Magnetic forces result in sunspots (photo courtesy of Rutgers)

Magnetic forces result in sunspots (photo courtesy of Rutgers)


Do Sunspots Contribute to Global Warming?

by Kristina G.

If you could look at the Sun through a small solar-filtered telescope, you would most likely see small, dark blotches speckled across its surface. Over a few hours or days, these sunspots—which can be several times the size of Earth and usually travel in groups—appear to slowly churn across the Sun’s equator. While observed for centuries, sunspots have recently been highlighted in the media for their possible connection to global warming. So what are sunspots, and might they be responsible for climate change?

Like other stars, the Sun is made up of dense gases and plasma that swirl together, creating complex magnetic interactions. Sunspots are knots of magnetism that block the Sun’s core energy, compelling the energy to eke out from sides of the spots. This obstruction of energy makes sunspots cooler than the rest of the Sun’s surface (6,700-7000 degrees Fahrenheit instead of 10,000 degrees) which is why they appear darker. The Sun’s magnetic forces strengthen and weaken in a roughly 11 year cycle, the peak of which can see anywhere from 100 to 200 spots, while the low corresponds to only a handful. 

The Sun also burns more intensely during times of heightened magnetic activity. During these peaks, sunspots arise in myriad clusters and explosions occur that are more violent than any nuclear blast or volcanic eruption on Earth. This magnetic activity douses Earth with radiation, damaging satellites and disrupting power grids. Scientists theorize that this energy surge may also affect Earth's weather in complex, indirect ways and potentially play a part in global warming.

Aside from the 11 year flux, the Sun also has longer cycles—that vary over centuries or potentially millennia —of changing magnetic intensity, but these patterns are not yet well understood. Scientists have found that at several points during history sunspots seem to correlate to weather. During the “Little Ice Age” (roughly between 1500-1800), sunspots were unusually low for several cycles and so too were global temperatures.  In some places it was so cold Venice's canals, the Thames River, and the New York Harbor regularly froze. 

Even though the scarcity of sunspots and low temperatures occurred at the same time, no one is sure how or to what extent the Sun's cycles influenced Earth's weather.  Most scientists agree, however, that the human-induced increase of carbon dioxide plays a bigger role than the Sun in today's climate shift.

So while sunspots are not the direct cause of anything, they may be harbingers of climate change. Until scientists better understand the Sun's magnetic cycles, their effect on Earth's weather will remain mysterious and controversial.