"The problem is that it's not like a race where we reach that doubling goal and then just stop belching out CO2. What happens if we double it again? That's why I'm in favor of purchasing insurance, in the form of Obama's energy plan."

There are a number of problems with this idea.
Obama energy plan unless it includes significantly reducing China's CO2 emission, can't reduce global CO2 emission from human activity- in any significant manner. I don't know much about Obama plan, but if it's similar to what Europe is doing, then Obama's Plan won't even reduce American emissions- because Europe has not reduce their CO2- despite spending tens to hundreds of billions of dollars attempting to do this.

Now if we have another great depression, that will have some affect upon CO2 emission. Increasing the cost of energy will reduce economic growth. If everyone pays twice the amount for electricity and twice as much for transportation fuel, it would similar to large tax increase- a tax increase with most affect upon lower and middle class incomes. Or if you cause significant inflation this also is a similar type of tax. Inflation with no increase in energy cost [not adjusted for inflation] will be the same as reducing the price of energy. But if you causing inflation and you causing an increase in energy cost, you will get stagflation- little or no growth and high inflation.
So if we repeat what done during the Carter years this could cause some reduction in CO2 emission, but it's rather insignificant even in terms of US emissions.

But suppose Obama's Plan was actually brilliance and works better than anyone expects- let's say it reduced US emission by %50 in 10 years. China by itself produces more CO2 than than the US and in 10 years will produce more CO2 per year than this 50% reduction in US emission. The result of China ever increasing emission in terms of global CO2 would be as if tomorrow US emission was halved, it would effectively be reducing China emission increase of 9% to about 5%.
Or if China become as efficient as the US in term of CO2 emission and reduced it's emission to less than 5% increase per year, within 10 years in terms of global CO2 emission it be as though the US had no emission of CO2.

The other part of the problem is there is no direct relation between human emission and global CO2. In other words if human emission CO2 doubles every 20 year the increase in global CO2 does not double in 20 years [or 40 or 60 years].

In 1990 the world consumed 3461Mt of hard coal and in 2007 consumed 5522Mt.
In 2007 China produced 2549Mt of hard coal and US produced 981Mt

http://www.worldcoal.org/pages/content/index.asp?PageID=188

"1.83 kg CO2 for every 1 kg of coal burned"
http://wiki.answers.com/Q/How_much_co2_is_produced_from_burning_coal

So in terms of hard coal if burned globally: 3461Mt is 6.3 billion tonnes and in 2007: 5522Mt is 10 billion tonnes of CO2- close to doubling every 20 years.
In China it's more than doubling every 10 years.

So, US domestic policy can not significantly affect global CO2 emission, even if it achieved dramatic reduction in CO2 it will be lost in the noise of increases in China and elsewhere. It does not seem reasonable to expect that Obama's policy will have a significant effect if it resembles what was done in Europe over the last decade.

Then we have other issues. First being that there probably isn't enough fossil fuels that exist in the world that if all could be burned that could double global CO2, so worrying about doubling again is problematic.

So, you have to ask the question how much of world supply of fossil fuels have been used already.
If 1/2 of it has been used, then obviously at most this produced 100 ppm, so 100 plus 385 ppm is 485 ppm.
Or suppose we have used 1/3 of the total amount that we will use, so in the very simplistic model then we then get a doubling of CO2 385 plus 200 ppm equal 585 ppm. But then where we going to get 560 + 560 ppm? How could get to 1120 ppm? It would mean that we have only used less than 1/8th of the fossil fuel that we have hundreds of years of fossil fuel at the current rate of ever increasing use. Does anyone believe this?

But as I said the rate of increase in human CO2 emission does not match the rate of increase in global CO2. Though I will note that no one is claiming it does.
Some claim that about 1/2 of human emission results in global CO2. So, if take that less generous assumption then we would need to have consumed about 1/16 of global fossil fuels. Does anyone believe that?

So all this insurance plan does is help people delude themselves that something is being done. It does nothing in terms of providing you relief in the future if "something happens". And it's going to be expensive. If the govt says something will cost X, as general rule, reasonable people should assume will cost 10 times to amount.