The sun's record-breaking sleep is over. Its eternal "pulse," in which it grows brighter and stormier, then dimmer and quieter in an 11-year rhythm, produced a strangely deep "solar minimum" from 2006 to 2009 that surpassed anything ever seen by today's scientists. But it has now ended, and solar storms have returned with a vengeance.
A few weeks ago one of the most spectacular ever noted erupted in our general direction. This new cycle, numbered 24 in a system that began in the 18th century, holds great mystery and ominous threat. Most researchers expect its peak around May 2013, less than two years from now. Here is why we cannot ignore it.
First, scientists for the National Oceanic and Atmospheric Administration recently concluded that human carbon emissions are just one of four factors that determine global temperatures. The others are the presence of major volcanic eruptions, the Pacific El Nino pattern and, lastly, the sun's activity. The past decade's so-called plateau in global warming was almost certainly the result of El Nino being absent, volcanoes being present and the sun being exceptionally dim. Ever-rising carbon dioxide was then working alone to boost our surface heat. Despite this, global temperatures are now so steadily high that even with the recent reduced rate of warming, 2010 and 2005 still managed to join 1998 as the three warmest years ever recorded.
If the upcoming solar max of cycle 24 is normal or robust, and especially if an El Nino follows it two years later (as often happens), then the middle of this decade will be the hottest period since humans arrived on Earth. However, if the upcoming maximum is wimpy, as most solar researchers expect, or if the sun is now entering an extended period of low activity, that is the best thing it could possibly do for us. Such a scenario would mitigate climate change. Essentially, the sun has been buying us time.
But there's much more. A government panel of solar experts convened in 2008 to ascertain the effects of a major solar storm on our electronics and power grid. They agreed that a super-storm would do more than damage and destroy satellites, potentially kill astronauts and halt jetliner flights over the poles by creating high radiation and radio blackouts. It also would disable our power grid and induce damage requiring $1 trillion to $2 trillion in repairs. They concluded that such a "low frequency, high consequence event" is typically ignored -- until it happens.
The last such hyper-storm was in 1921, when the New York Central Railroad was knocked out of operation, buildings were set aflame and telegraph operations throughout the country were disrupted. That was before we had electronics, pipelines, satellites, GPS, jets flying polar routes, a manned space station or long-distance high-voltage power lines.
In the solar-max year of 1989, a lesser solar storm plunged one quarter of Canada's population into darkness. While new solar-monitoring satellites have greatly increased our knowledge since then, our electrical grid has grown larger, more complex and more vulnerable. Moreover, we've become reliant on satellites and electronics that can be downgraded or disabled by such an event.
For all these reasons, the growing violence on the sun is not some distant abstract affair that we can enjoy through its generation of the beautiful Northern Lights, which will indeed become periodically spectacular during these next five years. Rather, our economic health and our climate very much depend on what the sun will do during this newly born cycle 24 -- whose behavior is still very much unknown.
Bob Berman of Woodstock is the astronomy editor of the Old Farmers Almanac and a contributing editor of Astronomy magazine. He is the author of "The Sun's Heartbeat -- And Other Stories from the Life of the Star that Powers Our Planet," published this month by Little, Brown.