In the Thursday December 19, 2019 edition the Wiltshire and Gloucester Standard published this letter
Whilst this is a Letter from an individual and not officially an Editorial, several of our Cirencester Extinction Rebellion group read this and were very concerned with prominence of the piece, the tone of the material and the factual inaccuracies, and on behalf of all decent people seek the right to a robust reply.
This rebuttal is written by Vijay Shah is a chartered engineer and polar explorer.
He is a member of the Arctic Club and of the All Party Parliamentary Group for the Polar Regions.
This is the second part of the rebuttal with more details and scientific references.
The Part 1 can be found at https://xrcirencester.co.uk/2019/12/21/countering-mis-information-in-wilts-glos-standard-part-1/.
#1. Global average temperature has increased by more than one degree celsius since pre-industrial times
To set the scene, let’s look at how the planet has warmed. In the chart we see the global average temperature relative to the average of the period between 1961 and 1990.
The red line represents the average annual temperature trend through time, with upper and lower confidence intervals shown in light grey.
We see that over the last few decades, global temperatures have risen sharply — to approximately 0.7℃ higher than our 1961-1990 baseline. When extended back to 1850, we see that temperatures then were a further 0.4℃ colder than they were in our baseline. Overall, this would amount to an average temperature rise of 1.1℃.
Because there are small year-to-year fluctuations in temperature, the specific temperature increase depends on what year we assume to be ‘pre-industrial’ and the end year we’re measuring from. But overall, this temperature rise is in the range of 1 to 1.2℃.
In this chart you can also view these changes by hemisphere (North and South), as well as the tropics (defined as 30 degrees above and below the equator). This shows us that the temperature increase in the North Hemisphere is higher, at closer to 1.4℃ since 1850, and less in the Southern Hemisphere (closer to 0.8℃). Evidence suggests that this distribution is strongly related to ocean circulation patterns (notably the North Atlantic Oscillation) which has resulted in greater warming in the northern hemisphere.3
Ref. Delworth, T. L., Zeng, F., Vecchi, G. A., Yang, X., Zhang, L., & Zhang, R. (2016). The North Atlantic Oscillation as a driver of rapid climate change in the Northern Hemisphere. Nature Geoscience, 9(7), 509-512. Available online.
How much warming by 2100:
#2. ICE AGE
This time around, the myth appears to have been sparked by a Sky News interview with Northumbria University mathematics professor Valentina Zharkova. The story was quickly echoed by the Daily Mail, International Business Times, Sputnik News, Metro, Tru News, and others. Zharkova was also behind the ‘mini ice age’ stories in 2015, based on her research predicting that the sun will soon enter a quiet phase.
The most important takeaway point is that the scientific research is clear – were one to occur, a grand solar minimum would temporarily reduce global temperatures by less than 0.3°C, while humans are already causing 0.2°C warming per decade.
The global mean temperature difference is shown for the time period 1900 to 2100 for the IPCC A2 emissions scenario. The red line shows predicted temperature change for the current level of solar activity, the blue line shows predicted temperature change for solar activity at the much lower level of the Maunder Minimum, and the black line shows observed temperatures through 2010. Illustration: Adapted from Feulner & Rahmstorf (2010) in Geophysical Research Letters by SkepticalScience.com
So the sun could only offset at most 15 years’ worth of human-caused global warming, and once its quiet phase ended, the sun would then help accelerate global warming once again.
The myth ultimately stems from a period climate scientists have coined “The Little Ice Age” (LIA). This was a modestly cool period running from about the year 1300 to 1850. It was particularly cold in the UK, where the River Thames sometimes froze over, and ‘frost fairs’ were held.
A team led by University of Reading physicist and solar expert Mike Lockwood wrote a paper reviewing the science behind frost fairs, sunspots, and the LIA. It included the figure below showing northern hemisphere temperatures along with sunspot number and the level of volcanic particles in the atmosphere over the past millennium:
Sunspot number, northern hemisphere temperatures, and volcanic aerosol optical depth (AOD) around the time of the Little Ice Age. Illustration: Lockwood et al. (2017), News & Reviews in Astronomy & Geophysics
During full blown ice ages, temperatures have generally been 4–8°C colder than in modern times. As this figure shows, during the LIA, temperatures were at most only about 0.5°C cooler than the early 20th century. Thus, Lockwood calls the Little Ice Age “a total misnomer.”
As the authors put it:
Compared to the changes in the proper ice ages, the so-called Little Ice Age (LIA) is a very short-lived and puny climate and social perturbation.
For comparison, temperatures have risen by a full 1°C over the past 120 years, and 0.7°C over just the past 40 years.
#3. Glacier retreat
Figure 1: Long-term changes in glacier volume adapted from Cogley 2009.
Figure 2: Percentage of shrinking and growing glaciers in 2008–2009, from the 2011 WGMS report
#4. Arctic Sea Ice and temperatures:
At +1.7° C, the mean annual surface air temperature (SAT) anomaly for October 2017-September 2018 for land stations north of 60° N is the second highest value (after 2016) in the record starting in 1900 (Fig. 1). Currently, the Arctic is warming at more than twice the rate of global mean temperatures; a phenomenon known as Arctic Amplification (Fig. 1). Recorded annual mean Arctic temperatures over the past five years (2014-18) all exceed previous records.
Fig. 1. Arctic (land stations north of 60° N) and global mean annual land surface air temperature (SAT) anomalies (in °C) for the period 1900-2018 relative to the 1981-2010 mean value. Note that there were few stations in the Arctic, particularly in northern Canada, before 1940. Source: CRUTEM4 dataset, which is available at www.cru.uea.ac.uk/cru/data/temperature/.
Arctic Sea Ice:
Arctic sea ice reaches its minimum each September. September Arctic sea ice is now declining at a rate of 12.85 percent per decade, relative to the 1981 to 2010 average. This graph shows the average monthly Arctic sea ice extent each September since 1979, derived from satellite observations.
#5. Sea level rise:
Ground Data: 1870-2013 – Data source: Coastal tide gauge records.
#6. Extreme Weather Events:
COST OF ACTION:
The Organisation for Economic Co-operation and Development (OECD) estimates that without immediate action that sealevel rises alone damage will be USD 35, 000 billion of urban assets in danger, more than 10 times current levels.
The risk of floods will be much greater in many urban areas. Depending on the climate scenarios, global urban flood damages are projected to amount to USD 0.7 to 1.8 trillion by 2080.
While the cost of not acting varies depending on the region, the consequences of climate will be negative everywhere.
Implementing climate change mitigation measures will help us avoid such huge costs. Mitigation measures sufficient for a 2 degree scenario would only slightly affect future economic growth. Concrete actions can, and should, be taken.
#7. GLOBAL EMISSIONS:
Thanks to Vijay and all the others who contributed to collating this article, and to all the brave scientist collating the source data over so many years to provide us with this information.
All we have to do is
- Continue to Tell the Truth
- Act Now on the science to get to net zero by 2025
- Go beyond Politics to unite ourselves against the greatest challenge we have all ever faced…
on behalf of Co-Co
XR Cirencester Coordination & Communications Working Group