Life on Earth revolves around the sun. When science shows that the sun is going through changes — like the recent solar minimum, or a period of decreased activity on the sun — it leaves the average person scratching their heads as to whether they should be concerned about their solar panels, their crops and even the climate at large.
But scientists say that the sun’s activity is believed to have minimal impact on Earth’s environment and the climate.
The sun is an active celestial body, with solar flares and sunspots peppering the surface. W. Dean Pesnell, project scientist of NASA’s Solar Dynamics Observatory, explained that the sun goes through 11-year cycles of high to low activity. During times of decreased activity known as the solar minimum, sunspots — fleeting cool patches on the sun that are caused by changes in its magnetic field — and solar flare activity diminishes.
“We just ended [a solar minimum] last year,” Pesnell said. “It’s just a regular cycle of a lot of sunspots and then a few sunspots and back to lots of sunspots. We see them all the time, and we have a 400-year record of them.”
The “grand solar minimum,” occurs when several solar cycles exhibit lesser than average activity for decades or centuries.
That’s something conspiracy theorists, particularly those looking to find explanations for the changing climate other than human-caused emissions, have grasped onto. But science debunks their nonscientific theories.
While the sun has been in a steady decline of solar activity over the past few decades, it isn’t in a grand solar minimum currently, according to Pesnell. Even if it was, scientists predict the outcome would only result in a degree Celsius or so of cooling, which would hardly put a dent in the warming attributed to human activity.
“We had a peak in 1957 and ever since the solar activity has gone down even when the peak sunspot number continues to go up,” Pesnell said. “We are lower than we were in 1957 but we are not much lower than average. [As far as] the grand solar minimum, we have not reached that level yet.”
Another common argument by non-scientists is that climate change is just part of the Earth’s natural cycles and will right itself with time. Others connect solar activity to agricultural issues like droughts and extreme rainfall, while arguing that it will cause solar panels to stop functioning.
While Pesnell said that scientists do not fully understand the connection between solar activity and climate, they do know that the sun’s fluctuations have a relatively small impact on the Earth.
“Changes in solar irradiance over the 11-year solar cycle are small — varying by about 0.15 percent — and are estimated to have only a very minor impact on global temperatures compared to the much larger accumulated impact from greenhouse-gas emissions over the past century,” said Sean Birkel, research assistant professor Maine state climatologist at the Climate Change Institute & School of Earth and Climate Sciences at the University of Maine.
Birkel said that some research suggests solar variability can impact atmospheric circulation, most likely from changes in ultraviolet radiation and resultant effects on the stratosphere. However slight that impact may be, though, decreased solar activity is connected to lower temperatures.
Meanwhile, temperatures are on the rise while the amount of solar energy reaching the Earth has slightly decreased, according to Jessica Spaccio, climatologist at the Northeast Regional Climate Center in Ithaca, New York.
“Increased solar energy would warm the layers of Earth’s atmosphere from the outside in, but we have seen an increase in temperatures in the lowest layer of the atmosphere, where we live and most of our weather occurs, because of increasing greenhouse gases,” Spaccio said.
Birkel said that current climate models have already taken solar fluctuations into account — along with other so-called natural forcings like volcanic eruptions — and consistently show that increasing greenhouse-gas concentrations in the atmosphere have driven the rise in global temperatures onward from at least the 1960s.
“There will continue to be year-to-year or even decadal variability, but in projecting decades into the future we should prepare for a warmer climate,” Birkel said. “Climate model simulations with natural forcings only — without increasing greenhouse-gas concentrations — suggest that the climate now would be cooler, more like the early 1900s.”
Pesnell said that many solar minimum “truthers” often find themselves in a “logical bind” trying to explain away climate change with solar cycles.
“You can no longer say that the world is not warming,” Pesnell said. “You’re kind of in a logical bind trying to figure out what’s going on. At this point, the most optimistic person would say if solar activity went away completely we would overcome the current levels [of warming], that’s essentially an impossibility.”
Pesnell worries that despite the scientific evidence, the theories related to the solar minimum will be difficult to dispel.
“It’s a difficult thing to respond to because it’s more of a belief system than it is scientific,” Pesnell said. “The trouble is that you can argue particular points in detail and I had a guy who argued with some meteorological station in northern Michigan that shows it’s getting colder and that meant that the other 4,000 stations that show it’s getting warmer must be wrong. I don’t know how to argue with that.”