英格蘭布里斯托大學(xué)的安迪博士及其同事在最近一期的《當(dāng)代生物學(xué)》（Current Biology）上發(fā)表的報(bào)告中提出,，世界上許多國(guó)家可通過(guò)種植特定類型的農(nóng)作物將更多的陽(yáng)光反射回太空,，以此來(lái)降低自然地表溫度。
研究人員認(rèn)為,，與自然界的野生植物相比,，農(nóng)作物在生長(zhǎng)過(guò)程中可以反射更多的太陽(yáng)光，因此起到了為地球降溫的作用,。另外,，同一農(nóng)作物的不同變種，其太陽(yáng)光反射率存在很大差異（即星體反照率）,，因此在夏季的生長(zhǎng)期內(nèi),，可以選擇種植反射率高的農(nóng)作物品種以期對(duì)氣候變化加以控制，這與目前農(nóng)民培育特定農(nóng)作物變種以使產(chǎn)量最大化的方式類似,。由于可耕種農(nóng)業(yè)是一個(gè)全球性產(chǎn)業(yè),，因此降溫幅度會(huì)更大。
植物的星體反照率不同的原因是,，其葉子表面的特性和葉子的排列不同,，這被稱為冠層形態(tài)學(xué),。因此，研究小組建議,，可根據(jù)農(nóng)作物反射特性來(lái)選擇種植其不同變種,，同時(shí)在種植農(nóng)作物時(shí)也要考慮其他因素，如谷物的食品加工特性等,。
該研究小組強(qiáng)調(diào),，與種植生物質(zhì)燃料作物不同的是，無(wú)論是在產(chǎn)量還是類型上,，該計(jì)劃都不會(huì)影響糧食生產(chǎn),。安迪博士解釋說(shuō)：“我們建議選擇同一種作物的不同變種，以使太陽(yáng)光反射率最大化,，而不是改變農(nóng)作物類型,，雖然后者也能帶來(lái)環(huán)境效益。”
據(jù)估計(jì),，在未來(lái)百年里,，采取這種方法相當(dāng)于避免向大氣中排放1950億噸的二氧化碳。在夏季植物生長(zhǎng)期,，歐洲和北美的廣大地區(qū)溫度可降低最多1攝氏度,。這相當(dāng)于全球每年氣溫降低超過(guò)0.1攝氏度，大約占19世紀(jì)工業(yè)革命以來(lái)全球氣溫升高總和的1/20,。
研究人員表示,，可通過(guò)發(fā)放碳信用額來(lái)鼓勵(lì)農(nóng)民種植此類農(nóng)作物。據(jù)研究人員測(cè)算,，如果實(shí)行這樣的機(jī)制而避免了氣溫升高,，預(yù)計(jì)農(nóng)民每公頃每年會(huì)收益23歐元。雖然目前生物燃料作物每公頃每年可以收益45歐元,，但占用了種植糧食的寶貴農(nóng)業(yè)用地,。
研究人員稱，現(xiàn)在人們還不愿意大幅度減少化石燃料使用以減少二氧化碳排放,，而像種植反射率更強(qiáng)的農(nóng)作物這種簡(jiǎn)單的替代方法是幫助減輕一些地區(qū)的熱浪和干旱形勢(shì)的比較現(xiàn)實(shí)的方式,，而且很快就能以極低的成本看到效果。（生物谷Bioon.com）
生物谷推薦原始出處：
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.
