A global assessment of data since 1970 shows it is likely that anthropogenic warming has had a discernible influence on many physical and biological systems with observational evidence from all continents and most oceans showing temperature rises.

Much more evidence has accumulated over the past five years to indicate that changes in many physical and biological systems are linked to anthropogenic warming, the IPCC says, adding that billions of people could face shortages of food and water and increased risk of flooding as a result. The IPCC report says that by 2020, for example, up to 250M Africans will face drought. Drought-affected areas are also likely to increase in extent, while heavy precipitation events are very likely to increase in frequency and will augment flood risk.

Perhaps most alarmingly, the report concludes that the resilience of many ecosystems to climate change is likely to be exceeded this century while over the course of this century net carbon uptake by terrestrial ecosystems is likely to peak before mid-century and then weaken or even reverse.

Nearly all regions, European, African, Asian and American, are anticipated to be negatively affected by some future impacts of climate change and these will pose challenges to many economic sectors, the IPCC says, concluding that adaptation will be necessary to address impacts resulting from the warming which is already unavoidable due to past emissions. However, adaptation alone is not expected to cope with all the projected effects of climate change, and especially not over the long-term as most impacts increase in magnitude, says the report.

Commenting on the report Germany’s Chancellor Angela Merkel noted that it confirms the reality of climate change, saying: ‘We need to act rapidly and with determination to reduce carbon dioxide emissions and limit global warming.’ Merkel added that she will be addressing the issue at the G8 summit in Heiligendamm in June with the objective of getting as many nations as possible to assume responsibility for climate protection.

UK environment and climate change minister Ian Pearson said: ‘This report provides further evidence of why all countries need to work urgently to agree a global deal to combat climate change. People are already being affected, and if we don’t act now millions more will suffer.’

More information is available on the IPCC website: http://www.ipcc.ch.