Twenty-four trains, nine countries, 13,500 miles.
24趟列车，9个国家，13500英里（21726千米）。
They are the numbers behind the epic train journey one man took from Southampton in the UK to eastern China.
这是一个人从英国南安普敦到中国东部史无前例的火车之旅背后的数字。
Roger Tyers, 37, spent a month on board trains and over $2,500 -- almost triple the cost of a return flight -- to travel to the Chinese port city Ningbo for academic research in May.
37岁的罗杰·泰尔斯坐了一个月火车，花了2500多美元（约合人民币1.8万元）——往返机票价格的近三倍——才在五月份抵达中国港口城市宁波做学术研究。
It was the climate crisis, not a love of trains, that drove the sociologist to choose this complicated route over a return flight. Tyers told CNN that he felt compelled to stop flying when UN climate experts warned last year that the world has less than 11 years to avoid catastrophic levels of global warming.
驱使这位社会学家选择这条复杂路线，而不是坐飞机往返的，不是对火车的热爱，而是气候危机。泰尔斯告诉CNN说，联合国气候专家去年警告称，世界距离灾难性的全球变暖只剩不到11年的时间，这让他觉得有必要停止坐飞机。
Tyers is not the only person to shun air travel in response to climate change. Thousands of people worldwide have publicly pledged to stop flying, including teenage activist Greta Thunberg, who has inspired youth climate protests around the world.
泰尔斯不是唯一一个避免坐飞机来应对气候变化的人。全世界有数千人公开承诺停止坐飞机，其中就包括青少年活动家格蕾塔·桑伯格，她激励全球各地的年轻人起来抗议气候变化。
Activist Maja Rosen launched the "Flight Free" campaign in Sweden in 2018 with the aim of encouraging 100,000 people not to fly for one year.
2018年，活动家玛雅·罗森在瑞典发起了“无飞行”活动，目标是鼓励10万人一年内不坐飞机。
Although only around 14,000 people signed the online "#flightfree2019" pledge, Rosen told CNN that the campaign had made more people aware of the urgency of the climate crisis and motivated them to travel by train more often.
尽管只有约1.4万人在#无飞行2019 线上承诺书签了字，罗森告诉CNN说，该活动让更多人意识到了气候危机的紧迫性，并激励他们更多地乘坐火车出行。
According to a survey released in May 2019 by Swedish Railways (SJ), 37% of respondents chose to travel by train instead of plane where possible, compared to 20% at the start of 2018. An SJ spokesperson said: "Rail travel is soaring thanks to climate fears."Domestic passenger numbers in July fell by 12% compared to the previous year, according to Swedavia, a company which operates Sweden's 10 busiest airports.
根据瑞典铁路在2019年5月发布的一项调查，37%的受访者尽可能选择坐火车而不是飞机旅行，而在2018年初做出同样选择的只有20%。瑞典铁路的一名发言人称：“多亏了人们对气候变化的担忧，乘坐火车旅行的人数大增。”运营瑞典最繁忙的10个机场的Swedavia集团称，今年七月国内乘客数量同比下降了12%。

Rosen, who stopped flying 12 years ago, says the collective pledge helps combat the sense of hopelessness many people feel when it comes to tackling climate change.
十二年前就停止坐飞机的罗森说，这份集体承诺书有助于对抗许多人在应对气候变化时的那种无助感。
"One of the problems is that people feel there's no point in what you do as an individual. The campaign is about making people aware that if we do this together, we can actually make a huge difference," she said.
她说：“其中一个问题是，人们觉得个体做出的努力是徒劳的。这个活动就是要让人们意识到，如果我们一起来做这件事，我们就能发挥巨大的作用。”
A passenger's footprint from an individual flight depends on a number of factors, including how far they fly and how full the plane is, but also on what class they travel in: First class passengers are given more space than economy passengers, meaning they're responsible for a bigger proportion of the plane's emissions.
一名乘客在一次飞行中产生的碳足迹取决于许多因素，包括他们的飞行距离、飞机上座率，但也取决于他们的舱位等级：头等舱的乘客得到的空间比经济舱的乘客大，这意味着他们出行产生的排放更多。
Emissions from train travel also depend on many factors, including how the train is powered. An electric train powered by clean energy will have much lower emissions than a diesel-powered train, for example.
乘坐火车旅行所产生的排放量也取决于许多因素，包括火车的动力来源。举例来说，以清洁能源为动力的电力火车排放量比柴油驱动的火车低得多。
Tyers calculated that his train journey to China produced almost 90% less emissions than a return flight.
据泰尔斯估算，他到中国的火车之旅所产生的排放物比乘飞机往返要少近90%。
The aviation industry accounts for 2% of man-made carbon dioxide emissions (CO2). By 2050, this is expected to increase to 22% if nothing changes.
人类活动造成的二氧化碳排放物中，航空业占了2%。如果保持现状，到2050年这一数字将增长到22%。
A passenger on a return flight from London to New York generates as much CO2 as the average person in the European Union does by heating their home each year, according to the European Commission.
根据欧盟委员会的数据，一名旅客乘坐飞机从伦敦到纽约往返所产生的二氧化碳相当于欧盟每人每年取暖所产生的二氧化碳平均水平。