The International Science Congress just released a state of the science in preparation for upcoming climate summit in Copenhagen in December, 2009. The scientists summarized six steps for policy makers. See Step 4, though they are all important. (See full article from The Guardian here.)

1) Climatic trends

Recent observations confirm that, given high rates of observed emissions, the worst-case IPCC scenario projections (or even worse) are being realised…. 

2) Social disruption

The research community is providing much more information to support discussions on “dangerous climate change”. Recent observations show that societies are highly vulnerable to even modest levels of climate change, with poor nations and communities particularly at risk. Temperature rises above 2C will be very difficult for countries to cope with,…. 

3) Long-term strategy

Rapid, sustained, and effective mitigation based on coordinated global and regional action is required to avoid “dangerous climate change” regardless of how it is defined. Weaker targets for 2020 increase the risk of crossing tipping points and make the task of meeting 2050 targets more difficult. Delay in initiating effective mitigation actions increases significantly the long-term social and economic costs of both adaptation and mitigation.

4) Equity dimensions

Climate change is having, and will have, strongly differential effects on people within and between countries and regions, on this generation and future generations, and on human societies and the natural world. An effective, well-funded adaptation safety net is required for those people least capable of coping with climate change impacts, and a common but differentiated mitigation strategy is needed to protect the poor and most vulnerable.

5) Inaction is inexcusable

There is no excuse for inaction. We already have many tools and approaches – economic, technological, behavioural, management – to deal effectively with the climate change challenge…. 

6) Meeting the challenge

To achieve the societal transformation required to meet the climate change challenge, we must overcome a number of significant constraints and seize critical opportunities. These include reducing inertia in social and economic systems; building on a growing public desire for governments to act on climate change; removing implicit and explicit subsidies; reducing the influence of vested interests that increase emissions and reduce resilience….