The United Kingdom is at the forefront of tackling dangerous climate change, underpinned by world-class scientific expertise and advice.
Crucial decisions will be taken soon in Copenhagen about limiting and reducing the impacts of climate change.
Climate scientists from across the world are in overwhelming agreement about the evidence of climate change, driven by the human input of greenhouse gases into the atmosphere.
The 2007 assessment report of the United Nation’s climate change panel, the Intergovernmental Panel on Climate Change (IPCC) — made up of the world’s foremost climate scientists — provided evidence for a warming climate, and a high degree of certainty that human activities are largely responsible for global warming since the middle of the 20th century.
But the IPCC process is based only on information already published and even since the last assessment report the scientific evidence for dangerous, long-term and potentially irreversible climate change has strengthened significantly:
- Global carbon dioxide concentrations continue to rise, and methane concentrations have started to increase again after a decade of near stability;
- The decade 2000-2009 has been warmer, on average, than any other decade in the previous 150 years;
- Observed changes in precipitation (decreases in the subtropics and increases in high latitudes) have been at the upper limit of model projections;
- Arctic summer sea ice cover declined suddenly in 2007 and 2008, prompting the realisation that this environment may be far more vulnerable to change than previously thought; and
- There is increasing evidence of continued and accelerating sea-level rises around the world.
We expect some of the most significant impacts of climate change to occur when natural variability is exacerbated by long-term global warming, so that even small changes in global temperatures can produce damaging local and regional effects.
Year on year the evidence is growing that damaging climate and weather events — potentially intensified by global warming — are already happening and beginning to affect society and ecosystems. This includes:
- In the UK, heavier daily rainfall leading to local flooding such as in the summer of 2007;
- Increased risk of summer heat waves such as the summers of 2003 across the UK and Europe;
- Around the world, increasing incidence of extreme weather events with unprecedented levels of damage to society and infrastructure. This year’s unusually destructive typhoon season in South-East Asia, while not easy to attribute directly to climate change, illustrates the vulnerabilities to such events;
- Sea level rises leading to dangerous exposure of populations in, for example, Bangladesh, the Maldives and other island states; and
- Persistent droughts, leading to pressures on water and food resources, and the increasing incidence of forest fires in regions where future projections indicate long-term reductions in rainfall, such as south-west Australia and the Mediterranean.
These emerging signals are consistent with what we expect from our projections, giving us confidence in the science and models that underpin them.
In the absence of action to mitigate climate change, we can expect much larger changes in the coming decades than have been seen so far.
Some countries and regions are already vulnerable to climate variability and change, but in the coming decades all countries will be affected, regardless of their affluence or individual emissions.
Climate change will have major consequences for food production, water availability, ecosystems and human health, migration pressures and regional instability.
The accumulation of carbon dioxide in the atmosphere will lead to long-term changes in the climate system that will persist for millennia.
Reducing emissions of greenhouse gases can substantially limit the extent and severity of long-term climate change.
This is an edited joint statement by Professor Julia Slingo, chief scientist at the UK’s Met Office, Professor Alan Thorpe, chief executive of the Natural Environment Research Council and Lord Rees, president of the Royal Society on the state of the science of climate change ahead of the Copenhagen climate conference