30/09/2013
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Climate change "even more certain"

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A map showing the tracks of all tropical cyclones (aka hurricanes) worldwide from 1985 to 2005. Image: Nilfanion (commons.wikimedia.org).
A map showing the tracks of all tropical cyclones (aka hurricanes) worldwide from 1985 to 2005. Image: Nilfanion (commons.wikimedia.org).
An evidence-based international report has stated it is confident that human-caused climate change is happening, and BirdLife has called for governments to take more action.

The United Nations-established Intergovernmental Panel on Climate Change (IPCC) predicts that global surface temperature is likely to exceed 1.5°C more at the end of the 21st century than it was between 1850 and 1900 in a report launched today. This will result in more frequent and prolonged heat waves, increased concentrations of water in the wet regions of the earth and less rainfall in the planet's dry regions. Parallel ocean warming and reduction in glaciers and ice sheets, will continue to raise global mean sea levels, but at an ever faster rate.

Human influence is detectable in all these changes, and CO2 concentrations have increased by 40 per cent since pre-industrial times, primarily from fossil fuel emissions and land use change. The ocean has absorbed about 30 per cent of the emitted carbon dioxide, increasing the acidity of the oceans. The panel warns that continued emissions of greenhouse gases like CO2 will cause further warming and changes in all components of the climate system. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.

The IPCC re-emphasised that the warming of earth’s climate system is unequivocal. Each of the last three decades has been successively warmer on average at the earth’s surface than any preceding decade since 1850. In the Northern Hemisphere, the period 1983 to 2012 was probably the warmest 30-year period of the last 1,400 years. As a result, the atmosphere and oceans have warmed, the area of land and sea covered by ice has diminished and sea level has risen.

Climate change poses new challenges for conservationists, birds and other wildlife and habitats,  biodiversity and climate being closely interlinked. Observed changes in climate have already badly affected biodiversity at species and ecosystem level. Plant and animal distribution ranges are shifting, often in a pole-ward and altitudinal direction, increasing the threat of extinction to species in places with geographic limits to such shifts.

Studies suggest that many more species will not be able to keep up with the rapid shifts in location of suitable climates. An increase in extreme weather events is already damaging coastal and island, with some bird species now even facing extinction because of an increase in the frequency and strength of hurricanes.

“Once again, we see a profound mismatch between the level of action demanded by our best scientific knowledge and the current level of ambition of the world’s governments to reduce greenhouse gas emissions”, said Melanie Heath, BirdLife International’s Head of Policy. "But as a result of our past, present and expected future emissions of CO2, the Earth is already committed to climate change, and the effects will persist for many centuries even if emissions of CO2 stop.

“In the face of this now inevitable change to the Earth’s climate, healthy, bio-diverse ecosystems have a vital role to play in maintaining and increasing the resilience and reducing the vulnerability of human communities,” Heath added. “That is why BirdLife is calling for the importance of healthy ecosystems to be effectively written into national, regional and international climate change and development policy.”

The IPPC Working Group's assessment comprises draws on millions of observations and over 2 million gigabytes of numerical data from climate model simulations. Over 9,200 scientific publications are cited, more than three quarters of which have been published since the last IPCC assessment in 2007. A total of 859 authors and editors from 39 countries contributed to the preparation of the report. More than one thousand expert reviewers worldwide contributed their expertise in preparation of this assessment.

In the report, the IPCC states with greater confidence and authority than ever that climate change is happening, and that the human influence on climate is clear. The evidence is stronger, thanks to improved and more numerous observations, an improved understanding of the climate system’s response and better climate models.
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