Their message to politicians is that if a binding agreement is not reached at Copenhagen and emissions are not reduced immediately, then we should expect global warming that is beyond anything yet experienced by humanity.
It can be done.
Six months before the Oxford conference, government ministers showed that unprecedented global agreements are now achievable. The 20 wealthiest countries with the richest economies agreed to carry out an unprecedented and coordinated response to the global recession. They agreed to take "whatever action is necessary for a sustained effort to revive economic growth for however long it takes". It took one-and-a-half days to reach this global agreement.
This is the 15th consecutive year that the UN Framework Convention on Climate Change (UNFCCC) has held a meeting to discuss whether countries can all agree to do something about climate change. Discussions on what to do about climate change have yet to begin. Taking action is long overdue.
So why the 15 years of negotiations leading to Copenhagen when it took just a few days for the G20 to decide their rescue plan?
There is one overarching agreement that has to be made at Copenhagen now on behalf of future generations. The UN Intergovernmental Panel on Climate Change says that long-term emissions targets have to be agreed on that are at least 50-80% lower by 2050 compared to 1990 levels of carbon dioxide and its equivalent greenhouse gas pollution.
A 50% reduction is calculated to achieve a concentration of 500 parts-per-million of carbon dioxide equivalent in the atmosphere. This sets the likelihood of a 4 degree temperature rise at 11 percent, according to the model designed by the UK's Hadley Centre.
This 500 parts-per-million emissions target allows each person of the predicted nine billion people by 2050 to have personal carbon dioxide emissions of 2 tonnes per person.
10-12 tonnes is the current amount emitted by each person in rich industrialised countries, the amount doubles for people in the U.S. An 80% cut in emissions will be necessary to limit global atmospheric concentrations to 500 parts-per-million.
Ministers have to agree to action by setting a mandatory and legally-binding target. Secondly they need to figure out the amount of financial and technical assistance extended to developing countries so they can grow low instead of high-carbon economies.
Will such an agreement be reached in Copenhagen by more than 160 Ministers and Heads of State? If they want to avoid an irreversible shift in our climate, they will have to. Let's all hope that in the dark of the Copenhagen winter they will have not forgotten that they once summoned up the will to work together in the warmth of England's spring.