The ocean's invisible forest - Marine phytoplankton play a critical role in regulating the earth's climate. Could they also be used to combat global warming
The ocean's invisible forest - Marine phytoplankton play a critical role in regulating the earth's climate. Could they also be used to combat global warming
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DOI：
10.1038/scientificamerican0802-54
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发表时间：
2002-08-01
影响因子：
3
通讯作者：
Falkowski, PG
中科院分区：
文献类型：
--
作者：
Falkowski, PG
科学美国人公司拥有数千种被称为浮游植物的自由漂浮的微观植物群。这些单细胞生物——包括硅藻和其他藻类——居住在地球表面的四分之三，但它们只占地球光合生物量所含6000亿吨碳的不到1%。但小并不妨碍这片几乎看不见的森林在地球上最关键的自然循环中留下大胆的印记。可以说，海洋浮游植物最重要的活动之一是它们对气候的影响。然而，直到最近，很少有研究人员意识到这些小型海洋居民能够从大气中吸收温室气体二氧化碳并将其储存在深海中。新的卫星观测和广泛的海洋学研究项目终于揭示了这些生物对全球温度、海洋环流和养分可用性的变化是多么敏感。有了这些知识，某些研究人员、企业家和政策制定者就产生了一种诱惑，他们想通过向海洋中添加营养物质来控制浮游植物的数量，以减缓全球变暖。今年年初在南大洋进行的一项为期两个月的实验证实，向表层海水注入微量的铁可以刺激浮游植物的生长；然而，广泛的商业海洋施肥计划的有效性和谨慎性仍在激烈争论中。探索人类活动如何改变浮游植物对地球碳循环的影响，对于预测此类活动的长期生态副作用至关重要。
COPYRIGHT 2002 SCIENTIFIC AMERICAN, INC. contains thousands of free-floating, microscopic flora called phytoplankton. These single-celled organisms—including diatoms and other algae—inhabit three quarters of the earth’s surface, and yet they account for less than 1 percent of the 600 billion metric tons of carbon contained within its photosynthetic biomass. But being small doesn’t stop this virtually invisible forest from making a bold mark on the planet’s most critical natural cycles. Arguably one of the most consequential activities of marine phytoplankton is their influence on climate. Until recently, however, few researchers appreciated the degree to which these diminutive ocean dwellers can draw the greenhouse gas carbon dioxide (CO2) out of the atmosphere and store it in the deep sea. New satellite observations and extensive oceanographic research projects are finally revealing how sensitive these organisms are to changes in global temperatures, ocean circulation and nutrient availability.With this knowledge has come a temptation among certain researchers, entrepreneurs and policymakers to manipulate phytoplankton populations—by adding nutrients to the oceans—in an effort to mitigate global warming. A two-month experiment conducted early this year in the Southern Ocean confirmed that injecting surface waters with trace amounts of iron stimulates phytoplankton growth; however, the efficacy and prudence of widespread, commercial ocean-fertilization schemes are still hotly debated. Exploring how human activities can alter phytoplankton’s impact on the planet’s carbon cycle is crucial for predicting the long-term ecological side effects of such actions.