It takes around 250KW per year to run an ice machine (108kg of carbon dioxide generated). 10 ice machines generate a tonne of CO2 per year.
In terms of carbon offsetting (or carbon laundering, depending on your viewpoint) that's about one and a half trees.

What I don't know yet is how many ice machines there are in the world, sitting in hotel corridors in the  just in case anyone wants to use them. But not having all the data to hand doesn't undermine the science. All contributions are gratefully received.
If you’ve got the data or would like to have a crack at collecting it, do get in touch.

In the meantime, here's some information about refridgeration from The Green Consumer Guide www.greenconsumerguide.com

"Refrigeration
Monday 28 February 2005
Refrigerated food is a luxury which we now take for granted. Most households have fridges, freezers or both and most diets include items, like dairy products, fast foods and ice cream, which would perish at normal room temperature. But while we may see fridges as benign tools quietly doing their job, like most electrical appliances there is an environmental price to pay for the service they provide...
" According to the Energy Savings Trust a power station annually emits up to 0.5 tonnes of CO2 to power an average sized fridge. Refrigeration also accounts for 36% of electricity consumed by all domestic appliances. Energy efficient refrigeration can use up to 70% less energy than existing, less efficient models. The most energy efficient unit is completely CFC and HFC free and has an energy consumption of 0.1kW/h/100l/24h, which is the equivalent energy consumption of a 15 watt light bulb. Friends of the Earth recommend buying fridges that run on less than 150kW/h annually and freezers or fridge/freezers which run on 350kW/h or less annually. This amounts to savings of 160kg and 320 kg on CO2 emissions, respectively."

Read Jim Carlton’s piece from the Wall Street Journal written in December 2005 on what’s happening to the polar bears as their home melts away because this is what I'm keeping in mind. http://www.ncpa.org/abo/quarterly/20054th/clip/pdf/15--121405.pdf

Then for balance, there’s Myron Ebell, an adviser to George Bush and Director of global warming at the Competitive Enterprise Institute in Washington, who believes that global warming is a concept invented by European businesses and governments in an attempt to hinder the US economy, speaking on BBC Radio 4 in 2004. http://www.bbc.co.uk/radio4/today/interview/octnov_2004.shtml.

Download the Energy Savings Trust's 2020 Report: Energy and Waste in an Age of Excess and find out what kind of energy consumer you are.
http://www.est.org.uk/uploads/documents/myhome/2020%20Report%20Executive%20summary.pdf

Here’s The Guardian’s climate change site, news, opinions, information and practical resources. http://environment.guardian.co.uk/climatechange.

Visit Greenpeace www.greenpeace.org.uk.