科普知识学英语 全球生态健康临界点似乎不会出现

海量资料下载 免费学习英语 www.englishvip.com/xinlw.htm （申请网址） A group of international ecological scientists led by the University of Adelaide have rejected a doomsday-like scenario of sudden, irreversible change to Earth's ecology. In a paper published February 28 in the journal Trends in Ecology and Evolution, the scientists from Australia, US and UK argue that global-scale ecological tipping points are unlikely and that ecological change over large areas seem to follow a more gradual, smooth pattern.   This opposes recent efforts to define 'planetary tipping points' ‒ critical levels of biodiversity loss or land-use change that would have global effect ‒ with important implications for science and policy-makers.   "This is good news because it says that we might avoid the doom-and-gloom scenario of abrupt, irreversible change," says Professor Barry Brook, lead author of the paper and Director of Climate Science at the University of Adelaide. "A focus on planetary tipping points may both distract from the vast ecological transformations that have already occurred, and lead to unjustified fatalism（宿命论） about the catastrophic effects of tipping points.   "An emphasis on a point of no return is not particularly helpful for bringing about the conservation action we need. We must continue to seek to reduce our impacts on the global ecology without undue attention on trying to avoid arbitrary（任意的） thresholds."   A tipping point occurs when an ecosystem attribute such as species abundance or carbon sequestration responds rapidly and possibly irreversibly to a human pressure like land-use change or climate change.   Many local and regional-level ecosystems, such as lakes and grasslands, are known to behave this way. A planetary tipping point, the authors suggest, could theoretically occur if ecosystems across Earth respond in similar ways to the same human pressures, or if there are strong connections between continents that allow for rapid diffusion（扩散，传播） of impacts across the planet.   "These criteria, however, are very unlikely to be met in the real world," says Professor Brook. "First, ecosystems on different continents are not strongly connected. Second, the responses of ecosystems to human pressures like climate change or land-use change depend on local circumstances and will therefore differ between localities."   The scientists examined four principal drivers of terrestrial ecosystem change ‒ climate change, land-use change, habitat fragmentation and biodiversity loss ‒ and found they were unlikely to induce global tipping points.   Co-author Associate Professor Erle Ellis, University of Maryland, Baltimore County, says: "As much as four fifths of the biosphere is today characterised by ecosystems that locally, over centuries and millennia, have undergone human-driven regime shifts of one or more kinds. Recognising this reality and seeking appropriate conservation efforts at local and regional levels might be a more fruitful way forward for ecology and global change science." A组由阿德莱德大学的科学家领导的国际生态拒绝了世界末日般的场景突然，不可逆转的变化，地球的生态环境。在生态学与进化趋势杂志2月28日发表的一篇论文中，来自澳大利亚，美国和英国的科学家认为，全球规模的生态临界点是不可能的，大面积的生态变化似乎遵循一个循序渐进，平稳格局。   反对最近努力定义“行星临界点” - 生物多样性的丧失或土地使用的变化，将有全球影响的临界水平 - 与科学和政策制定者的重要意义。   “这是个好消息，因为它说，我们可能避免厄运和忧愁突然的，不可逆转的变化的情况，说：”教授，主要作者的论文，并在阿德莱德大学的气候科学主任巴里·布鲁克。“把重点放在行星的临界点可能分散从浩瀚的生态变革已经发生，并导致不合理的宿命论（宿命论）的灾难性影响的临界点。   “强调一个点的不归路带来保护行动，我们需要的不是特别有帮助，我们必须继续努力试图避 ​​免任意（任意的）阈值，以减少我们对全球生态的影响没有过分关注。“   物种丰富度或固碳等生态系统属性的一个临界点时，就会发生反应迅速，可能是不可逆的人类压力，如土地利用变化或气候变化。   许多本地和区域一级的生态系统，如湖泊，草原，知道这样的行为。行星的临界点，笔者建议，理论上可以发生，如果整个地球生态系统类似的方式来回应人类相同的压力，或是否有较强的大洲，使整个地球的影响迅速扩散（扩散，传播）之间的连接。   布鲁克教授说：“这些标准，但是，是不太可能在现实世界中得到满足，”。“首先，在不同的大洲的生态系统并不强烈连接。第二，生态系统对人类的压力，如气候变化或土地利用变化的反应取决于当地情况，因此，不同地区之间。”   科学家们研究的四个主要陆地生态系统变化的驱动因素 - 气候变化，土地利用变化，栖息地破碎化和生物多样性丧失 - 发现他们不大可能引发全球性的临界点。   合著者副教授，马里兰州巴尔的摩县大学厄尔埃利斯说：“多达五分之四的生物圈今天特征的生态系统，在本地，在世纪和千年，经历了一个或多个人力驱动的政权转变种。认识到这一现实，并寻求适当的保护力度，在地方和区域层面，可能是一个更有效的方法，生态学和全球变化科学。“ “成千上万人疯狂下载。。。。。。 更多价值连城的绝密英语学习资料， 洛基内部秘密英语，技巧，策略 请在 网上 申请报名” 洛基国际英语 竭诚为您服务