The Queen is planning to offset the carbon emissions from her forthcoming flights to the US. The problem is how to go about it. Hilary Osborne offers Her Majesty some advice on the subject

Queen goes green ... on her US trip Queen Elizabeth II will offset her carbon emissions for the first time. Photograph: AP/Rob Griffith

Your Majesty (if that's not too middle class),

I understand you are looking into ways to offset your next trip to the US. I should begin by mentioning that offsetting is not as straightforward as it might seem and there are some people who think it's a bit of a waste of time (an accusation you are probably familiar with). In New Internationalist magazine Adam Ma'anit described them as "at best a distraction and at worst a grandiose carbon laundering scheme" and even people who believe in the principle of offsetting are not keen on all the schemes available.

Tree-planting seems to attract the biggest criticism, with offset firms accused of causing damage in some of the areas they are trying to cultivate, and scientists pointing out that when the tree dies and decays it will release CO2 back into the atmosphere. So I'd probably avoid that type of scheme - you get enough flak already.

You could consider the type of scheme that invests in projects to reduce emissions overseas. Lots of companies offer these now. The Guardian offsets its journalists' travel emissions and offers readers a calculator to do the same with Climate Care. Then there are other established companies including the CarbonNeutral Company. These invest in a wide range of small projects, such as low-carbon stoves in Africa and wind-power schemes in India.

I understand that you're going to Virginia and then to Washington, so by my reckoning with one of those companies it will cost you about £12 to offset your own emissions from those journeys - a small fraction of the total cost of your trip. Admittedly the price climbs when you add in Prince Philip and the rest of your entourage - for all 37 of you it's going to be around £444. But when you compare that with the cost of chartering the plane, that's pretty small beer.

However, their choice of schemes means they fall outside the guidelines the government has proposed for regulating offset schemes, so the Department for Transport may steer you away from them.

The government has its own fund, which invests in small-scale projects that have been approved under the Kyoto Protocol's clean development mechanism which it uses to offset ministers' flights. With this scheme, no money changes hands until the emissions reductions have been made. Rather than get your man to shop around, this will probably be your first choice.

But even with the government's backing, it's not ideal - the best way to cut your carbon footprint would be to stay at home. That strategy would have the added benefit from saving your hosts from Prince Philip.