With the upcoming UN General Assembly in New York and the G20 Heads of State meeting in Pittsburgh, climate change is becoming an increasingly pressing issue in the lead up to the UN Climate summit in Copenhagen. As part of a group of forty of the world’s leading climate scientists (including the Australians Professor Lesley Hughes, Professor Anthony J McMichael, Dr Barrie Pittock), we have signed an open letter calling for industrialised countries to make a commitment to cut carbon emissions by at least 40 per cent below 1990 levels by 2020:

Copenhagen climate targets must be more ambitious

At the UN Climate Conference in Copenhagen this December, world leaders have the opportunity to agree a historic global climate deal. To avoid dangerous climate change, the deal must be based on the most up-to-date scientific understanding of the emissions reductions required, with obligations divided equitably between developed and developing countries. This means that developed countries must reduce greenhouse gas emissions by at least 40 per cent below 1990 levels by 2020.

Copenhagen represents our best chance to avert the worst impacts of climate change on people, species and ecosystems. More than 120 countries, including the members of the G8, the EU, and key emerging economies such as China, South Africa and Mexico, agree that the rise in global temperature must stay well below 2°C. Beyond this point climate impacts will be more severe, with the risk of crossing ‘tipping points’ with dangerous and irreversible effects.

To stand a good chance of achieving this goal, the last Intergovernmental Panel on Climate Change report (2007) recommended that developed countries should reduce emissions by 25-40 per cent on 1990 levels by 2020. Yet more recent evidence shows that only reductions at the top end of this range will be sufficient to avoid the worst impacts of climate change.

Developed countries have so far committed to reduce greenhouse gas emissions by only 10-16 per cent by 2020, a level dangerously inconsistent with their commitment to the 2°C target. The latest scientific evidence clearly shows that these countries must increase their ambition and reduce emissions by 40 per cent by 2020 to maintain a credible ambition of avoiding dangerous climate change.

Signed in our personal capacity:

Dr Paulo Artaxo, Brazil
Lead author of IPCC 4th Assessment Report, Institute of Physics, University of Sao Paulo

Samar Attaher, Egypt
IPCC contributor and Climate Change Researcher, Ministry of Agriculture, Cairo

Prof Peter Barrett, New Zealand
Professor of Geology, Antarctic Research Centre, Victoria University

Dr Nancy Bertler, New Zealand
Leader of the New Zealand Ice Core Programme, Victoria University

Sophie des Clers, United Kingdom
IPCC corresponding author and Fisheries Geographer, University College London

Dr Valérie Masson-Delmotte, France
IPCC contributor, Paleoclimatologist and Head of Research at the “Laboratoire des sciences du climat et de l’environnement”

Prof John Harte, USA
Professor of Environmental Science, University of California

Prof Ove Hoegh-Guldberg, Australia
Director, Centre for Marine Studies, University of Queensland

Dr Lars R. Hole, Norway
Senior Scientist, Norwegian Meteorological Institute

Sir John Houghton, United Kingdom
Former Chair of Scientific Assessment, IPCC and Former Chief Executive, Met Office

Prof Lesley Hughes, Australia
IPCC Lead Author, Department of Biological Sciences, Macquarie University

Dr Saleemul Huq, United Kingdom
Lead Author, IPCC 3rd Assessment Report and Senior Fellow, Climate Change Group, International Institute for Environment and Development

Henry P. Huntington, USA
Lead Author, Arctic Climate Impacts Assessment

Prof Philippe Huybrechts, Belgium
IPCC contributor and Professor of Climatology and Glaciology, Vrije Universiteit Brussels

Jiang Kejun, China
Lead Author, IPCC Working Group III and Director of Energy System Analysis and Market Analysis Division at the Energy Research Institute of National Development and Reform Commission

Bernardus H.J. de Jong, Mexico
IPCC contributor, El Colegio de la Frontera Sur

Prof Rik Leemans, The Netherlands
Environmental Systems Analysis group, Wageningen University

Dr José Marengo, Brazil
IPCC Lead Author and Researcher at National Institute for Space Research

Prof Anthony J McMichael, Australia
Professor of Population Health, The Australian National University, and Honorary Professor of Climate Change and Human Health, University of Copenhagen

Dr Charles K. Minns, Canada
Adjunct Professor, Ecology and Evolutionary Biology, University of Toronto, and Scientist Emeritus, Fisheries and Oceans Canada

Prof Abhijit Mitra, India
Department of Marine Science, University of Calcutta

Dr Carlos Afonso Nobre, Brazil
IPCC Lead Author, Head of the Scientific Committee of the International Geosphere-Biosphere Program, Co-ordinator of the Centre for Earth System Science at the National Institute for Space Research and Executive Secretary of the Brazilian Network for Climate Change Research

Pan Jiahua, China
IPCC advisor to Working Group III and Executive Director of Research Centre for Sustainable Development at the Chinese Academy of Social Sciences

Dr Barrie Pittock, Australia
IPCC Lead Author and Honorary Fellow, CSIRO Australia

Dr Dave Reay, Scotland
IPCC contributor and Senior Lecturer in Carbon Management, Edinburgh University

Andy Reisinger, New Zealand
Coordinator of IPCC Synthesis Report and Senior Research Fellow, Climate Change Research Institute, Victoria University, Wellington

Dr Suzana Kahn Ribeiro, Brazil
Vice-Chair of IPCC Working Group III and Coordinating Lead Author of IPCC 4th Assessment Report

Dr Luis Pinguelli Rosa, Brazil
Head of Brazilian Forum on Climate Change and Director at Alberto Luiz Coimbra Institute for Post-Graduation and Research in Engineering, Federal University of Rio de Janeiro

Antonio Ruiz de Elvira, Spain
Professor, Applied Physics, Universidad de Alcala, European Climate Forum

Dr Jim Salinger, New Zealand
Lead Author for IPCC 3rd and 4th Assessment Reports, Honorary Associate Professor, School of Environment, University of Auckland and President of the World Meteorological Society’s Commission for Agricultural Meteorology

Dr Roberto Schaeffer, Brazil
IPCC Lead Author and Researcher at Federal University of Rio de Janeiro

Dr Michael Schirmer, Germany
Climate Change Impact Research, University of Bremen

Bernard Seguin, France
IPCC contributor, Institut National de Recherche agronomique

Dr Vijai Pratap Singh, India
Program Manager (Climate Change), Leadership for Environment and Development India (LEAD India), New Delhi

Prof Peter Smith, Scotland
IPCC Lead Author and Convening Lead Author, and Royal Society-Wolfson Professor of Soils & Global Change, University of Aberdeen

Dr Armi Susandi, Indonesia
Vice Chair, IPCC Working Group on Adaptation, National Council on Climate Change, Indonesia, and Head of Department of Meteorology, Bandung Institute of Technology

Wang Yi, China
Deputy Director of the Institute of Policy and Management, Chinese Academy of Sciences

Dr Wong Poh Poh, Singapore
Lead Author, IPCC 3rd Assessment Report, Coordinating Lead Author, IPCC 4th Assessment Report, National University of Singapore

Dr Richard W. N. Yeboah, Ghana
Department of Agricultural Economics and Extension, University for Development Studies

Zhou Dadi, China
Senior Advisor and Researcher, Energy Research Institute of National Development and Reform Commission (NDRC)