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In the climate debate, hear both sides | Watts Up With That?
In May 2015, the Pennant, a biannual magazine for retired UK armed forces personnel, carried an article entitled The Earth’s Climate by Rob Varley, chief executive of the Met Office, the world’s oldest national weather bureau.
The Met Office article does not represent a fair or balanced summary of the science on the climate question.
This detailed response, prepared at the suggestion of a reader of the Pennant, is illustrated with some 50 well-sourced graphs that are intended to be clear at a glance.
The key facts that restore balance to the discussion may be gained from these graphs in five minutes....
However, the questions whether all other things are equal, and how much warming our sins of emission may cause, and whether the cost of mitigation today is less than that of adaptation the day after tomorrow, are by no means settled.
Are today’s temperature changes unprecedented?
Mr Varley says:
“… warming of the global climate system is unequivocal. Many of the observed changes are unprecedented over decades to millennia. In just over 100 years, the world’s surface has warmed by around 0.85 Cº. This represents a significant rate of increase in mean global temperature …”
Here as elsewhere, Mr Varley’s statement only gives one side of the story. His implication that the warming of five-sixths of a Celsius degree over a century is “unprecedented” is false. The following are among the points he has omitted:
Ø The Central England Temperature Record, which is not a bad proxy for global temperature change, shows warming from 1693-1733 at a rate exceeding 4 Cº/century equivalent – more than twice the maximum rate sustained for 15 years or more in the 20th century. Therefore, there is nothing special about the 20th-century warming rate.
Ø Our associates at co2science.org have compiled a list of some 500 peer-reviewed papers demonstrating by measurement of proxies for pre-thermometer temperatures that the Middle Ages were warmer than the present. As Ljungqvist (2010) shows, the Roman and mediaeval warm periods were at least as warm as the present, and the mediaeval warming rate was not much less than the rate observed in the 20th century:
Was 2014 “the warmest year on record”? And does it matter?
Mr Varley says:
“The WMO confirmed that globally 2014 was the warmest year on record, with 14 of the 15 hottest years occurring this century.”
Yet again we are given only part of the story. The following are among the relevant considerations omitted or erroneously presented:
Ø When one talks of “the warmest year on record”, the “record” only goes back to 1850 (HadCRUT4), or 1880 (NASA GISS and NCDC), or 1979 (RSS and UAH). The first three depend on the same historical climate data network. They all show 2014 as the warmest year since 1850 (or 1880). So what?
Ø The RSS and UAH satellite datasets do not show 2014 as the warmest year. It would have been fairer if this fact had been mentioned.
Ø The Mediaeval Optimum was warmer than today by up to 3 Cº in some places. The Roman, Minoan and Old Kingdom climate optima were also warmer. The Holocene Climate Optimum was warmer than today for 4000 years.
Ø According to the two satellite datasets, there has been no global warming at all for more than 18 years. The trend is zero. In a briefing on global warming, you should surely have mentioned that fact.
Mr Varley says:
“Closer to home, Met Office statistics show that in 2014 the UK as a whole experienced its warmest year on record with the eight warmest years in this series all occurring since 2002. It was also the warmest year on record in the Central England Temperature series which extends back to 1659.”
Yet again, balancing considerations are omitted:
Ø Cherry-picking an individual year, or a selection of individual years, is not how statistical trends on time-series are determined.
Ø The Central England Temperature Record, is cited, but with no mention of the fact that from 1693-1733 the rate of global warming was twice that which occurred over any period of 15 years or more during the 20th century.
Imagined effects of global warming
Mr Varley says:
“In addition to the Earth’s surface temperature, many tens of other climate variables are measured, extending from high in the atmosphere to the depths of the oceans. These are analysed at academic and research centres around the world, with thousands of scientists pooling their findings and expertise to build a picture of past and current climate. Emerging from these observations is evidence of change: global and regional temperatures are increasing; Arctic sea ice, mountain glaciers and snow cover are shrinking; warming oceanic waters are expanding, leading to sea level rise; atmospheric humidity is rising as a warmer atmosphere’s capacity to hold water increases; the frequency of rainfall and temperature extremes has increased. These changes are already impacting on natural and human systems.”
Now for the balance:
Ø Of course there is “evidence of change”: the climate has been changing for 4.5 billion years and it will continue to change.
Ø No one denies that the climate changes. The question is whether Man has had or may yet have a significant effect, and whether that effect, if significant, will be beneficial or detrimental.
Ø Mr Varley makes no mention of the real difficulties in distinguishing between natural and anthropogenic climate change.
Ø Mr Varley’s statement that global and regional temperatures are increasing is scientifically meaningless in the absence of a stated start date.
Ø Global temperature has not increased for more than 18 years, and has not increased significantly in the quarter of a century since the IPCC’s First Assessment Report in 1990.
Ø Some regions, such as Antarctica and central Africa, have scarcely warmed, if at all.
Ø Global temperatures are lower than during previous climate optima during the Holocene.
Ø Global temperatures are also lower than in each of the previous four interglacial warm periods.
Ø Mr Varley says Arctic sea ice, mountain glaciers and snow cover are shrinking, but he is silent on the fact that Antarctic sea ice has grown; that mountain glaciers in the Himalayas, in Greenland and in Antarctica show a long-established and unalarming pattern of advance and retreat; and that winter snow cover in the Northern Hemisphere shows no particular trend:
Ø Mr Varley says warming oceanic waters are expanding, leading to sea level rise, but he is very careful not to quantify this. According to the GRACE gravitational-recovery satellites, sea level actually fell from 2003-2008:
...Is sea ice really declining rapidly?
Next, Mr Varley shows a graph of September sea-ice extent in the Arctic similar to the following:
What he does not show is the Antarctic sea-ice extent. It has increased somewhat:
Moreover, in the Arctic as in the Antarctic, the amplitude of the seasonal variation dwarfs the relatively small changes in sea-ice extent:
Mr Varley says:
“Observations of the climate to current day show that the poles have warmed at twice the global average, and computer model predictions suggest this trend will continue.”
Here is a more complete picture:
Ø In recent decades the south polar region has shown little or no warming, as even the IPCC concedes.
Ø The extent of global sea ice shows remarkably little change over the past 35 years:
Ø “Computer model predictions” of 1.4-4.5 Cº global warming per CO2 doubling have remained unchanged for 36 years: yet the IPCC’s medium-term global warming predictions made 25 years ago have proven exaggerated by a factor of two. Would it not have been appropriate at least to mention the models’ continuing exaggerations?
Ø Likewise, there is now a substantial list of papers in the reviewed journals suggesting that climate sensitivity could be as little as one-fifth of the IPCC’s current central estimate of about 3 Cº per CO2 doubling. Mr Varley has given only one side of the climate-sensitivity case.
Rising CO2 concentration and its effect on global temperature
Mr Varley says:
“Since pre-industrial times, the atmospheric concentration of CO2 has risen by 40% to a level unprecedented in at least 800,000 years … This has led to an enhanced greenhouse effect.
“Scientists have calculated that more than half of the observed warming since the mid 20th century was caused by the increase in man-made greenhouse gases.”
Once again, there is plenty of balancing evidence:
Ø Today’s CO2 concentration may be unprecedented in 800,000 years, but, notwithstanding the increase in anthropogenic emissions, to the nearest tenth of one per cent there is no CO2 in the air at all.
Ø In the Neoproterozoic era, 750 million years ago, the atmosphere was 30% CO2 and the planet did not fry.
Ø In the Cambrian era 550 million years ago the concentration was 20-25 times today’s.
Ø In the Jurassic era it was 12-15 times today’s. Yet here we all are.
Ø Mr Varley has mentioned only the theoretical harm that he imagines warmer weather may cause, without mentioning the many benefits of increased CO2 concentration, not least in increasing the net primary productivity of trees and plants worldwide by 2% per decade; increasing the yield of staple crops by up to 40% per CO2 doubling; and increasing the resistance of plants and crops to drought.
Ø Also, cold is a far worse killer than warmth. It is no accident that 90% of all species live in the tropics, and fewer than 1% at the Poles.
Ø Mr Varley says, “Scientists have calculated that more than half of the observed warming since the mid-20th century was caused by the increase in man-made greenhouse gases.” Certainly that is what the IPCC has long maintained. However, in this respect the IPCC is not honoring its obligation to reflect the peer-reviewed scientific literature.
Ø Though propagandists have sought to maintain that there is a “97% consensus” to the effect that recent global warming is mostly manmade, the truth – given in Legates et al.(2013) – is that only 0.3% of climate science papers published in the 21 years 1991-2011 stated that recent global warming was mostly manmade:
Ø The truth is that at present we are unable to distinguish between the respective magnitudes of the anthropogenic and natural components in the global warming that unaccountably stopped more than 18 years ago.
Ø In one sense, however, it might legitimately be said that global warming is manmade. For the terrestrial temperature records have been relentlessly and unidirectionally altered to make early-20th-century temperatures cooler and later temperatures warmer, in a manner calculated falsely and perhaps substantially to overstate the true warming rate in the 20th century:
Ø The NCDC’s adjustments are influential, because all three of the longest-standing terrestrial temperature records rely on its historical climate network for the compilation of their datasets. The changes made by the NCDC to the historical climate network data in just eight years are shown here:
Ø The tampering over the past seven years shows how earlier temperatures have been pushed ever lower and later temperatures pushed ever higher. There may or may not be legitimate reasons for this tampering, which always appears to go in the direction of amplifying Man’s influence on climate (the equivalent GISS “adjustment” is even larger than for NCDC), but it introduces an additional uncertainty to temperature measurements that Mr Varley’s article fails to reflect:
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A quick education that really clears the mind!
As I have written about previously, there were a total of 3,542 volcanic eruptions during the entire 20th century. 
