Over the last decade, I have become convinced (as most people are), that the Earth's atmosphere is warming dangerously; almost certainly from fossil fuel burning. Since last fall ('08) though, a theory, new to me, has been circulating. This theory says that a low incidence of sunspots on Sol's disc, means that the sun is cooling slightly. If true, lower sun temperatures could easily trump anything that we humans could do. The theory says that low sunspot activity 300 years ago was the actual cause of the "Little Ice Age" which occurred at that time.
Sunspot activity itself can be checked easily on spaceweather.com, which reports day by day on visible spots (as well as a daily archive back to 2000, auroras, meteor showers, passing asteroids, etc.), with each new spot identified by number. Normally sunspots average about 120 per year, with peak years of 450 or so, and minimum years of few spots, in an 11-year cycle. The last two years have been at the minimum point of the cycle, with only 30 spots in 2008; and only four spots in November, through January ('09). January's spots, #1010 & #1011, were very weak. This is not proof yet of anything, but if a correlation can be found with colder weather it will make for an interesting hobby for years. Several avenues are possible
The Weather Channel, TWC-TV; periodically reports running totals of record high, and record low, temperatures, as they occur randomly across America. For the eight years, through 2008, they report that record High/Low readings were 266,000 to 133,000 (by chance, 2.0 to 1). To me, this is proof positive of global warming. America, a large country in middle latitudes, should be a fair sample of the entire world. Depending on how they keep reporting this data, either as a new running total for 2009, or just as updates on the 8-year score; catching their figure every few months, or every quarter could show if a trend (2.0 to 1, ratio decreases over time),toward dropping world temperatures develops. This would be a clear sign that the Ice Age is coming. Accurate data will be supplied eventually by NOAA (National Oceanic & Atmospheric Administration), but their site only shows data (slow temperature rise) through 2005; it will be more fun to guess before real data appears.
Many scientists say that the sunspot theory is not correct. However, if the sunspots stay rare, and world temperatures drop for years, it will become time for concern; there is no assurance that a drop will not exceed 2-degrees C, as in the Maunder Minimum, "Little Ice Age", 300 hundred years ago. Worry, worry.
CORRECTION: I believe there is an error in my logic above. With 6% of world population, we have 25% of the world's economy. 25% of CO2 over only 1.5% of the Earth's surface may cause the most intense fossil heating in the world (not a fair sample area). The US may be the last place where slight solar cooling would overcome fossil heating. Any warning of an Ice Age, must be from NOAA world temperatures (http://wps.prenhall.com/wps/media/objects/2513/2574258/pdfs/E17.9.pdf), (great data; check it out), but they will take several years to catch up with the current era of minimum sunspot activity.
Nuclear Energy Can Save US--America�s 100 nukes equal four million barrels of oil per day.
Billions of lives and civilization itself may be at risk from the Global Warming & End of Cheap Oil, Crisis. Rising sea levels and rising oil prices could be the end of civilization as we know it. The problem is so huge that the most powerful answer, many nuclear plants, must be deployed. Currently, America‘s 100 nukes deliver the energy of four million barrels of oil per day. Wind and solar cannot do the job, and may delay the real answer too long. Still, all kinds of clean energy, plus conservation, plus reducing deforestation, will be needed to help the poor half of the world, and for civilization to survive through this century.