|MadSci Network: Earth Sciences|
There are quite a few questions in your message, but unfortuantely the jury is still out on climate change and although plenty of cut-and-dried answers are on offer the increasing politicisation of the problem means that any simple treatment of this complex question should be treated with circumspection. It seems clear that there is a warming trend, and a significant increase in CO2 in the atmosphere, but the cause or causes are far from obvious, as are the solutions. Glaciers, like rivers, are dynamic structures depending upon a balance between input and output. The recession of glaciers could be due to reduced snowfall, but is just as likely to be due to increased melting in the lower reaches. In fact, global warming should result in increasing amounts of water vapour in the air, and thus precipitation, as higher temperatures mean more evaporation from the ocean surface. The point that no-one seems to get past the biodiversity issue is an interesting one. I believe that climate change is now seen as an issue behind which different varieties of campaigners can unite, and while an individual may be campaigning on a simple climate change ticket, they may actually be more concerned about other types of pollution or biodiversity loss, and see the restriction of mindless industrial development as a good thing for all sorts of reasons. Whether destruction of forests contributes to the increase in CO2 is debateable because the carbon in living organisms is part of the natural carbon cycle - the carbon circulating in the atmosphere and biosphere, which is normally in balance. It is carbon from the burning of fossil fuels which comprises the extra amount, forest destruction being a bad thing for many other reasons. Of course, destruction of trees does release CO2 into the atmosphere, but a similar amount should be re-absorbed by the plants which grow to replace those lost trees. For the same reason, deliberate re-afforeststion is unlikely to reduce the amounts of CO2 in the atmosphere significantly as those new trees must die eventually, but planting forests may be a good thing for other reasons. Yes, all plants absorb CO2 when photosynthesising, and give off oxygen. The carbon from the CO2 is used by the plant as the basis for manufacturing the various compounds such as proteins, fats and carbohydrates from which all living things are made. More CO2 is absorbed by plankton in the surface waters of the oceans than by terrestrial plants, however, and it is more likely to be permanently sequestered on the bottom of deep oceans when these organisms die and sink.
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