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 Mike Leonard wrote: > > Lee, > > In Massachusetts, they built a bunch of natural gas fired electric > power plants in the late 80's and early 90's because it was far less > polluting than coal but we still get about 50% of our power from coal. > But that was when gas was cheap; now that it's much more expensive, so > I don't think we'll be seeing any more gas fired plants. > > That's interesting about using crops that reflect more light. How > about producing more food on less acreage by using genetically > modified crops? I know a lot of people don't like the idea of creating > new GM plants but it can greatly improve farm productivity. And then > maybe we can reforest a lot of the marginal farm acreage. > > There are still some things that don't quite add up for me. During the > medieval warming period from 800 - 1300 AD, global temperatures were > much warmer (up to 5 degrees warmer?) but CO2 atmospheric levels were > much lower than they are today. The Vikings had farms in Greenland! > Then it got colder. How does one explain that? In fact there have been > lots of periods of global warming over the millennia. How did the > earth warm up after the last ice age? > > I guess my argument would be that these natural fluctuations will > probably dwarf anything mankind can affect. > > Glad to see you agree that cap & trade would not be a good solution to > reduce CO2 emissions. A carbon tax would be much simpler and far more > efficient. But Al Gore needs more money; he's only worth about $100 > million now. > > Mike > > -----Original Message----- > From: [email protected] [mailto:[email protected]] > On Behalf Of Lee Frelich > Sent: Sunday, June 07, 2009 6:10 PM > To: [email protected] > Subject: [ENTS] Re: High elevation forest response to climate change > and other factors > > > Mike: > > I have some figures for the U.S.: about 44% of CO2 emissions result from > > burning petroleum products, 20% from natural gas and 36% from coal. > > Natural gas only emits 50-55% as much CO2 per unit energy obtained when > > burned compared to coal. Gasoline and similar products are somewhere > > between natural gas and coal. If we had enough natural gas and used only > > that in place of petroleum and coal, we could reduce CO2 emissions by > > 30-40% even if we kept all else in society the same. > > Geo-engineering is being looked at more seriously these days than a few > > years ago. I think low tech geo-engineering like using crops with > > variegated leaves in the vast agricultural lands of central North > > America (what I call 'The Corn Ocean', which lies to the south and west > > of Minneapolis) to reflect more sunlight would work best. For most > > crops, the intensity of summer sunlight is beyond their saturation point > > anyway. > > Incidentally, I agree that cap in trade would not be a good solution to > > the CO2 problem. Surely we can think of something simpler. > > Lee > > > > Mike Leonard wrote: > > > > > > Lee, > > > > > > How about the occasional Krakatoa or that Philippine volcano Pinatubo? > > > > > > Aren't the emissions from one of those big volcanic blasts equal to > > > many years of CO2 emissions in an average year? > > > > > > Do you know what the breakdown is for fossil fuels: oil, coal, natural > > > gas? > > > > > > So if you want to reduce emissions enough to make a difference we all > > > need to drive electric vehicles charged with electricity generated by > > > nuclear, wind, or solar power; heat our homes, schools, and factories > > > with something other than fossil fuel; stop deforestation; and become > > > vegetarians. All these are highly commendable but a tall order. > > > > > > How about if we think of "geo-engineering" the weather if global > > > warming does in fact get worse such as: seeding the oceans with iron > > > to grow more plankton; building giant reflectors in space; creating > > > more dust in the upper atmosphere to dim sunlight; or finding some > > > economical way to extract CO2 from the atmosphere to keep the > > > percentage constant. > > > > > > Mike > > > > > > Paul and Mike: > > > > > > I found some figures on the proportion of CO2 entering the atmosphere: > > > > > > Soils (except for agriculture), weathering of rocks, oceans and > > > > > > vegetation are a net sink for CO2 out of the atmosphere. > > > > > > Net sources are deforestation/agriculture: 35% of the new CO2 going into > > > > > > the atmosphere > > > > > > fossil fuels: 65% > > > > > > volcanoes: 1% > > > > > > (Note this adds to 101% due to rounding error when rounding to the > > > > > > nearest 1%) > > > > > > It looks like Bush's DOE figures are off by a couple orders of > > > > > > magnitude, but then thats what happens when you compare the amount of > > > > > > CO2 in fossil fuels that are burned to the flux of carbon rather than > > > > > > the pool of carbon in the atmosphere to deliberately mislead the public. > > > > > > Comparing CO2 relative to other greenhouse gases and aerosols in heat > > > > > > retention (global average heat trapping change since 1750): > > > > > > CO2: +1.5 watts per square meter > > > > > > CFC, N2O and methane: +1.2 watts per square meter > > > > > > Ozone: +0.4 watts per square meter > > > > > > Black carbon (soot): +0.6 watts per square meter > > > > > > Output from the sun, change since 1750: +0.3 watts per square meter > > > > > > 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] -~----------~----~----~----~------~----~------~--~---
