Tag Archives: AR5

IPCC Hones Its Language on Climate Change

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The Athabasca Glacier, a part of the Columbia Icefields in Alberta, Canada, is receding on an average of 16 feet per year.

The Athabasca Glacier, a part of the Columbia Icefields in the Rocky Mountains of Alberta, Canada, has receded 0.93 miles (1.5 km) over the last 125 years.

Yesterday the Intergovernmental Panel on Climate Change (IPCC) released its latest Synthesis Report (SYR5) – a summary of the IPCC’s Fifth Assessment Report (AR5) on the state of knowledge on climate change. The big news with the SYR5’s release is the change in language used within the report – words like “unequivocable” and “clear” now replace the earlier usage of “probable” and “likely” when describing global warming and the role that human activity has played in the temperature increase. Text from the SYR5 underscores this major language shift:

 “Warming of the climate system is unequivocal, and since the 1950s, many of the observed changes are unprecedented over decades to millennia. The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen.”

…and

“Human influence on the climate system is clear, and recent anthropogenic emissions of greenhouse gases are the highest in history.”

The SYR5 summarizes IPCC’s three other major reports on various facets of climate change that were released in 2013-2014. These reports are all available from the IPCC website:

  • Climate Change 2013 – The Physical Science Basis;
  • Climate Change 2014 – Impacts, Adaptations, and Vulnerability; and
  • Climate Change 2014 – Mitigation of Climate Change.

The Carbon Brief 11/2/2014 blog gives a listing and good, brief descriptions of what else is noteworthy in the SYR5. Here’s a quick recap on their list:

  • Global warming continues unabated
  • Human influence on warming is clear
  • Ocean acidification, sea level rise, glacial ice decline
  • IPCC’s new carbon budget
  • Consequences of inaction – climate change impacts
  • Low carbon transition – costs and savngs

Human Influence On The Climate System Is Unmistakable

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The Intergovernmental Panel on Climate Change‘s (IPCC) much awaited report, the Fifth Assessment Report (AR5), concludes that scientists are 95% certain that humans are the “dominant cause” of global warming since the 1950s. A policy makers’ summary for AR5, IPCC’s latest report on physical evidence for climate change, was released today. The full report will be released on September 30th.

As noted in IPCC’s 9.27.2013 press release on the AR5:

Human influence on the climate system is clear. This is evident in most regions of the globe, a new assessment by the Intergovernmental Panel on Climate Change (IPCC) concludes.

 

It is extremely likely that human influence has been the dominant cause of the observed warming

since the mid-20th century. The evidence for this has grown, thanks to more and better observations, an improved understanding of the climate system response and improved climate models.

 

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. Each of  the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850, reports the Summary for Policymakers of the IPCC Working Group I

assessment report, Climate Change 2013: the Physical Science Basis, approved on Friday by member governments of the IPCC in Stockholm, Sweden.

 

“Observations of changes in the climate system are based on multiple lines of independent evidence. Our assessment of the science finds that the atmosphere and ocean have warmed, the amount of snow and ice has diminished, the global mean sea level has risen and the concentrations of greenhouse gases have increased,” said Qin Dahe, Co-Chair of IPCC Working Group I.

Thomas Stocker, the other Co-Chair of Working Group I said: “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,” said Co-Chair Thomas Stocker. “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,” he added.

 

Projections of climate change are based on a new set of four scenarios of future greenhouse gas concentrations and aerosols, spanning a wide range of possible futures. The Working Group I report assessed global and regional-scale climate change for the early, mid-, and later 21st century.

 

 

“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,” said Co-Chair Qin Dahe. The report finds with high confidence that 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.