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Archive for the '环境科学' Category

网络计算预测全球气温升高

Saturday, March 10th, 2007

climategraphs.jpg迄今为止规模最大的气候模拟提出警告,未来气温可能会升高11℃。该项研究发表于最近的自然杂志(Nature)上。

根据世界最大的气候模拟研究,温室效应可能比气象专家们曾经预计的还要严重。在最坏的情形下,即二氧化碳含量加倍时,全球气温会比前工业时代增加超过11℃。该研究同时还预测发生气温变化的区域也会相应扩大。

该研究是通过climateprediction.net网站进行的。该网站的目的是利用全球个人电脑空闲的计算能力来进行气候模拟,目前已经有九万多人下载了模拟软件。

模拟显示二氧化碳含量增加会使全球升温,其范围在1.9℃到11.5℃之间,气温变化的不确定度比从前预测的2℃至5℃要大很多。

不确定度变大是因为climateprediction.net网站比从前的模拟考虑了更多因素。领导该研究的英国剑桥大学 David Stainforth教授解释说,以前的模拟只计算了几十次,而现在进行了2000多次。

目前研究者们对于未来温度升高的过程还不能给出一个准确的时间表,尽管他们认为极端的温室效应可能要经过几十年甚至是几个世纪。目前大气中二氧化碳含量为百万分之三百七十九,预计到本世纪中叶将达到前工业时代的两倍(前工业时代的含量仅为百万分之二百八十)。

全球气温升高的不确定性可能意味着无法确立一条安全的预警线,以前制定防止温室效应政策时可能忽略了这一点。剑桥大学的物理学家 Myles Allen是这样认为的,他说,“尽管如此,我们可以在未来的许多年里致力于降低造成温室效应的气体含量。危机并不是在将来的某个时刻,”他说,“我们现 在已经身处这个危险的过程中了。”

宏大的计划

该研究每一次模拟都是基于大气环流模型(general circulation model)模拟程序的各种特定的情况。该模型把全球分为上千个区域,然后依据云量、热流和雨量等特定的初始假设来预测未来温度。从前的研究只考虑了上述 参数的最可能取值,而现在 climateprediction.net网站允许研究者们通过更多(两至三套)参数设置来研究气候的变化。

该研究的最终结果是在对目前气候的2017次模拟的基础上得出的。每一次模拟都预测温度会升高,大部分大约升高3.4℃,这正好是以前预测的气温升高的平均值。

研究者们计划改进他们的模拟,包括热量是如何穿越海洋的细节、区域性数据和本世纪气温变化的精确细节。“尽管我们已经拥有如此巨大的数据,但仍很难说我们已经对其进行了哪怕是肤浅的利用。” 研究小组成员Mat Collins这样认为。

climateprediction.net还希望有更多的计算机用户无偿提供他们计算机的空闲计算能力来运行他们的模拟软件。Stainforth教授说:“还有许多许多事情等着我们去做呢。”(李天喜 译自news@nature, 2005年2月02日

原文Internet project forecasts global warming

参考文献:
Stainforth, D. A. et al Nature 433, 403−406 (2005).