disha wrote:JohneeG/Neshant., please answer my question.
To your carbon recycling - what happens when forests are destroyed? And their wood burnt? What happens to your CO2 cycle then? Will not CO2 accumulate?
If forests are cut for firewood, then it would effect the nature in two ways: CO2 would increase due to burning wood and less plants to recycle the CO2 back into oxygen. So, cutting forests for firewood leads to increase in CO2. But, if fossil fuels are used, then Forests are cut less. Forests used to be cut more for firewood when fossil fuels were used less. This is particularly true in countries other than India or China where the populations are much less. So, using fossil fuels is better than firewood to reduce CO2.
As for your question: I thought Gus saar answered your question. The theory that Gus saar said was actually Kelvin's theory. He was also the guy who came up with Absolute Zero Temperature. There was another theory called Uniformism which believed that the world existed as it is. Initially, both these theories were opposed to each other and contradicted each other. Before, these two theories, there was already Ice age theory. Then, there is also continental drift theory which was proposed later and it was not accepted for a long time(until the lifetime of the proposer). I think today geologists mostly believe in all these theories. So, some kind of syncretic theory seems to have been evolved at some point by mixing together all these theories.
So, earth was once hot enough to be melted according to Kelvin. Then, earth became cold and this is ice age. Then, the ice age came to an end and earth became warm enough for the life to thrive.(You see warming is not a bad thing according to this theory). And during all this period the continents were shifting all over the place according to continental drift theory. So, according to mainstream geology, climate has been warming and cooling naturally without human intervention.
There are many theories about such long past. And different theories say different things about the actual conditions. And future may bring more theories.. I think it shows that past is as much a mystery as future.
As for the Ice cores: CO2 is soluble in water. Even the coldest ice cores have some water which can and does absorb CO2 and so, they can't be used as a metric for past atmospheric CO2.