At the end of his Presidency, Lord May reflects on the most urgent challenges

During my five years as President of the Royal Society I have had the opportunity to become involved in many important scientific issues.

I think none is so critical as climate change and the loss of our planet’s biodiversity. And while scientists can sound the alarm about these crises, achieving action relies on policy makers and politicians understanding and heeding the warnings.

So, how do we take a complex issue like the science of climate change and explain it in a way that is useful for policy making?

Incorporating dissent

A unique model is the Intergovernmental Panel on Climate Change (IPCC) – the world’s leading authority on climate change and its impacts. Its first assessment report served as the basis for negotiating the United Nations Framework Convention on Climate Change (UNFCCC) and ultimately the Kyoto Protocol.

The Panel’s role is to assess on a comprehensive, objective, open and transparent basis the best available scientific, technical and socio-economic information on climate change from around the world. IPCC reports seek to ensure a balanced reporting of existing viewpoints, which means incorporating the views of scientists that may differ significantly from the majority.

In this way the IPCC is able to build a consensus view of the current state of the weight of opinion on climate change, which is why its work is strongly supported by the Royal Society and other national science academies. However, the scientific consensus is sometimes misunderstood to mean that scientists have some kind of compromise position which, in effect, silences all dissenting voices. But in fact dissenting voices are incorporated into the IPCC’s reports by explicitly expressing the degree and nature of uncertainty involved in specific aspects of the scientific understanding.

Open to questioning

In the early stages of studying a new phenomenon, many ideas usually contend, each attracting supporters who form a kind of many-hills landscape of opinion.  As observation and information accumulates, some ideas fail experimental tests, and the landscape simplifies.  Eventually, as in the understanding that HIV causes AIDS or that smoking is a major cause of lung cancer – one peak dominates the scientific landscape.  Even so, some adherents of earlier ideas cling doggedly to their original views: you can still assemble a handful of ‘deniers’ who assert that HIV does not cause AIDS, that smoking does not cause lung cancer, or that climate change is not human associated.

All this being said, it is hugely important that scientists do not convey a false sense of certainty, for example by attributing extreme weather events entirely to climate change (even though such change may play a significant part in changing the likelihood or severity of such an event).  Above all, science should always be open to honest questioning.

However, because of this process of building knowledge, let us be clear that the science of climate change is now certain enough for us all to demand that our leaders take prompt action to cut emissions of greenhouse gases.

Off targets on biodiversity

In contrast to climate change, the loss of biodiversity on our planet is an issue where there is less controversy about the nature of the problem (although here too, there is a denial lobby, involving many of the same characters who deny the reality of climate change).  Even here, however, this has not generated the kind of action that we would hope for.

The living world is disappearing before our eyes. According to the Millennium Ecosystem Assessment, published earlier this year, approximately 60 percent of the ecosystem services that support life on Earth – such as fresh water, exploited fisheries, air and water cleansing and regulation, and the regulation of pests, climate, and natural hazards – are being degraded or used unsustainably.

One of the targets that came out of the World Summit on Sustainable Development in Johannesburg in 2002 was to achieve ‘a significant reduction in the current rate of biodiversity loss by 2010’. The EU has set the challenging target of halting biodiversity loss by 2010. Despite the scientists’ warnings it’s not clear what progress, if any, we are making towards the targets – and not just because, as the Royal Society warned in its report in 2003, no appropriate measures of progress have yet been agreed.

The big events which caused previous waves of extinctions demonstrate the long-term resilience of life on Earth. However while advances in science and technology may allow humans to survive in a Bladerunner-esque kind of world with depleted natural resources and an uncertain climate, we must ask ourselves if this is the kind of world that we want our children to live in.

Lord May is the former President of the Royal Society