| Yulegoat said: As far as the main argument of AGW goes, it's clear that greenhouse gases warm up the atmosphere, but again, there is not certainity of how much. IPCC states that the climate sensitivity, that is, the rise of temperature resulting from doubling the amount of CO2, is 1.4-5.5 degrees celsius. Now you may think that it doesn't matter how strong the effect is, because the cumulation keeps on going. (I agree that we should get rid of fossil fuels as soon as possible because that has to be done at some point anyway (they don't last forever), so my points aren't meant to encourage polluting more.) However, the climate sensitivity works on a logarithmic base. That is, the doubling of the amount of CO2 in atmosphere results in very similar rise in temperature no matter what the starting values are. For example, if the rise from 200 ppm to 400 ppm would raise the temperature by X degrees, so would the rise from 2000 ppm to 4000 ppm. This means that we would most probably die off because of CO2-poisoning before we could make this planet too hot to live due to increased CO2-levels. In addition, there has been as far as 20 times more CO2 in the atmosphere compared to the levels of today and the time is known as the Ordovician glaciation period, one of the coldest epochs ever. That would suggest that the Earth's climatic balance is not easily altered by rise in greenhouse gases. Some of you might have now thought that why has the climate warmed so little if the percentual increase of greenhouse gases is the one that matters. That surely has been a big problem. The warming should have been fastest from 1950-1970 because of the high forcing, but instead there was no rise in temperature at all in that period. This is explained with global dimming, which results from increased pollution. Now that the technique is cleaner, less pollution is created and the Earth should warm faster. However, the warming hasn't been very fast after year 2000. Here's a graph to show what I mean: http://www.cru.uea.ac.uk/cru/data/temperature/_nhshgl.gif This might be due to the stabilizing of methane levels or solar activity, for example. We'll see how the climate keeps changing. |
First: I agree with you, that the most catastrophic scenarios will not become true. There will be more storms, droughts and people will dying in lesser developed countries and in higher developed countries the economy will be hurted. But the mankind will exist on. But these sentences about CO2 and it's effects to climate are mere simplifications. Climate changes dont happen over night. So the pollution we did in 19th century (yes back then) will influence climate in the next years. The Emissions in the 20th century will need hundred years or more, to show their full effects on climate. Thats why the european countries no longer want to avoid global warming (it's already impossible), they want to reduce it to 2 degrees. And to the Ordovicium-argument: Climate change is not linear. There were always warm and cold periods in earths history. But, the general trend is, that the earth is cooling down, as plants converts the CO2 into oxygen.
