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Originally Posted by kramer
In that ice core data that shows temperature increases and decreases leading CO2 increases and decreases by hundreds of years, how much of a factor is CO2 in heating the atmosphere given that it's 1/720 times as powerful as water vapor as a greenhouse gas and that it made up about 0.030000% of the atmosphere?
The energy output of the sun has been increasing (overall) since about 1700 AND the last 70 years of sunspot activity has been higher than at any other period of time going back 8000 years... In addition, the energy output of the sun has been increasing by 0.05%/decade since the 1970's.
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Perhaps there is a lag for the earth heating to take place.
And ice core data shows that it takes hundreds of years for the CO2 to catch up to the temperature...
Kramer |
Before I answer your post, I'd just like to say thanks for stating your opinion in a reasonable way. I don't agree with what you posted, but I respect the way in which you did so. Thanks. Reasonable discourse isn't seen very often on this board, and I'm afraid supporters of both major political parties share the blame here.
Now for the meat of your argument.
Unfortunately, you present a couple of arguments that have been thoroughly debunked, and not recently either (I even don't think I'm even the first poster to show info on these on this board).
1) It's well known that CO2 is a minor gas in the atmosphere (but is the second most abundant greenhouse gas) and no one worth their salt would argue differently. However, your argument is somewhat disingenious in thinking that the low abundance of CO2 in relation to other gases means it has little effect when it comes to retaining heat. CO2, though in low abundance compared to nitrogen and other gases, is the second most abundant greenhouse gas, and is responsible for 9-26% (depending on who you talk to) of the greenhouse effect on earth. There is a lot of research to back that up (Kiehl and Trenberth 1997 is a good place to start). Those numbers are nothing to sneeze at.
But, what about water vapor? It's true, it's a more powerful greenhouse gas than CO2 and more abundant (responsible for about 3/4s of the greenhouse effect). However, your argument is flawed in thinking that these compounds in the atmosphere are independent of one another. They are not, they interact with one another. For instance, CO2 can trap heat, making the atmospheric temperature rise. This allows for air to hold more water vapor which also increases heating. So, increasing amounts of CO2 in the atmosphere can increase the amount of water vapor in the atmosphere. (one recent paper on this = Held and Soden 2006). Additionally, increasing temperature can also increase the amount of CO2 the atmosphere can hold.
2) You state that sunspot activity can be the culprit for the heating. It is true that sun activity has increased, but the increase can't explain the amount of heating that has taken place. In fact, no natural phenomenon can. Onon is the resident expert on evidence for this, so prod him to provide references if you want them.
3) You state that historically temperature increases proceed an increase in CO2. This is true. Yet, it doesn't mean that CO2 is not the culprit for heating. In fact, climatologists PREDICTED that this would be the case before they could measure historical CO2 concentrations. Are these climatologists just idiots? How could they not see that CO2 can't be the culprit for heating...(which, I might add, is a really good question, no joke)
Well, it turns out that it is due to one of those feedback mechanisms again. Climate changes, like the end of ice ages, forced by Milankovitch cycles (from the wobble of the earth), decrease the albedo effect (less ice = less reflection = more heating) which cause temperatures to rise (higher atmospheric temperatures = more atmospheric CO2 = more heating). So both ice and CO2 changes SHOULD lag temperature, which is what has been found in ice cores. CO2 acts as an amplifier for these temperature changes, and historically these lags take about 100 years or more (depending on who you talk to), but always the temperature goes up again once CO2 goes up. So, given today's rising CO2 concentrations, you can expect more temperature increase in the future.
Don't take my word on it. Here's a great
webpage I found that addresses your question far more lucidly than I could. It's even got a lot of references that you can check up on if you'd like.