Communist Party of Australia

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Issue #1614      October 16, 2013

Climate change red alert

The Intergovernmental Panel on Climate Change’s (IPCC) Fifth Assessment Report (AR5), Climate Change 2013: The Physical Science Basis, leaves no doubts as to the impact that human activity is having on the climate and the rapidity of that change.

The IPCC is an intergovernmental body with 194 member countries, sponsored by United Nations Environment Program and World Meteorological Organisation. The report is the product of 209 Lead Authors and 50 Review Editors from 39 countries and more than 600 Contributing Authors from 32 countries.

The IPCC was established in 1988, and from time to time publishes reports on topics relevant to the implementation of the United Nations Framework Convention on Climate Change (UNFCCC). Since then there have been four Assessment Reports, the last one in 2007.

The function of the IPCC is to assess on a comprehensive, objective, open and transparent basis the scientific, technical and socio-economic information relevant to understanding the scientific basis of risk of human-induced climate change, its potential impacts and options for adaptation and mitigation.

The full report, some 2,500 pages of text, draws on millions of observations and over two 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.

The authors have gone to great lengths to be as objective and accurate as possible in estimating possible scenarios based on the outcome of different levels of greenhouse gas emissions. In addition it has been subjected to extensive reviews by experts and member governments.

The report draws the conclusion that it is extremely likely (95 percent) that human influence has been the dominant cause of the observed warming since the mid-20th century.

“Warming in the climate system is unequivocal and since 1950 many changes have been observed throughout the climate system that are unprecedented over decades to millennia,” the report states in its 36-page Summary for Policymakers. (www.climatechange2013.org)

The report’s findings are alarming and require urgent action on the part of all nations. They include the following:

Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850 …

The atmospheric concentrations of carbon dioxide (CO2), methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years. CO2 concentrations have increased by 40 percent since pre-industrial times, primarily from fossil fuel emissions and secondarily from net land use change emissions. The ocean has absorbed about 30 percent of the emitted anthropogenic carbon dioxide, causing ocean acidification.

Human influence has been detected in warming of the atmosphere and the ocean, in changes in the global water cycle, in reductions in snow and ice, in global mean sea level rise, and in changes in some climate extremes. This evidence for human influence has grown since the fourth Assessment Report in 2007. It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.

Continued emissions of greenhouse gases 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.

Global surface temperature change for the end of the 21st century is projected to be likely to exceed 1.5°C relative to 1850 to 1900 in all but the lowest scenario considered, and likely to exceed 2°C for the two high scenarios.

Cumulative emissions of CO2 largely determine global mean surface warming by the late 21st century and beyond. Most aspects of climate change will persist for many centuries even if emissions of CO2 are stopped. This represents a substantial multi-century climate change commitment created by past, present and future emissions of CO2.

Heat waves are very likely to occur more frequently and last longer. As the Earth warms, we expect to see currently wet regions receiving more rainfall, and dry regions receiving less, although there will be exceptions.

It is very likely that the Arctic Sea ice cover will continue to shrink and thin and that Northern Hemisphere spring snow cover will decrease during the 21st century as global mean surface temperature rises. Global glacier volume will further decrease.

As the ocean warms, and glaciers and ice sheets reduce, global mean sea level will continue to rise, but at a faster rate than we have experienced over the past 40 years.

The report finds with high confidence that ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90 percent of the energy accumulated between 1971 and 2010.

Climate Change 2013: The Physical Science Basis, is part one of the full Fifth Assessment Report. Part two is being prepared by Working Group II (WGII) on impacts, adaptation and vulnerability and will be considered by the IPCC in Yokohama, Japan, on March 25-29, 2014. The third part, from Working Group III (WGIII), on mitigation of climate change, will go before the IPCC in Berlin, Germany, on April 7-11, 2014.

Next article – RMIT staff to strike for a new Enterprise Agreement

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