Conference bolsters call for a zero-carbon world with data on global warming

16 November 2015

The imperative of transforming to a zero-carbon world was the motivation for a conference supported by 24 learned societies, including the Institute of Physics, that was held ahead of the international climate change summit, which starts in Paris on 30 November.

Global warming

Evidence for human-induced climate change and the risks that it poses were presented at the meeting for academics, members of the public and others on 5 November. The aim was to substantiate a joint communiqué on climate change that was issued by the 24 bodies in July, and to discuss possible responses to global warming.

The opening sentence of the communiqué says there is overwhelming evidence that the climate is warming and that “human activity is largely responsible for this change through the emission of greenhouse gases”. Speaking at the meeting, Dr Peter Stott, of the Met Office Hadley Centre, said: “Science has certainly not contradicted this – if anything the evidence is even more robust.” Concentrations of CO2 in the atmosphere had now risen to about 400 parts per million (ppm), compared to pre-industrial levels of about 278 ppm, he said, and average global temperatures had risen by about 0.6–0.7 °C in the period from 1951 to 2010 alone.

The greenhouse effect was “textbook physics” Stott said, and though air pollution had had some cooling effect, the climate system had continued to accumulate energy during the past 15 years, with much of it going into the oceans. Sea-level rise would continue for some time to come as the effect on the oceans operated over a very long timescale, he said, and Arctic sea ice was “in peril”.

Professor Corinne Le Quere, of the University of East Anglia, said that a “business-as-usual” scenario without interventions to limit carbon emissions could result in global average temperatures rising by 3.2 °C to 5.4 °C. Such rises had not been experienced in the last 56m years and would not be expected this century, but the biggest uncertainty was in how countries would respond to the challenge, she said.

The Intergovernmental Panel on Climate Change says that in order to avoid serious consequences, global warming must be limited to 2 °C or less by the end of the century, and this is the current focus of global action. Current policies and pledges by individual countries (Intended Nationally Determined Contributions) take us half-way between 2 °C and 3.2–4 °C, Le Quere said.

Dr Nathalie Pettorelli, of the Zoological Society of London, said climate change was one of a suite of factors affecting biodiversity. Changing precipitation and temperature patterns can affect the amount of land available to different species and disrupt their seasonal behaviour, she warned. Extreme weather events, which are associated with global warming, can have catastrophic effects, with some species losing up to 90% of their number, she said.

Professor Neil Adger, of the University of Exeter, said the social impacts on human communities and individuals had also been studied. Groups having to relocate because of flooding or loss of habitable land, for example, could experience insecurity and loss of cultural identity or family relationships, with people’s lives being affected 20 to 30 years into the future.

Professor Andy Haines, of the London School of Hygiene and Tropical Medicine, said climate change could have direct impacts on health. The 2003 heatwave had led to around 70,000 extra deaths in Europe, for example, and changes to the ecosystem could aggravate the incidence of vector-borne diseases such as malaria, he said. Droughts and crop failure could contribute to ill-health, but there were other factors that were not always taken into account when measuring poverty due to climate change, such as the reduced ability to work during the hottest months of the year in some parts of the world.

Several speakers discussed ways to achieve zero net carbon emissions or mitigate climate change. These included fuel efficiency, carbon capture and storage, better building design and governmental action such as carbon pricing, support for low carbon electricity and removing barriers to energy efficiency.

Malcolm Wilkinson, from the Institution of Chemical Engineers, was adamant that the technologies to decarbonise our infrastructure were available now, but the real question was whether we had the time to mobilise and use them before the effects of climate change became more serious.

In a panel discussion, participants said geoengineering was not really a solution and could have negative unintended consequences. The consensus of the panel, in response to a question from the audience, was that rising consumption rather than rising population was the essential issue.

The summit in Paris from 30 November to 11 December is the 21st Conference of the Parties to the United Nations Framework Convention on Climate Change (COP21). How far COP21 would lead to lasting solutions was an open question, the panel thought.