如果全世界保持現(xiàn)在的經(jīng)濟(jì)模式不變，聯(lián)合國(guó)政府間氣候變化專門委員會(huì)（IPCC）預(yù)測(cè)，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)，俄亥俄州和賓夕法尼亞州以北的大部分美國(guó)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 “tipping points” 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“氣候引爆點(diǎn)”，這會(huì)帶來許多嚴(yán)重得多的變化。“氣候引爆點(diǎn)”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(kù)中，冷凍食品在經(jīng)過長(zhǎng)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(shì)就失控了。
The climate problem is the unintended consequence of our success. We depend on fossil energy to keep our homes warm in the winter, cool in the summer, and lit at night; we use it to travel across town and across continents. Energy is a fundamental reason for the prosperity we enjoy, and we will not surrender this prosperity. The United States has 3 percent of the world population, and yet, we consume 25 percent of the energy. By contrast, there are 1.6 billion people who don’t have access to electricity. Hundreds of millions of people still cook with twigs or dung. The life we enjoy may not be within the reach of the developing world, but it is within sight, and they want what we have.
氣候問題是我們的經(jīng)濟(jì)發(fā)展在無意中帶來的后果。我們太依賴化石能源，冬天取暖，夏天制冷，夜間照明，長(zhǎng)途旅行，環(huán)球觀光。能源是經(jīng)濟(jì)繁榮的基礎(chǔ)，我 們不可能放棄經(jīng)濟(jì)繁榮。美國(guó)人口占全世界的3%，但是我們消耗全世界25%的能源。與此形成對(duì)照，全世界還有16億人沒有電，數(shù)億人依靠燃燒樹枝和動(dòng)物糞便來煮飯。發(fā)展中國(guó)家的人民享受不到我們的生活，但是他們都看在眼里，他們渴望擁有我們擁有的東西。
Here is the dilemma. How much are we willing to invest, as a world society, to mitigate the consequences of climate change that will not be realized for at least 100 years? Deeply rooted in all cultures, is the notion of generational responsibility. Parents work hard so that their children will have a better life. Climate change will affect the entire world, but our natural focus is on the welfare of our immediate families. Can we, as a world society, meet our responsibility to future generations?
這就是新的挑戰(zhàn)。全世界作為一個(gè)整體，我們到底愿意付出多少，來緩和氣候變化？這種付出至少在100年內(nèi)，都不會(huì)有明顯效果。代際責(zé)任深深植根于所有文化中。家長(zhǎng)努力工作，為了讓他們的孩子有更好的生活。氣候變化將影響整個(gè)世界，但是我們的天性使得我們只關(guān)心個(gè)人家庭的福利。我們能不能把全世界看作一個(gè)整體？能不能為未來的人們承擔(dān)起責(zé)任？
