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On Friday 27 September 2013, the Intergovernmental Panel on Climate Change (IPCC) released the first part of its Fifth Assessment Report (AR5) on global climate change. The first part of AR5, the Working Group I contribution, was complied by a team of 259 lead authors and over 600 contributing authors from 39 countries. The report, published as Climate Change 2013: The Physical Science Basis, provides a comprehensive assessment of the most upto date evidence and science behind the physical science basis of global climate change. According to a press release by BirdLife International, calling for ambitious respone to climate change, the report "states with greater confidence and authority than ever that climate change is happening, and that human influence on climate is clear. The evidence is stronger, thanks to more and better observations, an improved understanding of the climate system’s response, and improved climate models".
As may be expected, the report has been met with mixed reactions. According to George Monbiot, Environmental Columnist for the Gaurdian newspaper (UK) "Already, a thousand blogs and columns insist the Intergovernmental Panel on Climate Change's new report is a rabid concoction of scare stories whose purpose is to destroy the global economy". But, the report is the concensus output of over 850 expert contributors, recieved input from more than 1000 expert reviewers and 1855 comments from 32 governments. As George Monbiot goes on to note in his article, it is "perhaps the biggest and most rigorous process of peer review conducted in any scientific field, at any point in human history" and "there are no radical departures in this report from the previous assessment, published in 2007". It is just that the evidence is now becoming overwhelming that warming and purterbation in the Earth’s climate system is unequivocal and the signature of human-driven change undeniable.
For global biodiversity, the predictions are dire. Global surface temperature change for the end of the 21st century is likely to exceed 1.5°C relative to 1850-1900 and unless emissions are cut radically there is little chance of staying below 2°C, the upper limit to prevent dangerous anthropogenic interference with the climate system agreed by the United Nations Environment Programme. Heat waves are very likely to occur more frequently and last longer. Wet regions of the earth will recieve more rain, dry regions less. As the ocean warms, and glaciers and ice sheets reduce, global mean sea level will continue to rise, at an ever faster rate.
In the marine environment, global climate change in likely to lead to changes in water temperatures, circulation, sratification, nutrient input, oxygen content and ocean acidification as the oceans absorb carbon dioxide. So far, CO2 concentrations have increased by 40% since pre-industrial times, primarily from fossil fuel emissions and the ocean has absorbed about 30% of the emitted anthropogenic carbon dioxide. These changes, because of physical intolerance in many species to new environmental conditions, will lead to altered species distributions, reduced structure and diversity in marine communities and changes in species interactions. Many of these impacts are already evident and are set to get worse. For penguins, which are already amongst the most threathened groups of birds in the world, climate change is a big concern. The International Union for the Conservation of Nature (IUCN) currently recognises 18 species of penguin and "climate change" or "ocean warming" are recognised as current or potential threats to 10 of them on the IUCN Red List.
To find out more about how you can help the call for action, check out the responses of global NGOs like WWF and BirdLife International. The summary (36 pages) of the IPCC AR5 Working Group I contribution can be read here and the full report will be released on Monday.