I'm inclined to think that the best use of this type of intervention would be to influence circulation by growing high- and low-albedo varieties in different areas. After all, the global mean surface temperature isn't really what matters: droughts, floods, storms, and melting of the ice caps are.
On Jan 15, 4:59 pm, "John Nissen" <[email protected]> wrote: > http://www.newscientist.com/article/dn16428-a-highalbedo-diet-will-ch... > > Journal reference: Current Biology (DOI: 10.1016/j.cub.2008.12.025) > A high-albedo diet will chill the planet > a.. 18:19 15 January 2009 by Catherine Brahic > b.. For similar stories, visit the Climate Change Topic Guide > The low-calorie diet is so 20th century - follow the high-albedo diet if you > want to be in with the latest trend. You could help save the planet from > climate change and will be able to keep eating everything you do normally. > (And you won't lose a gram.) You read it here first. > > Researchers are proposing that one way of temporarily reducing global > temperatures would be to replace existing crops with variant strains that > reflect more solar energy back out to space. The overall effect would be the > same as making large areas of the planet more mirror-like. Their calculations > suggest this could cause average summer temperatures in temperate zones to > fall by as much as 1°C. > > Politicians have generally adopted the aim of limiting global warming to 2°C > above 19th century averages, so a 1°C is not something to be taken lightly. > > Plants reflects short wave energy back out to space much like snow and other > light surfaces do. This is known as the albedo effect and is a key component > of calculating the effects of climate change. As Arctic ice melts and is > replaced by dark water, for instance, the region's warming is expected to > accelerate. > > Plants have higher or lower reflectivity depending on things like the shape > and size of their leaves and how waxy they are. To Andy Ridgwell and > colleagues of the University of Bristol in the UK, what is key is that > different varieties of a same species can have more or less albedo. > > Modelling the diet > "Different varieties of maize have different morphologies - their leaves are > arranged in different ways from variety to variety," explains Ridgwell. > Different varieties of barley and millet, two other major crops, have more or > less waxy leaves. > > Ridgwell and colleagues used a leading computer model to see what would > happen if all crops worldwide were switched to higher-albedo varieties. They > found that the global temperature averaged over 150 years would drop by > 0.1°C. That's not much, but when the researchers took a closer look they > realised that temperate regions would be far more affected than others. > > In fact, because much of the land area in North America and Eurasia is taken > up by agriculture, temperatures there could drop by as much as 1°C during > summers. This would be welcome relief for regions which are forecast to > suffer dangerous heat waves in the coming century. > > "There is a real chance that dangerous levels of global warming could be > realised. To avoid this, we need massive emissions reductions and soon. > However, it is also prudent to plan in the event that this does not occur," > says Chris Huntingfordthe UK Centre for Ecology and Hydrology. He adds that > this particular proposal may have fewer unwanted consequences than other > proposals to "geo-engineer" the climate, such as fertilising entire oceans > with iron filings. > > Bio-geo-engineering > Ridgwell's model suggests that crop yields would not suffer if farmers > preferentially planted high-albedo varieties. Indeed for some crops yields > might increase. > > To be effective, the proposal, which the group call "bio-geo-engineering", > would have to be rolled out world-wide. "It might sound a tall order to > change the varieties grown of all major crop plants," concedes Ridgwell. > > Farmers would need to be given incentives - most likely financial ones - to > buy high-albedo varieties. The researchers say one way of setting up these > incentives would be to make high-albedo farms eligible for carbon credits > which could be sold on the carbon trading markets. > > Ridgwell told New Scientist he had done "back-of-the-envelope" calculations > that show that given the current price of carbon on the European carbon > market, these credits could be worth $50 billion a year over 100 years. He > says farmers could gain as much from selling the credits as they obtain from > the EU biofuel subsidy. > > "Climate change mitigation through plant breeding is a rather novel idea that > merits consideration," says Eric Kueneman of the UN Food and Agriculture > Organization. "The down side might be that if this were to be promoted, it > would take 10 to 15 years to get the varieties developed and into farmers > fields in a major way." --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
