They take two years to biodegrade – and Scottish mountains are littered with them

I have climbed Ladhar Bheinn, one of Scotland's finest peaks. The view was glorious. And I threw a banana skin at it. I have stood on the magnificent Aonach Eagach ridge and gazed down on Loch Achtriochtan. And I threw a banana skin at that, too.

In fact, there are few mountains in Scotland I haven't thrown a banana skin on. Forget all those energy drinks: nothing gets you up a ben like a banana. What's more, they come in handy biodegradable wrappers. So I'm practically doing the mountain a favour, feeding the eco-cycle of nature.

But apparently I'm not. The John Muir Trust, which protects many of Scotland's wild places, has just given banana-skin chuckers a stern ticking off. The trust estimates that there are now 1,000 banana skins strewn across Ben Nevis. Walkers, it seems, don't realise that it takes ages for a banana skin to degrade: two years, in fact.

This comes as a shock. I have tutted my way round the litter-strewn shores of Loch Lomond and chased Mars Bars wrappers grabbed by the wind. Now I find that I am part of a "significant minority, who are littering and spoiling the experience for everyone else".

And it gets worse. According to Keep Scotland Beautiful, orange peel, another of my happily jettisoned waste products, is pretty bad too. Still, at least I've never left a glass bottle. They last 1 million years, apparently – though I wonder how they know.

A load of rot: how long your litter takes to biodegrade

Paper bag - 1 month

Apple core - 8 weeks

Orange peel and banana skins - 2 years

Cigarette end - 18 months to 500 years

Plastic bag - 10 to 20 years

A plastic bottle - 450 years

Chewing gum - 1 million years

From Keep Britain Tidy (keepbritaintidy,org)