Cynthia wrote: "Well, some of you that responded to my email about change causing speciation have seemed to imply that in the past change has been gradual, much more gradual than our current 'global warming' that we are debating if it really exists."
Actually none of the responses I have read to your original posting implied either that environment or climate change in the past was only gradual, and that there hasn't been abrupt environmental or climate change. All the response I have read have said *evolution* is a relatively slow process. I think most people on this list would agree with you that the earth's climate has change dramatically in the past and can in the future. Cynthia wrote: "This was about 13/12,000 years ago, and look at the enormous diversity we have now." And 100 years ago we had an even greater number of species and more diversity then we do now. Most of the net loss of species, diversity and current endangerment of species extinction are directly related to human action. In the article you link "http://www.tos.org/oceanography/issues/issue_archive/issue_pdfs/17_4/17.4_alley.pdf";. He says that humans are causing climate change and it could be abrupt. "Human society is now conducting a vast experiment with the climate by rapidly pumping carbon dioxide and other greenhouse gases into the atmosphere. Each week, a typical American driver spends $30 or so to put nearly 100 pounds of gasoline into a car, and then turns that gasoline into about 300 pounds of carbon dioxide released into the atmosphere. Compared to solid trash, this waste is huge, but we don’t see it or smell it. Carbon dioxide traps heat and warms the planet, just as a blanket traps the warmth of your body in bed. By turning the 500-million-year accumulation of carbon in coal, oil, and natural gas into 500 years of easy energy and carbon dioxide emissions, we are exceeding the planet’s capacity to soak up carbon dioxide. The result will be a high carbon dioxide atmosphere7." "Hence, there is a possibility that our activities could shift the North Atlantic circulation and cause large impacts on ecosystems and economies.""One complex model was programmed recently to simulate a complete shutdown of North Atlantic circulation. The results included widespread drying, with strong shifts in precipitation patterns much like those of the past, and projected reduction in total plant growth on Earth.""Could there be other surprises out there in the climate system, thresholds that, if crossed, will rapidly switch us into a new and very different pattern? Again, the answer appears to be yes." I am not specifically sure what your are arguing beyond what you have posted. I do commend you for reading about climate change. This is what I think and believe. I think humans, as a single species has had more of an impact on environmental change, climate change, and the endangerment or extinction of species, then any other single species in the history of the earth. Most of this impact has happened in the last hundred years. I do believe that if we continue using earth resources with little thought and continue extinguishing species by our action that even though we will survive the current climate change we will continue extinguishing many of the new species that you think are a silver lining to climate change. I do believe, while this current climate change hasn't played itself out, we do have choices, and we can change our actions. We can use the earth's resources more wisely. We can care about conservation of what we may think are trivial species. I am open to any evidence you find that disputes the above. The article you linked to does not. Are there aspects of climate change that could be good? Sure. Few things are black and white. Bert doesn't have to take his orchids in now because frost has hit in many years. (I am not saying Bert doesn't see the downside to climate change.) It is all a matter of perspective. Mark Sullivan _______________________________________________ the OrchidGuide Digest (OGD) [email protected] http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
