Hi all Correlation may be an interesting pointer but does not prove causation or even the direction of causation. If nitrogen-rich trees need more water maybe we should ask if the water that is doing something we do not understand. Given that trees are at present bathed in 80% nitrogen and have surfaces which are highly permeable, how can we change the equilibrium they prefer? Why not just plant species that already have a high albedo especially if they also have other good uses?
Talking of correlation, it may be a rude question but can anyone explain how we had so many dramatic sharp rises in world temperatures revealed by ice cores before there were any Americans to drive gas-guzzling SUVs? Stephen Emeritus Professor of Engineering Design School of Engineering and Electronics University of Edinburgh Mayfield Road Edinburgh EH9 3JL Scotland tel +44 131 650 5704 fax +44 131 650 5702 Mobile 07795 203 195 [EMAIL PROTECTED] http://www.see.ed.ac.uk/~shs Alvia Gaskill wrote: > http://www.newscientist.com/article/dn16061-could-fertilising-trees-save-the-climate.html?DCMP=OTC-rss&nsref=climate-change > > <http://www.newscientist.com/article/dn16061-could-fertilising-trees-save-the-climate.html?DCMP=OTC-rss&nsref=climate-change> > > > > Could fertilising trees save the climate? > > * 22:00 17 November 2008 by *Catherine Brahic* > <http://www.newscientist.com/search?rbauthors=Catherine+Brahic> > * For similar stories, visit the *Climate Change* > <http://www.newscientist.com/topic/climate-change> Topic Guide > > Should we "dope" trees with nitrogen fertiliser to engineer a cooler > global climate? New findings suggest the nutrient could be a switch > for determining how much solar energy forests in Earth's cooler > regions reflect back out into space. > > Scott Ollinger > <http://www.unh.edu/natural-resources/fac-ollinger.html> of the > University of New Hampshire, Durham, and colleagues measured the > concentrations of nitrogen in forest canopies in 181 plots across the > US, sampling trees that were anywhere from 15 to 500 years old. > > The team compared this data with satellite data of albedo - a measure > of how much solar energy is reflected by various surfaces - and data > on the amount of carbon absorbed by the forests. > > "The principal findings are that the nitrogen concentration of forest > canopies is a good predictor of their capacity to absorb carbon > dioxide, and that forests with high nitrogen levels reflect more solar > radiation than nitrogen-poor forests," says Ollinger. > > "A simplistic implication is that fertilising trees with nitrogen, or > simply planting trees that have naturally higher nitrogen > concentrations, might help offset climate change." > > While this is theoretically possible, Ollinger warns that more > research should be done "before we run around spraying trees with > nitrogen". > > For starters, the exact relationship between nitrogen and albedo > remains a mystery. Nitrogen could act like a switch, changing the > structure and cellular properties of leaves so that they become more > mirror-like. If this is the case, nitrogen fertilisation might work. > > > Doping downsides > > But if there is a correlation between the albedo of certain tree types > and the amount of nitrogen they hold, then governments would have to > plant species that naturally have high albedo in order to take > advantage of the effect. > > There could also be serious disadvantages to nitrogen doping. > "Increasing the amount of nitrogen in the environment can have its own > negative consequences, including leaching of nitrate to groundwater > and emissions of nitrous oxide - itself a greenhouse gas - from soils." > > Tree species that hold a lot of nitrogen also tend to need more water, > which means doping trees with nitrogen could contribute to drying up > streams and groundwater reservoirs. "This would be an undesirable > consequence in dry climates," says Ollinger. > > Federico Magnani of the University of Bologna in Italy says doping > trees with nitrogen is "what we have been doing for almost a century > now." In 2007, Magnani showed that industrial nitrogen pollution from > cars and fertilisers among others is driving trees to absorb more > carbon > <http://www.newscientist.com/article/dn12058-nitrogen-pollution-drives-trees-to-soak-up-more-cosub2sub.html>. > > "It is crucial that we fully understand what the effects are, both > positive and negative, so as to devise the best environmental policies > for the next century," say Magnani. > > Magnani and his colleagues have put a proposal forward to the European > Union to study nitrogen fertilisation and carbon uptake. The team > would like to look at the consequences of intentionally fertilising > forests with nitrogen and the possibility of locating new forest > plantations in areas where nitrogen pollution is already fertilising > ecosystems. > > Journal reference: /Proceedings of the National Academy of Sciences/ > (DOI: 10.1073/pnas.0810021105) > > > > -- The University of Edinburgh is a charitable body, registered in Scotland, with registration number SC005336. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
