Global Warming Question 1: What is the explaination of past changes in CO2 and Temperatures?

Question

Data from Ice core sampling show that atmospheric CO2 levels and global temperatures have moved through cycles for at least the past 425,000 years. In these cycles, the atmospheric CO2 typically goes from a low of about 180 ppm to a high of about 280 ppm and temeratures go from levels of about 12 degrees C colder than current to a high of about 3 degrees greater than current. See the data here: http://www.ncdc.noaa.gov/paleo/icecore/antarctica/vostok/vostok_data.html

Since these changes cannot have been due to green house gas emissions from human use of fossil fuels, what it the cause of these cycles.

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1) answers must be responsive to the question
2) answers must be supported by data and the source must be identified
3) Disagreement is welcome, but ad hominum attacks on anyone will be reported as abuse. If you don't know the difference, maybe you should not answer.
4) Nonresponsive or unsupported answers will be given negative feedback.

Answer 1

The following does not answer the specific question, but it may answer the underlying one; "Should we be concerned about global warming?"

The Skeptical Environmentalist: Bjørn Lomborg,

Lomborg points out that, given the amount of greenhouse gas reduction required to combat global warming, the current Kyoto protocol is grossly insufficient. He goes on to argue that the economic cost of the restrictions which have to be put in place to actually reverse or even slow down global warming is impractically high compared to the alternative of coordinating the international communities to adjust to global warming. Moreover, he asserts that the cost of combating global warming would be disproportionately shouldered by poor developing countries. Since the policy combating global warming places unrealistic limits on economic activities, the countries that suffer from pollution and poverty due to the state of their economies will be condemned to continue in such a state. He proposes that the importance of global warming in terms of policy priority may be low compared to other policy issues such as fighting poverty and disease and aiding poor countries, which has direct and more immediate impact both in terms of welfare and the environment.

Answer 2

Yes! CO2 values have been controlled by microorganisms that photosynthesize, plants, and animals (us included). Anything that respirates produces carbon dioxide. By the same token, plants and animals are carbon life forms, so when they die, they basically take their carbon out of the cycle. Shells aren't just shelter, they are made up of carbonate! another storehouse for carbon. So hopefully you have noticed that when the dinosaurs were around and plant life was abundant, there was also a higher CO2 level and an abundance of carbonate from shelly life forms (chalk). Cretaceous means chalk (look at the white cliffs of Dover, England which is made up of microscopic shells) and the Cretaceous was one of the warmest times in the Phanerozoic.
Finally, many geologists believe that "global warming" is responsible for life on Earth. This planet experienced a series of ice ages in the PreCambrian that threatened to freeze it solid. Why isn't the Earth a snowball? Because organisms in sheltered pockets "exhaled" greenhouse gases , survived, reproduced and multiplied, and breathed more greenhouse gases while the sun was evolving to enter its main sequence and solar warmth and light could increase to near modern levels.
A good review:http://www.as.miami.edu/geology/Competition_results/env_geo.html
Also, if you are seriously interested try to find an edition of Earth's Climate by William F. Ruddiman- it's a college text and very informative- Dr. Ruddiman has interpreted a lot of the ice core data and does an excellent job of explaining climate history and the factors that influence climate.

Answer 3

The temperature could drop extensively and the glaciers could be on the march back. Ottawa could be buried below ice interior 20 years after the passing of "thermostat rules". no one looks to desire to correctly known the reality that the best purchase of recorded human historic past has been lived for the duration of an interglacial era of an ice age. shrink CO2 emissions and the planet gets that lots less warm. it extremely is a delicate stability, and one that is tipping in the direction of too lots CO2 and has been for a while now. Our efforts at industry heat the planet and save us soft, yet we are going too a techniques with it. Jack down the emissions only sufficient, yet no longer too lots. the two way, we won't be able to save the ice from coming back. it extremely is inevitable.

Answer 4

Preindustrial climate change on long term scales is primarily caused by orbital forcing, with solar activity cycles also playing a part. Current orbital forcing patterns should be slowly cooling the earth. Prediction of solar activity is uncertain at best.

http://www.sciencemag.org/cgi/content/abstract/207/4434/943

Preindustrial CO2 variation is not completely understood, but it appears to have been caused by primarily by climate change.

One hypothesis centers on phytoplankton, which thrive in cold water (cold water is better at mixing deep water nutrients than warm water.) Therefore cooler temps from orbital forcing should cause cooler oceans and larger phytoplankton populations, hence less CO2 -- which causes even cooler temps, in a classical feedback loop.

Another idea is that cooler (hence drier) air in cool cycles is a cause of drought, which in turn causes more iron-laden dust to blow off continents and into oceans. Iron is the "bottleneck" nutrient to phytoplankton.

http://tracer.env.uea.ac.uk/glacial.htm

Answer 5

I believe it's related to the glacial/interglacial cycles within the current ice age. The glacial cycles themselves are, for the most part, caused by changes in Earth's orbit (i.e. Milankovitch cycles), and these changes influence the carbon cycle, which in turn feeds back into the glacial system.

Answer 6

CO2 levels go up and down because of plants. First there is a lot of CO2 being released. Then, when the plants start blooming in the spring, they absorb some of it.