Joe Bastardi of Accuweather has a more complete set of reasoning on why the cooling could be worse than anyone is anticipating.
Triple Crown of global cooling could pose serious threat to humanity
http://www.examiner.com/x-32936-Seminole-County-Environmental-News-Examiner~y2010m5d19-Triple-Crown-of-global-cooling-could-pose-serious-threat-to-humanity
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“There are some wild cards that are different from what we saw when we came out of the last warm PDO [Pacific Decadal Oscillation] and entered its cool phase [1947 to 1976]. Now we have a very weak solar cycle and the possibility of increased volcanic activity. Together, they would create what I call the ‘Triple Crown of Cooling,’” says Accuweather meteorologist Joe Bastardi.
If all three climate-change ingredients come together, it would be a recipe for dangerously cold temperatures that would shorten the agricultural growing season in northern latitudes, crippling grain production in the wheat belts of the United States and Canada and triggering widespread food shortages and famine.
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And the Sun is going to play an important role in all this
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Declining solar activity
Another real concern – and the second climate driver in the Triple Crown of Cooling – is the continued stretch of weak solar activity Earth is experiencing. We recently exited the longest solar minimum –12.7 years compared to the 11-year average – in 100 years. It was a historically inactive period in terms of sunspot numbers. During the minimum, which began in 2004, we have experienced 800 spotless days. A normal cycle averages 485 spotless days.
In 2008, we experienced 265 days without a sunspot, the fourth-highest number of spotless days since continuous daily observations began in 1849. In 2009, the trend continued, with 261 spotless days, ranking it among the top five blank-sun years. Only 1878, 1901 and 1913 (the record-holder with 311 days) recorded more spotless days.
In 2010, the sun continues to remain in a funk. There were 27 spotless days (according to Layman’s sunspot count) in April and, as of May 19, 12 days without a spot. Both months exhibited periods of inexplicably low solar activity during a time when the sun should be flexing its “solar muscle” and ramping up towards the next solar maximum.
Why are sunspot numbers important? Very simple: there is a strong correlation between sunspot activity and global temperature. During the Dalton Minimum (1790 - 1830) and Maunder Minimum (1645 -1715), two periods with very low sunspot activity, temperatures in the Northern Hemisphere plummeted.
During the Dalton Minimum, the abnormally cold weather destroyed crops in northern Europe, the northeastern United States and eastern Canada. Historian John D. Post called it “the last great subsistence crisis in the Western world.” The record cold intensified after the eruption of Mount Tambora in 1815, the largest volcanic eruption in more than 1,600 years (see details below).
During the 70-year Maunder Minimum, astronomers at the time counted only a few dozen sunspots per year, thousands fewer than usual. As sunspots vanished, temperatures fell. The River Thames in London froze, sea ice was reported along the coasts of southeast England, and ice floes blocked many harbors. Agricultural production nose-dived as growing seasons became shorter, leading to lower crop yields, food shortages and famine.
If the low levels of solar activity during the past three years continue through the current solar cycle (Solar Cycle 24), which is expected to peak in 2013, we could be facing a severe temperature decline within the next five to eight years as Earth’s climate begins to respond to the drop-off in solar activity.
“The sun is behaving very quietly – like it did in the late 1700s during the transition from Solar Cycle 4 to Solar Cycle 5 – which was the start of the Dalton Minimum,” D’Aleo says. If the official sunspot number reaches only 40 or 50 – a low number indicating very weak solar energy levels – during the next solar maximum, we could be facing much lower global temperatures down the road.”
Even NASA solar physicist David Hathaway has said this is “the quietest sun we've seen in almost a century.”
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If you can’t model the past, where you know the answer pretty well, how can you model the future? - William Happer Cyrus Fogg Brackett Professor of Physics Princeton University