Cold sun rising
Sam Khoury
Special to The Nation November 11, 2015 1:00 am
New studies flip climate-change notions upside down
The sun will go into “hibernation” mode around 2030, and it has already started to get sleepy. At the Royal Astronomical Society’s annual meeting in July, Professor Valentina Zharkova of Northumbria University in the UK confirmed it – the sun will begin its Maunder Minimum (Grand Solar Minimum) in 15 years. Other scientists had suggested years ago that this change was imminent, but Zharkova’s model is said to have near-perfect accuracy.
So what is a “solar minimum”?
Our sun doesn’t maintain a constant intensity. Instead, it cycles in spans of approximately 11 years. When it’s at its maximum, it has the highest number of sunspots on its surface in that particular cycle. When it’s at its minimum, it has almost none. When there are more sunspots, the sun is brighter. When there are fewer, the sun radiates less heat toward Earth.
But that’s not the only cooling effect of a solar minimum. A dim sun doesn’t deflect cosmic rays away from Earth as efficiently as a bright sun. So, when these rays enter our atmosphere, they seed clouds, which in turn cool our planet even more and increase precipitation in the form of rain, snow and hail.
Solar cycles
Since the early 1800s we have enjoyed healthy solar cycles and the rich agriculture and mild northern temperatures that they guarantee. During the Middle Ages, however, Earth felt the impact of four solar minimums over the course of 400 years.
The last Maunder Minimum and its accompanying mini-Ice Age saw the most consistent cold, continuing into the early 1800s.
The last time we became concerned about cooler temperatures – possibly dangerously cooler – was in the 1970s. Global temperatures have declined since the 1940s, as measured by Pacific Decadal Oscillation. The PDO Index is a recurring pattern of ocean-atmosphere climate variability centred over the Pacific Ocean. Determined by deep currents, it is said to shift between warm and cool modes. Some scientists worried that it might stay cool and drag down the Atlantic Decadal Oscillation with it, spurring a new Ice Age. The fear was exacerbated by the fact that Earth has been in the current inter-glacial period for 10,000 years (depending on how the starting point is gauged).
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