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Claim: The sun controls the climate and the solar cycles Bray and Eddy are causing climate change.
Fact: Misinformation. Evidence suggests solar cycles are not causing recent climate change.
Claim post:
What does the post say?
A viral twitter post by the handle @ClimateCraze has a caption that says, “The sun controls our climate. This graph only shows the Bray and Eddy solar cycles. They are just two of several sun-driven cycles controlling climate. They all overlap in a complex dance called climate change.”
The post has called the climate change issue a #ClimateScam
What we found?
The post shows a graph of solar cycles and the time frame depicting that they are the cause of climate change. Scientists, including Hale Prize winner Prof. Sami Solanki, deny the fact.
What are solar cycles? How are solar cycles connected to Earth’s climate?
The entire Sun is a giant magnet from the North to the South Pole. The magnetic fields of the Sun are constantly shifting, and the north and south magnetic poles alternate roughly every 11 years. The poles will reverse after 11 more years. Total solar irradiance is the sum of all solar radiation, waxes, and wanes in a semi-regular cycle by up to 0.15% between flips. The short-term variations in solar irradiance are not significant enough to affect Earth’s climate over the long run.
The image shows incoming solar irradiance on earth.
Climate models incorporate information about solar brightness variations along with a range of other natural and man-made effects because these variations, which occur over decades or centuries, may have an impact on Earth’s climate system.
The Hallstatt (or Bray) cycle is thought to be associated with long-term solar variations, specifically related to changes in solar irradiance. This cycle refers to a proposed climatic cycle with a periodicity of approximately 2,300 to 2,400 years. The 976-year Eddy cycle, also referred to as the millennial cycle, is one of the most constant solar periodicities reported.
It is believed that these variations in solar activity may influence Earth’s climate over extended periods.
Scientists from NASA believe that the current changes in Earth’s climate cannot be primarily attributed to the solar cycle and its associated short-term variations in irradiance. One reason is that, over the course of the cycle, the Sun’s energy output only varies by up to 0.15%, which is less than what would be required to drive the shift in temperature that we observe. Additionally, there is no convincing evidence that the 11-year cycle is reflected in any climate features that are not related to the stratosphere, such as surface temperatures, rainfall, or wind patterns.
Can the current change in Earth’s climate be attributed to changes in solar irradiation throughout centuries?
While humans have observed the solar cycle by observing the rise and fall of magnetically active sunspots, which can be used to estimate longer-term changes in solar irradiance, since the beginning of the 1600s, there have only been highly accurate, space-based measurements of solar irradiance since 1979. Prior to that, ice core and tree ring data provide inferred measurements of solar activity.
These longer-term data points point to the possibility of significant cycle variation. In fact, there were essentially no sunspots observed during the Maunder Minimum, which lasted from 1645 to 1715. Even if the total irradiance hasn’t changed much over the past 35 years of space-based studies, anomalies like this one demonstrate that the magnetic activity and energy output from the Sun can fluctuate over decades. The magnitude of Solar Cycle 24, which started in December 2008 and is anticipated to finish in 2020, was less than that of Solar Cycles 20 and 21.
The image shows the Sun’s magnetic field.
The potential impact of long-term patterns in solar cycles on the Earth’s climate has been subject to numerous estimations. Computer simulations predict that the Earth’s average temperature would alter if the Sun’s irradiation changed over a long period of time. There is some evidence for solar-cycle-related regional enhancements of the effects in the North Atlantic and surrounding regions, even though the magnitude of those changes would probably be small – around a couple of tenths of degrees in the global mean.
Could the change in Earth’s climate observed over the past 35 years be attributed to long-term variations in the Sun’s energy output?
No. The majority of the last 35 years of space-based observations have not detected significant variations in the Sun’s energy output. Nevertheless, while examining climate change, scientists take into account all the factors they can, including solar variations. According to these projections, a modest drop in solar irradiance over the past 35 years would have resulted in a slight cooling of the climate over this time, but only in the absence of additional climate-altering factors.
The concept that variations in the Sun constitute a significant driver behind the current climate change is likewise not supported by the physics of the situation. The high atmosphere of Earth is most affected by the Sun’s irradiance, whereas the lower atmosphere protects Earth from the added heat. It would be reasonable to anticipate that the higher atmosphere would warm up more if the Sun were the primary driver of Earth’s warming. As opposed to this, observations reveal that the high atmosphere is becoming colder while the lower atmosphere is becoming hotter. Instead, this closely resembles the alterations brought on by a rise in carbon dioxide.
Fact check story
By Aayushi Sharma
References:
- https://www.nasa.gov/mission_pages/sunearth/solar-events-news/Does-the-Solar-Cycle-Affect-Earths-Climate.html
- https://link.springer.com/article/10.1007/bf01884410
- https://euanmearns.com/periodicities-in-solar-variability-and-climate-change-a-simple-model
- https://history.aip.org/climate/solar.htm
- https://www.sciencedirect.com/science/article/abs/pii/B9780444883513500337
- https://www.researchgate.net/publication/227716894_Solar_variability_and_climate_change_Is_there_a_link
- https://www.space.com/32278-sun-magnetic-field-sdo-image.html
