As I was researching some of the comments on a previous post, here are some interesting items that I found:
1. C02 has historically lagged temperature, a fact that is often cited by global warming skeptics.
Temperature and CO2 are difficult to measure and compare. The time resolution is low, and while C02 is an atmospheric gas with a more global nature, temperature is always relatively local. Tom Rees explains this and gives links to data that you can review.
RealClimate explains that while it is true that CO2 lags temperature, this does not affect the global warming theory. The CO2 amplifies the temperature rise. So the concern is not that the increased CO2 we are creating today caused the rise, but that it will continue to amplify it.
2. The best explanations so far regarding why global warming is human caused:
RealClimate gives an explanation based on the measurement of carbon isotopes.
Ecobridge describes outputs of human activity that cause carbon dioxide and greenhouse gas.
Here’s what NASA has to say,
Climatologists (scientists who study climate) have analyzed the global warming that has occurred since the late 1800’s. A majority of climatologists have concluded that human activities are responsible for most of the warming. Human activities contribute to global warming by enhancing Earth’s natural greenhouse effect. The greenhouse effect warms Earth’s surface through a complex process involving sunlight, gases, and particles in the atmosphere. Gases that trap heat in the atmosphere are known as greenhouse gases.
The main human activities that contribute to global warming are the burning of fossil fuels (coal, oil, and natural gas) and the clearing of land. Most of the burning occurs in automobiles, in factories, and in electric power plants that provide energy for houses and office buildings. The burning of fossil fuels creates carbon dioxide, whose chemical formula is CO2. CO2 is a greenhouse gas that slows the escape of heat into space. Trees and other plants remove CO2 from the air during photosynthesis, the process they use to produce food. The clearing of land contributes to the buildup of CO2 by reducing the rate at which the gas is removed from the atmosphere or by the decomposition of dead vegetation.
A small number of scientists argue that the increase in greenhouse gases has not made a measurable difference in the temperature. They say that natural processes could have caused global warming. Those processes include increases in the energy emitted (given off) by the sun. But the vast majority of climatologists believe that increases in the sun’s energy have contributed only slightly to recent warming.
Finally, see the “Causes of Change” in the IPCC Fourth Assessment Report, as well as these global warming and climate change policy research sites: