全球气候变暖已是不争的事实，全面评估其风险是一项迫在眉睫的科学任务，也是非常有趣的科学话题。近期，Lesk等发现，北半球冬季变暖可能会对北美地区（美国和加拿大）松树林产生很大的负面影响，主要是因为，原本不适合北方寒冷地区的南方松大小蠹（Dendroctonus frontalis）将入侵越来越温暖的北方，引起大面积森林死亡。南方松大小蠹是一种侵袭各类松树和杉树的甲虫，是美国南部针叶林最具毁灭性的害虫。大小蠹会在树干上形成大量弯曲的蛀洞，破坏树木水分和养分的输送系统。据称，受侵袭的树木即使经过治理也很难存活。

相关研究论文“Threats to North American forests from southern pine beetle with warming winters”已经发表在Nature Climate Change上。

评论：气候变暖不仅导致树木生境的北移，植食性昆虫、包括不少植食性脊椎动物也会北移，其结果是，早先树木被虫子吃，造成破坏，长时间二者可能形成动态平衡。树木北移，昆虫北移，植物-昆虫关系此消彼长，最后达到新的稳态。至于能否出现气候模型预测的灾难，还需要结合昆虫和树木的生理学特点，以及可能的快速共进化关系进行更细致的研究。

Abstract

In coming decades, warmer winters are likely to ease range constraints on many cold-limited forest insects^1,2,3,4,5. Recent unprecedented expansion of the southern pine beetle (SPB, Dendroctonus frontalis) into New Jersey, New York and Connecticut in concert with warming annual temperature minima highlights the risk that this insect pest poses to the pine forests of the northern United States and Canada under continued climate change⁶. Here we present projections of northward expansion in SPB-suitable climates using a statistical bioclimatic range modelling approach and current-generation general circulation model output under Representative Concentration Pathways 4.5 and 8.5. Results show that by the middle of the twenty-first century, the climate is likely to be suitable for SPB expansion into vast areas of previously unaffected forests throughout the northeastern United States and into southeastern Canada. This scenario would pose a significant economic and ecological risk to the affected regions, including disruption of local ecosystem services⁷, shifts in forest structure⁸, and threats to native biodiversity⁹.