在太空中架設(shè)造價上萬億美元的遮陽板,，將全世界各個城市中的屋頂涂上白漆……科學(xué)家想盡了各種創(chuàng)造性的方法與全球變暖作斗爭。如今,，研究人員又提出一個更具有成本效益的地球工程解決方案——多種植一些“有光澤的”農(nóng)作物。一項新的研究發(fā)現(xiàn),，增加莊稼表面的反射率可以在夏季的幾個月中讓北美洲中部和歐亞大陸變得更涼爽一些,。
包括玉米和大麥在內(nèi)的農(nóng)作物的蠟質(zhì)層能將太陽輻射反射回天空，植物的這一特性被稱為“反照率”,。英國布里斯托爾大學(xué)的地質(zhì)學(xué)家及氣候科學(xué)家Andy Ridgwell說,，科學(xué)家曾估計，如果沒有莊稼的反照率,，地球表面的溫度將比現(xiàn)在高出0.5攝氏度,。對他來說，顯而易見,，如果研究人員能想辦法增加莊稼的反照率,，則將有助于冷卻我們正在逐漸變熱的星球。
為了實現(xiàn)這一目標(biāo),，Ridgwell和同事搜集了有關(guān)全球農(nóng)田的數(shù)據(jù),，其中大部分集中在北美地區(qū)以及歐亞大陸。隨后,，研究人員模擬了莊稼反照率的變化將如何通過大氣環(huán)流,、海冰形成以及其他已知的氣候模式對全球溫度造成影響。研究結(jié)果顯示,，如果莊稼反照率增加20%,，將在夏季使該地區(qū)的平均氣溫降低1攝氏度。在100年里,，這種效應(yīng)相當(dāng)于在大氣中減少1950億噸的二氧化碳氣體排放量,；換句話說,，也就等于停飛了1.95億架次從洛杉磯飛往紐約的航班。研究小組在最新出版的《當(dāng)代生物學(xué)》（Current Biology）雜志上報告了這一研究成果,。
Ridgwell指出,，增加農(nóng)作物反照率的一種途徑便是有選擇性地種植那些表面蠟質(zhì)層更厚的植物。他說,，這種變化并不會影響植物的產(chǎn)量,，同時這種經(jīng)過改良的莊稼也不會給消費者的健康帶來麻煩，這是因為誰也不會吃它們的葉子,。Ridgwell表示,，經(jīng)過改良的農(nóng)作物還將為農(nóng)民帶來其他的實惠——“蠟質(zhì)更多的葉子提供了另一些好處，例如減少植物水分的流失”,。
北卡羅來納州羅利市美國農(nóng)業(yè)部的植物生理學(xué)家Fitzgerald Booker相信,，改良莊稼的反照率“提供了一些在其他地球工程方案中未曾發(fā)現(xiàn)的優(yōu)勢，例如實用性以及實施的低成本”,。但Ridgwell承認,，使莊稼更加有光澤并不能通過其自身解決全球變暖問題，“它只是我們開始向著產(chǎn)生一點變化所邁出的簡單一小步”,。(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.
