you do not believe in the heat island effect, then on a hot, sunny summer day, can you explain to me why you would prefer to stand in grassy field rather than in an asphalt parking lot?
Miles, I'm no climatologist, but my (admittedly limited) understanding of the importance of the urban heat island affect is its affect on temperature *measurement", not on actual global temperatures. Most measurements are taken at airports. In the past, airports were fairly removed from the metropolitan areas they served, which meant that the recordings were little affected by the heat island affect. Over time, development encroached on the airports, in effect, bringing the urban heat island to the airport. The same pattern occurred in city after city, skewing temperature measurements upward, thereby making it difficult to disentangle regional/global temperature increases from purely local temperature increases. Please correct me if I'm wrong.
Jim, that seems to be exactly right ... so I'm not sure why the EPA has a whole site dedicated to heat islands, their effects, mitigation, etc.
Miles- The reason the EPA is concerned about the heat island effect is because it can be costly and unpleasant. One reason people move out of the city and into to the country is because the country is cooler.
The heat island effect makes it more expensive to cool our homes in the summer time. However
Oh the, "UN's Intergovernmental Panel on Climate Change," said it so it must be true. Give me a break. Those beaurocrats have a vested interest in keeping the "Global Warming" propaganda alive. They are damaged goods, they are biased, and most of all, the United Nations is an International Socialist organization.
You do not display one ounce of skepticism when you say, "UN's Intergovernmental Panel on Climate Change." Golly.
The UHI is Global Warming.
Those Global warming temperature increases, those fancy graphs which go up, those big evil red splotched maps, are all measured temperature increases AT GROUND LEVEL. Not 100 feet up, not 1,000 feet up, Not in the Stratosphere, just a fraction of the Troposphere. Ground level.
Thermometers 100 years ago were at the courthouses, or on campuses of in small towns with wooden buildings. Today the thermometers are in the middle of large concrete cities subjected to the UHI. Global Warming 'IS' the UHI effect.
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