英格兰布里斯托大学的安迪博士及其同事在最近一期的《当代生物学》(Current Biology)上发表的报告中提出,世界上许多国家可通过种植特定类型的农作物将更多的阳光反射回太空,以此来降低自然地表温度。
研究人员认为,与自然界的野生植物相比,农作物在生长过程中可以反射更多的太阳光,因此起到了为地球降温的作用。另外,同一农作物的不同变种,其太阳光反射率存在很大差异(即星体反照率),因此在夏季的生长期内,可以选择种植反射率高的农作物品种以期对气候变化加以控制,这与目前农民培育特定农作物变种以使产量最大化的方式类似。由于可耕种农业是一个全球性产业,因此降温幅度会更大。
植物的星体反照率不同的原因是,其叶子表面的特性和叶子的排列不同,这被称为冠层形态学。因此,研究小组建议,可根据农作物反射特性来选择种植其不同变种,同时在种植农作物时也要考虑其他因素,如谷物的食品加工特性等。
该研究小组强调,与种植生物质燃料作物不同的是,无论是在产量还是类型上,该计划都不会影响粮食生产。安迪博士解释说:“我们建议选择同一种作物的不同变种,以使太阳光反射率最大化,而不是改变农作物类型,虽然后者也能带来环境效益。”
据估计,在未来百年里,采取这种方法相当于避免向大气中排放1950亿吨的二氧化碳。在夏季植物生长期,欧洲和北美的广大地区温度可降低最多1摄氏度。这相当于全球每年气温降低超过0.1摄氏度,大约占19世纪工业革命以来全球气温升高总和的1/20。
研究人员表示,可通过发放碳信用额来鼓励农民种植此类农作物。据研究人员测算,如果实行这样的机制而避免了气温升高,预计农民每公顷每年会收益23欧元。虽然目前生物燃料作物每公顷每年可以收益45欧元,但占用了种植粮食的宝贵农业用地。
研究人员称,现在人们还不愿意大幅度减少化石燃料使用以减少二氧化碳排放,而像种植反射率更强的农作物这种简单的替代方法是帮助减轻一些地区的热浪和干旱形势的比较现实的方式,而且很快就能以极低的成本看到效果。(生物谷Bioon.com)
生物谷推荐原始出处:
Current Biology, 15 January 2009 doi:10.1016/j.cub.2008.12.025
Tackling Regional Climate Change By Leaf Albedo Bio-geoengineering
Andy Ridgwell1,,,Joy S. Singarayer1,Alistair M. Hetherington2andPaul J. Valdes1
1 Bristol Research Initiative for the Dynamic Global Environment, School of Geographical Sciences, University of Bristol, Bristol BS81SS, UK
2 School of Biological Sciences, University of Bristol, Bristol BS81UG, UK
The likelihood that continuing greenhouse-gas emissions will lead to an unmanageable degree of climate change [1] has stimulated the search for planetary-scale technological solutions for reducing global warming [2] (geoengineering), typically characterized by the necessity for costly new infrastructures and industries [3]. We suggest that the existing global infrastructure associated with arable agriculture can help, given that crop plants exert an important influence over the climatic energy budget [4,5] because of differences in their albedo (solar reflectivity) compared to soils and to natural vegetation [6]. Specifically, we propose a bio-geoengineering approach to mitigate surface warming, in which crop varieties having specific leaf glossiness and/or canopy morphological traits are specifically chosen to maximize solar reflectivity. We quantify this by modifying the canopy albedo of vegetation in prescribed cropland areas in a global-climate model, and thereby estimate the near-term potential for bio-geoengineering to be a summertime cooling of more than 1C throughout much of central North America and midlatitude Eurasia, equivalent to seasonally offsetting approximately one-fifth of regional warming due to doubling of atmospheric CO2[7]. Ultimately, genetic modification of plant leaf waxes or canopy structure could achieve greater temperature reductions, although better characterization of existing intraspecies variability is needed first.