| Common Misconceptions |
| Monday, 03 March 2008 22:29 |
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I’ve heard that volcanoes emit more CO2 per year than humans have done in their entire existence. That is incorrect, humans currently release 130 times more CO2 per year than volcanoes do.
See http://volcanoes.usgs.gov/Hazards/What/VolGas/volgas.html which states this as their source: Marland, G., Boden, T.A., and Andres, R.J., 2006, Global, Regional, and National Fossil Fuel CO2 Emissions, In Trends: A Compendium of data on global change, Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory, U.S. Dept. of Energy, Oak Ridge, Tenn., U.S.A. (http://cdiac.ornl.gov/trends/emis/meth_reg.htm)
I’ve heard that the activity of the sun is driving earth’s temperature, and that CO2 has nothing to do with it. It is true that the sun strongly affects earth’s climate and temperature. This has been studied in great detail and low activity of the sun was likely one of the reasons for the “little ice age”. But CO2 and other greenhouse gases also do their share. It seems to be a complex picture. Look at this graph over temperature and CO2 levels during the past 400 000 years. CO2 concentration has varied between 200 and 300 ppm, while we are now beyond 382 ppm, a raise that has occurred within 150 years. That is a dramatic increase in CO2 concentration in our atmosphere, and the increase seen in the perspective of 400 000 years is just astonishing. Greenhouse gases currently keep our planet roughly 20 degrees C warmer than it would be without greenhouse gases. I find it logical that an increase in the concentration of greenhouse gases would also increase their heat keeping effect.
But I’ve heard that CO2 concentration levels don’t increase the temperature, it’s the other way around! It’s hard to tell what drives what from the available data. Sometimes CO2 levels goes up first, sometimes temperature goes up first. They seem to be related. I don't know if CO2 increases the temperature, or other forcings has increased both CO2 levels and temperature at the same time, thereby making it look like they are affecting each other. But when I look at this graph above I have to say that I think they are related. Perhaps they both affect each other? Why does it have to be a one way interaction? One thing is certain. Humans have now increased the CO2 levels from some 280 ppm to 382 ppm. Whether temperature will follow the CO2 levels as before or not remains to be seen. But looking at the graph we might be up for some 12 degrees C increase in temperature. What I can't tell from the picture is how long of a delay we can expect from increasing the CO2 levels to get the increased temperature. If at all.
Higher temperatures will be just fine by me; I don’t like it cold anyway! The temperature has always varied, so a change in temperature wouldn't be anything new. But what is troubling is that it occurs during our lifetime. We depend on the weather to be relatively stable. Trees, plants and animals depend on the weather to be relatively stable as well. The line at which leaf-based trees stop growing in Sweden is being moved upwards every year, and that causes a shift in the local fauna and flora. The cold winters also used to protect us from a lot of unwanted animals and insects that are now entering our country. Consider such a simple thing as our homes. They are built for a certain type of weather and there is major difference in the way homes are built in Spain and in Sweden - for a valid reason. They were built to suit our local needs, and a large part of that is the weather. It's all about predictability, and we seem to be entering unknown territories now. I have eastern lilies in bloom one month early this year. And I had strawberry plants blooming and making little green berries in October last year. That’s not common, and it is not something I would have predicted. It's just plain wrong. What else will happen that I cannot predict, since it hasn't happened before?
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