Monday, August 18, 2014

New paper finds the Sun controls Greenland climate

An important paper published today in Nature Geoscience finds a persistent link between solar activity and Greenland climate during the last ice age, and finds the link is similar to modern solar forcing of regional climate. 

According to the authors, 
"We suggest that solar minima could have induced changes in the stratosphere that favour the development of high-pressure blocking systems located to the south of Greenland, as has been found in observations and model simulations for recent climate. We conclude that the mechanism behind solar forcing of regional climate change may have been similar under both modern and Last Glacial Maximum climate conditions."
The authors describe a solar amplification mechanism by which solar minima favor the development of high-pressure blocking systems which block the jet stream and cause increased jet stream dips of the polar vortex [just like we have seen over the past few record cold winters in the US and Europe]. Many other papers have described this solar amplification mechanism via solar effects on the stratosphere, which in turn affect the QBO, which in turn affects large scale planetary waves such as Rossby Waves and the jet stream. This is only one of many solar amplification mechanisms described in the scientific literature. 

The authors also provide a new reconstruction of solar activity using the cosmogenic isotope 10Be, which shows a remarkable correlation over relatively short time-scales to ice core temperatures and precipitation: 

d18O [mean of 2 ice cores shown as blue line] is a proxy of temperature and precipitation. 10Be [orange line] is a proxy of solar activity [note 10Be is inversely correlated to solar activity]
Note 10Be concentration at end of 20th century was ~0.6, much less than mean of ~1 from first chart above, indicating solar activity was much greater at end of 20th century than during the last glacial maximum. 

Excerpt explaining the solar amplification mechanism

Climate alarmists such as Jennifer Francis and Heidi Cullen claim man-made CO2 from your SUV is the control knob of Greenland climate, and that increased CO2 causes jet stream dips and record cold weather. However, this new paper and many others provide a much more plausible explanation: it's the Sun. 





Persistent link between solar activity and Greenland climate during the Last Glacial Maximum

Nature Geoscience
 
 
doi:10.1038/ngeo2225
Received
 
Accepted
 
Published online
 
Changes in solar activity have previously been proposed to cause decadal- to millennial-scale fluctuations in both the modern and Holocene climates1. Direct observational records of solar activity, such as sunspot numbers, exist for only the past few hundred years, so solar variability for earlier periods is typically reconstructed from measurements of cosmogenic radionuclides such as10Be and 14C from ice cores and tree rings23. Here we present a high-resolution 10Be record from the ice core collected from central Greenland by the Greenland Ice Core Project (GRIP). The record spans from 22,500 to 10,000 years ago, and is based on new and compiled data456. Using 14C records78 to control for climate-related influences on 10Be deposition, we reconstruct centennial changes in solar activity. We find that during the Last Glacial Maximum, solar minima correlate with more negative δ18O values of ice and are accompanied by increased snow accumulation and sea-salt input over central Greenland. We suggest that solar minima could have induced changes in the stratosphere that favour the development of high-pressure blocking systems located to the south of Greenland, as has been found in observations and model simulations for recent climate910. We conclude that the mechanism behind solar forcing of regional climate change may have been similar under both modern and Last Glacial Maximum climate conditions.




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2 comments:

  1. This summary of the paper was published at ScienceDaily later in the day:

    Sun's activity influences natural climate change

    http://www.sciencedaily.com/releases/2014/08/140818095204.htm

    ReplyDelete
  2. http://wattsupwiththat.com/2014/08/20/unexpected-link-between-solar-activity-and-climate-change-found-in-greenland-ice/

    ReplyDelete