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Into Climate Change
FoS Climate Science Newsletter - 2018

By: Ken Gregory

 

CliSci # 275      2018-01-02

 

Cosmic Rays Supports Growth of Aerosols into Cloud Condensation Nuclei

A paper by Henrik Svensmark et al published in Nature Communications last month shows that the flux of cosmic rays, which are modulated by changing solar activity, creates ions that significantly promotes the growth of aerosols to a size that enhances cloud formation by several percent. A decreasing solar wind  increases the cosmic ray flux which increases the amount of cloud condensing nuclei (CCN), increasing cloud cover which reduces the solar energy reaching the earth’s surface, causing cooling. Experiments performed in a reaction chamber found that an increase in ionization results in a faster aerosol growth, which lowers the probability for the growing aerosol to be lost to existing particles, and more aerosols can survive to CCN sizes. The effect would be significant only in pristine marine settings away from pollution where the density of aerosols is small. The paper says “The mechanism could therefore be a natural explanation for the observed correlations between past climate variations and cosmic rays, modulated by either solar activity or caused by supernova activity in the solar neighborhood on very long time scales.”. See a discussion here. Several studies of cloud data shows that the ionization effect on total cloud cover is small, see here.

 

Weak Stratospheric Polar Vortex States Linked to Cold Extremes

The extra-tropical stratosphere is characterized by a strong circumpolar westerly jet, named the polar vortex, that confines the coldest air at high latitudes. A paper published in the Bulletin of the American Meteorological Society shows the polar vortex was weakened in the winter resulting in cold extremes in mid-latitude Eurasia. In this region, 60% of the observed cooling since 1990 can be explained by the increased frequency of weak stratospheric polar vortex states.

 

Impact of Volcanic Eruptions on Fluctuations of Arctic Sea Ice Extent

A paper published in the Journal of Climate shows that large volcanic forcing is necessary to explain the start of the Little Ice Age. Volcanic eruption were followed by a positive response of the Atlantic Multidecadal Overturning Circulation, followed by a centennial-scale enhancement of the Northern Hemisphere sea ice extent. Decreasing solar activity of the Maunder Minimum added to the sea ice extent and further cooled the climate during the Little Ice Age.

 

20th-Century Climate Change in the Central USA From Agricultural

A paper published in Geophysical Research Letters, Alter et al 2017, used regional climate model simulations and observational analysis to determine that in the central United States, the observed rainfall increase, the decrease in temperature and the increase in humidity during the summer over the 20th century is attributed mainly to agricultural intensification, with natural variability and greenhouse emissions playing secondary roles. Human activity has caused a significant long-term cooling trend (-0.35°C between the 1940s and 2009) and higher rainfall totals via the mechanism of “agricultural intensification” – a photosynthesis-associated increase in the air’s water vapor or humidity levels due to an explosive (400%) increase in crop production and yield since the 1940s. The author’s say the post 1940’s cooling trend conflict with the climate model simulations which project a warming trend. See more here.

 

Ocean Surface Temperature Variability: Large Model–Data Differences

This paper compared decadal to millennial sea surface temperature variability to that simulated by global climate models. The abstract says “SST [sea surface temperature] variability obtained from coral, foraminifer, and alkenone records are shown to be consistent with one another and with instrumental records in the frequency bands at which they overlap. General circulation models, however, simulate SST variability that is systematically smaller than instrumental and proxy-based estimates. Discrepancies in variability are largest at low latitudes and increase with timescale, reaching two orders of magnitude for tropical variability at millennial timescales.” The authors used an Earth system model that extends over the last 1,200 years and a set of 8 CMIPS models. The models include greenhouse gas and volcanic forcings, land use changes, but only the total solar irradiance component of solar forcings. At low latitudes (30°S−30°N), the proxy estimates average 45 times greater variance than is associated with model SST variability at multi-centennial timescales and this discrepancy grows to more than a factor of 100 at millennial timescales. A graph of the SST variation discrepancy at various timescales is here. This indicates a major problem with the models.

 

Germany Electricity Prices Keep Rising

The prices of electricity in Germany are among the world’s highest largely due to the transition to highly variable wind and solar power. The price of electricity for a representative household was 28.2 Euro-cents per kWh in 2017. The price is expected to rise to 28.44 Euro-cents per kWh on January 1, 2018. By comparison, the average price of residential electricity in the USA in October 2017 was 12.84 US-cents per kWh, equivalent to 10.92 Euro-cents per kWh. The average price in Germany is 2.6 times that in the USA.


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