Post by nautonnier on Mar 20, 2019 18:34:55 GMT
FORCE MAJEURE
The Sun’s Role in Climate Change
HenrikSvensmark
Executive summary
Over the last twenty years there has been good progress in understanding the solar influ-ence on climate. In particular, many scientific studies have shown that changes in solar activ-ity have impacted climate over the whole Holocene period (approximately the last 10,000years). 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 taskhas 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 1.0–1.5 W/m2.Thisis nearly an order of magnitude larger than what would be expected from solar irradiancealone, 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 particlesoriginating 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 Holocene period. This understanding is in contrast to the official consensus fromthe Intergovernmental Panel on Climate Change, where it is estimated that the change insolar radiative forcing between 1750 and 2011 was around 0.05 W/m2,a value which is en-tirely 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 im-plications for the estimated climate sensitivity to carbon dioxide, suggesting that it is muchlower than currently thought.Insummary, the impact of solar activity on climate is much larger than the official consen-sus suggests. This is therefore an important scientific question that needs to be addressed by the scientific community.
www.thegwpf.org/content/uploads/2019/03/SvensmarkSolar2019-1.pdf
The Sun’s Role in Climate Change
HenrikSvensmark
Executive summary
Over the last twenty years there has been good progress in understanding the solar influ-ence on climate. In particular, many scientific studies have shown that changes in solar activ-ity have impacted climate over the whole Holocene period (approximately the last 10,000years). 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 taskhas 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 1.0–1.5 W/m2.Thisis nearly an order of magnitude larger than what would be expected from solar irradiancealone, 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 particlesoriginating 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 Holocene period. This understanding is in contrast to the official consensus fromthe Intergovernmental Panel on Climate Change, where it is estimated that the change insolar radiative forcing between 1750 and 2011 was around 0.05 W/m2,a value which is en-tirely 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 im-plications for the estimated climate sensitivity to carbon dioxide, suggesting that it is muchlower than currently thought.Insummary, the impact of solar activity on climate is much larger than the official consen-sus suggests. This is therefore an important scientific question that needs to be addressed by the scientific community.
www.thegwpf.org/content/uploads/2019/03/SvensmarkSolar2019-1.pdf