Trees are probably the best-behaved species on the planet, and that includes human beings, who come well down the list. It's difficult to find anything negative to say about trees.

They are directly solar powered to take in CO2 to make their food and give out the oxygen the animal kingdom needs, and then they tuck away the carbon as the wood and store it for up to a century or more if left alone.

When the leaves open to let in the CO2 they also let water out, and mature trees can transpire up to 800 gallons on a warm summer day. This keeps the air humid and increases the rainfall as well as reducing the run-off from the soil, so limiting local flooding.

Trees have a very impressive CV - storing carbon, reducing drought, providing oxygen, binding slopes together, stopping soil erosion and giving building material, shade and fruit. They are easily grown from seed, from conkers, acorns and apple pips, and they look good in our gardens and open spaces.

There is evidence that this central role of trees is now well accepted and the UN has just acknowledged that this year more than one billion extra trees have been planted worldwide following pledges made a year ago.

Last week there were 18 million more planted in one day in Indonesia on the day before the Bali Climate Conference began, to reduce the damage caused by illegal logging and clearance for biofuel oil palm plantations.

European figures show an expansion of forest cover, and since 1990 an extra 126 million tonnes of CO2 have been absorbed, some 11 per cent of total emissions. The UK played a part and our 95 million tonnes of carbon in living biomass in 1990 rose to 112 million in 2005.

Forested areas in the UK have more than doubled in the last 60 years and part of this increase has happened in Bradford, mainly due to the efforts of the Forest of Bradford group, part of BEAT, the Bradford Environmental Action Trust (01274 718420).

Working with volunteers from schools, community groups, and businesses, the group has planted more than 250,000 trees in the last nine years, with 37,000 last year, on more than 250 sites in the district.

The website, www.beat.org.uk, gives all the details of the planting days, and the next one is on Saturday, in Queensbury. There are opportunities for business team-building days, and a carbon offsetting scheme, at £5 a tree or £25 for a tonne of carbon.

However worldwide deforestation still produces 20 per cent of global CO2 emissions, more than that from all transport and flying, and still on any one day, for every extra hectare planted, two are cut down for food and bio-fuel production.

It needs to be the other way round, and our Forest of Bradford is helping to do just that.