飛行和駕駛：我們能讓旅行變得更有可持續性嗎？

讓我們更詳細地看一下 :

飛行產生的碳排放量

Over 4 billion passengers are flown each year , often over long distances. With 133g of CO₂ emitted per passenger per km (for domestic flights) , this adds up to over a billion tonnes of CO₂ every year . This is equivalent to 2.4% of global CO₂ emissions !

飛行產生的非碳排放量

Flying does not only emit CO₂. In fact, over half of its climate impact comes from non-CO₂ emissions .

Contrails are the trails you see behind planes. They are made of condensed water vapour, which is released from aircrafts at high altitude . The water vapour instantly freezes to form ice-crystals, which then produce special clouds called contrail-induced cirrus clouds . These clouds can trap in the earth’s heat, which causes a warming effect .

Planes also emit NOx, a gas that contributes to climate change by forming the greenhouse gas ozone . However, there is some disagreement over how big an effect NOx has, because it also destroys the greenhouse gas methane . Even so, if the buildup of ozone outweighs the removal of methane, there will be a net warming effect .

你如何才能減少飛行對環境的影響？

對于某些旅程，有替代飛行的方法。 例如，乘渡輪每人每公里排放18克二氧化碳當量。 與此相比，國內航班每位乘客每公里則釋放255克二氧化碳當量！

但是，當沒有這樣的替代方案時，乘坐經濟艙是下一個最佳的選擇。 坐商務艙的二氧化碳排放量是經濟艙的2至3倍，而坐頭等艙的二氧化碳排放量是坐商務艙的2至3倍！ 這是因為高級座位佔用了更多空間。

碳補償

Sometimes taking a flight is unavoidable. What can you do to reduce the impact of these flights?

By paying a little extra when you fly, money can be given to support projects that take in an equivalent amount of CO₂ to that released from your journey . This is called carbon offsetting. Projects supported by carbon offsetting include reforestation  or purchase of zero-carbon energy .

If conducted well, offsetting causes a net reduction in emissions, and may be worth considering should you find yourself faced with an unavoidable flight . Since 2005, projects have helped to reduce, sequester, or avoid over 437.1 MtCO₂e .

也就是說，減少排放的最好方法是直接做到這一點，而不是依靠碳補償。 此外，嚴格檢查特定的碳補償計劃實際上去除來多少碳是至關重要的，因為某些方法比其他方法更有效。 你可以通過檢查它們是否具有適當的證書，以及是否由可信任的第三方（例如非政府環保組織）進行驗證來執行此操作。

來自汽車的排放

在歐盟，公路運輸（包括汽車，卡車和公共汽車）佔運輸總排放量的72％！ 

An easy way to reduce your carbon footprint is to share journeys with other people who are going to the same place .

However, if you’ve got the choice, the best alternative is still to take public transport whenever possible .

你應該買一輛電動車嗎？

電動汽車將電能存儲在電池中，該電池用於為電動馬達提供動力，從而推動汽車向前行駛。 這不同於依靠化石燃料燃燒的普通汽車。

在許多地方，仍通過燃燒化石燃料 來發電，而電池生產每千瓦時電池容量可產生56-494公斤的二氧化碳。

與傳統的汽油車相比，電動汽車在其生命週期內產生的排放量仍然較少。

即使在美國，84.3％的能源是由化石燃料產生的，電動汽車的碳排放量也是汽油汽車的50％左右。

電池技術以驚人的速度持續改進，未來的創新將降低生產它們所需的碳排放量。 隨著各國轉向零碳電力的來源，電動汽車將成為減少我們的碳足蹟的更好選擇（更多信息，請觀看能源課程）。

That said, electric cars still cause the same problems associated with all cars: traffic and road accidents .

Plus, cars release particles called PM₂.₅, which cause air pollution in cities . Most of these don’t come from the exhaust, but from friction rubbing in the breaks and the tyres. This means they will occur for any type of car, electric or not .

結論

在我們日益相互連結的世界中，旅行帶來了社會和經濟的增長。 不幸的是，它仍然是碳排放的一個重要來源。 汽車，卡車和公共汽車的電氣化，以及可持續能源的部署，將大大減少這些排放。 同時，如果我們都限制出行量，並選擇碳足跡較低的運輸方式，我們可以在減少排放中發揮作用。

 回饋意見

https://climatescience.org/zh-tw/advanced-flying-driving/

下一章節