【正文】 th has warmed up by roughly degrees Celsius since the beginning of the Revolution. There is already approximately a 1 degree rise built into the system, even if we stop all greenhouse gas emissions today. Why? It will take decades to warm up the deep oceans before the temperature reaches a new equilibrium.
　　過去幾十年中，我們的氣候一直在發(fā)生變化。氣候變化并不是現(xiàn)在才有的，過去60萬年中就發(fā)生了6次冰河期。但是，現(xiàn)在的測量表明氣候變化加速了。北極冰蓋在9月份的大小，只相當(dāng)于50年前的一半。1870年起，人們開始測量海平面上升的速度，現(xiàn)在的速度是那時(shí)的5倍。一個(gè)重大的科學(xué)發(fā)現(xiàn)就這樣產(chǎn)生了。科學(xué)第一次在人類歷史上，預(yù)測出我們的行為對(duì)50~120xx年后的世界有何影響。這些變化的原因是，從工業(yè)革命開始，人類排放到大氣中的二氧化碳增加了。即使我們立刻停止所有溫室氣體的排放，氣溫仍然將比過去上升大約1度。因?yàn)樵跉鉁剡_(dá)到均衡前，海水溫度的上升將持續(xù)幾十年。
　　If the world continues on a businessasusual path, the Intergovernmental Panel on Climate Change predicts that there is a fiftyfifty chance the temperature will exceed 5 degrees by the end of this century. This increase may not sound like much, but let me remind you that during the last ice age, the world was only 6 degrees colder. During this time, most of Canada and the United States down to Ohio and Pennsylvania were covered year round by a glacier. A world 5 degrees warmer will be very different. The change will be so rapid that many species, including Humans, will have a hard time adapting. Iamp。rsquo。ve been told for example, that, in a much warmer world, insects were bigger. I wonder if this thing buzzing around is a precursor.
　　如果全世界保持現(xiàn)在的經(jīng)濟(jì)模式不變，聯(lián)合國政府間氣候變化專門委員會(huì)(IPCC)預(yù)測，本世紀(jì)末將有50%的可能，氣溫至少上升5度。這聽起來好像不多，但是讓我來提醒你，上一次的冰河期，地球的氣溫也僅僅只下降了6度。那時(shí)，俄亥俄州和費(fèi)城以下的大部分美國和加拿大的土地，都終年被冰川覆蓋。氣溫上升5度的地球，將是一個(gè)非常不同的地球。由于變化來得太快，包括人類在內(nèi)的許多生物，都將很難適應(yīng)。比如，有人告訴我，在更溫暖的環(huán)境中，昆蟲的個(gè)頭將變大。我不知道現(xiàn)在身旁嗡嗡叫的這只大蒼蠅，是不是就是前兆。
　　We also face the specter of nonlinear amp。ldquo。tipping pointsamp。rdquo。 that may cause much more severe changes. An example of a tipping point is the thawing of the permafrost. The permafrost contains immense amounts of frozen organic matter that have been accumulating for millennia. If the soil melts, microbes will spring to life and cause this debris to rot. The difference in biological activity below freezing and above freezing is something we are all familiar with. Frozen food remains edible for a very long time in the freezer, but once thawed, it spoils quickly. How much methane and carbon dioxide might be released from the rotting permafrost? If even a fraction of the carbon is released, it could be greater than all the greenhouse gases we have released to since the beginning of the industrial revolution. Once started, a runaway effect could occur.
　　我們還面臨另一個(gè)幽靈，那就是非線性的amp。ldquo。氣候引爆點(diǎn)amp。rdquo。，這會(huì)帶來許多嚴(yán)重得多的變化。amp。ldquo。氣候引爆點(diǎn)amp。rdquo。的一個(gè)例子就是永久凍土層的融化。永久凍土層經(jīng)過千萬年的累積形成，其中包含了巨量的凍僵的有機(jī)物。如果凍土融化，微生物就將廣泛繁殖，使得凍土層中的有機(jī)物快速腐爛。冷凍后的生物和冷凍前的生物，它們?cè)谏飳W(xué)特性上的差異，我們都很熟悉。在冷庫中，冷凍食品在經(jīng)過長時(shí)間保存后，依然可以食用。但是，一旦解凍，食品很快就腐爛了。一個(gè)腐爛的永久凍土層，將釋放出多少甲烷和二氧化碳?即使只有一部分的碳被釋放出來，可能也比我們從工業(yè)革命開始釋放出來的所有溫室氣體還要多。這種事情一旦發(fā)生，局勢就失控了。