Global climate change is accelerating beyond expectations and the human role is now firmly established, according to a some of the world's top climate scientists.
The Copenhagen Diagnosis has been prepared by 26 researchers from around the world, most of whom are authors of published Intergovernmental Panel on Climate Change (IPCC) reports. The UK authors include Prof Jane Francis and Dr Alan Haywood from the University of Leeds.
· Satellite and direct measurements now demonstrate that both the Greenland and Antarctic ice-sheets are losing mass at an increasing rate and that Arctic sea-ice has melted far beyond the expectations of climate models.
· Sea level rise has accelerated and may exceed one metre by 2100, with a rise of up to two metres considered an upper limit by this time. Both the recent sea level rise and the 2100 levels are much higher than previously projected by the IPCC. Beyond 2100, sea level rise of several metres must be expected over the next few centuries.
· The global rate of carbon dioxide emissions from fossil fuel burning accelerated from 1 per cent per year during the 1990s to 3.4 per cent during 2000-2008. Global CO2 emissions are now tracking near the highestscenario considered so far by the IPCC.
· Recent global temperatures demonstrate human-induced warming: Over the past 25 years temperatures have increased by 0.19°C per decade. Even over the past ten years, despite a temporary decrease in solar forcing, the trend continues to be one of warming.
Jane Francis, Professor of Paleoclimatology at the University of Leeds, said: "New ice-core records confirm the importance of greenhouse gasses for past temperatures on Earth, and show that CO2 levels are higher now than they have ever been during the last 800,000 years. The last time Earth experienced CO2 levels this high was millions of years ago."
The Copenhagen Diagnosis, which was a year in the making, documents the key findings in climate change science since the publication of the landmark IPCC Fourth Assessment Report in 2007.
The report concludes that global emissions must peak then decline rapidly within the next five to ten years for the world to have a reasonable chance of avoiding the very worst impacts of climate change.
To stabilise climate, global emissions of carbon dioxide and other long-lived greenhouse gases need to reach near-zero well within this century, the report states.
Dr Alan Haywood, Reader in Paleoclimatology, also at the University of Leeds said: "The reconstruction of past climate reveals that recent warming in the Arctic and in the Northern Hemisphere is highly inconsistent with natural climate variability over the last 2000 years."
Peter Cox, Professor of Climate System Dynamics at the University of Exeter, added: "Reducing tropical deforestation could prevent up to a fifth of human CO2 emissions, slowing climate change and helping to maintain some of the planet's most important hotspots of biodiversity."
Notes to Editors
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The report concludes that several important aspects of climate change are already taking place at levels beyond the expectations of only a few years ago.