Science and technology.

科技。

Climate change.

气候变化。

Good news at last?

终于来了好消息？

The climate may not be as sensitive to carbon dioxide as previously believed.

气候对二氧化碳的敏感性可能低于先前的预期。

CLIMATE science is famously complicated, but one useful number to keep in mind is "climatesensitivity". This measures the amount of warming that can eventually be expected to follow adoubling in the atmospheric concentration of carbon dioxide. The Intergovernmental Panel onClimate Change, in its most recent summary of the science behind its predictions, published in2007, estimated that, in present conditions, a doubling of CO2 would cause warming of about3°C, with uncertainty of about a degree and a half in either direction. But it also says there is asmall probability that the true number is much higher. Some recent studies have suggestedthat it could be as high as 10°C.

气候科学的复杂程度众所周知，但把一个指标记在脑中非常好用，那就是"气候敏感性"。该指标表示预计大气中二氧化碳浓度翻倍所能引致的升温量。政府间气候变化专门委员会（IPCC）在其最近一次关于其预测背后的科学性的概要中（发布于2007年）估计，在如今的情况下，二氧化碳浓度翻倍将造成3°C左右的升温，上下误差在1.5度左右。但该概要也声称，真实数据有少许可能还要高得多。一些近期的研究也猜测气温上升可能达到10°C之高。

If that were true, disaster beckons. But a paper published in this week's Science, by AndreasSchmittner of Oregon State University, suggests it is not. In Dr Schmittner's analysis, theclimate is less sensitive to carbon dioxide than was feared.

如果这种猜测属实，灾难说来就来了（直译：灾难朝我们挥手）。但美国俄勒冈州立大学的安德烈亚斯-施密特纳在本周《科学》杂志上刊登的一篇报告认为，情况并非如此。在施密特纳博士的分析中，气候并不像先前人们所担忧的那样对二氧化碳那么敏感。

Existing studies of climate sensitivity mostly rely on data gathered from weather stations,which go back to roughly 1850. Dr Schmittner takes a different approach. His data come fromthe peak of the most recent ice age, between 19,000 and 23,000 years ago. His group is notthe first to use such data (ice cores, fossils, marine sediments and the like) to probe theclimate's sensitivity to carbon dioxide. But their paper is the most thorough. Previousattempts had considered only small regions of the globe. He has compiled enough informationto make a credible stab at recreating the climate of the entire planet.

现有的关于气候敏感性的研究主要基于气象站收集的数据，可以追溯到公元1850年左右。施密特纳博士采用了另外一种方法。他的数据来源于最近一次冰河时期的顶峰（介于一万九千到两万三千年前之间）。他的团队不是第一个使用这些数据（冰芯，化石，海洋沉积物诸如此类）来探测气候对二氧化碳的敏感性的团队。但他们的报告是最全面彻底的。过去的研究只考虑了全球的小部分地区。而他汇编了足够的信息，可以确凿地尝试一下重建整个地球的气候模型。

The result offers that rarest of things in climate science-a bit of good news. The group's mostlikely figure for climate sensitivity is 2.3°C, which is more than half a degree lower than theconsensus figure, with a 66% probability that it lies between 1.7° and 2.6°C. Moreimportantly, these results suggest an upper limit for climate sensitivity of around 3.2°C.

研究的结果给出了气候科学中最为罕见之物——一丁点好消息。该研究组给出最有可能的气候敏感性数字是2.3°C，比公认的数据低了半度多，并且该数字有66%的几率位于1.7°C到2.6°C之间。更重要的是，研究结果指出，气候敏感性的上限在3.2°C左右。

Before you take the SUV out for a celebratory spin, though, it is worth bearing in mind thatthis is only one study, and, like all such, it has its flaws. The computer model used is of onlymiddling sophistication, Dr Schmittner admits. That may be one reason for the narrow rangeof his team's results. And although the study's geographical coverage is the mostcomprehensive so far for work of this type, there are still blank areas-notably in Australia,Central Asia, South America and the northern Pacific Ocean. Moreover, some sceptics complainabout the way ancient data of this type were used to construct a different but related piece ofclimate science: the so-called hockey-stick model, which suggests that temperatures have risensuddenly since the beginning of the industrial revolution. It will be interesting to see if suchsceptics are willing to be equally sceptical about ancient data when they support their point ofview.

但是在你把SUV开出去兜风以作庆祝之前，要记住这只是一项研究而已，并且——就如同所有这类研究一样——研究自身也有缺陷。施密特纳博士承认，该研究采用的电脑模型的复杂程度一般。这可能也是他的团队实验结果范围较窄的一个原因。而且，尽管这项研究的地理覆盖范围是迄今为止同类中最大的，它仍有空白区域——尤其指澳洲，中亚，南美和北太平洋地区。此外，一些怀疑论者对这些远古数据被用来构建一个不同的但是相关的气候学分支：所谓的"曲棍球棒模型"（认为气温自从工业革命以后就突然上升）满腹牢骚。看看当远古数据支持这些怀疑论者的观点时，这些人是否还愿意以同等的怀疑态度对待，这一定会非常有趣。