The Smart Money: Global Warming and Ice Ages

Posted Tuesday, August 26, 2014 in Analysis

by Gina Hamilton

 

Last winter, in the midst of an unarguably cold winter, it was not uncommon to hear people say things like, “Where’s global warming NOW?” Others argued that (based on erroneous internet information) meteorologists don’t accept human-caused, or anthropogenic, global climate change.  In fact, the vast majority of meteorologists do accept that humans are causing global warming; about 25 percent aren’t sure that climate change is responsible for more severe hurricanes and other weather patterns. 

But there’s a difference between climate and weather, anyway. In global terms, the weather is getting hotter. Dry places are getting drier. Winters are getting milder, generally. Summers are getting warmer.  Sea temperatures are increasing. Since 1901, temperatures worldwide at the surface — both water and land — have risen 1.4 degrees F. Since the late 70s, that rise has accelerated.  Seven of the ten warmest years on record have occurred since 1998, and 2012 was the warmest year on record.

That’s what climatologists see, and what is so alarming to them. They also connect warmer sea surface temperatures in late summer with stronger storm patterns.

To be fair, there are smaller climate changes, too, and those are cyclical in nature. El Nino, La Nina, volcanic eruptions, and other small-scale climate changers affect local climate ... and weather. 

Weather is different. It’s immediate — it is difficult to predict the weather with any accuracy more than a few days out — and it changes from minute to minute. Climate is what we expect to happen — a long hot summer, say ... and weather is what we experience — a hot day with a pop-up thunderstorm.

But both the small scale patterns, such as El Nino, and the larger, global pattern affect local weather, causing massive change to established weather patterns. Remember when your parents lamented about having to walk through three feet of snow (uphill both ways, probably) to get to school? Except for the hill, there is truth to what they said. Winters were snowier and colder in the first half of the century and even beyond, except in some surprising microclimates, such as northern Michigan. It turns out that a single degree of temperature increase makes a huge difference in local weather.

Loss of snowpack and warmer winters have had some effects on the economy we’ve looked at already — pests survive winters and move more readily from place to place, sea levels rise, storms become stronger later in the summer and winter storms are more ferocious.

Over the longer term, the doomsday scenario for us in Maine and for northern Europe, which is at an even higher latitude, involves changes to sea currents, especially the Gulf Stream. The Gulf Stream ferries warm water from equatorial regions to northern regions by both wind currents and warm surface water currents.

The scenario goes like this: As sea ice melts, the less dense and colder freshwater sits atop the denser and warmer sea water. This slows down or weakens the northern gyre part of the Gulf Stream, and could, in theory, even stop it.  This has happened before.  

A slowdown of the Gulf Stream is thought to have been responsible for the “Little Ice Age” in Europe beginning in the late 13th century. While Maine’s inhabitants weren’t leaving written records of the experience, it’s entirely probable that Maine also experienced a period of significant cooling. In Europe — the UK, Ireland, France, and the Nordic countries primarily — suffered crop losses and famine, and wave after wave of serious disease, regularly through the whole period. 

Most recently, measurements in 2004, 2005, 2008, and 2010 suggested a weakening of the Gulf Stream, with up to a 30 percent reduction in warm water currents. No one is sure whether these are caused by the cold water entering the ocean from ice melt or from natural fluctuations owing to increasing El Nino cycles, but so far they do not seem to have the effect that was feared, that is, markedly colder temperatures in Europe. Models of the shutdown show a major difference in temperature in the North Atlantic — between 8 degrees and 14 degrees F — but they are not showing a marked difference in temperature on the land masses. 

Other things that are likely to happen during this kind of event are crashes of the plankton system. Since plankton form the basic food chain for all ocean life, great and small, oceanic mass extinctions would be possible. It would certainly affect fisheries. After the currents die off, the water would become oxygen-depleted locally pretty quickly, leading to more extinctions. 

In the worst case scenario, such an event would cause glaciation over the Northern Hemisphere. Maine could become unable to support life. And this wouldn’t happen over millions of years, or even a decade. Researchers say that these abrupt climate shifts occurred in as little as a few months. Imagine Maine suddenly pulled into the Arctic Circle. Rivers freeze solid, lakes freeze, harbors freeze. The ground becomes permanently frosted at a depth of just a few inches. Large trees can no longer hold the soil and fall over. Even smaller plants are unable to get a toehold. Animals dependent on the forests perish. The smallest photosynthesizers — lichens, bacteria, mosses — may survive if they can obtain enough liquid water. Those that feed on them would have to be small, too, or may be migratory.  Humans and their livestock in Maine and elsewhere in the northern tier of states would probably evacuate for warmer climes. 

The “environmental refugees” would be moving into areas already stressed by drought and barely able to sustain themselves. It’s not difficult to imagine how they would be welcomed. 

It’s beyond economic calculation to determine how the world would be affected by such a calamity. 

Scientists still consider an abrupt climate change unlikely in the next hundred years, and understanding of the phenomenon is a work in progress. But it’s yet one more reason why climate change has to be taken seriously now, while we’re not drowning with six-meter sea level rises or fleeing an ice-covered state. 

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