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Researchers Warn That 2C Temperature Rise Cap Is At Risk If CO2 Emissions Are Not Curbed...

 

Carbon dioxide emissions continue to track the high end of emission scenarios, eroding the chances to keep global warming below 2°C, according to the Centre for International Climate and Environmental Research (CICERO). The warning was issued as world leaders gathered for the United Nations climate summit on 23 September. Global carbon dioxide emissions from fossil fuel combustion and cement production grew 2.3 per cent to a record high of 36.1 billion tonnes of CO2 in 2013. In 2014 emissions are set to increase a further 2.5 per cent, 65 per cent above the level of 1990. CICERO said that in its annual analysis of trends in global carbon dioxide emissions, the Global Carbon Project (GCP) published three peer-reviewed articles identifying the challenges for society to keep global average warming less than 2°C above pre-industrial levels. The top-four emitters of CO2 have a critical role in global emissions growth: Chinese emissions grew at 4.2 per cent, due to slower economic growth and faster improvements in carbon intensity of the economy compared to the previous decade; US emissions increased 2.9 per cent, due to a rebound in coal consumption potentially reversing the downward trend since the start of the shale-gas boom in 2007; Indian emissions grew at 5.1 per cent, due to robust economic growth and a continued increase in the carbon intensity of the economy; EU28 emissions decreased 1.8 per cent, due to a weak economy and emission decreases in some countries offsetting a return to coal led by Poland, Germany and Finland. Graphic courtesy: the Intergovernmental Panel on Climate Change (from the AR5 report). Story here.

 

 

...As "Climate Dynamics" Paper Becomes Latest To Give Low End Estimation Of CO2 Sensitivity...

 

Research published in the journal Climate Dynamics on 25 September 2014 was the 14th paper to conclude that the warming effect of CO2 is at the lower end of the range that has been assumed, according to the Cato Institute, a right wing climate sceptic US think tank. The new paper by independent UK-based climate researcher Nicholas Lewis and professor Judith Curry of the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology, derives estimates of the warming effect of CO2 – climate sensitivity - using observational data. This raises the possibility that projections made by the Intergovernmental Panel on Climate Change (IPCC) in its most recent scientific report (known as AR5) for future temperature trends may be too high because they rely on over-estimates of the Earth's climate sensitivity. The graphic illustrates carbon sensitivities estimated in the various papers. It shows climate sensitivity estimates from new research beginning in 2011 (colored), compared with the assessed range given in the IPCC Fifth Assessment Report (AR5) and the collection of climate models used in the IPCC AR5. The “likely” (greater than a 66% likelihood of occurrence)range in the IPCC Assessment is indicated by the gray bar. The arrows indicate the 5 to 95 percent confidence bounds for each estimate along with the best estimate (median of each probability density function; or the mean of multiple estimates; colored vertical line). Ring et al. (2012) present four estimates of the climate sensitivity and the red box encompasses those estimates. The right-hand side of the IPCC AR5 range is actually the 90% upper bound (the IPCC does not actually state the value for the upper 95 percent confidence bound of their estimate). Spencer and Braswell (2013) produce a single ECS value best-matched to ocean heat content observations and internal radiative forcing. Courtesy: Cato Institute. See our report on the new Climate Dynamics paper here and our report on the Cato assessment including a full listing of abstracts, and links to, all the papers here.

 

 

...While Antarctic Sea Ice Extent Sets New Record Smashing Through 20 Million Square Kilometers...

 

Antarctic sea ice extent has smashed through the 20 million square kilometer level to set a new record for the period since satellite observations started back in 1978. Satellite measurements indicate that Antarctic sea ice extent – the extent of ocean that is covered by sea ice over at least 15 per cent of its area peaked at 20.14 million square kilometers on 20 September. This is 1.57 million square kilometers above the long term average over the period from 1981 to 2010 and 530,000 square kilometers above the last record high which was set last year - on 1 October 2013. The causes of this significant and continuing growth in the extent of Antarctic sea ice remains a mystery  - as the Intergovernmental Panel on Climate Change (IPCC) implicitly acknowledged in itsAR5 report last year although there have been a number of possible explanations discussed in the scientific literature. Image shows Antarctic sea ice extent and concentration on 27 September 2014 and is courtesy of the University of Bremen. See our report including brief summaries of the research papers detailing various possible explanations here.

 

 

...But Recent Data Is Not Sufficient To Substantiate Suggestions Of A Recovery In Arctic Sea Ice

 

Can we say Arctic sea ice has started to recover? Not on the basis of current data despite what recent press reports, particularly in Britain's Mail newspaper, may claim. To say that recent data, showing that this year's summer minimum in sea ice extent is above the record low of 2012, is consistent with a recovery in Arctic sea ice, is to miss the point that, given the variability in the record, the data is also consistent with a continued decline. It is true that the summer minimum sea ice extent this year was above the record low of 2012 for the second year in a row and above the previous record minimum low set in 2007. It is also true that the overall trend in Arctic sea ice extent since 2007 is slightly upwards as the blue and red lines on the graphic above show. True too that Arctic sea ice thickness has been increasing leading to an accumulation of multiyear ice, according to data from the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) at the Polar Science Center which shows that sea ice volumes have recovered sharply from their 2012 low and are now just below 2009 levels. However, the latest data is not sufficient to make any reliable claims regarding the long-term recovery in Arctic sea ice. Sea ice extent in 2014 was the sixth lowest on record, according to data from the US National Snow and Ice Data Center (NSIDC). The data in the table on the right in the above image is from NSIDC and from the Japan Aerospace Exploration Agency (JAXA). It lists the summer minimum Arctic sea ice extent in millions of square kilometers for each of the last eight years between 2007 and 2014 for both data sets. The graphic on the left is the plot of this data. The NSIDC data is presented in blue and JAXA in red. The blue line is the linear regression trend line for NSIDC and the red is the trend for JAXA. Both show a very slight upward gradient; but huge variability in the data results in a very low coefficient of determination (or r - which is a technical measure of the reliability of a trend). The green horizontal line is the average sea ice extent for the period 1981 to 2010 while the yellow horizontal line is the average from 1979 to 2000. To put the recent data into context it is worth looking at the graphic below. This is the NSIDC plot of September sea ice anomaly (the variance with the long term average) for the period from 1979 to 2013 – the long term trend is clear. It would require several more years data showing flat or recovering sea ice extent to make any claims for a pause or for a recovery in Arctic sea ice decline that could be substantiated on the basis of observational data. See our report on NSIDC's sea ice extent analysis here.