UN Report says Human Cause of Global Warming is Near Certainty


30 January 2014 – Geneva, Switzerland and New York, USA – According to the final version of a United Nations (UN) report released today, global warming is unequivocal, human influence has been the dominant cause since the mid-20th century, and atmospheric concentrations of greenhouse gases, already at levels not seen in at least 800,000 years, will persist for many centuries.

140130-pmwj19-climate-IMAGE“Continued emissions of greenhouse gases will cause further warming and changes in all components of the climate system,” according to the report, which finalizes a summary of findings by the UN-backed Intergovernmental Panel on Climate Change (IPCC) issued in September, outlining a litany of threats from the melting of the Greenland and Antarctic ice sheets to rising oceans to extreme weather events such as cyclones and heat waves.

“Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions,” it stresses, using the term “extremely likely” for human causality since the mid-20th century, meaning there is a 95 to 100 per cent probability that humankind, and not naturally occurring phenomena, are to blame, a 5 percent increase from the 90 to 100 per cent “very likely” probability of if the IPCC’s last report in 2007.

Even if emissions of global warming carbon dioxide (CO2) emissions are stopped, most aspects of climate change will persist for many centuries. “This represents a substantial multi-century climate change commitment created by past, present and future emissions of CO2,” the report warns.

“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,” it says. “This evidence for human influence has grown since AR4 (the last IPCC report). It is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century.”

The report says it is extremely likely that more than half the observed increase in global average surface temperature from 1951 to 2010 was caused by the increase in greenhouse gas caused by humans and other human causes. Some of the major warming emissions caused by humankind since the birth of the industrial era 250 years ago – CO2, methane (CH4), and nitrous oxide (N2O) – have all increased since 1750 due to human activity.

“Concentrations of CO2, CH4, and N2O now substantially exceed the highest concentrations recorded in ice cores during the past 800,000 years. The mean rates of increase in atmospheric concentrations over the past century are, with very high confidence, unprecedented in the last 22,000 years.”

It notes that each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850, changes in many extreme weather and climate events have been observed since about 1950, the frequency of heat waves has likely increased in large parts of Europe, Asia and Australia.

For more about this report and its conclusions, go to http://www.ipcc.ch/ or http://climatechange2013.org/.

The United Nations (UN) is an international organization established in 1945 to facilitate cooperation in international law, international security, economic development, social progress, human rights and world peace. Currently with 193 members states, the UN and its specialized agencies meet regularly throughout the year. The UN Headquarters is in New York City, with other main offices in Geneva, Nairobi, and Vienna. More information at http://www.un.org/en/

Source: United Nations