Matty Cramp: I don't know if it's exponential, but it's definitely cumulative. The more water vapor there is in the atmosphere, the greater the warming effect from trapped radiation from the sun, which leads to more water vapor forming. That means it's perfectly reasonable for temperature to rise more rapidly near the end of a warming trend than the beginning of one.
This is provable by graphing it using some math I don't remember clearly. It's been a long time since I had to do any pure math, so I'll do my best here and hope someone more in touch with mathematics now than I currently am can fill in the holes.
Suppose every x amount of greenhouse gas traps y amount of radiation, and every y amount of radiation releases x/1000 extra greenhouse gas to the atmosphere each year from various sources, including man-made sources. For ease of calculation, let's let y = 1 and x = 1, and every extra x of water vapor = an extra 0.01 degrees C. Let's suppose we're starting at -15 degrees C, just like the average temperature was 18,000 years ago. Each year the amount of greenhouse gas in the atmosphere is (1 + 1/1000)^n where n is the number of years gone by. Since x = 0.01 degrees, temperature change will be whatever the resulting value is - 1, multiplied by 0.01. So here are some results after certain years:
after 1 year: 1.001 = 0.00001 degree increase
after 10 years: 1.01 = 0.0001 degree increase
after 100 years: 1.105 = 0.001 degree increase
after 500 years: 1.648 = 0.0065 degree increase
after 1000 years: 2.717 = 0.0172 degree increase
after 2000 years: 7.382 = 0.0638 degree increase
after 3000 years: 20.055 = 0.1906 degree increase
after 5000 years: 148.043 = 1.4704 degree increase
after 7500 years: 1801.279 = 18.0128 degree increase
after 10000 years: 21916.681 = 219.1568 degree increase
after 18000 years: 65072070.823 = 650720.6908 degree increase
So the first 5000 years increase the temperature from -15C to -13.5C, but the next 5000 years increase the temperature to 204.2C. Anyone caught in the middle of that second 5000 years would certainly be aware that the planet is getting warmer, but because it's a natural and uncontrollable process there would be nothing they can do about it. That's the same boat we're in, and yes I'm that sure of it. Now suppose that after 7500 years we are able to decrease the amount of added greenhouse gasses by 50%, the amount I believe is targetted for 2015 or something, to x/2000. What happens then?
after 7500 years: 1801.279 = 18.0128 degree increase
after 8000 years: 2312.744 = 23.1274 degree increase
after 9000 years: 3812.593 = 38.1259 degree increase
after 10000 years: 6258.118 = 62.5812 degree increase
after 15000 years: 76520.584 = 765.2058 degree increase
after 18000 years: 342812.930 = 3428.1293 degree increase
Looks promising, right? almost 160 degrees cooler after 10,000 years is a huge change. There's just one problem:
total greenhouse gasses isn't what we're talking about cutting by 50%! CO2 is the gas we're talking about, and even if wikipedia is right about CO2 accounting for 12% of the greenhouse effect, that means the difference between pre-reduction and post-reduction temperatures must be multiplied by 0.12. So that's roughly (219-62) * 0.12 for the total impact of our efforts, which means after 2500 years of 50% reduced CO2 output the total impact is about 18.84 degrees, meaning all we've done is slow the natural process by an average of 0.007536 degrees C/year.
So what about a more practical example then. Let's say the temperature went up last year by about 0.1C due to greenhouse gasses. It didn't, but it's what I've seen claimed in some places, so we'll use it because it's easy to work with. Since the effect of greenhouse gas is still cumulative, the same general formula can be applied with some slight variations: x=1 degree C instead of x = 0.01 degrees C. The current amount of greenhouse gas is still x = 1. The general formula is then (1 + i)^n. Since we know the temperature went up by 0.1C, we can calculate i as follows:
(1 + i)^1 = 1 (status quo) + 0.1 (variation)
1 + i = 1.1
i = 0.1
That means our specific formula for this equation is (1 + 0.1)^n, or 1.1^n without our influence, or 1.094^n with our influence lowering total CO2 production by 50%. So how does it stack up?
Years No action Action
1 year 1.1 1.094
10 years 2.593 2.456
20 years 6.727 6.030
30 years 17.449 14.809
40 years 45.259 36.366
50 years 117.391 89.303
Again, it looks helpful, right? There's just one problem: humans can't survive in an environment hotter than about 40C. That means by the time the effect is noticeable and relevant it's already too late, because we're all dead anyway. It'll just take 40 years instead of 37. You can take heart in this though: there has never in the history of the planet been a 100 year temperature increase of 1C or more. Going by the historical records, we'll be in another ice age long before the world is too hot to live in.
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Deploy the... I think it's a yellow button... it's usually flashing... it makes the engines go... WHOOSH!
You should. As long as you are not absolutely sure that there is no risk I think you ought to care about the possability of global warming (were man is involved). Espescially since reducing our burning of fossil fueles is a very good thing anyway.
As has already been pointed out in this thread it is not unheard of that scientists get bribed. I know that there were strong, strong forces trying to lessen the threat presented in the UN report, namely USA, China and India.
