Spare me Al Gore and George Bush on Earth Day. The topic is much too important for either junk science or simple answers.

And please no more hysterical articles about the glaciers retreating. Where my house is in Vermont was under a mile of ice around 12,000 years ago.

Last Ice Age (12,000 years ago)

With a few notable reversals, the glaciers have been retreating ever since; get over it. Through most of its history, the earth has not had polar ice caps. Global warming is NOT new and it does predate the BushAdministration (pronounced as one word, please).

Global warming won’t be solved by the Kyoto treaty even if the US joined it and the joinees observed it.

But global warming may be accelerated by burning fossil fuels. On the other hand, we could go into a deep freeze. Worst of all, climate change – real change, not just a gradual creep – could easily happen in our lifetimes. Or not!

It’s all about nonlinear change. Scientists used to assume that change happened at a pretty steady pace. Evolution. Geography. Climate. All stately change over long periods of time. Not! Doesn’t happen that way unless you’re far enough away not to see the messy details.

Continents drift but they do so in lurches called earthquakes. Evolution (probably) happens as sudden punctures of an equilibrium. And the climate lurches violently. In fact, climate is just weather writ large and, not surprisingly, is just as chaotic.

According to Abrupt Climate Change: Inevitable Surprises published by The National Academies Press and available free online: “Recent scientific evidence shows that major and widespread climate changes have occurred with startling speed. For example, roughly half the north Atlantic warming since the last ice age was achieved in only a decade, and it was accompanied by significant climatic changes across most of the globe. Similar events, including local warmings as large as 16°C, occurred repeatedly during the slide into and climb out of the last ice age.”

They’re referring to a very short period at the end of the Younger Dryas event (a pause in the most recent deglaciation). “The most spectacular aspect of the YD is that it ended extremely abruptly (around 11,600 years ago), and although the date cannot be known exactly, it is estimated from the annually-banded Greenland ice-core that the annual-mean temperature increased by as much as 10°C in 10 years,” according to The Earth Institute at Columbia University whose site also contains the chart below.

Now notice something else. After this abrupt event, climate change has been relatively smooth. And it is during this relatively and atypically calm 12,000 years that we humans have built our civilization. No wonder we think that climate change is gradual.

Apparently, climate is now changing more quickly than it has in many thousands if not millions of years. The evidence for this is good although not indisputable because we don’t yet have the means to make exact comparisons between antique evidence of climate change and what we’re seeing today. Certainly the warming trend that has been going on for the last fifteen thousand years or so is continuing if not accelerating. (But it has been known to reverse; ask George Washington’s troops at Valley Forge).

Moreover, carbon dioxide and methane concentrations in the atmosphere are at historic highs (as far as we know). Concentrations of these “greenhouse” gasses are associated with warming periods. What is less clear is how much they are a cause and how much an effect of warming – quite possibly both which causes a feedback loop we may be in today. For example, thawing of tundra releases greenhouse gasses which may then cause more warming and more thawing of tundra.

The melting of glaciers is also a positive feedback loop. The more of the earth that is covered with ice, the more sunlight the earth reflects. The more sunlight the earth reflects, the cooler it is. Conversely, as the glaciers melt, the earth absorbs more solar radiation and gets warmer and melts more glaciers.

What we don’t know is what causes the earth to oscillate between periods of cooling – both long and short term – and periods of warming. We don’t know if we’re at the tipping point of a major change or just in a short term oscillation. We don’t know if human release of hydrocarbons can cause a tipping point. We do know that it wasn’t necessary to have humans around burning things to cause the last abrupt changes – it may be just our ego that makes us think that we’re the cause this time. But we could be!

Chaos theory and the math of nonlinear change (and fractals) tells us that the cause of momentous change doesn’t have to be very large at all. If a butterfly’s wing flapped in China can cause a hurricane in Georgia, a bunch of brand new cars in India could cause global warming – or a new ice age. Or nothing.

Unfortunately, the civilizations we built during a period of relative climate stability are highly dependent on both current climate and current ocean levels – would be surprising if it were otherwise. So any change is likely to be overall for the worse – although a little rain in the desert wouldn’t hurt. If change were as gradual as we are used to, we could probably accommodate it (peacefully might be another question).

If climate change is abrupt as it might be, we’re in a hell of a mess!

This post is already too long so a subsequent one will explore what we might do given that we don’t know whether the pace of global warming since the last ice-age is going to continue accelerating, whether we’re affecting it or not, whether we CAN affect it, and whether we’re in for more heat, more cold, or no more change at all.

What we can’t afford to do is make policy based on hysterical observations that the glaciers are continuing their fifteen-thousand year retreat OR a complacent assumption that things will stay the way humans have always seen them.