Lord Turnbull: Evidence Counts Against Climate Change Alarmists
Financial Times, 31 January: Sir, Edward Luce (“Obama must make up for his carbon omissions”, January 21) writes that “the reality of global warming is starker than four years ago – in most respects alarmingly so”. The evidence points in the opposite direction. Since the Intergovernmental Panel on Climate Change produced its last report in 2007, global temperatures, as measured by the HadCRUT3 series, have not increased but have moved sideways, extending the standstill in temperature to more than a decade.
Since carbon dioxide concentrations, seen as the driving force of global warming, have continued unabated, it suggests that something else is at play: the link between CO2 and temperature may not be as strong as assumed in the IPCC model, or other factors such as the sun, oceans or clouds are having a greater influence. Either way, it must call into question the confident assertions based on the prevailing assumptions. As for Arctic ice, its coverage is now back almost exactly to where it was in January 2007.
All this suggests that our climate continues to warm gradually, as it has done since early in the 19th century (which is long before CO2 concentrations started to rise). It may be more plausible to conclude that global warming is around 1°C per century with periods of faster and slower growth fluctuating around the trend, rather than the 3°C predicted by the IPCC. If so what is happening is interesting but it hardly justifies the epithet alarming.
Andrew Turnbull, House of Lords, UK
Professor Chris Rapley responds
Sir, Lord Turnbull (Letters, January 31) is dismissive of the epithet “alarming” to describe the nature and speed of global warming. He argues that the recent flatlining of global average temperature data, while the atmospheric carbon dioxide level remains high, shows that human factors are not dominant.
He fails to mention that on climate timescales of a decade or more, each recent period, including the present, has been warmer than its predecessor, or that the planetary energy accumulation, revealed by the thermal expansion and increased water content of the world ocean, continues unabated. Moreover, no climate scientist has ever suggested that the global average temperature will rise smoothly; in a complex interconnected system variations occur as the accumulating energy from the sun redistributes and adjusts. Lord Turnbull’s argument is thus a straw man.
Regarding Arctic sea ice, it is currently the depth of winter and sufficiently cold, even in a warming world, for the surface of the ocean to freeze. However, from research pioneered in the UK we know that the ice is significantly thinner than in the past. From this, we can be confident that the rapid decline of Arctic summer sea ice is set to continue.
If Lord Turnbull wishes to know more about the climate system and how it is changing, the UK has many climate experts to whom he could turn.
Chris Rapley, Department of Earth Sciences, University College London, UK
Dr David Whitehouse comments:
Professor Rapley’s response to Lord Turnbull’s letter in the Financial Times gives an incomplete picture of the climate system and how it is changing.
Lord Turnbull is right to point to the global temperature standstill of the past 16 years as an important event requiring explanation. The peer-reviewed scientific literate shows he is not alone. It is not a straw man argument as Rapley believes because climate models find it difficult to explain. The current explanation is that it is due to natural climatic variability being stronger than human effects but that soon natural climatic variability will give way to the ever-rising human influence. The IPCC maintains that the average rate of warming due to human influences is 0.2 deg C per decade. Given that the majority of years since 1980 have not been statistically warmer than their predecessors, the data is suggestive that the situation is more complicated than many once believed, as many scientists are beginning to suspect.
Professor Rapley fails to mention that peer-reviewed literature indicates that the rise in sea level has been constant for the past 100 years, and possibly with a constant but lower rate of increase for the previous century. Sea level behavior is unchanged since the time when human influences on the climate were insignificant. There is also some evidence that in recent years the rate of sea level increase has declined.
Arctic sea ice has been declining for at least 50 years and when satellite observations became available in the late 1970s they showed a decline already in progress. It remains to be seen if those changes are cyclic or if the increase seen in sea ice loss seen in the past few years will also prove cyclical. In any case it is not universally accepted that the changes in the Arctic are a direct result of human influences on the climate,
In October 2012 talking to the Institute of Physics Professor Rapley said that Anthropogenic Global Warming rests on lots of small examples none of which are individually important. He said it was the overall pattern of evidence that was important even if individual pieces of evidence might or might not be enough on their own.
Not all those individual pieces of evidence are well understood, telling the same story, or in themselves alarming.
Professor Rapley responds
Dr Whitehouse claims that sea level rise has been constant for 100 years, that its behaviour has been unchanged since human influences on the climate have been significant, and concludes against the connection with human actions which I had taken as evident. In fact the data show an acceleration of sea level rise from a low level in the late C19 to 1.8mm/y on average in the C20th and to 3mm/y today. (A summary can be found on the website Skeptical Science). The current rate is already 20% of that sustained during the transition from the last ice age when the great northern ice sheets melted and sea level increased by 120m. The predictions of polar science (shown to have been conservative in the past by events in the Arctic) indicate that the ice-age transition rate is likely to be exceeded before the end of this century. Had today’s rate of sea level rise applied over the recent 5,000 year period of unusual climate stability in which human civilisation has developed, a further 15m (50 feet) of rise would have been added. It did not; the current surge is extraordinary. Its synchronicity with the rise of industrialisation and correspondence with the curve of human carbon emissions invites the search for a connection. The human-enhanced greenhouse effect, plus a contribution from soot-enhanced polar melting, provide an explanation – and a conclusion opposite to that drawn by Dr Whitehouse.
Regarding Arctic sea ice, Dr Whitehouse asserts that this was reducing before the satellite record began, and suggests that the changes might be cyclical. In reality Arctic sea ice decline has shown a dramatic acceleration, and changes in northern hemisphere snowfall, glacier retreat, summer surface melting of the Greenland ice sheet, permafrost melting, the release of methane from tundra and shallow ocean clathrates, temperature data from boreholes and even the emerging changes in the interaction between polar and mid-latitude weather systems (which have already been disruptive and have impacted economies) all indicate that we are witnessing changes in the Arctic that lie outside the bounds of recent natural variability.
Dr David Whitehouse comments
Professor Rapley takes the connection between sea level rise and human actions as evident, and says the data shows an acceleration of sea level rise from a low level in the late 19th century of 1.8 mm/yr to 3 mm/yr today, citing the unevenhanded website www.skepticalscience.com as a reference. In so doing Professor Rapley is not fairly representing the various strands of research into sea level rise, and has cherry picked one particular outcome without placing it into its all-important context. It is a very poor example of communicating climate change.
I do not take the connection between sea level and human actions as evident until I am convinced by the data, which I discuss in my analysis below that references the peer-reviewed scientific literature. It is not as clear cut as Professor Rapley maintains.
Rapley points out that had today’s rate of sea level rise applied for the period of human civilisation the seas would have been 50 m higher! What exactly does that prove about the link between human activities and sea level rise? The current rate of sea level rise is unusual but, as the graphs below show, it began about 200 years ago and changed 100 years ago long before humans had any influence on the seas or the wider environment (which the IPCC says took place between 1960 -80). Professor Rapley’s suggestion that this change in sea level behavior was influenced by the start of the Industrial Revolution is fanciful when one considered how small that start was. The human-enhanced greenhouse effect, with or without soot modification, has not the strength so far back in time.
Regarding the Arctic, we do not know what is cyclical and what is not. It is obvious that the commencement of satellite observations in the late 1970s caught a long-tern decline in action. This week’s paper on CryoSat-2 observations of the Arctic ice stresses it comes after an at least 30-year decline. Data from earlier times suggest great changes in that region. It will be very interesting to see if the more rapid decline seen since the middle of the last decade continues. Until we have more data beyond three decades I maintain we cannot judge what are the bounds of natural variability or assess human influences. We can consider dire predictions, and debate what action we should take in the interim, but there is no alternative to finding out the scientific facts, and we need more science to do that.
Professor Rapley extolls us to ask a climate scientist about climate matters. I don’t agree though perhaps his comments suggest that it should be one with more than a very scant publication record in actual climate science. Professor Rapley’s certainty overrides the reality, the uncertainties and the unknowns of the science of climate change and has the whiff of looking for evidence to support a particular conclusion and ignoring everything else. One should not cherry pick ‘facts’ when communicating climate change. It’s too important for that.
Sea Level Rise
There is a considerable body of evidence that something happened about 200 years ago to increase the rate of sea level rise. Proxy observations of sea levels over past 2,000 – 7,000 years using shells, tree stumps, corals, salt marches, and even Roman fish pools show that in the Mediterranean there was little change before 200 years ago. Observations elsewhere in the world are not quite as definitive.
There is some evidence for a recent increase in the rate of sea level rise but there is also some evidence against it and given the short duration of the datasets I don’t think it is convincing.
In many analyses there is some discrepancy between measurements using tidal gauges and those obtained by satellite altimetry. Satellite data has always shown a much larger rate of increase than in situ measurements and although some analyses seem to resolve the differences I still think the comparisons and merging of these two datasets is problematic.
Merrifield and Merrifield (2009) in the Journal of Climate look at tidal gauges for the period 1955 – 2007, splitting the data into 15-year segments, and producing an area-weighted global mean trend. They find during 1962 – 90 the rate of rise is 1.5 +/- 0.5 mm/yr. After 1990, using only five years of present century data, they find it increases to 3.2 +/- 0.4 mm per year, matching satellite altimetry.
But on the other hand there is Gregory et al (2012) who in a paper which includes scientists from the Met Office and the UK National Oceanography Centre looking at global mean sea level rise in the 20th century remarking on the approximate constancy of the rate of global sea level rise, “which shows small or no acceleration, despite the increasing anthropogenic forcing.” They add that any postulated relationship between global climate change and the global mean sea level rise is “weak or absent” during the 20th century.
Writing in the Journal of Geophysical Research – Oceans, Wenzel and Schroter (2010) use a neural network analysis technique and conclude; The global mean sea level for the period January 1900 to December 2006 is estimated to rise at a rate of 1.56 ± 0.25 mm/yr which is reasonably consistent with earlier estimates, but we do not find significant acceleration.
Jevrejeva at al (2006) in Journal of Geophysical Research – Oceans uses a Monte Carlo spectral analysis of global mean sea level data and obtain lower than Merrifield at al (2009) but within its lower bounds. They estimate the global sea level trend as 2.4 ± 1.0 mm/yr for the period from 1993 to 2000 is comparable with the 2.6 ± 0.7 mm/yr sea level rise calculated from TOPEX/Poseidon altimeter measurements. However, they show that over the last 100 years the rate of 2.5 ± 1.0 mm/yr occurred between 1920 and 1945, is likely to be as large as the 1990s. Again this should raise caution in saying the rate of change of sea level has recently accelerated due to anthropogenic effects.
That more time is needed to determine what is going on is emphasised by Schmith et al 2012 in the Journal of Climate. The authors find a relationship between sea level and land-ocean temperature suggesting that the recent ocean warming is due to radiative forcing but they found that sea-level itself does not depend upon radiative forcing and that ten times the data is needed to determine if it might be.
Woodworth et al (2008) in the International Journal of Climatology is another good demonstration of the pitfalls that over simplistic interpretation can bring. They point out that any modification to the rate of change of sea level is an important climate-related signal, but that the evidence is for weak acceleration between 1920 – 30 and a deceleration around 1960. They point out that modeling has not been able to describe the relationship between globally averaged temperature changes and sea level changes.
Bruce Douglas – a long-time and highly respected scientists in this field – (2012) of NOAA’s National Oceanographic Data Center, writing in the Journal of Geophysical Research – Oceans looks for sea level acceleration in long-duration (> 75 years) tidal gauge data. He found a global sea level acceleration of -0.001 +/- 0.012 mm/yr2 and with a larger set of data -0.001 +/- 0.008 mm/yr2. He concluded, “there is no evidence for an apparent acceleration in the past 100+ years that is significant either statistically, or in comparison to values associated with global warming.” Many more decades of data are required he says.
Further problems come from any quasi-periodic signals that might be found in sea level data. Chambers et al (2012) finds evidence of a 60-year oscillation in global mean sea level and caution that its recent rising phase could be mistaken for a recent acceleration in sea level.
Church and White (2011) is an excellent paper on sea level trends.
Looking at the 16-year period 1993–2009 and after correcting for glacial isostatic adjustment, their estimated rate of rise is 3.2 ± 0.4 mm/yr from the satellite data and 2.8 ± 0.8 mm/yr from the in situ data. The linear trend from 1900 to 2009 is 1.7 ± 0.2 mm/yr and since 1961 is 1.9 ± 0.4 mm/yr. There is considerable variability in the rate of rise during the twentieth century and in contrast to other researchers they find a statistically significant acceleration since 1880 and 1900 of 0.009 ± 0.003 mm/yr and 0.009 ± 0.004 mm/yr respectively.
But this paper requires a closer look and consideration of the timescales on which short-term conclusions are based. . The linear trend from 1900 to 2009 is 1.7 ± 0.2 mm/yr and from 1961 to 2009 is 1.9 ± 0.4 mm/yr. However, there are periodic departures from a linear trend on shorter timescales. This is obvious when one looks at the considerable variability in the data. Using the yearly average data, they produced trends for successive 16 year periods (about the length of the satellite altimeter data set) from 1880 to the present. They found maxima in the rates of sea-level rise of over 2 mm/yr in the 1940s and 1970s and nearly 3 mm/yr in the 1990s. Crucially the most recent rate of rise over these short 16 year windows is at the upper end of a histogram of trends but is not statistically higher than the peaks during the 1940s and 1970s. This the 1993-2009 data must not be seen in isolation.
However there is no substitute for looking at the data. This graph, produced by Bruce Douglas was on Wikipedia for many years.
It is obvious that the rise since 1910 has been linear and unchanging.
The next figure is from Church and White (2012).
This shows the same thing as the previous graph but with the linear trend going back to 1930. Is there really acceleration in the past few decades?
From Sally Weintrobe to Benny Peiser
Dear Benny Peiser,
Having followed the correspondence in the FT and on the Global Warming Policy Foundation’s website following Edward Luce’s piece in the FT on the need for President Obama to act decisively to reduce CO2e emissions and to introduce carbon pricing, it is hard to avoid the conclusion that GWPF’s aim is primarily to sew (sic) doubt on the findings of mainstream climate science in order to undermine action urgently needed on warming. Your trustee Lord Turnbull’s letter to the FT of 5th February 2013, is out of step with the grim reality that climate scientists have if anything underestimated the pace of human made warming. And, the issue GWPF does not address is that your views are minority views, disagreed with by 90% of climate scientists.
Sally Weintrobe, Climate Psychologist and editor of Engaging with Climate Change (2012)
From Benny Peiser to Sally Weintrobe
Dear Ms Weintrobe
Thank you for your interest in the GWPF and Lord Turnbull’s contribution to the climate debate.
Please allow me to set the record straight.
You claim that “the grim reality [is] that climate scientists have if anything underestimated the pace of human made warming.”
I’m afraid you are in denial. The empirical evidence contradicts your assertion.
There is now growing agreement among climate scientists that the warming trend since the mid 1990s has been significantly slower than predicted and has been decelerating rather than accelerating.
The Met Office has recently scaled back its projections of global warming they expect in coming years compared with their previous estimates.
As the BBC’s climate expert Paul Hudson points out, the Met Office’s new projection, if correct,
“would mean there will have been little additional warming for two decades despite rising greenhouse gases. It’s bound to raise questions about the robustness and reliability of computer simulations that governments around the world are using in order to determine policies aimed at combating global warming….”
I am pleased to hear that you are keen to ‘engage’ in the climate debate.
The most important requirement for such an engagement, however, is to accept rather than deny empirical observations.
We have posted the ongoing debate about Lord Turnbull’s FT letter on our website <<http://www.thegwpf.org/lord-turnbull-evidence-counts-climate-change-alarmists/>.
We would be happy to add your own contribution to this webpage and hope you are indeed interested in engaging with the climate debate.
With best regards
From Sally Weintrobe to Benny Peiser
Dear Benny Peiser,
While not a climate scientist myself, I would like to quote from a letter I read in The New Scientist of 26th January 2013 written by Prof Chris Rapley about the UK Met Office predicting little change in the global mean surface temperature over the next five years in which he states:
“Global mean surface temperature is an insufficient, often misleading measure of the real issue. What matters is the energy imbalance of the planet, the climate disruption it is driving, and the consequences for humanity. … 90% of the energy imbalance is accumulating in the oceans – something that is invisible to the global surface temperature data. The continuing rise in global mean sea level as a result of thermal expansion (and contribution from ice melt on land) shows this accumulation has not ceased.”
And, I do note that you have not answered the last sentence of my e-mail: ”the issue GWPF does not address is that your views are minority views, disagreed with by 90% of climate scientists.”
Benny Peiser comments
Whatever the alleged ‘energy imbalance’ may be, it is obvious that it has not been detected in global ocean temperature data. The latest research shows that there has been no significant rise in global ocean temperatures during the first decade of the 21st century. In fact, several regions of the oceans were actually warmer during the 20th century than during the last decade while large regions of the oceans reportedly have experienced cooling since the 1990s.