The world is getting rapidly hotter, and human actions are the driving force behind global warming. This is the conclusion of a report by The Intergovernmental Panel on Climate Change (IPCC), released on February 2 in Paris. The fourth assessment of its kind by the IPCC, the study builds on past assessments and six years of research by 400 authors from 40 countries.
The report states in a straightforward manner that “global atmospheric concentrations of carbon dioxide, methane and nitrous oxide have increased markedly as a result of human activities since 1750 and now far exceed pre-industrial values.” The causes of the increase in carbon dioxide concentration is determined to be due to fossil use and land-use changes. Agriculture takes the blame for increases in nitrous oxide and methane.
In the last 10 years carbon dioxide, the main factor in global warming, has risen faster than any other time since atmospheric measurements began in the 1960s. Globally both land and sea temperatures are rising at an alarming rate. Because the atmosphere is warming, water vapor content has increased since the 1980s because warmer air can hold more vapor. Melting glaciers and polar ices have caused rising sea levels, and annual average Arctic sea ice has shrunk by 2.7 % per decade, increasing to 7.4% in the summer.
Consequences of global warming can be seen in changing weather patterns, with hotter temperatures becoming increasingly common across the planet. Increased precipitation has been noted in eastern parts of North and South America, northern Europe, and through northern and central parts of Asia. Mid-latitude westerly winds have also increased in strength since the 1960s. For the last 30 years, longer and more widespread droughts have been seen in many areas, especially in the tropics and subtropics. Tropical cyclones are also thought to have increased in intensity and number.
The confident tone of the report stems from several developments that improve the reliability of data. Analysis of multiple indicators, including tree rings and polar ices, improved computer models, and data from actual current climate change support the conclusions. And the future? All indicators point to global warming continuing, and human activity ranges from a likely contributor to “more likely than not.”
The Intergovernmental Panel on Climate Change (IPCC) has been established by the World Meteorological Organization (WMO) WMO and the United Nations Environment Program (UNEP) to assess scientific, technical and socioeconomic information relevant for the understanding of climate change, its potential impacts and options for adaptation and mitigation. The IPCC is open to all member nations of the United Nations and WMO.
Richard A. Kerr, “It’s Getting Hotter in Here … And It’s Your Fault.” ScienceNOW Daily Newshttp://sciencenow.sciencemag.org/cgi/content/full/2007/202/1
The IPCC Working Group, “Fourth Assessment Report Summary for Policymakers (SPM).” PCC / WMO-UNEP http://ipcc-wg1.ucar.edu/