This week, the queen of England will be visiting the United States, not a rare occurrence for her majesty, who loves to travel.
During her 55 years on the throne, Queen Elizabeth has visited 129 countries. She has traveled the length and breadth of the earth, making her perhaps the best-known, best-loved and most-informed British sovereign of all time.
But according to environmental activists, the queen's many expeditions have come at a dreadful cost to the planet. They see aviation as a prime cause of global warming.
"We're talking about a global emergency," said Graham Thompson of the environmental advocacy group Plane Stupid. "We're talking about something that could wipe out most life on Earth."
To her credit, the queen has tried to change her environmental ways. Her limousines now run on propane. Her husband cuts about town in a propane-powered cab. She travels by train, the greenest option, whenever possible.
But her flying, said Thompson, still poses a problem.
"With aviation, there is no technology on the horizon to make it clean," he said.
To travel to the United States, the queen will use her Boeing 777, which holds 366 tons of carbon dioxide, three tons of luggage and a staff of 35 onboard.
"I can't say I'm expert enough in what all of those 35 people do, but my guess would be that she could possibly shave a few off," said Thompson.
But the queen can't carry her own bags, blow dry her own hair or deal with pesky journalists. She needs an entourage. And the queen doesn't just emit carbon when she's on the move, she also emits carbon at home, too, when she's reading the paper or having a spot of tea. That's because the queen's home is a lot bigger than most people's -- Buckingham Palace has 775 rooms.
As the sun goes down, the lights in the palace come up. And while the palace uses energy-saving bulbs, which are 10 times more efficient than conventional ones, there are another 40,000 light bulbs inside.
"Does the queen go round turning lights off herself? I don't know," said Penny Russell-Smith, the queen's press secretary. "The queen, being from a wartime generation, it may well be the case. But certainly we do -- at the palace we are encouraged to switch lights off when we don't need them."
The queen's household spews 3,750 tons of carbon dioxide every year. The average British family sheds just 44 tons, but the queen seems to be doing all she can to lower her output, even planning a turbine in the Thames to power her weekend retreat, Windsor Castle.
"A borehole has been dug in Buckingham Palace garden, which helps with the air-conditioning in the gueen's gallery," said Russell-Smith, "and has also recently been used to air-condition the wine cellars where, of course, the wine is stored for official occasions."
Keith Leinster, a thermographer and analyst at Infrared Thermographic Surveys, snapped images of the palace with a special camera that picks up heat, not light. He was looking for wasted energy, and thankfully wasn't arrested for loitering around the gates after dark.
"It's looking pretty good," said Leinster. "Although there are some areas of concern."
These areas were prominent around the windows and beside the balcony.
"It's an old building," said Russell-Smith. "It would be very, very expensive indeed to double glaze, so there is some heat loss."