the current warmth is unusual in the past 1000 years (see Temperature record of the past 1000 years).

climate models predict more warming, and other climate effects (sea level rise, etc) in the future.

the IPCC reports correctly summarise the state of climate science.

the historical temperature record shows a rise of 0.4-0.8 degrees celsius over the last 100 years.

climate models can reproduce this trend, but only when using greenhouse gas forcing. see: simulated annual global mean surface temperatures

the warming of the last 50 years is likely caused by human activity (see attribution of recent climate change), using analysis based on climate modeling; and that natural variability or solar variation cannot explain the recent change.

humankind is performing a great geophysical experiment and if it turns out badly - however that is defined - we cannot undo it.

action should be taken now to prevent or mitigate warming (see Precautionary principle).

Right now, there is an observed trend in numerous areas: higher ocean temperatures, melting polar icepacks, a consistent trend of stronger storms, and higher air temperatures. There is also a plausible cause - greenhouse gasses from combustion of fossil fuels. You can say that the trend of increasing temperature is a coincidence. 40 years ago, one could also have said that the reduction in population of birds mirrored the extinction of dinousaurs. Of course, the true cause was DDT. In the past 50 years, numerous environmental concerns have been shown to be significant problems. Some of these include MTBE, clear-cutting trees, leaded fuel, mercury poisoning, and smog.

The evidence is VERY clear, spend the time and do the research if you're going to take a position on this EXTREMELY important issue.

Any measurable changes in global temperature are due to natural and historical climate variability, and have nothing to do with human carbon emissions. <a href="http://en.wikipedia.o rg/wiki/Climate_variability" ;>wikipedia - climate variability</a>

Earth's climate has been both colder and warmer than today, and these changes are adequately explained by mechanisms that do not involve human greenhouse gas emissions.

Climate science can not make definitive predictions yet, since the computer models used to make these predictions are still evolving and do not yet take into account recently discovered feedback mechanisms.

Since carbon dioxide levels have no significant impact on global temperatures, support for the Kyoto Protocol is entirely misguided.

Global temperatures are directly related to sunspot activity.

There is no significant global warming relative to the expected natural trends.

Climate models will never be able to predict the future climate, until they can predict solar and volcanic activity.

Global warming studies have errors or have not been reproduced.