If you take the train, then you'll cut carbon dioxide (CO2) by half compared to the plane. A key reason is that the train (or the diesel bus) may be a big carbon emitter, but it's designed to carry a lot of passengers, so the per capita emissions are a lot lower.

Whether a train is "worse" than a plane depends entirely on the distance of the journey and your personal priorities regarding time, cost, and comfort. For distances under 500 miles (such as Paris to London or Tokyo to Osaka), trains are often superior because they travel from city center to city center, eliminating the need for long airport commutes and intensive security lines. Trains also offer a much higher level of comfort, with larger seats, more legroom, the ability to walk around freely, and no "middle seats" on most routes. However, for long-haul travel across continents or oceans, planes are objectively "better" in terms of speed and efficiency; a 6-hour flight would take several days on a train. Planes are also often cheaper for long distances due to the competitive "budget airline" market. From an environmental perspective, trains are significantly "better," producing up to 80-90% less carbon emissions per passenger than a flight. Ultimately, trains excel at regional, scenic, and eco-friendly travel, while planes remain the only practical choice for global, time-sensitive transportation.