Flashback to 2009: Researchers Say Sun Cycle Alters Earth’s Climate

Variation in solar activity during a recent sunspot cycle [credit: Wikipedia]

This seems worth another airing in the face of today’s insistent, but evidence-light, claims from climate obsessives that the world’s present and future weather is going to be largely determined by human activities.

If the energy from the sun varies by only 0.1 percent during the 11-year solar cycle, could such a small variation drive major changes in weather patterns on Earth? – asks Universe Today.

Yes, say researchers from the National Center for Atmospheric Research (NCAR) who used more than a century of weather observations and three powerful computer models in their study.

They found subtle connections between solar cycle, the stratosphere, and the tropical Pacific Ocean that work in sync to generate periodic weather patterns that affect much of the globe.

Scientists say this will help in predicting the intensity of certain climate phenomena, such as the Indian monsoon and tropical Pacific rainfall, years in advance.

“The Sun, the stratosphere, and the oceans are connected in ways that can influence events such as winter rainfall in North America,” says NCAR scientist Gerald Meehl, the lead author. “Understanding the role of the solar cycle can provide added insight as scientists work toward predicting regional weather patterns for the next couple of decades.”

The new study looked at the connection between the Sun’s impact on two seemingly unrelated regions. Chemicals in the stratosphere and sea surface temperatures in the Pacific Ocean respond during solar maximum in a way that amplifies the Sun’s influence on some aspects of air movement. This can intensify winds and rainfall, change sea surface temperatures and cloud cover over certain tropical and subtropical regions, and ultimately influence global weather.

The team first confirmed an earlier theory, that the slight increase in solar energy during the peak production of sunspots is absorbed by stratospheric ozone. The energy warms the air in the stratosphere over the tropics, where sunlight is most intense, while also stimulating the production of additional ozone there that absorbs even more solar energy.

Since the stratosphere warms unevenly, with the most pronounced warming occurring at lower latitudes, stratospheric winds are altered and, through a chain of interconnected processes, end up strengthening tropical precipitation.

At the same time, the increased sunlight at solar maximum causes a slight warming of ocean surface waters across the subtropical Pacific, where Sun-blocking clouds are normally scarce. That small amount of extra heat leads to more evaporation, producing additional water vapor.

In turn, the moisture is carried by trade winds to the normally rainy areas of the western tropical Pacific, fueling heavier rains and reinforcing the effects of the stratospheric mechanism.

The top-down influence of the stratosphere and the bottom-up influence of the ocean work together to intensify this loop and strengthen the trade winds. As more sunshine hits drier areas, these changes reinforce each other, leading to less clouds in the subtropics, allowing even more sunlight to reach the surface, and producing a positive feedback loop that further magnifies the climate response.

These stratospheric and ocean responses during solar maximum keep the equatorial eastern Pacific even cooler and drier than usual, producing conditions similar to a La Nina event. However, the cooling of about 1-2 degrees Fahrenheit is focused farther east than in a typical La Nina, is only about half as strong, and is associated with different wind patterns in the stratosphere.

Earth’s response to the solar cycle continues for a year or two following peak sunspot activity. The La Nina-like pattern triggered by the solar maximum tends to evolve into a pattern similar to El Nino as slow-moving currents replace the cool water over the eastern tropical Pacific with warmer water.

The ocean response is only about half as strong as with El Nino and the lagged warmth is not as consistent as the La Nina-like pattern that occurs during peaks in the solar cycle.

Full article here.