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Arctic ice cap melting 30 years ahead of forecast
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[QUOTE]Originally posted by andrew: [QB] After my own research I believe Global Warming is BS. This is my opinion until someone shows me that it is real. The earth naturally warms up and cools down. How much does the so-called 'greenhouse effect' warm the Earth? It's estimated that the Earth's surface would be about -18 °C (0 °F, 255 K) with atmosphere and clouds but without the greenhouse effect and that the (we'll call it "natural") greenhouse effect raises the Earth's temperature by ~33 °C (59 °F). Devoid of atmosphere it would actually be a less cold -1 °C (272 K) because the first calculation strangely includes 31% reflection of solar radiation by clouds (which could obviously not occur without an atmosphere) while clouds actually add significantly to the greenhouse effect - for simplicity, just stick with ~33 °C. [Edited for clarity, April 24] Theoretically, if the planet's surface cooled by radiation alone, then the greenhouse-induced surface temperature would be much warmer, about 350 K (77 °C), but atmospheric motion (convective towers carrying latent and sensible heat upwards and large scale circulation carrying it both upwards and polewards) significantly increase the "escape" of energy to space, leaving Earth's surface more than 60 °C cooler than a static atmosphere would do. So, despite there being far more greenhouse gas in the atmosphere than required to achieve the current greenhouse effect, and that has been so since before humans discovered fire, evapo-transpiration and thermals transport heat higher in the atmosphere where radiation to space is increased. This is why Earth remains about 15 °C rather than about 77 °C. Wait a minute! Those aren't the numbers I learned! Ah! Someone who remembers their science classes eh? Well, you got us. Reference works frequently list the planet's mean surface temperature as 16 °C (61 °F); sometimes 15 °C (59 °F) is mentioned and yes, these are about the expected temperatures by calculation -- in the 1960s and 1970s numbers as high as 65 °F (18 °C) were popular but we haven't seen those for some time. Here we run into a little bit of a problem, however -- taking the Earth's temperature is no trivial task. In fact, even defining precisely what we mean by the absolute surface air temperature is challenging. Current global temperature anomalies (the amount of warming or cooling reported) are estimated against an expected average of 14 °C (57 °F) -- the guess-timated mean temperature over the period 1961-1990. Part of the earths natural rhythm. [/QB][/QUOTE]
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