A company which plants trees to offset carbon usage has given a cautious welcome to a report which claims the practice is pointless outside equatorial regions.

Carbon Footprint made headlines in the techie press recently when it partnered Via to make a new processor "carbon neutral".

Under the deal Via employs Carbon Footprint to plant four trees per processor, which offsets three years usage.

John Buckley, managing director for Carbon Footprint, was apprehensive about the findings and likened the news to the rubbished claims that trees and vegetation emitting methane in large quantities.

Although the company started by planting and continues to plant trees in Manchester, Buckley was keen to highlight that "the largest tree plantation Carbon Footprint is supporting is in Kenya - where this report shows there are advantages".

He pointed out that planting trees is not simply about offsetting carbon becuase the provide wildlife habitats.

Via originally came under fire for ignoring the carbon dioxide produced during the manufacturing of its processors because manufacturing produces much more carbon than usage of electronics.

The new report could wound Via's scheme further because it surmises that north of 20 degrees latitude forests absorb enough warmth to cancel out the cooling effect brought about by trees, reducing the amount of carbon dioxide in the atmosphere.

Now Best Foot Forward, the company Via commissioned to calculate how many trees it would need to plant, has also changed its tone by admitting tree planting is an unreliable thing to do.

Craig Simon, co-founder of Best Foot Forward, said: "Planting trees is not a reliable way of sequestering carbon dioxide from the atmosphere because there is no guarantee of the perpetuity of trees."

This essentially means there is no guarantee the trees will not be ripped up in the future and he pointed out that when a tree dies, it decomposes, releasing any captured carbon dioxide into the atmosphere again.