In reply to Jed Rothwell's message of Wed, 11 Mar 2009 18:42:31 -0400: Hi, [snip] >Robin van Spaandonk wrote: > >>It is infinitely less complex than the human >> >body and brain, or the ecosystem of the Serengeti, or my back yard, >> >for that matter. >> >>It is more complex than all of those things, because they all form a >>part of it. >>Every living thing on the planet affects the weather to some extent, just by >>living. > >I realize that, but the effect of short term inputs from living >creatures (things that vary by the century or millennium) is much >smaller than inputs from chemicals which are present in stable >amounts. (Or chemicals that used to be present in stable amounts, >before the Industrial Revolution.) Obviously, life has a huge impact >on the atmosphere with plants freeing up oxygen, and animals >producing CO2 from respiration. Things like forest fires can only >happen on a planet with life. The color of the ground being green in >summer and brown in winter is another important input to weather. But >these inputs are stable over long periods of time, and predictable, >so they can be discounted -- you might say.
They are not necessarily stable. A drought, a flood, or human activity can change vast areas considerably. Migration of species due to changing climate can also. The average over the planet may stay stable for a while, but shifts in climate will change that too. IOW there are feedback loops between the climate and the biosphere, which can't be easily accounted for, and could result in rapid change. An example is the melting of the permafrost enabling the growth of bacteria, and release of CO2 and methane. IOW this is not simple to model (depending on how accurate an answer you want). If you insist on simplifying it, then you *will* get the occasional surprise, and some of those surprises will be massive (due to feedback generating a change of state in the whole system - e.g. change in the gulf stream). ...the beating of a butterfly's wings in the Amazon... > >The major contributions to weather are relatively simple and few in >number -- mainly sunlight and about a couple dozen chemicals I >believe -- and this is nothing compared chemicals that play a role in >cells. The fact that some of those dozen chemicals (such as O2) come >from living systems does not make them particularly unpredictable or complex. Oh, but it does. As soon as you include the biosphere in the calculations, then all the individual interactions that occur within the biosphere are also included, by default (and there are trillions of them). And you can't leave the biosphere out, because the annual swings in CO2 concentration due to seasonal changes are still about 2-4 times larger than the annual CO2 increase due to fossil fuel consumption. [snip] As an example of what could go wrong:- A slight warming might lead to a reduction in the viability of nitrogen binding bacteria in the soil, which in turn results in a severe reduction in plant growth over a wide area. That in turn results in a dramatic reduction in CO2 uptake, and a consequent increase in warming, resulting in a positive feedback loop. This is something I just made up, but it does demonstrate that there are potentially zillions of things that could have an effect, and that it's not at all simple. >> Humans perhaps more than most, because our intelligence magnifies our >>influence beyond our direct influence (i.e. beyond the amount of CO2 >>our bodies >>produce, and the amount of food we consume). > >That's the crux of the matter. Living creatures themselves have a >predictable effect on weather. See above. >Industrialize intelligent species are >a new phenomenon and the effect they may have is entirely different >from what other species have had. True. Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/Project.html
