The low-calorie diet is so 20th century 鈥� 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鈥檛 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掳C.
Politicians have generally adopted the aim of limiting global warming to 2掳C above 19th century averages, so a 1掳C is not something to be taken lightly.
Advertisement
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鈥檚 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 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
鈥淒ifferent varieties of maize have different morphologies 鈥� their leaves are arranged in different ways from variety to variety,鈥� 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掳C. That鈥檚 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掳C during summers. This would be welcome relief for regions which are forecast to suffer dangerous heat waves in the coming century.
鈥淭here 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,鈥� says the UK . He adds that this particular proposal may have fewer unwanted consequences than other proposals to 鈥済eo-engineer鈥� the climate, such as fertilising entire oceans with iron filings.
Bio-geo-engineering
Ridgwell鈥檚 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 鈥渂io-geo-engineering鈥�, would have to be rolled out world-wide. 鈥淚t might sound a tall order to change the varieties grown of all major crop plants,鈥� concedes Ridgwell.
Farmers would need to be given incentives 鈥� most likely financial ones 鈥� 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 杏吧原创 he had done 鈥渂ack-of-the-envelope鈥� 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.
鈥淐limate change mitigation through plant breeding is a rather novel idea that merits consideration,鈥� says Eric Kueneman of the UN Food and Agriculture Organization. 鈥淭he 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.鈥�
Journal reference: (DOI: 10.1016/j.cub.2008.12.025)
