應對全球變暖爲何如此緊迫 Climate weather and the politics of energy

Is climate change the cause of extreme weather events? Until now the link has been suspected but never confirmed with scientific confidence. That position is now changing. A new study from the US confirms that for some extreme events there is a causal connection.

氣候變化是極端天氣事件的元兇嗎？人們一直懷疑二者存在關聯，但從來沒有做出令人信服的科學證實。如今，這種情形正在發生變化。美國的一項新研究證實，氣候變化與某些極端天氣事件之間確實存在因果關係。

This link between climate science and immediate weather conditions can only strengthen the case of those arguing for policy change. The impact of a damaging heatwave in terms of deaths, sickness and other social and economic costs is much more likely to rouse public opinion than the distant prospect of what might to some sound like a modest increase in the global mean temperature. All politics are local, and they are also immediate. The discount rate applied to future possibilities is very high: what could happen to a future generation decades matters much less than what is happening to me here and now. It brings climate to the foreground and diminishes the argument of those who say that since we don’t know everything we should do nothing and wait until we see how things turn out. If the impact is immediate and people are dying as a result, the call for action will be loud.

氣候科學與即時天氣狀況之間的這種關聯，會讓那些主張轉變政策的人士更有底氣。也許在一些人聽起來，全球平均氣溫不過將略微升高，這樣的前景顯得很遙遠，相比之下，破壞性熱浪所造成的影響——致死、致病及造成其他社會和經濟損失——更容易激發公衆輿論。所有的政治都只顧本地和眼前。未來可能性的貼現率非常高：幾十年後未來一代人可能遇到的事情，遠沒有我本人在當下、在此地所將面臨的事情重要。上述關聯使得氣候問題備受關注，也削弱了持以下觀點的人士的理由：既然我們並不知曉一切，我們應該什麼都不做，直至看清事態發展的結果。如果說氣候變化的影響是即時的，並且造成了人的死亡，那麼要求行動的呼聲將很高。

One of the most dangerous illusions in the debate around the implications of climate change is the notion that the impact will only be material when the carbon concentration in the atmosphere exceeds some defined limit — usually quoted as 450ppm. At that point global mean temperatures will rise by an average of 2 degrees centigrade and the problems will begin. I do appreciate that the science is much more complicated but I think this is how the challenge is seen by many non-expert policy makers and politicians.

在圍繞氣候變化影響的爭論中，最危險的觀念之一是認爲只有當大氣中的碳濃度超過某個明確的限度——通常引用的是450百萬分率(ppm)——纔會產生切實的影響。到那時，全球平均氣溫將上升2攝氏度，問題將開始出現。我當然知道氣候科學要複雜得多，但我認爲這正是許多非專家型的政策制定者和政治家看待氣候挑戰的態度。

That view is mistaken. It implies an accuracy in the knowledge of the relationship between carbon concentration and the effect on temperatures that doesn’t yet exist — not least because, as Martin Rees, the former President of the Royal Society puts it, we are conducting an experiment with the earth’s atmosphere which has never been tried before. We don’t know with any degree of certainty that 450ppm will produce an average rise of 2 degrees and we don’t know what the variations around that average figure might be across the world. The case for action is driven by the precautionary principle. But there is another known unknown and that is the extent and nature of the impact in the shorter term — before we get to 450ppm.

這種看法是錯誤的。它暗含這樣一種意思，關於碳濃度與其對氣溫影響的關係，在我們所瞭解的知識中存在一種精確性。而實際上還不具有這樣的精確性，主要是因爲，正如英國皇家學會(Royal Society)前主席馬丁•里斯(Martin Rees)所言，我們正在進行一項人類從未嘗試過的地球大氣實驗。我們絲毫無法確定，450ppm的碳濃度是否將造成平均升溫2攝氏度，我們也不知道在那個平均值上下世界各地可能出現什麼變化。行動的理由是出於預防原則。但是還有另一個“已知的未知”，即在更短時期內（碳濃度達到450ppm之前）氣候變化造成的影響的程度和性質。

A new and important study from the National Academy of Sciences in the US focuses on the impact of climate change and weather conditions and explores the vexed question of event attribution. Can we say that a heatwave in Paris — as occurred in the summer of 2003 killing some 3,000 people, and again last year, killing another 700 or floods on the Somerset levels in southwest England as in the winter of 2013/14 are the direct consequence of climate change? Did the wildfires that swept western Russia in the summer of 2010 killing some 56,000 people, according to the independent estimate of the insurance company result from global warming?

美國國家科學院(National Academy of Sciences)一項重要的新研究着眼於氣候變化的影響和天氣條件，並探索了極端天氣事件歸因這個棘手難題。我們可以說巴黎的熱浪（2003年夏天造成約3000人死亡，去年又造成700人死亡）或者2013/14年冬天英格蘭西南部薩默塞特郡的洪水是氣候變化的直接後果嗎？2010年夏天席捲俄羅斯西部、造成約5.6萬人死亡（根據保險公司的獨立估算）的野火是由全球變暖引起的嗎？

Until now, the careful scientific answer has been that there may be a linkage but it cannot be proved. Now, however, the science of event attribution is changing that position. It is beginning to be possible to say that some weather events are directly linked and attributable to climate change. Events such as heatwaves fall within that category. For the moment, cyclones do not and nor do droughts because too many other factors are involved.

一直以來，謹慎的科學回答是：可能有關聯，但無法證實。然而，如今，極端天氣事件歸因的科學正在改變這一情形。我們開始可以稱一些天氣事件與氣候變化直接相關，或者是由氣候變化造成的。熱浪等事件就屬於這一類。目前來看，颶風和乾旱並不屬於這一類，因爲它們還牽涉到太多其他因素。

In the view of the authors of the NAS study, to justify attribution requires:

在上述NAS研究報告的作者們看來，證明極端天氣事件歸因需要滿足以下幾個標準：

- a long-term historical track record of data to set the context of any current event

-長期的數據跟蹤歷史記錄，爲當前所有天氣事件建立背景

- the ability to simulate the events accurately in climate models.

-能夠在氣候模型中精確模擬天氣事件。

- a position purely influenced by meterological data.

-一種只受氣象數據影響的狀況(position)。

- that there is an understood and robustly simulated physical mechanism that relates a given class of extreme events to long-term anthropogenic climate changes such as global-scale temperature increase or increases in water content of a warmer atmosphere.

-存在一個可理解的、可靠模擬的物理機制，將給定級別的極端天氣事件與長期人爲氣候變化——比如全球範圍的氣溫升高或變暖的大氣中含水量的增加——聯繫起來。

For heatwaves these standards can be met.

熱浪天氣可以滿足上述所有標準。

In areas where the standards cannot yet be met more work needs to be done — separating out the different factors involved in producing particular circumstances and showing what if any proportion of the outcome is due to climate change.

但對於還不能滿足上述標準的領域，則需要進行更多工作，要分解出造成特定氣象的各種有關因素，證明結果有多少是氣候變化所致。

This is an important advance. We may not yet be at the point of being able to predict the frequency of extreme weather events — that is, we cannot say that there is likely to be a heatwave in Paris at least once every five years but we are close to being able to say that heatwaves are much more frequent than they have been in the past and that the change in frequency is due to a change in the climate.

這是一個重要的進步。我們可能暫時還無法預測極端天氣事件的發生頻率，也就是說，我們無法肯定巴黎是否至少每隔五年就出現一次熱浪，但我們幾乎能夠肯定熱浪比過去更爲頻繁，而這種頻率變化是由於氣候變化造成的。

As this linkage becomes more obvious the public demand for action will grow more intense and that in turn will raise a serious political problem. Even politicians who fully accept the risks of climate change cannot change the weather because heatwaves and other current extreme weather conditions are being caused by the change that has already occurred. Cutting carbon emissions to zero immediately — even if that were practical — would not alter the situation although it could, of course, prevent further deterioration. Equally, countries cannot not isolate themselves. The weather does not recognise political boundaries. In such circumstances the only viable response is adaptation and the development of provision to cope with the increased risks. The approach is sensible but it can be expensive. Taking precautions against the risks of a heatwave is not a simple process.

隨着這種關聯變得越來越明顯，公衆將更加強烈地要求採取行動，這反過來將提出一個嚴重的政治問題。即使是完全同意氣候變化風險的政治家也無法改變天氣，因爲造成熱浪以及當前其他極端天氣情況的原因，是已經發生的氣候變化。就算能將碳排放立即減少到零也無法改變現狀，當然，這可以防止情況進一步惡化。同樣，各國無法獨善其身，天氣可不認識領土疆界。在這種情況下，唯一可行的對策就是去適應，以及制定預防措施，以應對不斷增加的風險。此方法雖明智，但代價會很高，不過想要防範熱浪風險本就不是個簡單的過程。

In politics, if a risk cannot easily be removed or managed the temptation is to look for someone to blame. In legal terms this will be translated into the concept of liabilities. If you are a shareholder in an energy business you might like to ask your company’s view of the issue. It would be fascinating to read their responses.

政治方面，如果一個風險無法輕易被消除或管控，政治家很可能會尋找一個替罪羊。從法律上講，這將轉換成責任的概念。如果你是一個能源公司的股東，你可能會問公司對此問題的觀點，看他們作何反應將是件有趣的事。