A very important conference took place 20 years ago, in June 1992 – the Rio Earth Conference, officially known as the United Nations Conference on the Environment and Development.

It was the first international recognition that our human activities are distorting the climate, and the deliberations were accepted by representatives from more than 170 nations, who returned home with one message – the solution would have to be found locally, with local people and local government taking the initiative.

This became known as the Local Agenda 21 initiative – the way that we ought to behave in the 21st century – and Bradford Council signed up for the task, with its own LA21 committee.

In the early days, progress was slow, though supported and informed by a loose coalition of local authorities, from Newcastle, Leeds and Bristol in the UK to Amsterdam, Lisbon, Munich and Aarhus in Europe.

Small steps began to raise the awareness of the need to behave sustainably, that is to make sure that we did not take so much out of the earth system that it would decline and leave less land, water and resources for the generations to come.

In Bradford, all the incandescent light bulbs in the main Council chamber were changed to low-energy ones, and over a period of time the recycling rate was raised through the introduction of wheeled bins. Energy-efficient controls were introduced in many Council buildings and the Council made sure that it only used copy paper made from recycled material.

More recently, Bradford Council has become very much better organised to take on the challenge of reducing the CO2 emissions in the district, with a formal Environment and Climate Change unit, working with others in the district to produce a Climate Change Framework for action. The detail, set out in an excellent document, Our District, Our Climate, Our Responsibility, should be available from the Council on (01274) 437778.

It’s ambitious, as it sets Bradford the task of reducing local CO2 emissions by 40 percent, from a 2005 baseline, by 2020. In effect, that means each one of us reducing our contribution from more than five tonnes of CO2 to just over three, by behaving differently. That’s a remarkable prospect.

This week, the second major Rio conference, 20 years on from the first, is taking stock of the global progress that has been made and will probably conclude that it has been patchy.

A relentless rise in CO2 from 359 parts per million to 397 in the last two decades, and a world population increase from five and a half billion to just over seven in the same period is a measure of the difficult, but not impossible, challenge that we face.