I am an environmental scientist, though I do not specifically study global warming, I think that it is a real deal, and that we shoould take it seriously (precautionary priniple).
Here are answers to some of your questions from the NOAA/NCDC...
1) Are temperatures rising?
NOAA SAYS:
Yes. Global surface temperatures have increased about 0.6C (plus or minus 0.2C) since the late-19th century, and about 0.4F (0.2 to 0.3C) over the past 25 years (the period with the most credible data). The warming has not been globally uniform. Some areas (including parts of the southeastern U.S.) have, in fact, cooled over the last century. The recent warmth has been greatest over North America and Eurasia between 40 and 70N. Warming, assisted by the record El Nio of 1997-1998, has continued right up to the present, with 2001 being the second warmest year on record after 1998.
Indirect indicators of warming such as borehole temperatures, snow cover, and glacier recession data, are in substantial agreement with the more direct indicators of recent warmth. Evidence such as changes in glacier length is useful since it not only provides qualitative support for existing meteorological data, but glaciers often exist in places too remote to support meteorological stations, the records of glacial advance and retreat often extend back further than weather station records, and glaciers are usually at much higher alititudes that weather stations allowing us more insight into temperature changes higher in the atmosphere.
2) Can changes in temperatures be explained by natural fluctuation and variability?
NOAA SAYS:
Since our entire climate system is fundamentally driven by energy from the sun, it stands to reason that if the sun's energy output were to change, then so would the climate. Since the advent of space-borne measurements in the late 1970s, solar output has indeed been shown to vary. There appears to be confirmation of earlier suggestions of an 11 (and 22) year cycle of irradiance. With only 20 years of reliable measurements however, it is difficult to deduce a trend. But, from the short record we have so far, the trend in solar irradiance is estimated at ~0.09 W/m2 compared to 0.4 W/m2 from well-mixed greenhouse gases. There are many indications that the sun also has a longer-term variation which has potentially contributed to the century-scale forcing to a greater degree. There is though, a great deal of uncertainty in estimates of solar irradiance beyond what can be measured by satellites, and still the contribution of direct solar irradiance forcing is small compared to the greenhouse gas component. However, our understanding of the indirect effects of changes in solar output and feedbacks in the climate system is minimal. There is much need to refine our understanding of key natural forcing mechanisms of the climate, including solar irradiance changes, in order to reduce uncertainty in our projections of future climate change.
3) Greenhouse gas issues?
NOAA SAYS:
Human activity has been increasing the concentration of greenhouse gases in the atmosphere (mostly carbon dioxide from combustion of coal, oil, and gas; plus a few other trace gases). There is no scientific debate on this point. Pre-industrial levels of carbon dioxide (prior to the start of the Industrial Revolution) were about 280 parts per million by volume (ppmv), and current levels are about 370 ppmv. The concentration of CO2 in our atmosphere today, has not been exceeded in the last 420,000 years, and likely not in the last 20 million years. According to the IPCC Special Report on Emission Scenarios (SRES), by the end of the 21st century, we could expect to see carbon dioxide concentrations of anywhere from 490 to 1260 ppm (75-350% above the pre-industrial concentration).
There is more at
http://www.ncdc/noaa.gov.html
I have seen graphs that show amazing correllation between post industrial revolution CO2 levels and increases in temperatures. I will try to find one online.
I suppose a basic starter would be whether or not someone understands the greenhouse effect. If you understand that, then I think the rest is a pretty logical extension.
As far as the Kyoto Protocol, I am not sure if it would have worked as well as everyone wanted it too. Reducing CO2 emissions below 1990 levels would be tough, but I sort of view it as I view hybrid cars. Like a bridge until the best solution (hydrogen) is reached, though not a complete solution, it is a heck of a lot better than doing nothing and expecting everything to be fine.
As to the global cooling fad, ironically enough, a possible outcome of global warming and melting glaciers and ice-caps, is to "short-circuit" the gulf-stream, which will certainly make lots of places much colder than they are now.
later
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