Causes of Climate Change

Confused about the causes of Climate Change I have been doing some more research.

If you want to know more about the causes of climate change then I'd recommend reading this http://en.wikipedia.org/wiki/Attribution_of_recent_climate_change entry on wikipedia, but to summaries

The exact proportion of this warming that is due to human influence is still open to question, but the current scientific "consensus", as expressed in 2007 by the Intergovernmental Panel on Climate Change (IPCC) is that Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations where "very likely" means greater than 90% probability.

Another candidate mechanism for climate change is solar forcing. Most global climate model (GCM) studies indicate that the direct effects of solar variation would be too small to significantly affect climate. Much of the solar research centers around possible mechanisms to amplify the effect, possibly through increasing solar activity reducing cosmic ray flux and, speculatively, modifying cloud cover [8]; however there is no agreement on whether this is correct within the scientific community. Since GCM can reproduce observed temperature trends (including early 20th century changes, where solar forcing is non-negligible) there is no obvious need for a high sensitivity to solar forcing. Indeed, a significantly higher sensitivity to solar forcing would make early 20th century temperature change inexplicableThe plateau in warming from the 1940s to 1960s can be attributed largely to sulphate aerosol cooling

It may be asserted that in the ice core record, temperature starts rising about 800 years before CO2 increases; therefore CO2 cannot have caused temperature changes in the past; therefore it cannot be causing temperature changes today. Temperature does indeed lead CO2 during deglaciations (but not at all times); but this does not prove that CO2 has no effect on climate. From studying all the available data (not just ice cores), the probable sequence of events at a termination goes something like this. Some (currently unknown) process causes Antarctica and the surrounding ocean to warm. This process also causes CO2 to start rising, about 800 years later. Then CO2 further warms the whole planet, because of its heat-trapping properties. This leads to even further CO2 release. So CO2 during ice ages should be thought of as a "feedback" [23].

For the full details see http://en.wikipedia.org/wiki/Attribution_of_recent_climate_change


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