"Back then" the earth was more violent. By this I meant volcanic activities which is the main producer of gases. I am sure none of us will want to live to see the kind of volcanic activities that created eg Deccan flats in India. Google Deccan flat or Deccan traps
QUOTE(weegee @ Nov 29 2009, 11:00 AM)
heres my claim.
say Co2 is the driver of the temperature, but how can it be when it has been happening repetitively throughout centuries and back then there were no factories to contribute that extra CO2? then some may say, what has been happening then is happening now, but why only now bring in internal combustion engines onto the table?
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Added on November 29, 2009, 3:01 pmOcean/ sea can absorb a certain level of Co2 and reprecipitate it as limestone
During the time of the dinosaurs, earth had more intense volcanic activities which is the main producer of gases. The super continent Pangaea was breaking up when dinosaurs started to rule the earth.
Tropical forest near the poles occurred after the dinosaur era.The dinosaur era ended some 67 millions years ago Arctic was tropical some 55 millions yrs ago. Base on geological modeling, the warm waters from the equator was not flowing to the north. The land bridge between North and South America better known as Panama was not created yet by volcanic activities. When the land bridge was created, it blocked the warm waters flow between the Atlantic and Pacific oceans, pushing the warm water northwards, The ice cap was located in Southern Europe/North Africa was pushed northward. Another thing to consider is the rise of mountain ranges eg Tibetan plateau, Rockies and Andes . If you looked at their ages, they are all created roughly in the same period, post Cretaceous era. These mountain ranges affect/ alter global wind patterns.
QUOTE(bgeh @ Nov 29 2009, 11:30 AM)
Ah right, we can finally discuss. Well the first thing we have to say is that it's true, the global mean temperature is a product of multiple causes, and yes, there have been periods in the past where the Earth has been warmer than today. It depends on the configuration of the continents - you can prevent a lot of warming at the poles from occuring if you can block warmer water closer to the Equator from flowing into the poles. There is also a natural variation in our climate, evidenced by past records of warm periods, followed by ice ages. But what's changed is CO2 levels have been much higher than at any time in the past 400,000 years or so, and there is no doubt that this is man's doing (see
http://en.wikipedia.org/wiki/File:Carbon_Dioxide_400kyr.png). What's currently being disputed is to what level is CO2 contributing to the warming, on which I'm not an expert in, and cannot answer, but the general consensus (approx 90-95% of scientists in general, it seems) is that the main driver is CO2 emissions, unless another new driver for warming can be found, and can show that it's led to this recent warming. The sceptics have proposed plenty, and plenty of them have been shown to not be the main driver, relative to the CO2 emissions anyway.♦
But I'd like to bring up another side effect of CO2 production, which is often forgotten about: Ocean acidification. I hope we're agreed that CO2 emissions will lead to acidification of oceans (they've absorbed most of the CO2 we've produced actually), and there are many unknown consequences that might affect us all with that.
Side note: An argument I see often is that CO2 concentrations were higher during the time of the dinosaurs, and life flourished even more back then (tropical forests up to near the poles). True, but it's the rate of change we're worried about.
This post has been edited by segamatboy: Nov 29 2009, 03:01 PM