I mentioned a few days ago an outstanding documentary about the global warming swindle. I did a little digging--and found that one of the key points of that documentary, that there is strong evidence that solar activity changes, by altering cosmic ray flux, which changes the amount of cloud cover--plays a substantial role in altering temperatures here on Earth. I knew that there were scientific papers published about this--but I had no idea how many. Here are some excerpts and abstracts that I found with this search string in scholar.google.com:
"Cosmic Rays, Clouds, and Climate," Space Science Reviews, November, 2000:
A correlation between a global average of low cloud cover and the flux of cosmic rays incident in the atmosphere has been observed during the last solar cycle. The ionising potential of Earth bound cosmic rays are modulated by the state of the heliosphere, while clouds play an important role in the Earth''s radiation budget through trapping outgoing radiation and reflecting incoming radiation. If a physical link between these two features can be established, it would provide a mechanism linking solar activity and Earth''s climate. Recent satellite observations have further revealed a correlation between cosmic ray flux and low cloud top temperature. The temperature of a cloud depends on the radiation properties determined by its droplet distribution. Low clouds are warm (>273thinspK) and therefore consist of liquid water droplets. At typical atmospheric supersaturations (sim1%) a liquid cloud drop will only form in the presence of an aerosol, which acts as a condensation site. The droplet distribution of a cloud will then depend on the number of aerosols activated as cloud condensation nuclei (CCN) and the level of super saturation. Based on observational evidence it is argued that a mechanism to explain the cosmic ray-cloud link might be found through the role of atmospheric ionisation in aerosol production and/or growth. Observations of local aerosol increases in low cloud due to ship exhaust indicate that a small perturbation in atmospheric aerosol can have a major impact on low cloud radiative properties. Thus, a moderate influence on atmospheric aerosol distributions from cosmic ray ionisation would have a strong influence on the Earth''s radiation budget. Historical evidence over the past 1000 years indicates that changes in climate have occurred in accord with variability in cosmic ray intensities. Such changes are in agreement with the sign of cloud radiative forcing associated with cosmic ray variability as estimated from satellite observations."Cosmic Rays, Clouds, and Climate," Science November 29, 2002:
It has been proposed that Earth's climate could be affected by changes in cloudiness caused by variations in the intensity of galactic cosmic rays in the atmosphere. This proposal stems from an observed correlation between cosmic ray intensity and Earth's average cloud cover over the course of one solar cycle. Some scientists question the reliability of the observations, whereas others, who accept them as reliable, suggest that the correlation may be caused by other physical phenomena with decadal periods or by a response to volcanic activity or El Niño. Nevertheless, the observation has raised the intriguing possibility that a cosmic ray-cloud interaction may help explain how a relatively small change in solar output can produce much larger changes in Earth's climate. Physical mechanisms have been proposed to explain how cosmic rays could affect clouds, but they need to be investigated further if the observation is to become more than just another correlation among geophysical variables."Influence of Cosmic Rays on Earth's Climate," Physical Review Letters, November, 1998:
During the last solar cycle Earth's cloud cover underwent a modulation more closely in phase with the galactic cosmic ray flux than with other solar activity parameters. Further it is found that Earth's temperature follows more closely decade variations in galactic cosmic ray flux and solar cycle length, than other solar activity parameters. The main conclusion is that the average state of the heliosphere affects Earth's climate."Altitude variations of cosmic ray induced production of aerosols: Implications for global cloudiness and climate," Journal of Geophysical Research 2002:
The indirect radiative forcing of atmospheric aerosols is sensitive to particle size and concentration, which are influenced significantly by nucleation processes. Via its role in aerosol formation, cosmic ray may affect the cloud condensation nuclei abundance and hence the global cloud properties and climate. Systematic variations in ionization rates due to the modulation of cosmic ray radiation by the solar cycle are sufficient to cause notable variations in aerosol production, and we find that the signs of such variations are altitude-dependent."The role of solar forcing upon climate change," Quarternary Science Reviews 18 (1999):
Our study indicates that an increase in cosmic ray fluxes generally leads to an
increase in particle production in the lower troposphere but a decrease in particle
production in the upper troposphere. The main reason of such an altitude-dependent
influence is that the dependence of particle production rate on ionization rate is a complex function of ionization rate itself, as well as precursor gas concentration and ambient conditions. The implications of altitude variations of cosmic ray-induced aerosol production on global cloudiness and climate are discussed. In addition to the reported positive correlation between cosmic ray variations and low cloudiness, our analysis reveals that high cloudiness may be anti-correlated with cosmic ray variations if volcano and El Nin˜o impacts are excluded. The observed different correlations between cosmic ray variations and low, middle and high cloud anomalies appear to be consistent with the predicted different sensitivities of particle production to cosmic ray changes at different altitudes. A systematic change in global cloudiness may change the atmosphere heating profile, and if confirmed, may provide the external forcing needed to reconcile the different surface and troposphere temperature trends. Much more work is needed to understand how and how much the cosmic ray variations will affect the global cloud properties and climate.
Evidence for millennial-scale climate changes during the last 60,000 years has been found in Greenland ice cores and North Atlantic ocean cores. Until now, the cause of these climate changes remained a matter of debate. We argue that variations in solar activity may have played a signiÞcant role in forcing these climate changes. We review the coincidence of variations in cosmogenic isotopes (14C and 10Be) with climate changes during the Holocene and the upper part of the last Glacial, and present two possible mechanisms (involving the role of solar UV variations and solar wind/cosmic rays) that may explain how small variations in solar activity are"The influence of cosmic rays on terrestrial clouds and global warming," Astronomy \& Geophysics August, 2000:
ampliÞed to cause signiÞcant climate changes. Accepting the idea of solar forcing of Holocene and Glacial climatic shifts has major implications for our view of present and future climate. It implies that the climate system is far more sensitive to small variations in solar activity than generally believed.
We analyse the new ISCCP (International Satellite Cloud Climatology Project) D2 cloud data to ascertain if a connection between cosmic-ray flux and cloud cover exists. Despite a previous finding that total-cloud factor and cosmic-ray fluxes were correlated, our results indicate that only the low-level cloud follows solar activity over the full period, 1983–94. Using several proxies for solar activity and the radiative forcing calculated by Ockert-Bell (1992) for the ISCCP cloud types, we estimate the possible impact that such a solar–terrestrial connection may have on climate. We conclude that, possibly excluding the most recent decades, much of the warming of the past century can be quantitatively accounted for by the direct and indirect effects of solar activity.And there are dozens, perhaps hundreds more papers that come to similar conclusions.