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Originally Posted by HOOT
How do they know what green house gases were 2000 years ago? Are they sure those numbers are accurate? Could they have changed in the 2000 years it took for us to actually be able to test it?
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There are various sources. Ice cores with trapped air bubbles can be measured directly, and there's various proxies for CO2 and other gases in sediments, rocks, etc.
As to how accurate they are, they will give the error bars in whatever paper it is so one can see how accurate they are and why.
Where the different methods overlap they of course check to see if the values fall within each others' error bars.. if they don't then obviously something is amiss and they have to go back and figure out which one was wrong and why.
We also know how much CO2 in our atmosphere currently is due to human production; the ratio of isotopes is different in sources like oil and natural gas so you can use those ratios to determine that.
Quote:
Originally Posted by HOOT
Personally I think we are giving man kind way too much credit to think we could destroy this planet.
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It's not about destroying the planet, it's about enough influence to negatively impact us and the other life. A 1cm rise in sea level is different than a 10cm rise, a 1m rise, a 10m, rise and a 100m rise. Each would have different impacts. A warming ocean changes the ocean's ecosystems, resulting in different food chains that may or may not impact us depending on how severe they are.
The planet and the life on it will long outlive humanity I'm sure.