Lee,
So the earth's orbital variations are cyclical and due to its "wobble" right? If true, then sometime in the future we'll be due for another ice age. I understand the albedo effect is huge. If we lose snow and ice cover then the darker ground absorbs more sunlight heating things up. I heard they are trying to counter this in the European Alps by spreading big white tarps in places. I suppose in a perfect world we could control the weather and climate to prevent any future ice ages or meltdowns. Maybe someday that will be a reality. Mike Mike: The earth warms up after ice ages from changes in distribution of sunlight (due to variations in the earth's orbit), followed by feedbacks including lower albedo as ice sheets disappear, CO2 coming out of the ocean, and other feedbacks. Its a slow process, over thousands of years. Changes in energy output by the sun, ocean currents, albedo, volcanic dust, and (on much longer time scales) changing position of the continents cause natural changes. Our impacts is so big compared to natural ones because we are putting an amount of CO2 and other greenhouse gases into the atmosphere at a much higher rate than natural processes, telescoping 1000s of years worth of natural change into one century. Regarding your questions about volcanoes--given the stage of development the earth is at now, we don't have a lot of volcanism, and therefore very small inputs of CO2 into the atmosphere. Many millions of years ago, areas of multiple volcanoes (perhaps the size of the 48 states) greatly changed the chemistry of the atmosphere by causing global warming. These events greatly influenced the evolution of trees that we have today. Lee --~--~---------~--~----~------------~-------~--~----~ Eastern Native Tree Society http://www.nativetreesociety.org Send email to [email protected] Visit this group at http://groups.google.com/group/entstrees?hl=en To unsubscribe send email to [email protected] -~----------~----~----~----~------~----~------~--~---
