New study claims low solar activity caused "the pause" in global temperature – but AGW will return!

This is on a tip from Dr. Leif Svalgaard, WUWT’s resident solar expert. It was just published in the journal Atmospheric and Climate Sciences, and is open access. I found this study’s conclusion a bit amusing, because there are numerous claims that solar activity (and the slight increase in TSI seen in the last 30 years) can’t explain the global warming we’ve seen, but yet somehow the recent period of low solar activity can explain the pause, and when solar activity resumes, global warming will return anew. Dr Svalgaard gives the author, Peter Stauning, high marks for his work in general, but disagrees with him on this paper.

I’m also more than a little bit puzzled how the journal editor and the peer reviewers let this sentence pass, everybody makes typos, but this one takes the cake. I kid you not:

But secondly, there must be a fair global coverage such that localized climate variations like the North-Atlantic Oscillation (NAO), or the El Ninjo/La Ninja in the Pacific would not affect the result too much.

Yes, I really want to see what the La Ninja effect looks like.

Here’s the paper abstract and excerpts:

Reduced Solar Activity Disguises Global Temperature Rise

DOI: 10.4236/acs.2014.41008  Author: Peter Stauning

ABSTRACT

The question whether human activities seriously affect climate is asked with increasing voice these days. Quite understandable since the climate appears to be out of control with the significant global temperature increases already seen during the last three decades and with still heavier temperature increases to come in the future according to prognoses, among others, in the recent comprehensive IPCC reports [1].

However, the most recent climate data [2], show global temperature development levelling off or even turning negative since 2001 in contrast to the anticipated course related to the steady increases in the concentration in the atmosphere of green-house gasses, primarily carbon dioxide and methane [1]. The purpose of this communication is to demonstrate that the reduced rate in the global temperature rise complies with expectations related to the decaying level of solar activity according to the relation published in an earlier analysis [3]. Without the reduction in the solar activity-related contributions the global temperatures would have increased steadily from 1980 to present.

1. Introduction

The alarming rise in global temperatures from about 1980 to 2000 gave much concern around possible serious future climate changes, global warming, that could result from the increasing levels of carbon dioxide, methane and other greenhouse gasses in our atmosphere. However, as shown in [2] the strong rise in global temperatures faded after year 2000 and was replaced by a rather steady level or even small decreases in the global temperatures from around 2001 to present (2013). This development took away some of the incitement to cut down on human-induced growth in greenhouse gasses.

The question is now whether the present fading of the temperature rise is related to the concurrent decrease in solar activity scaled, for instance, by the sunspot numbers. Scientists have linked past climate changes to solar activity. The so-called “Little Ice Age” in the 17’th century was linked to the Maunder minimum in solar activity by [4]. Many later works have linked climate changes to changes in solar activity (see reviews [5,6]).

In the earlier analysis [3] from the Danish Meteorological Institute (DMI) a quantitative assessment was made of the relation between solar activity represented by the cycle-average sunspot numbers and the terrestrial climate represented by the global temperatures averaged over the same interval length but delayed by 3 years. In the present communication the anticipated effects of the developments in solar activity on the recent global temperature changes are analyzed.

2. Sunspots and Global Temperatures

The former analysis [3] and the present work assume that solar activity can be represented through the classical international sunspot number SSN = k·(s + 10·g), where s is the number of sunspots, g the number of sunspot groups while k is a calibration parameter to ensure that different observatories derive the same sunspot number regardless of observational qualities. A discussion of this index and of modified versions of the sunspot number is provided by [7]. The sunspot number is used here rather than satellite-based observations of solar radiation be- cause of the extended length of the time interval of available data.

…

Presently (2013) we are about 4 years into cycle 24. Figure 1 also displays the extensions through 1.5 years derived at SIDC with different models (kfsm “clas- sical standard” and kfcm “combined” models). The fig- ure, furthermore, displays the predictions prepared by the Australian IPS Radio and Space Services [10] and the NASA solar cycle 24 predictions [11] as of October 2013.

The mean of the two SIDC extrapolations [8] 1.5 years ahead as well as the NASA prediction places the maxi- mum of cycle 24 in mid-2013. The currently observed and predicted sunspot numbers makes this sunspot cycle the weakest since cycle 14 which had a maximum in the smoothed data of 64.2 in February of 1906. When final sunspot data become available they may turn out still lower to make cycle 24 even weaker than cycle 14.

Sunspot numbers have been reconstructed back to around 1850 with quite good accuracy based on as- tronomers’ careful and detailed recordings of the ap- pearance of the solar surface. The yearly sunspot num- bers since 1850 available from SIDC [8] are shown by the thin blue line in the bottom panel of Figure 2. The extension shown by the dashed line from present through the remaining solar cycle 24 to 2020 is based on the mean of the IPS [10] and the NASA [11] predictions.

The bottom panel of Figure 2 also displays the averages of sunspot number from minimum to minimum (usual solar cycle) marked by squares and from maxi- mum in a cycle to maximum in the next cycle marked by filled circles.

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The top panel of Figure 2 displays global temperature variations since 1850 through the deviations from aver- age level 1961-1990.

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Presently, the series are extended up to October 2013 and comprise the combined land-surface/sea-surface global temperature series, HadCRUT-4gl [2], shown in the up- per panel of Figure 2, which is used here for the analyses. For the discussions here it should be noted that following

the steep rise between 1980 and 2000, the global average temperatures flatten out after year 2000. The extension of the temperatures beyond present shown by the dashed line represents the average of global temperatures from 2001 to 2013.

3. Relations between Solar Activity and Global Temperature

It should be recalled that solar activity-related changes in global temperatures must arrive after the activity changes. The former DMI analysis [3] examined the correlation between sunspots and global temperatures for the interval from 1850 to 1980 and derived a value of 3 years for the delay that provided optimum correlation. In Figure 2 the cycle-average global temperatures are presented by the squares and filled circles, respectively, for the min-to- min and max-to-max intervals shifted 3 years.

The averaging presented in Figure 2 over min-to-min or max-to-max solar cycle intervals delayed by 3 years include years beyond present for the last two points. In the summations a reference value equal to the mean value of global temperatures from 2001 to 2013 has been substituted for values beyond 2013. Error bars extending from the two points represent the results obtained with global temperatures beyond 2013 systematically defined 0.1˚C higher or lower than the reference value.

In Figure 3 the individual cycle values of the sunspot number, SSNA, averaged over either min-to-min or max- to-max intervals of the solar cycle (appr. 11 years) and the change in global temperatures, ΔTA, averaged over the same interval length but delayed by 3 years, are shown by filled squares and circles, respectively. This way of averaging reduces the scatter and makes it easier to se the persistent relation between sunspots and global tempera tures. The relation was found statistically in the former analysis [3] to be: ΔTA = 0.009 (±0.002)·SSNA − 0.70˚C.

…

6.  Conclusions

The decaying solar activity makes the recently recorded global temperatures flatten out and thus disguises the real climate development. With a steady level of cycle-average solar activity the global temperatures would have shown a steady rise from 1980 to present (2013) in agreement with the increasing atmospheric concentrations of green-house gasses, primarily carbon dioxide and methane [16], and not the levelling-off actually observed since 2001.

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.

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Open access to the full paper here: PDF (Size:544KB) PP. 60-63