More on Climate Inertia

HMAS Melbourne post Voyager collision

I confess that as a non-scientist the principle of inertia is one aspect of climate change I have had trouble coming to grips with. I remember in my last science classes at school the master posing the question at the beginning of each lesson ‘What is inertia?’ A question I clearly remember because of the enthusiasm of the teacher. Recently I used the example of the Titanic tragedy as an analogy for climate change inertia.

I could as easily have used the collision between our naval ships Melbourne and Voyager. The captain of HMAS Melbourne realised the collision was inevitable almost a minute before the collision occurred. This was in spite of every action and manoeuvre that both ships made to avoid it. The movement of ships is a popular analogy for inertia in the climate system with the sceptical science website using that of a supertanker trying to avoid a collision.

They note “The climate system also has a tremendous amount of inertia built in. And like with the supertanker, this means that early action is required if we want to change the climate’s course. This inertia is a crucial aspect of the climate system, both scientifically but also societally – but in the latter realm it’s a very underappreciated aspect. Just do a mental check: when did you last hear or read about the climate’s inertia in mainstream media or from politicians?”

The simplest definition of inertia is that it is ‘a property of matter by which it continues in its existing … uniform motion in a straight line’. The inertia in climate systems is defined by Wikipedia thus: “Inertia means a delay, slowness, or resistance in the response of climate, biological, or human systems to factors that alter their rate of change, including continuation of change in the system after the cause of that change has been removed.”  Wikipedia further noted the lags and delays in particular components of the climate system – in particular the thermal inertia of the oceans which in turn leads to the inertia of the ice melt of the poles.

The implications are clear. If CO2 and other greenhouse gases cannot be cut back then all aspects of the climate will continue warming. Even if we could somehow instantly stop greenhouse gas emissions the earth will continue to warm for hundreds of years.  Three million years ago when CO2 levels were last over 400ppm the earth was at least 2 degrees warmer and sea levels were about 25m higher. But civilisation may collapse well before this, perhaps even before sea levels have risen by little more than a metre, with heatwaves, droughts, and food scarcity causing mass movements of refugees.

Global warming is already causing large numbers of climate refugees most noticeably following the Syrian civil war and the failure of Honduran food crops – both after severe droughts. The movement of Syrian refugees has spawned an anti-immigration political reaction in Europe. Somewhat ironically it is these same political parties that deny or ignore climate science. Their reaction and the impetus of climate inertia means that humanity is in for a very rough ride. And this is only the beginning. Meanwhile we await the first climate emergency declaration in Gippsland.