Steve Short sent me this curious paper. Cosmic rays, cloud condensation nuclei and clouds – a reassessment using MODIS data by J. E. Kristjansson, C. W. Stjern, F. Stordal, A. M. Fjæraa, G. Myhre, and K. Jonasson. They looked at the response of clouds to sudden decreases in the flux of galactic cosmic rays (GCR) – Forbush decrease events using cloud products from the space-borne MODIS instrument, which has been in operation since 2000. They focussed on pristine Southern Hemisphere ocean regions where it is believed that a cosmic ray signal should be easier to detect than elsewhere.

This is an almost schizophrenic paper. The figures and table indicate highly significant results. For example, the response of clouds to GCR, averaged over all regions for the 18 day event is particularly apparent in cloud amount CA below.

Nevertheless, the conclusions were negative:

The overall conclusion, built on a series of independent statistical tests, is that no clear cosmic ray signal associated with Forbush decrease events is found in highly susceptible marine low clouds over the southern hemisphere oceans.

This can only be said it seems, because the lack of significance occurs after ‘adjustments for auto-correlation’. The standard results are highly significant.

Statistical p-values are given in parentheses; the first value is based on an assumption of statistical independence between the data points, while the second value is obtained by a reduction in the number of degrees of freedom due to auto-correlations.

While I am in favor of taking autocorrelation into account, there is no indication of how these adjustments were carried out! The description of the analysis is entirely inadequate. The quote below is about it. How were the area averages calculated? Were the time series based on a daily frequency or what? The methods section gives no clue.

The correlation coefficients and their significance (p-value<0.05 for 95% significance) were found by comparing each 18-day period of cloud parameters to the corresponding 18-day period of GCR values.

The most obvious analysis, plotting a regression of the peak Forbush reduction with the cloud parameter on the same day was not shown.

All in all it looks like another snow-job. The closing sentence, with its ritual deference to the sacred AGW, completely blows its credibility.

For the ongoing global warming, however, the role of galactic cosmic rays would be expected to be negligible, considering the fact that the cosmic ray flux has not changed over the last few decades – apart from the 11-year cycle (Lockwood and Fr¨ohlich, 2007).

Shaviv soundly refutes the assertions of Lockwood and
Fr¨ohlich, 2007 (see TRF). Shaviv first explains the increase in temperatures in the 90’s and peaking with the massive El Nino in 1998.

To begin with, L & W write that solar activity decreased after 1985. This may almost be correct for the sunspot number (which remained the same) and perhaps correct for other solar activity proxies, but this is not correct for the cosmic rays. As is apparent from the first two figures above and below, the 1990 solar maximum caused a larger decrease in the cosmic ray flux, which implies that the temperature should have been higher in the 1990’s than in the 1980’s.

He also attributes the warming to a lag effect.

They are ignoring the fact that over the 20th century, solar activity increased tremendously (see the third figure below). So, even though the 2001 maximum is weaker than the 1990 maximum, we are still paying for the extra heat absorbed over several decades, from the middle of the 20th century.

He goes on to explain the recent ‘cessation of warming’ this century.

Moreover, if you look directly at the mechanism through which solar activity affects climate, that is, the amount of cloud cover, you do see that the amount of cloud cover decrease in the 2001 maximum is smaller than the decrease in 1990. As it should! Thus, when you look at the whole picture, there are certainly no inconsistencies in the solar/climate picture. Au contraire.

Another response to L&F — Reply to Lockwood and FrÄohlich – The persistent role of the Sun in climate forcing — by Henrik Svensmarky and Eigil Friis-Christensen from Danish National Space Center, Copenhagen, Denmark, contains a stunning correlation of global temperatures with cosmic rays.

Here cosmic ray variations explain a massive 47% of the variance of global lower troposphere temperatures since 1960. This is by far one of the strongest correlations with temperature I have seen in climate data.

Kristjansson and Co have wiped out obvious strong correlations in their data for the shorter term Forbush events, with the device of ‘adjustments for autocorrelation’, and covered their tracks with a inadequate description of methodology that makes replication impossible.