If you wanted another reason to stay in Maine, here you go.

Those airline flights to Yellowstone or Disney World are starting to take a toll on the planet, according to a growing chorus of scientific studies. Commercial aviation is becoming a major focus of efforts to understand and combat global climate change.

To fly or not to fly already is a hot topic in Europe. Brits especially are being urged to fly less, although that hasn’t seemed to keep people on the ground.

Queen Elizabeth showed just how sensitive an issue it is when she flew to our side of the Atlantic this month.

Her majesty bought pollution offsets for her Monarch-class flight. Offsets, in theory, cancel out the impacts of one activity by paying an environmental service to reduce pollution somewhere else.

(The Queen’s gesture probably didn’t do much for the reputation of offsets as an indulgence of the wealthy.)

Offsets for air travel aren’t just for nobility. British Airways and the on-line travel agency Expedia even offer economy-class travelers a chance to buy offsets when they make airline reservations. Dozens of independent organizations sell them, too.

Offset deals vary widely, but it could cost $10, more or less, to offset a trip from Boston to Orlando. Here's a site with lots more on offsets and climate-friendly travel.

The issue of air travel and climate change has flown somewhat beneath the radar in the United States, although it increasingly comes up in policy discussions and in comments and questions from our readers.

Some argue the aviation industry is a major culprit that’s somehow escaped accountability.

Flying is clearly a contributor. Planes burn fossil fuels and therefore release carbon dioxide. They also emit nitrogen oxides and make cloud-like contrails that can also trap heat.

Just how much aviation affects the earth’s climate is one of many things climate scientists are still working on.

The aviation industry is estimated to account for between 2 percent and 4 percent of greenhouse gas emissions. But the gases are believed to have much more of an effect when put directly into the lower stratosphere. A big concern is that global airline travel is expected to double by 2020.

Here’s what the Intergovernmental Panel on Climate Change reported. “Although the task of detecting climate change from all human activities is already difficult, detecting the aircraft-specific contribution to global climate change is not possible now and presents a serious challenge for the next century.”

This isn’t intended to spoil anyone’s travel plans, really. There are lots of ways to reduce climate impacts that don’t involve canceling the family vacation. And let’s face it, avoiding flying is not as simple as combining trips to the grocery store and hardware store.

Driving is not a great alternative. Even if you can afford the gas, and even if there are roads between here and where you’re headed, driving puts a lot of carbon into the atmosphere, too.

Even if you could find a ship going your way, it would need to have sails. One recent European study said the shipping industry releases twice as much greenhouse gas as the aviation industry, and is growing nearly as fast.

Trains might be the answer. One train operator said they’re 10 times more efficient and less destructive than planes.

Of course, there’s always Bar Harbor and Baxter State Park. Vacationland never looked so good.

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