Recent IPCC report sites human influence cause of global warming
The Intergovernmental Panel on Climate Change (IPCC) made available today the final draft of the Fifth Assessment Report. The report resulted from a worldwide scientific collaboration between 39 countries, 259 authors and 54,677 comments.
Notable findings include:
- each of the last three decades was successively warmer at the Earth’s surface than any preceding decade since 1850;
- in the Northern Hemisphere, 1983—2012 was likely the warmest 30-year period of the last 1400 years;
- ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010;
- atmospheric concentrations of carbon dioxide (C02), methane and nitrous oxide increased to unprecedented levels, with C02 concentrations rising by 40% since pre-industrial times, primarily from fossil fuel emissions.
Scientists report human influence as the dominant cause of observed warming since the mid-20th century. Our subsequent and continued emissions of greenhouse gases will further warm and cause changes in all components of the climate system.
- continued warming of the global ocean, with heat penetrating from the surface to the deep ocean and affect ocean circulation;
- further decrease in global glacier volume ;
- 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;
- global mean sea level continue to rise and the rate of rising sea level will very likely exceed that observed during 1971–2010 due to increased ocean warming and increased loss of mass from glaciers and ice sheets;
- climate change will affect carbon cycle processes in a way that will exacerbate the increase of CO2 in the atmosphere (high confidence), while further uptake of carbon by the ocean will increase ocean acidification.
Scientists conclude that 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.