"The Bali Declaration"

more than 200 leading climate scientists...have warned the United Nations Climate Conference of the need to act immediately to cut greenhouse gas emissions

The 2007 IPCC report, compiled by several hundred climate scientists, has unequivocally concluded that our climate is warming rapidly, and that we are now at least 90% certain that this is mostly due to human activities. The amount of carbon dioxide in our atmosphere now far exceeds the natural range of the past 650,000 years, and it is rising very quickly due to human activity. If this trend is not halted soon, many millions of people will be at risk from extreme events such as heat waves, drought, floods and storms, our coasts and cities will be threatened by rising sea levels, and many ecosystems, plants and animal species will be in serious danger of extinction.

The next round of focused negotiations for a new global climate treaty (within the 1992 UNFCCC process) needs to begin in December 2007 and be completed by 2009. The prime goal of this new regime must be to limit global warming to no more than 2 ºC above the pre-industrial temperature, a limit that has already been formally adopted by the European Union and a number of other countries.

Based on current scientific understanding, this requires that global greenhouse gas emissions need to be reduced by at least 50% below their 1990 levels by the year 2050. In the long run, greenhouse gas concentrations need to be stabilised at a level well below 450 ppm (parts per million; measured in CO2-equivalent concentration). In order to stay below 2 ºC, global emissions must peak and decline in the next 10 to 15 years, so there is no time to lose.

As scientists, we urge the negotiators to reach an agreement that takes these targets as a minimum requirement for a fair and effective global climate agreement.

...in 1896 Svante Arrhenius..speculated that changes in the atmospheric concentration of carbon dioxide could alter the surface temperature of the earth.

Since then, climate scientists..have had a common goal: namely, exploring the earth's climate system..we've been organised enough to produce acclaimed reports on the science of climate change. The best example is the series of reports produced by the Intergovernmental Panel on Climate Change (IPCC).

..climate scientists have generally steered clear of telling the world how to set its emissions targets. The attitude has always been this: climate scientists should stick to the science, not set policy. But who is best placed to advise the world what greenhouse gas targets are needed to avoid dangerous climate change?

Climate scientists..have analysed in detail what the climatic impacts are likely to be for a whole range of greenhouse gas emissions scenarios..The science is not new; we are just living at a time when people have become aware of the findings because the predictions are urgent and dire.

At the high end is the "business as usual" case...we do nothing, and the planet is set on an unknown path toward unprecedented warming.

At the low end is what I'd call "The European scenario". Governments agree on drastic emissions reductions, the business sector invests heavily in a carbon-reduced economy, new technologies are born, we stabilise greenhouse gases at around today's concentrations

Two things are painfully sobering about the above two scenarios.

The first is that even under the low-emissions scenario we are only minimising the risk of dangerous climate change...We have already made a commitment to changing our climate into the 21st century from our 20th century emissions.

The second and vastly more sobering fact, though, is that we are currently tracking above the IPCC 'worst-case' emissions scenarios. This was unthinkable 20 years ago.."We'll never go there, that'd be ridiculous."

Yet we are there, and we are there now. And the scientific community is deeply troubled...This is why 212 of the world's leading climate scientists yesterday warned the United Nations Climate Change Conference in Bali of the need to act immediately to cut greenhouse gas emissions. The "Bali Climate Declaration by Scientists" set a window of only 10-15 years for global emissions to peak and decline, with a goal of at least a 50% reduction by 2050.

This declaration was signed by an elite group of climate scientists: to those in the field it reads as a "who's who" of lab directors, academy fellows, IPCC lead authors, and prize winners. And unlike the average scientific document, it is short and sharp, with a very clear conclusion. And it comes hot on the heels of a major statement by the world's business community seeking certainty in emissions reductions, and importantly, that these be set by scientists.

The Bali Climate Declaration has made the scientific view on emissions targets patently clear. It is now over to the policy makers to give the planet a decent future.