You need to consider the total picture and tackle every aspect of the greenhouse gas emission problem, not just air travel, and modify your day-to-days behavior along with your travel.
According to two climate-change -fighting sources I trust (The Sierra Club and Population Connection), food waste is a greater source of greenhouse gases in the US than the airline industry. This newspaper article explains how and why:
We are very careful about minimizing or eliminating food waste both at home and when we travel. Also we avoid excess packaging, particularly plastic. We carry our own shopping bags to Europe so we don’t have to use plastic bags. We plan our apartment meals carefully so there is no waste. We never get take-out (and did not during the pandemic) because it wastes so much packaging.
Other steps, not food-related: we minimize energy consumption by washing clothes only when actually soiled. We take shorter showers, and (don’t snicker) we often shower together. ( Who else remembers the 1970’s when Californians were advised to shower with a friend to save water ? ). We drink only tap water and carry our own re-usable water bottles Instead of buying bottled water. We try to patronize “green” hotels and other businesses that acknowledge the problem and take steps to be more sustainable.
We try to limit our consumer buying to things that are really necessary. Like the old Yankee slogan—- “-use it up, wear it out, make it do, or do without”. We have driven our cars for 17-20 years before replacing them, and the most recent replacement is an all-electric Chevy Bolt. Even that we try to drive as little as possible, by walking or biking for local errands. I try to choose clothing brands with the BlueSign label, meaning they are certified as following sustainable and eco-friendly practices throughout the manufacturing process. One reason I like Patagonia outdoor clothing so much, apart from the quality and design, is the company actively promotes the concept of “less is more” and encourages postponing purchasing of new gear until what you have is absolutely worn out. And then you return the item to then for recycling.
I am not saying all this because I am virtuous. These are all small steps that most of us can take, if we just stop to think about it. I am sure others have additional ideas and practices they can suggest ( isn’t that the point of this thread?)
And this doesn’t mean I am suggesting that air travel is not also a problem. We personally cannot sail to Europe ( my husband gets seasick easily), but we are cutting our international trips by half. And I am buying carbon offsets from a reliable source for the international flights we do take. The flights to and from the US are the only flights we take; no intra-Europe flying. Trains powered by electricity are much cleaner than cars or airplanes, so we do not rent cars either, unless necessary for a short distance to reach a village or other destination not served by bus or train. And I try to encourage others to do the same: whenever I see the question “car or train?” here on the forum, there is only one answer.