IPCC Fifth Assessment Report holds no big surprise

The first part of the Fifth Assessment Report (AR5) of the Intergovernmental Panel on Climate Change (IPCC) is out. The report of the Working Group I looks at the physical science basis for climate change.  That is, it has examined the scientific evidence to infer why climate change is happening and what are the changes observed in the climatic systems. Though the detailed scientific report will be released on September 30, the summary report was released today in Stockholm, Sweden.

IPCC reviews and assesses the most recent information produced worldwide, relevant to the understanding of climate change. It does not conduct any research nor does it monitor climate-related data or parameters. For Working Group I report of AR5, contributions came from a total of 209 lead authors and 50 review editors from 39 countries and more than 600 contributing authors from 32 countries.

So what does report have to say about climate change?

Well there are not many surprises. What this report, however, has done is to tell in no uncertain terms, more than any report before, that climate change is happening because of mankind. "It is extremely likely (95 per cent confidence) that human influence on climate caused more than half of the observed increase in global average surface temperature from 1951−2010," says the report. The 2007 report of IPCC had put the confidence level at 90 per cent.

The report has also reiterated the urgency of climate change. It states: “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, sea level has risen, and the concentrations of greenhouse gases have increased.”

The report has concluded:

• Each of the past three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850.
• Over the last two decades, the Greenland and Antarctic ice sheets have been losing mass, glaciers have continued to shrink almost worldwide, and Arctic sea ice and Northern Hemisphere spring snow cover have continued to decrease in extent.
• The rate of sea level rise since the mid-19th century has been larger than the mean rate during the previous two millennia. Over the period 1901–2010, global mean sea level rose by 0.19 m
• The atmospheric concentrations of carbon dioxide (CO2), methane, and nitrous oxide have increased to levels unprecedented in at least the last 800,000 years. CO2 concentrations have increased by 40 per cent since pre-industrial times, primarily from fossil fuel emissions and secondarily from net land use change emissions.
• 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.

Most of the issues that this report has said was known in the Fourth Assessment Report (AR4) which was released in 2007 and for which IPCC was awarded the Nobel Prize. In that sense, there are not many surprises. This report, like AR4, is asking for urgent action on reducing greenhouse gases. AR4 failed to convince the world for urgent action. We will have to wait and watch what AR5 is going to achieve.

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