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posted by mrpg on Wednesday March 13 2019, @09:00AM   Printer-friendly
from the SPF50 dept.

The sun is quiet ... very quiet.

In February, for the first time since August 2008, the sun went an entire month without any sunspots.

Sunspots are cooler regions of the sun. How many appear on the sun's surface depends on what cycle the sun is in. Every 11 years our star goes through a maximum, followed by a minimum (the entire magnetic cycle of the sun, when the poles flip, is 22 years).

Over the past three decades, the sun has been consistently dropping in activity. Maximum has been quieter than is typical; minimum has been particularly quiet. And this has caused some to make the false assumption that, as a result, Earth is going to cool.

It all stems from an incident that took place between 1645 and 1715, called the Maunder Minimum, where sunspots all but disappeared. This coincided with the "Little Ice Age" that stretched from 1500 to 1850 in the northern hemisphere. In England, the Thames River froze over; Viking settlers abandoned Greenland.

https://www.cbc.ca/news/technology/solar-activity-1.5049337


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  • (Score: 2, Informative) by Anonymous Coward on Wednesday March 13 2019, @10:40AM (5 children)

    by Anonymous Coward on Wednesday March 13 2019, @10:40AM (#813659)

    He explains that, while the sun does dim during a minimum, it's only by a tenth of a per cent, which translates into a tenth of a degree Celsius. And with the warming by about 1C that we've seen due to climate change — and the warming that is to come — it's unlikely that we'll notice.

    As far as I know there is no one who claims that tenth of a percent dimming is responsible for the "little ice ages", so he is arguing against a strawman. The claim is that the earth's magnetic field is affected by the sun to allow greater cloud formation:

    Over the last twenty years there has been good progress in understanding the solar influenceonclimate. In particular,many scientific studies have shown that changes in solar activity have impacted climate over the whole Holocene period (approximately the last 10,000 years). A well-known example is the existence of high solar activity during the Medieval Warm Period, around the year 1000 AD, and the subsequent low levels of solar activity during the cold period, now called The Little Ice Age (1300–1850 AD). An important scientific task has been to quantify the solar impact on climate, and it has been found that over the eleven year solar cycle the energy that enters the Earth’s system is of the order of 1.0–1.5W/m2. This is nearly an order of magnitude larger than what would be expected from solar irradiance alone, and suggests that solar activity is getting amplified by some atmospheric process. Three main theories have been put forward to explain the solar–climate link, which are:
      • solar ultraviolet changes
      • the atmospheric-electric-field effect on cloud cover
      • cloud changes produced by solar-modulated galactic cosmic rays (energetic particles originating from inter stellar space and ending in our atmosphere).

    Significant efforts has gone into understanding possible mechanisms, and at the moment cosmic ray modulation of Earth’s cloud cover seems rather promising in explaining the size of solar impact. This theory suggests that solar activity has had a significant impact on climate during the Holoceneperiod. This understanding is in contrast to the official consensus from the Intergovernmental Panel on Climate Change, where it is estimated that the change in solar radiative forcing between 1750 and 2011 was around 0.05 W/m2, a value which is entirely negligible relative to the effect of greenhouse gases, estimated at around 2.3 W/m2. However, the existence of an atmospheric solar-amplification mechanism would have implications for the estimated climate sensitivity to carbon dioxide, suggesting that it is much lower than currently thought.

    https://www.thegwpf.org/content/uploads/2019/03/SvensmarkSolar2019.pdf [thegwpf.org]

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  • (Score: 5, Informative) by PiMuNu on Wednesday March 13 2019, @10:59AM (4 children)

    by PiMuNu (3823) on Wednesday March 13 2019, @10:59AM (#813665)

    > at the moment cosmic ray modulation of Earth’s cloud cover seems rather promising in explaining the size of solar impact

    I thought CLOUD experiment at CERN demonstrated this was not the case.

    https://home.cern/science/experiments/cloud [home.cern]

    My understanding was that even Svensmark has accepted that solar cosmic rays are significant but not dominant in climate. Here is a paper:

    http://science.sciencemag.org/content/354/6316/1119 [sciencemag.org]

    Cut n paste of top matter for the lazy (emphasis mine):
    New particle formation in the atmosphere produces around half of the cloud condensation nuclei that seed cloud droplets. Such particles have a pivotal role in determining the properties of clouds and the global radiation balance. Dunne et al. used the CLOUD (Cosmics Leaving Outdoor Droplets) chamber at CERN to construct a model of aerosol formation based on laboratory-measured nucleation rates. They found that nearly all nucleation involves either ammonia or biogenic organic compounds. Furthermore, in the present-day atmosphere, cosmic ray intensity cannot meaningfully affect climate via nucleation.

    • (Score: 2) by PiMuNu on Wednesday March 13 2019, @11:23AM (3 children)

      by PiMuNu (3823) on Wednesday March 13 2019, @11:23AM (#813670)

      I didn't make it clear in parent, Svensmark was not author of paper I quoted, rather it was CLOUD collaboration.

      • (Score: 0) by Anonymous Coward on Wednesday March 13 2019, @11:42AM (2 children)

        by Anonymous Coward on Wednesday March 13 2019, @11:42AM (#813680)

        That document I linked is from 2019 and it cites stuff from 2018 but not that 2016 paper you linked to. He does discuss the CERN CLOUD project on page 13-14 though. I see there he is claiming the effect of the cosmic rays is on the growth of already nucleated particles, not nucleation rates like Dunne 2016 talks about.

        • (Score: 2) by PiMuNu on Wednesday March 13 2019, @12:22PM (1 child)

          by PiMuNu (3823) on Wednesday March 13 2019, @12:22PM (#813688)

          > That document I linked is from 2019

          Interesting. I found this publication by Svensmark et al:

          https://www.nature.com/articles/s41467-017-02082-2 [nature.com]

          referenced from here if you can't see through nature paywall:

          https://scitechdaily.com/how-cosmic-rays-from-supernovae-influence-earths-cloud-cover/ [scitechdaily.com]

          which supports your argument.

          (I am a terrible person so I tend to ignore the "some guy wrote something on the internet" and go for the journal papers instead. I don't believe the journal papers, but at least they have passed someone's credibility threshold and are not cranky nonsense).

          • (Score: 0) by Anonymous Coward on Wednesday March 13 2019, @12:30PM

            by Anonymous Coward on Wednesday March 13 2019, @12:30PM (#813692)

            Svensmark was the author of that document, so if you trust his journal articles to be non-cranky you can trust that as a high level review.