RE: [ENTS] Re: High elevation forest response to climate change and other factorsFYI: It looks like the blogger got his info from this site or one of it's references: http://www.geocraft.com/WVFossils/greenhouse_data.html
PJ ----- Original Message ----- From: Mike Leonard To: [email protected] Sent: Saturday, June 06, 2009 5:19 AM Subject: [ENTS] Re: High elevation forest response to climate change and other factors Lee, I got this from a blog in the Economist: "CO2 accounts for about 3% of the greenhouse gas theory, and man made CO2 is about 3% of the total atmospheric CO2." If true, are other agents or gases (like Methane) more responsible for the slight warming of the earth (about one degree) and could these agents or influences be natural or cyclical (ocean currents, volcanic eruptions, sunspot activity, etc.)? If the numbers above are not true, what do you think the real numbers are? Mike -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Lee Frelich Sent: Friday, June 05, 2009 9:09 AM To: [email protected] Subject: [ENTS] Re: High elevation forest response to climate change and other factors Mike: CO2 in the laboratory and in the real world atmosphere traps more heat. There is absolutely no doubt there. Its as well proven as the existence of gravity. Physicists had established the validity of that conclusion within a few decades after it was proposed by Arrhenius in his paper published in 1896, and have continued to reaffirm it time after time with more sophisticated equipment and observations in recent decades. Where we find the difference between the lab and real world ecosystem is for the effects of increasing CO2 on plant growth. Growth increases in the laboratory, but apparently not in real ecosystems. Water, nitrogen, and other factors become limiting when plants are supplied with more CO2, and therefore growth does not increase much if at all. That was proven at least for one savanna ecosystem in Minnesota by the free air carbon enrichment project where several plots of land were fumigated with CO2 so that it was at 560 ppm for several years. Water and N became limiting almost immediately and there was no increase in growth. If we could also supply more water and N everywhere to match the increase in CO2, then growth would increase. In areas that experience increased drought as a result of climate change, the opposite happens, there is less water available and the trees can't make use of the extra CO2. N is particularly limiting in most temperate ecosystems, and water is often limiting. Also, the enhancement of rate of photosynthesis by increasing CO2 eventually reaches an assymptote, and we are approaching the flat part of the curve already at our current CO2 concentration. Using 180 ppm CO2 at the end of the last glaciation as a starting point, a large majority of the increased growth that we might have seen (if water and N were not also limiting) would already be behind us (having occurred during the Mid Holocene), and future increases in growth (again with ideal water and N supplies) would likely be on the order of 15 or 20%. I agree that invasive species and deforestation are two of the major problems we have today. Lee Mike Leonard wrote: > > Lee, > > Yes more CO2 increases plant growth while I agree that more CO2 in > laboratory conditions traps more heat. You admit that scientists have > different opinions on the methods for filtering out different factors > so it will remain a complicated puzzle. Maybe the best thing to do is > to agree to disagree and work on some commonly accepted goals like > supporting a real energy policy that will declare a moratorium on all > new coal fired power plants and reduce our use of all fossil fuels. I > am very concerned with how continued acidic precipitation is changing > soil chemistry i.e., leaching important nutrients like calcium and > magnesium. While more CO2 increases plant growth, this leaching slows it. > > We also need to do a better job of protecting more forest land and > slowing down deforestation not only here but around the world. I heard > the state of Maryland is promoting a no net loss of forest land? > > Finally, the introduction of non-native plants, insects, and diseases > continues to be a major problem which has reduced forest diversity and > threatens whole ecosystems. > > Too much energy (no pun intended) has been wasted on the CO2 boogeyman > taking attention and money away from these other problems. Climate > Expert Hansen says we need to keep CO2 levels down to 330 ppm. Well > you can just forget about that especially since Obama and Reid have > killed nuclear power as an option when they pulled the plug on Yucca > Mountain. > > So if we reduce our forest fuel use while protecting as much forest as > we can then I think we won't have to worry about the extra CO2. Some > may say that's wishful thinking but I think the cure (cap & trade) > being proposed by the climate change scaremongers is much worse than > the disease. > > Mike > > -----Original Message----- > From: [email protected] [mailto:[email protected]] > On Behalf Of Lee Frelich > Sent: Thursday, June 04, 2009 12:58 PM > To: [email protected] > Subject: [ENTS] Re: High elevation forest response to climate change > and other factors > > > Mike: > > The direct impacts of increasing CO2 would lead to wider rings, due to > > CO2 fertilization and possibly modestly increased drought resistance. > > However, severe droughts, competition from other trees and other local > > factors that affect growth could easily override the rather modest > > direct impacts of CO2 (i.e. direct CO2 effects may only partially offset > > other negative influences). > > Increasing CO2 in the atmosphere causes heat to be retained near the > > surface of the earth (i.e. global warming), which causes a change in > > atmospheric circulation systems and redistribution of heat around the > > world, with varying climate change in different regions (warmer, cooler, > > drier, wetter in various combinations). If a given region gets drier as > > a result of climate change, then increased drought frequency will show > > up as narrower ring indices. It is possible to factor out various > > influences in tree ring analyses, including factors such as tree age, > > competition, temperature and phenomena such as El Nino (although climate > > change itself might change El Nino frequency or intensity, and it might > > be the object of study rather than something to factor out). These > > factors can be taken into account in experimental design (i.e. choosing > > trees that are more likely to be influenced by the factor of interest > > and less likely to be influenced by unwanted factors in a given study), > > as well as by filtering the tree sequences themselves. > > There are hundreds of papers in the scientific literature that present > > methods for filtering out various factors, and one scientists junk to be > > filtered out may be another scientists signal to be retained. For > > example, in many studies of climate, competition among trees is factored > > out (i.e. information on competition is thrown away as junk), whereas > > most of my studies have done the opposite, and filtered out the climate > > influences to retain just the competition signal, because I am > > interested in releases from suppression in trees and reconstructing the > > history of succession into gaps. > > 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] -~----------~----~----~----~------~----~------~--~---
