Global climate change

Latest Climate Report from the IPCC

11/04/2014, 9:52:20 AM

The Intergovernmental Panel on on Climate Change (IPCC) this past weekend released the Synthesis Report from the Fifth Assessment.

***A level of confidence is expressed using five qualifiers: very low, low, medium, high, and very high, and typeset in italics, e.g., medium confidence. The following terms have been used to indicate the assessed likelihood of an outcome or a result: virtually certain 99–100% probability, very likely 90–100%, likely 66–100%, about as likely as not 33–66%, unlikely 0–33%, very unlikely 0–10%, exceptionally unlikely 0–1%. Additional terms (extremely likely: 95–100%, more likely than not >50–100%, more unlikely than likely 0–<50% and extremely unlikely 0–5%) may also be used when appropriate. (from the IPCC report)

Below are some of the key points from the latest report.....

--Warming of the climate system in unequivocal.

--Human influence on the climate system is clear.

--Many of the observed changes are unprecedented over decades to millennia.

--The 1983-2012 period was likely the warmest 30-year period of the last 1,400 years in the Northern Hemisphere.

--Anthropogenic greenhouse gas emissions are extremely likely to have been the dominant cause of the observed global warming since the middle of the 20th century.

Image below courtesy of the IPCC Synthesis report.

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--Anthropogenic greenhouse gas emissions are mainly driven by population size, economic activity, lifestyle, energy use, land-use patterns, technology and climate policy.

--Very likely that the # of cold days and nights has decreased and the # of warm days and nights has increased globally.

--A nearly ice-free Arctic Ocean during the summer sea-ice minimum in September before mid-century is likely.

--Globally averaged surface temperature exhibits substantial decadal and inter-annual variability. Due to this natural variability, trends based on short records are very sensitive to the beginning and end dates and do not in general reflect long-term climate trends.

--Surface temperatures are projected to rise over the 21st century under all assessed emission scenarios. Very likely that heat waves will occur more often and last longer. Precipitation events will become more intense and frequent in many regions.

--Many aspects of climate change and associated impacts will continue for centuries, even if anthropogenic emissions of greenhouse gases are stopped.

--Warming is projected to continue under all Representative Concentration Pathway (RCP) scenarios except one.

--Virtually certain that global mean sea-level rise will continue for many centuries beyond 2100 with amount of rise dependent on future emissions.

--Unrestricted use of fossil fuels should be phased out by 2100 if the world is to avoid dangerous climate change.

--Most of the world's electricity can and must be produced from low-carbon sources by 2050 or we face severe, pervasive and irreversible damage.

--Without additional mitigation efforts beyond those in place today and even with adaptation, warming by the end of the 21st century will lead to (high to very high) risk of severe, widespread and irreversible impacts globally (high confidence).

--Many adaptation and mitigation options can help address climate change, but no single option is sufficient by itself.

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2014 IPCC Synthesis Report (long version)

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Global climate change