Getting to the point, sooner or later

Graham Saunders
A version of this article was first published in Weather Whys in the Thunder Bay Chronicle-Journal on July 16, 2006

The term "tipping point" is now in vogue in some media news reports of climate change.

The idea comes from the concept of "attractors" in chaos mathematics. In most non-linear systems, as weather and climate certainly are, a change produces small effects at first but eventually, the system can flip and go rapidly into another state, or attach to another attractor.

Speculation about a shut-down of the Gulf Stream is an ominous example. A halt in this massive heat transfer from the tropics to the higher latitudes would, in theory, initiate an ice age in the worst-case scenario.

I am not a big believer in this one, though it made an exciting movie - "The Day After Tomorrow".

In Al Gore's documentary, "An Inconvenient Truth" he discusses a number of dangers human society faces because of climate change, and suggests urgent actions to avoid tipping points.

Positive feedback loops that increase greenhouse gases entering the atmosphere pose the greatest danger.

An example is what is happening in the Canadian Arctic. Warmer temperatures have reduced the amount of ice coverage and duration of snow on the ground. More solar radiation is absorbed by the Arctic Ocean and the land area. This results in more warmth, hence more melting.

More evaporation from open waters and warmer air mean more water vapour - a powerful greenhouse gas (GHG) - in the atmosphere. These two loops reinforce each other.

Usually "tipping point" is used to suggest a point of no return. It is likely that this point is relatively close for polar bears. They depend on ice for movement and hunting. Less ice means less food, poor health and reduced reproduction. Many people with expertise are predicting that these boars will only live in zoos, not the Arctic, within 20 or 30 years.

A closer feedback is located in our own Northwest region. The Hudson Bay Lowlands have permafrost and a belt of discontinuous permafrost extends well south of this. As these areas thaw, it is likely that methane, a potent GHG, is released into the atmosphere in major amounts.

Permafrost extends around the Northern Hemisphere and the Northwest has a small fraction. However, it is estimated that nearly twice as much methane is contained in permafrost as there is in all the world's natural gas fields.

Some ecosystems are more vulnerable to tipping points that others. Polar regions have relatively simple food chains and interdependencies. Change in these connections is likely to bring more disruptions, sometimes extinctions, than many southern areas with more diversity.

Points of no return

Dr. Jim Hansen, who directs NASA's Goddard Institute for Space Studies, ignored the Bush Administration's attempts to muzzle him earlier this year. He stated that it was probable that only 10 years remained in which serious actions could be taken to avoid "dangerous anthropogenic interference" on climate. He described this as a tipping point. Drastic reductions of emissions, according to Jim Hanson have to begin immediately, not 2016, to reduce dangerous interference.

Jim Hanson skills and his risk-taking need to be considered when assessing his predictive warning. Of course, it is an estimate and could be alarmist by a few years. On the other hand, we look back and complain that he was an optimist.

The 10-year limit is not an easy task or a likely scenario. Now it has become more problematic with the Harper government adopting the Bush Administration cavalier policies of rejecting international commitments in favour of volunteer efforts.

Steve and Georgie: It really is about time to understand the point.