Federico Mayor, president, Initiative for Science in Europe, former UNESCO director general and Dr Luc van Dyck, secretary, Initiative for Science in Europe

The challenges addressed by the Copenhagen Climate Summit affect the common destiny of mankind. Most of the diagnoses have been made and, in many cases, correct treatments are known. The answer is to translate scientific knowledge into action. So far, however, this has largely been deemed unfit for a market economy that regularly submits human rights to short-term approaches and financial interests. The major questions, therefore, are no longer 'what' and 'how', but the political will and the awareness and involvement of civil society, which too often remains too silent.

Sapere aude! Dare to know! is written in the Oxford County Wall Crest, but we must know how to dare, how to share, how to care. There is a crucial role for the scientific community: be close to – but never dependent on – policy-makers and civil society to provide science and technology assessment, to advise, to foresee and anticipate, to be watchtowers.

Now more than ever, it is urgent to present the world with affordable solutions. Moments of deep crisis also create opportunities. Scientists ought to become actively involved in a new farsighted vision of otherness and brotherhood taking into account the Earth as a whole. There are no frontiers anymore. And there should not be privileged citizens when a lot of citizens live in difficult, sometimes inhuman, conditions.

The United Nations organisations and programmes were wisely created to promote development worldwide. But before long, aids were substituted by loans, and the values and democratic principles of the UN ("We, the peoples...") by those of a plutocracy (G-7, G8: "We, the powerful..."). International cooperation resulted in exploitation. This collective shame is still a reality, as shown by many abuses of the natural resources of the South. Reinforcing the UN System would undoubtedly provide better governance to prevent supranational traffics, deal with environmental crimes or coordinate the fight against natural and man-made hazards.

Ecological consciousness is on the rise: global warming is a major public concern. The reaction must not be fear but resolution for action, utilising all new scientific developments. What is needed is a radical change. At present, whilst more than 60,000 human beings die of hunger daily, $3bn are spent per day on armaments. Extreme poverty and exclusion lead to desperate migration fluxes and, eventually, to violence. Civil society, with the leadership of the scientific community, must decide to end this immense tragedy. For the first time in history, it has the possibility, using remote participation tools such as the internet, of firmly requesting their democratic representatives to adopt measures for the transition to a social economy, bridging divides and spreading the benefits of a global sustainable development.

The scientific community can help mobilise citizens with attractive and comprehensive explanations of the real challenges faced by humankind. Huge investments are needed in renewable energies to reduce carbon dioxide emissions and save oil, a natural and finite 'jewel' on which organic chemistry is based – for food production; to ensure availability of and access to drinkable water for all; for health, with increased efforts in fields such as infectious diseases or neurological disorders associated with longevity; for environmentally-friendly transport systems, etc.

Rising sea levels, melting poles... News must reach society accompanied by possible solutions. The scientific community ought to help bridge the gap between science 'and' society, develop science 'in' society, and provide science 'for' society.

Science can be wisely utilised by post-crisis governments to mitigate or prevent effects, potentially irreversible, of climate change and ecological deterioration. Now it is time for action. That is precisely the outcome and legacy that the succeeding generations deserve.