More On Global Warming!

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Yet another paper written on global warming! I find this one particularly interesting because it is not fighting for one side or the other. But it is [i][/i]definitely informative! So, from the RoguePundit: Global Warming from Increased Sunspots The sun does not put out a steady amount of energy. Sure we know the sun is cooling very gradually as the star ages (well, not really...stars actually gradually brighten over much of their lifetime)*. But, the activity on the sun's surface does vary some as well. Scientists have long known that sunspot activity runs on approximately 11-year cycles, with the most recent peak being in 2001. Though sunspots themselves are cooler than the surrounding sun surface, their presence corresponds with increased sun activity overall, which produces a slightly brighter sun. The brighter the sun is, the more it warms the earth. Scientists know that the sun has been abnormally active the last 60 years when compared to previous observations. But it's only been since the invention of the telescope that people have been able to regularly examine and document the sun's activity. Until fairly recently, it wasn't possible to determine what the sun's activity was before the year 1610. So how have scientists learned to measure previous sunspot activity? Well, first a refresher on carbon-dating. Cosmic rays from the sun react with air molecules in the earth's upper atmosphere, creating Carbon-14, a radioactive version of the standard carbon molecule. It combines with oxygen to make carbon dioxide, disperses pretty evenly throughout the atmosphere, and ends up being absorbed into the living tissue of plants and animals in tiny concentrations. C-14 production is fairly constant (sans nuclear testing), thus the concentrations absorbed into living tissue are also fairly constant. C-14 decays with a half-life of 5,730 years, thus scientists can use its declining concentrations in organic matter (wood, old clothing and skins, ancient peat layers under glaciers, ancient tree trunks preserved in acidic conditions, etc.) to determine an approximate age...back tens of thousands of years. Scientists have helped calibrate their age determinations with things like readings from the tree rings of 6,000 year-old bristlecone pines, the oldest trees in the world. Those slight inconsistencies in C-14 production are very important. The more active the sun is, the less cosmic rays it produces. That means during periods of more sunspots, flares, eruptions, etc., less C-14 is produced in our upper atmosphere...meaning less is available for living tissue to aborb. The difference isn't huge, but it is statistically significant. Scientists can measure the amount of C-14 in things like old and ancient trees, note the variations, and determine the sun's activity in the past...up to 11,400 years ago thus far. That's to the end of the most recent ice age. And, they can varify this data with the decay of another radioisotope (Beryllium-10) deposited in layers in polar ice fields. We now know that the recent 60 years of increased sun activity are the greatest period of such activity in the last 8,000 years. __________ Researchers had already determined some of the earth's recent cooler periods coincided with periods of low sun activity. The most recent period was from 1645-1715, when a drastic reduction in the number of sunspots (known as the Maunder Minimum) corresponded with a mini-ice age. The same correlation with cooler weather has been shown from 1420-1530 (the Spoerer Minimum), 1280-1340 (the Wolf Minimum), and 1010-1050 (the Oort Minimum). From 1100-1250, there were was more sunspot activity than normal, and that's when the Vikings settled parts of Greenland. So in this period of much more sun activity than normal, one must figure that natural heating is contributing to global warming to some degree. So, the $64,000 question is how much of the current global warming is natural versus man-made? Well... - During the last two 11-year sunspot cycles, sun activity has been about the same, but the earth has warmed slightly. That seems to be at least indirect evidence that man's activities are indeed causing some global warming. - It's only been since the late 1970s--in the middle of this busy 60-year sunspot period--that experts were worried about us going into at least a mini-ice age. Some of them are the same experts who are most vocal about global warming now. - We're often told that greenhouse gasses, most notably carbon dioxide levels in the atmosphere, have risen steadily with man's development and are much higher than they used to be. This is true. So why has global warming underperformed compared to the percentage increase of carbon dioxide and the accompanying predictions? Well, that's because carbon dioxide is over-hyped...the most common and important greenhouse gas is water vapor. Factor it into the equations, and the percentage change in greenhouse gasses is much less pronounced than is claimed. And, we're still a long ways from understanding how water's dynamic movement through the atmosphere, muchless evaporation & condensation, freezing & thawing, weather systems, irrigation, dams, etc. impacts global warming, and/or vice versa. - We know that the earth's distance from the sun varies in more than just annual cycles. The Milankovitch Theory shows that the earth's orbit around the sun varies for a couple other reasons: the earth has a bit of a wobble in the rotation about its axis, and the direction of the earth's axis slowly changes. These vary over a 19,000-23,000 year cycle. Currently, the earth is tilted in a way that puts the northern hemisphere closer to the sun than the southern hemisphere overall, which makes the winters a bit less severe than average in the northern hemisphere. Milankovitch tried to use his theory to explain the expansions and contractions of the polar ice caps, but at best it's only a partial explanation. - Man's activities, from various means of polluting to farming, increase the amount of dust and other particulates in the air. We know that when there's a volcanic eruption that puts a massive amount of dust into the upper atmosphere, global weather is cooler for years. As man puts more dust and other particulates into the atmosphere, we're likely contributing a bit to global cooling. I could go on, but suffice to say that there's plenty we still don't understand about our planet, the natural weather cycles (whether they cycle over millenia or just a few years), man's impact on those cycles, etc. Some of the changes occuring in nature that are viewed as disastrous consequences of global warming are natural change. That doesn't change the fact that we're increasing the amount of carbon dioxide and some other greenhouse gasses in the air. Water vapor's role as the key greenhouse gas...we just don't have a good handle on it yet. In general, whether it reduces global warming or not, reducing the amount we pollute is a good thing. But bottom line...if the answer to global warming looks simple, it's too simple. So there's the non-political science to it. Ready to go buy that V-8?