19 "consensus" climate scientists all claiming that a continued high level of temperature forcing cannot cause continued warming, plus similar statements from three separate scientific bodies
List compiled by Alec Rawls (last updated 1/2013)
Solar activity remained at what what Usoskin and others have called "grand maximum" levels from 1920 to 2000, reaching peak levels from the 1940's through the mid 90's. Could this high level of solar activity be responsible for the warming that was experienced over this period?
On the surface this seems likely, given the numerous paleo-climate studies that find as strong correlation between solar activity and global temperature going back many thousands of years (see the second section here). But numerous "consensus" climate scientists say "no." They claim that because solar activity did not increase after 1950 (but only remained steady at "grand maximum" levels), it cannot possibly have caused the warming that occurred post 1975 (as if it is the change in the level of solar activity, rather than the level of solar activity, that would cause warming). In-effect they are saying that to heat a pot of water (like planet earth) you can't just turn the burner to high and leave it there, you have to turn the flame up slooooowly, or the water won't heat.
Presumably the scientists who are making these claims are assuming that the climate system rapidly equilibrates to a higher level of forcing, otherwise continued forcing at the new higher level would continue to cause warming until equilibration was reached, but no such assumptions are ever stated. Again and again leading climate scientists (all part of the "consensus" that late 20th century warming could only have been caused by human increases in atmospheric CO2), make the bald assertion, with no qualifying conditions whatsoever, that only rising solar activity could cause warming. Below is a compilation of such quotes from 19 individual scientists and from three major scientific organizations.
Professor Rasmus Benestad (2004, 2005):
Svensmark and others have also argued that recent global warming has been a result of solar activity and reduced cloud cover. Damon and Laut have criticized their hypothesis and argue that the work by both Friis-Christensen and Lassen and Svensmark contain serious flaws. For one thing, it is clear that the GCR does not contain any clear and significant long-term trend (e.g. Fig. 1, but also in papers by Svensmark).
A further comparison with the monthly sunspot number, cosmic galactic rays and 10.7 cm absolute radio flux since 1950 gives no indication of a systematic trend in the level of solar activity that can explain the most recent global warming.
Raimund Muscheler (2012):
Solar activity & cosmic rays were relatively constant (high solar activity, strong shielding and low cosmic rays) in the second part of the 20th century and, therefore, it is unlikely that solar activity (whatever process) was involved in causing the warming since 1970.
[Personal communication, posted by me at WUWT: http://wattsupwiththat.com/2012/10/19/muscheler-retracts-offers-a-new-excuse-for-why-solar-activity-cant-be-responsible-for-post-70s-warming/]
Professor Joanna Haigh (2012):
Haigh points out that the sun actually began dimming slightly in the mid-1980s, if we take an average over its 11-year cycle, so fewer GCRs should have been deflected from Earth and more Earth-cooling clouds should have formed. "If there were some way cosmic rays could be causing global climate change, it should have started getting colder after 1985."
Professors Lockwood and Fröhlich (2007):
Abstract: There is considerable evidence for solar influence on the Earth's pre-industrial climate and the Sun may well have been a factor in post-industrial climate change in the first half of the last century. Here we show that over the past 20 years, all the trends in the Sun that could have had an influence on the Earth's climate have been in the opposite direction to that required to explain the observed rise in global mean temperatures.
Since about 1985,… the cosmic ray count [inversely related to solar activity] had been increasing, which should have led to a temperature fall if the theory is correct - instead, the Earth has been warming. … This should settle the debate.
Professors Usoskin, Schussler, Solanki and Mursula (2005):
The long term trends in solar data and in northern hemisphere temperatures have a correlation coefficient of about 0.7 — .8 at a 94% — 98% confidence level. …
Note that the most recent warming, since around 1975, has not been considered in the above correlations. During these last 30 years the total solar irradiance, solar UV irradiance and cosmic ray flux has not shown any significant secular trend, so that at least this most recent warming episode must have another source.
Solanki to BBC News (2007):
"Since 1970, the cosmic ray flux has not changed markedly while the global temperature has shown a rapid rise," he says. "And that lack of correlation is proof that the Sun doesn't cause the warming we are seeing now."
In the same 2007 BBC interview Solanki explained that solar activity over the second half of the 20th century was especially high compared to solar activity over the rest of the Holocene
"We reconstructed solar activity going back 11,000 years," relates Sami Solanki. "And across this period, the level of activity we are seeing now is very high - we coined the term 'grand maximum' to describe it. We still have the 11-year modulation on top of the long-term trend, but on average the Sun has been brighter and the cosmic ray flux lower."
Thus when Solanki claims that solar activity would have to be going up to cause warming he is perfectly aware that he is talking about a sustained high level of solar activity that in his own estimation is near the highest in 11,000 years, but keeping the solar flame on maximum is in his view not enough to cause sustained warming, as if it is actually the change in the level rather than the level of forcing that causes warming. Seriously, this is what these people keep saying, over and over and over again.
Solanki and Krivova 2003(1):
Clearly, correlation coefficients provide an indication that the influence of the Sun has been smaller in recent years but cannot be taken on their own to decide whether the Sun could have significantly affected climate, although from Figure 2 it is quite obvious that since roughly 1970 the Earth has warmed rapidly, while the Sun has remained relatively constant.
Solanki and Krivova 2003 (2), p. 281:
Note that between 1970 and 1985 the [inverted] cosmic ray flux, although still behaving similarly to the temperature, lags it and cannot be the cause of the rise.
[After 1985 they see inverted GCR as turning in the opposite direction from temperature, so a fortiori in their view it could not be the cause of the rise. - AR]
Professor Phil Jones (interview with the BBC, February 2010):
Natural influences (from volcanoes and the Sun) over this period [1975-1998] could have contributed to the change over this period. Volcanic influences from the two large eruptions (El Chichon in 1982 and Pinatubo in 1991) would exert a negative influence. Solar influence was about flat over this period. Combining only these two natural influences, therefore, we might have expected some cooling over this period.
Dr Piers Forster (quoted by the BBC, October 2009):
The scientists' main approach was simple: to look at solar output and cosmic ray intensity over the last 30-40 years, and compare those trends with the graph for global average surface temperature.
And the results were clear. "Warming in the last 20 to 40 years can't have been caused by solar activity," said Dr Piers Forster from Leeds University, a leading contributor to this year's Intergovernmental Panel on Climate Change (IPCC).
Professor Johannes Feddema (quoted in the Topeka Capital-Journal, September 2009):
Feddema said the warming trend earlier in the century could be attributed to anything from solar activity to El Ninos. But since the mid 1980s he believes data doesn't correlate well with solar activity, but does correlate well with rising CO2 levels.
Professor Kristjánsson (2009):
Kristjansson also points out that most research shows no reduction in cosmic rays during the last decades, and that an astronomic explanation of today’s global warming therefore seems very unlikely.
Gerald Meehl et al. (2009):
The role of the Quasi-biennial Oscillation (QBO) in the response to solar forcing has been noted in earlier studies (3). ... This response also cannot be used to explain recent global warming because the 11-year solar cycle has not shown a measurable trend over the past 30 years (10).
Caspar Ammann et al. (2007):
A small role of solar forcing for late 20th century climate change is additionally supported by the absence of a trend in the satellite-based irradiance record covering the past 30 years (21).
Foukal et al. 2006:
Variations in the Sun’s total energy output (luminosity) are caused by changing dark (sunspot) and bright structures on the solar disk during the 11-year sunspot cycle. The variations measured from spacecraft since 1978 are too small to have contributed appreciably to accelerated global warming over the past 30 years.
However, the GCR trends (as seen in Graph 2) underwent monotonic decrease from 1900 to 1970 and then leveled off. The trends do not seem to reflect the large warming trend during 1970-2010, he [Ramanathan] points out.
Peter Stauning 2014 turns the continued-forcing-can't-cause-continued-warming claim in the cooling direction. Stauning believes that the cessation of warming is largely a product of low 21st century solar activity but he thinks that if the low solar activity continues it will not cause continued cooling. For it to cause continued cooling, solar activity would have to continue fall in his view, and since there isn't room for solar to fall any further he opines that the cooling effect of continued low solar should soon be petered out, allowing CO2-driven warming to "resume":
The solar activity is now at the lowest level seen in the past 100 years and could not go much lower. Thus, the observed global temperatures may soon resume the steady rise observed from around 1980 to 2001. If solar activity starts increasing then the global temperatures may rise even steeper than that seen over the past three decades.
Similar statements from scientific organizations
In addition to these individual scientists who suggest that temperature change is driven not by the level of forcing but by the change in forcing, several scientific bodies have put forward similar claims in their official statements.
IPCC (2012). Fifteen co-lead authors of chapter 7 of the Second Order Draft of AR5, p. 7-44:
The lack of trend in the cosmic ray intensity over the last 50 years (Agee et al., 2012; McCracken and Beer, 2007) provides another strong argument against the hypothesis of a major contribution of cosmic rays to ongoing climate change.
Coordinating Lead Authors: Olivier Boucher (France), David Randall (USA)
Lead Authors: Paulo Artaxo (Brazil), Christopher Bretherton (USA), Graham Feingold (USA), Piers Forster (UK), Veli-Matti Kerminen (Finland), Yutaka Kondo (Japan), Hong Liao (China), Ulrike Lohmann (Switzerland), Philip Rasch (USA), S. K. Satheesh (India), Steven Sherwood (Australia), Bjorn Stevens (Germany), Xiao-Ye Zhang (China)
27 contributing authors and 4 review editors would also have had a chance to weigh in on this abomination.
AR5 SOD contains further such statements as well, if you are familiar with the research that is cited. On page 10-18:
... several studies show that solar variations cannot explain warming over the past 25 years, since solar irradiance has declined over this period (Lockwood and Fröhlich, 2007, 2008; Lockwood, 2008(Lockwood, 2012)).
The reference given for this statement is the Lockwood and Frohlich paper quoted above, which claims that cooling should begin as soon as a forcing passes its peak, as if the day starts cooling at noon, or the the warmest day of the year is the longest day (the first day of summer), but here this utterly unscientific nonsense is endorsed by the fifteen co-lead authors of chapter 10 (different than the 15 co-lead authors of chapter 7).
The Royal Society (2008):
While there is evidence of a link between solar activity and some of the warming in the early 20th Century, measurements from satellites show that there has been very little change in underlying solar activity in the last 30 years – there is even evidence of a detectable decline – and so this cannot account for the recent rises we have seen in global temperatures.
From the Society's "Climate Change Controversies," pamphlet. See the appropriately titled "Misleading argument 6."
The American Physical Society (2010). In its 2010 clarification of its official statement on climate change the APS council voted to affirm the following language, where the second sentence is to be understood as justifying the first:
While there are factors driving the natural variability of climate (e.g., volcanoes, solar variability, oceanic oscillations), no known natural mechanisms have been proposed that explain all of the observed warming in the past century. Warming is observed in land-surface temperatures, sea-surface temperatures, and for the last 30 years, lower-atmosphere temperatures measured by satellite.
Temperatures rose after 1980, they are saying, but this cannot be explained by the sun, with the implicit rationale being that solar activity was not rising over this period. They are not explicit, but the meaning is perfectly clear. They are claiming that post-peak forcing should cause cooling, or at least not cause warming, regardless of its level.
Attempts at clarification
I sent an email to many of these scientists suggesting that they must be assuming rapid ocean equilibration to an increased level of forcing, otherwise the oceans would continue to warm and surface temperatures would continue to rise until equilibrium was reached. Rapid ocean equilibration would be a highly contentious assumption which would obviously need to be defended, but nowhere is this implicit assumption ever even mentioned, never mind defended. Lockwood and Solanki respond.
How high was 20th century solar activity?
Not everyone accepts that the high levels of solar activity over most of the 20th century constituted a "grand maximum," but there IS a broad consensus that 20th century levels were high. For instance, Raimund Muscheler's 2007 paper on paleo and recent GCR deposition suggests that 20th century solar activity was merely "high instead of exceptional," and even if post-1945 Waldmeier-era sunspot counts are reduced by 20%, as Leif Svalgaard urges, solar activity would still have been at grand maximum levels from 1950 on according to Usoskin's "high activity threshold" (over 50) and his estimated sunspot numbers (75 ± 3 since 1950).
For present purposes, it makes no difference whether the above quoted scientists are saying that continued high levels of solar activity could cause continued warming or they are saying that continued very high levels of solar activity could not cause continued warming, either way they are making the same unscientific claim: that it is not the level of the forcing, but the change in the level of the forcing, that causes warming.
These scientists really seem to believe that a continued high level of temperature forcing cannot cause continued warming, not conditional on any assumptions about rapid equilibration, and no matter how strong the forcing is. From their statements they really seem to believe that to heat a pot of water (and the earth in-effect is a pot of water) you really do have to turn up the flame up slowly: turning the flame to high and leaving it there will not cause continued warming. Quite amazing, what even supposed top scientists will accept in order to reach a preferred conclusion.