Fly less, sit in coach, and avoid gimmicky offsets. Here's how to make your next trip more sustainable, according to experts.

Paying attention to what kind of flight you're booking and considering carbon offsets can significantly reduce a plane passenger's carbon footprint.

• By flying direct, economy, and on new aircrafts you can reduce the impact of your flight up to 45%.
• Airlines offer options to buy offsets and fuel surcharges to ease one's travel carbon impact.
• Experts say carbon offsets are good, but they need to be chosen carefully.

Like many people living in New York City, I'm not from here. I'm originally from Milan, Italy, and, being a good, committed daughter, I fly back home at least twice a year to visit my family. 

That's 4 flights, over 16,000 miles, and 5.29 tons of carbon dioxide emissions, according to the online emissions calculator Native. 

That's more than what a standard gas-based car emits in a year, and a third of what the average American emits in a year, according to MIT Climate Portal. 

Flying is polluting. Aviation accounts for 2.5% of global carbon dioxide emissions — the US accounts for 25% of all global aircraft emissions. 

Start-ups and engineers are laboring to power planes with batteries and hydrogen. and airlines are adopting newer, more efficient aircraft, but at the moment fully carbon-neutral travel is non-existent. 

But aside from flying less, or not flying at all — which my mother would frown upon — there are ways to reduce one's impact on the environment while flying. 

Simple steps like flying direct, flying economy, and picking newer planes can reduce the impact of a specific trip up to 45%, according to Sanchali Pal, founder and CEO of Commons, an app that allows you to track and offset your carbon emissions. 

25% of a flight's total emissions happen during takeoff and landing, which is a reason why layovers are discouraged and some airports are adopting optimized profile descents with idle engines. The more people get on an airplane, the more efficient the whole process is, which is why economy is better than business.

Airlines have also been offering passengers the option to buy offsets and surcharges to ease the impact of their travel.

Should you take them?

Offsets — yes, but which ones  

If a passenger takes a one way flight from New York to Los Angeles, they emit 471.68 lbs of carbon dioxide, according to Southwest Airlines' estimating tool. Pay $3.59, the airline says, and you can offset that. 

Southwest will take that $3.59 and invest it in a project that reduces or removes carbon dioxide from the atmosphere. The offer is tempting, but some experts are skeptical about whether that money is actually going to do any good. 

"If you're buying an offset for 3 dollars, you're not flying carbon neutral," Daniele Rao, an expert of the decarbonization of aviation at non-profit watchdog Carbon Market Watch, told Insider. "That's impossible." 

Last year, Carbon Market Watch commissioned a study that looked at the effectiveness of carbon offsets bought by major European airlines. According to the study, "most of the carbon offsetting options offered by the airlines were from cheap and low-quality projects with uncertain benefits for the climate, and no guarantee of permanence." 

A popular, and cheap, kind of offset project is a forestry project in a developing country, according to Carbon Market Watch. A standard forestry project includes "storing" carbon in a forest, by protecting it or planting trees.

"The challenge with forestry projects is that maybe those trees were gonna be protected anyway, your dollars didn't do anything extra to keep them there," Sanchali Pal of Commons told Insider. "And how long were the trees there for? The trees have to be there for 30 years in order to absorb the amount of carbon that we want them to. And what if they get burned down by forest fire?" 

Pal's company, Commons, spends a lot of time researching offsets to make sure they have impact. The same New York-Los Angeles one-way flight offset that Southwest has for $3.59 would cost three times as much on the app. 

Commons has a guide on its website on how to best pick offsets. 

Pitching in for fuel 

Sustainable aviation fuel — similar to conventional jet fuel but up to 80% less carbon intensive — is what all airlines are betting on to become more sustainable. But at the moment it's scarce and expensive — it can cost up to 8 times what conventional jet fuel costs.  

Some airlines, predominantly European for now, are asking passengers to pitch in for the extra cost. AirFrance, for example, has increased all its ticket prices by an amount varying from 1 Euro to 24 Euro to cover for the company's increased use of sustainable aviation fuel. 

Other airlines, like Brussels Airlines, are asking passengers whether they want to pay more for sustainable aviation fuel. A 174 Euros ticket from Brussels, Belgium, to Milan, Italy has a 132 Euros surcharge fee if you want to buy sustainable aviation fuel, almost double the price, which doesn't make it the most appealing option for customers.