全球气候变暖的原因和后果仍然在争论中，但究竟对所有植物带来什么影响还不得而知。PLOS BIOLOGY杂志日前发表的一项由夏威夷大学科学家进行的新研究回答了这个问题。

植物通过提供食物、纤维等来维持人类社会的运转，但只有气候合适的时候它们才能提供这些福利。以往的研究认为，全球变暖的一个关键潜在“好处”是，北半球的植物会在更暖和的世界中生存、生长。

然而，这种假设忽略了这样一个事实，北半球植物仍然会受到太阳辐射的限制，进而使气候变暖和多余二氧化碳带来的积极影响遭到遏制。此外，气候变暖程度可能会超过热带地区植物的耐热程度，伴随而来的旱灾威胁也似不可避免。

新的研究表明，到2100年，正在发生的气候变化会导致的全球变暖、大面积干旱和太阳辐射减少，最终将导致植物生长期缩减。

总体看来，在气候变暖后整个地球的植物生长期会减少11%，到2100年，热带地区适宜的植物生长期更是减少高达200天。

虽然研究确实发现气候变暖会增加高纬度适宜植物生长天数达7%，但这些地区同样会受到太阳辐射量减少的影响，以往专注于温度变化的研究常会将这一点给忽略掉。

“未来高纬度地区地面的霜雪会减少，但是植物仍然无法享受升高的温度，因为光照还不足够充沛。”论文作者、夏威夷大学社会学院教授卡米拉·莫拉说，“那些认为气候变暖会让植物受益的人应该认真地考虑光照因素，狭隘地注重影响植物生长的因素会低估气候变暖给植物带来的潜在影响，这种影响不仅在更高的纬度上如此，对热带地区也是如此，会给全球植物带来可怕的后果。”（来源：科技日报 房琳琳）

Suitable Days for Plant Growth Disappear under Projected Climate Change: Potential Human and Biotic Vulnerability

Abstract  Ongoing climate change can alter conditions for plant growth, in turn affecting ecological and social systems. While there have been considerable advances in understanding the physical aspects of climate change, comprehensive analyses integrating climate, biological, and social sciences are less common. Here we use climate projections under alternative mitigation scenarios to show how changes in environmental variables that limit plant growth could impact ecosystems and people. We show that although the global mean number of days above freezing will increase by up to 7% by 2100 under “business as usual” (representative concentration pathway [RCP] 8.5), suitable growing days will actually decrease globally by up to 11% when other climatic variables that limit plant growth are considered (i.e., temperature, water availability, and solar radiation). Areas in Russia, China, and Canada are projected to gain suitable plant growing days, but the rest of the world will experience losses. Notably, tropical areas could lose up to 200 suitable plant growing days per year. These changes will impact most of the world’s terrestrial ecosystems, potentially triggering climate feedbacks. Human populations will also be affected, with up to ~2,100 million of the poorest people in the world (~30% of the world’s population) highly vulnerable to changes in the supply of plant-related goods and services. These impacts will be spatially variable, indicating regions where adaptations will be necessary. Changes in suitable plant growing days are projected to be less severe under strong and moderate mitigation scenarios (i.e., RCP 2.6 and RCP 4.5), underscoring the importance of reducing emissions to avoid such disproportionate impacts on ecosystems and people.

原文链接：http://www.plosbiology.org/article/fetchObject.action?uri=info:doi/10.1371/journal.pbio.1002167&representation=PDF