Earlier this year the United Nations Intergovernmental Panel on Climate Change produced its fourth assessment, four years after the third.

Three working groups looked at the scientific background, the impact on life and the economy, and on how to cope with the problems.

Very recently they produced a summary that updates what is happening, and what might be done about it. This is timely as the world's nations meet in Bali to discuss how to follow the Kyoto agreement which ends in 2012 as much has happened since the original meeting in 1997.

The report states "unequivocally" that the climate is warming and quotes increasing air and sea temperatures, melting ice, and rising sea levels. This is despite a reduction of solar radiation and volcanic eruptions over the last fifty years that should have produced global cooling.

Eleven of the last 12 years have been the warmest on record, with the largest increases in high latitudes and with the land warming more than the sea. The rate of warming is also increasing, as it was 0.6 degC from 1901-2000, but 0.74 degC from 1906-2005. Before 1993, sea level rises averaged 1.8mm a year but since then it is 3.1mm.

All global greenhouse gases have grown since pre-industrial times with 70 per cent of the increase since 1970 and 80 per cent of CO2 since that date. The present concentrations are the highest for 650,000 years.

There is "high agreement" that with energy and agricultural emissions continuing to grow at the present rate, the temperature will increase by 0.2 degC every decade, that is 2 degC this century. It may well be higher as the take up of CO2 by the oceans and plant growth will slow as the temperature increases.

By 2020 millions of Africans will suffer from droughts, by 2030 much of southern and western Australia will be in water crisis and southern Europe will have regular heat stress and more wildfires. By 2050 the eastern Amazon rainforest will be replaced by grassland.

The good news is that it is possible to do something about the threat using a range of current technologies. Some change will need to come from individuals and some from government intervention.

A mix of better public transport, fewer flights, more renewables, accepting nuclear power, mandatory fuel economy for vehicles, improved energy efficiency, less waste, tighter planning regulations for housing design, a reduction in fertiliser use, carbon taxing for industry, paying countries to protect forests and to plant more trees and so on.

Kyoto really only required countries to monitor emissions, but for the sake of flooded and hurricane battered Bangladesh and Darfur the new Bali Agreement must require us to reduce them.