You are now entering the nonlinearity zone…

By Paul Beckwith

Adapted from a September 28, 2012, post at the Sierra Club Canada blog

Push something and it moves a little. Push it a little more and it moves a little more. This is called a “linearity” response. But sometimes a little push can lead to something totally unexpected! This is called “nonlinearity” and, contrary to what one might think, nonlinearities are inherent in most systems - like our atmosphere, for example. In fact, abrupt and unexpected change happens at some point in most systems - we even have a saying for such unexpected outcomes: a tipping point.

Until recently, our atmosphere and oceans behaved like linear systems: incremental dumping of greenhouse gases into the atmosphere caused incremental changes, like rising temperatures and predictable rates of ice melt. But things are now changing unexpectedly fast – nonlinearity is kicking in! We only have to look at the rapidly vanishing arctic icecap for astonishing evidence.

A few years ago, I felt compelled to leave my previous pursuits in Engineering Physics (and chess master) to begin a PhD thesis focusing on abrupt climate change. I felt the planet’s climate was approaching several tipping points and analysis of Paleoclimatology records (tree rings, ice cores, ocean sediment, etc.) may provide evidence on what tipping points – nonlinearities – we might expect to see first (and maybe prevent).



Sadly, I’m late to the game. The rapidly disappearing Arctic icecap is a tipping point in motion. In all likelihood, statistically speaking, it’s gone, history. Within a few years when the ice disappears entirely, for the first time in 3 (or as many as 13) million years, hold on because our weather patterns will be drastically destabilized. Most folks in my field are still reluctant to acknowledge this 800 pound gorilla staring us right in the face.

Image credit: Sam Carana in Methane in the Arctic 

Methane, an extremely potent greenhouse gas (105 times more efficient at trapping heat in the atmosphere than carbon dioxide over 20 years, see image left) is a product of ancient wetlands, locked in permafrost and ocean sediments for millions of years. Today, warming air and seawater causes methane to be released more quickly. In the ocean off Siberia, methane plumes greater than one kilometre in diameter have been observed. Shocking stuff in my business.

And other tipping points abound. If the melting Arctic icecap isn’t bad enough, how about persistent droughts turning the Amazon rainforest into dry savannah? Much of the forest would burn first, delivering the double whammy of massive carbon emissions and the loss of a vital carbon sink.

Or how about collapsing boreal forest ecosystems. In Canada, drought-stressed trees, not already under attack by mountain pine beetles and emerald ash borers, would surely burn in the new norm of arid heat waves.

Perhaps the Greenland ice sheet will be the ultimate smoking gun. It contains enough water to raise global sea level by seven metres. With melt rates doubling every few years, knowing what I know, I can honestly say I am gravely concerned. Many models predict Greenland’s ice sheet will be ‘ok’ for another 3 centuries, but as I wrote in my last blog, you can officially pitch those models out the window.

Unlike our ancestors, humanity has a shot at stopping this – that is, if we throw everything we have at it. But we need to urgently focus on doing two things: radically reduce carbon emissions and prevent further warming of the Arctic Ocean; and keep as much methane locked underground as possible (we have the technology to do this today).

We have officially entered the realm of unknown-unknowns; the nonlinearity zone.

The question is will politicians reach the tipping point of reason?

Posted with author's permission. Earlier posted at Sierra Club Canada. Paul Beckwith is a PhD student with the laboratory for paleoclimatology and climatology, department of geography, University of Ottawa.