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Politics : Foreign Affairs Discussion Group -- Ignore unavailable to you. Want to Upgrade?

To: Nadine Carroll who wrote (224068)	3/14/2007 12:27:24 AM
From: neolib	Read Replies (1) \| Respond to of 281500

It's never in equilibrium. It changes constantly As are most dynamic systems. Equilibrium is a relative term. If one can observe the system state (or at least inputs & outputs if the state is not known) one can generally understand what is safe to call equilibrium for the sake of specific models, as well as compensate for the output dynamics induced by other input sources (such as solar induced CO2 production). Nobody says it is easy of course. That's why they mint lots of Phds. Over the last thousand years, you had the medieval warm period, followed by the Little Ice Age, which started getting warmer again about 1750, and we've been in an overall warming trend since then. Now obviously those changes were not manmade. They are not a problem either. The question here is if the industrial revolution forward & fossil fuel are having an effect. We can compute this input with pretty good accuracy, and we can measure current atmospheric CO2 levels with accuracy. The question is 1) will CO2 levels keep rising and 2) will this cause temps to rise. Hence the question is equivalent to asking if temps will rise as a result of some input of CO2 on the scale of what humans are known to be doing. It has nothing whatsoever to do with if other sources could cause warming as well (or CO2 as well). Let me explain it another way that perhaps you can understand. Suppose your car has bad shocks. When you hit a bump in the road, the wheels shake violently afterwards. Now the best way to test for this is to stop the car, make sure it is at rest (equilibrium) then give it a sharp vertical push over a fender. If the shock is bad, the car will bounce several times with decaying amplitude. But it is still possible to deduce this while driving, even though the constant road adds additional motion factors which you must filter out. The ability to pull out the signal of interest from a background of clutter is what makes many electronic items (like cell phones) function.

To: Nadine Carroll who wrote (224068)	3/14/2007 3:28:44 AM
From: geode00	Read Replies (1) \| Respond to of 281500

Medieval Warm Period - 9th to 14th Centuries Norse seafaring and colonization around the North Atlantic at the end of the 9th century was generalized as proof that the global climate then was warmer than today. In the early days of paleoclimatology, the sparsely distributed paleoenvironmental records were interpreted to indicate that there was a "Medieval Warm Period" where temperatures were warmer than today. This "Medieval Warm Period" or "Medieval Optimum," was generally believed to extend from the 9th to 13th centuries, prior to the onset of the so-called "Little Ice Age." In contrast, the evidence for a global (or at least northern hemisphere) "Little Ice Age" from the 15th to 19th centuries as a period when the Earth was generally cooler than in the mid 20th century has more or less stood the test of time as paleoclimatic records have become numerous. The idea of a global or hemispheric "Medieval Warm Period" that was warmer than today however, has turned out to be incorrect. nhem-millenium.gif For larger viewing version of graph, please click here or on image. There are not enough records available to reconstruct global or even hemispheric mean temperature prior to about 600 years ago with a high degree of confidence. What records that do exist show is that there was no multi-century periods when global or hemispheric temperatures were the same or warmer than in the 20th century. For example, Mann et al. (1999) generated a 1,000 year Northern Hemisphere temperature reconstruction (shown above) using data from multiple ice cores and tree ring records. This reconstruction suggests that the 1998 annual average temperature was more than two standard deviations warmer than any annual average temperature value since AD 1,000 (shown in yellow). (For complete scientific reference of this study, please click here. Link to Mann 1999 FTP Data.) In summary, it appears that the 20th century, and in particular the late 20th century, is likely the warmest the Earth has seen in at least 1200 years. To learn more about the so-called "Medieval Warm Period", please read this review published in Climatic Change, written by M.K. Hughes and H.F. Diaz. (For complete review reference click here.) ncdc.noaa.gov

To: Nadine Carroll who wrote (224068)	3/14/2007 3:31:11 AM
From: geode00	Respond to of 281500

"...climate change is not just about temperature. As carbon dioxide has changed in the past, many other aspects of climate changed too. During glacial times, snow-lines were lower, continents were drier, and the tropical monsoons were weaker. Some of these changes may be independent, others tightly coupled to the changing level of carbon dioxide. Understanding which of these changes might occur in the future, and how large those changes might be, remains a topic of vigorous research. The Paleoclimatology Program exists to help scientists document these changes that have occurred in the past as one approach to understanding future climate change. ncdc.noaa.gov

To: Nadine Carroll who wrote (224068)	3/14/2007 11:54:38 AM
From: Wharf Rat	Read Replies (1) \| Respond to of 281500

"you had the medieval warm period, followed by the Little Ice Age, which started getting warmer again about" Didn't happen; regional phenomenon. We are talking global warming, not regional climate. Big mudball. So big that the US is only half of one continent, the 7 of which make up only 1/7 of the planet. And the 6/7th part which is water is really three dimensional; stores lots of heat. I'll try and make it simple. A conservative republican congressman, Roscoe Bartlett, tried to explain it to a dinosaur from SoCal. Bartlett is a physiologist, so he gets it... If you have a see-saw perfectly in balance, and you add 1000 pounds to one side, it will move. If you only add 100 lbs, it will still move." In case you aren't with Roscoe at this point, if you add one lb, it will move. And we are adding 7.5 GT every year.