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Posts Tagged ‘Climate system’

[This post received the 1st award by the Fundación Biodiversidad (2011) on Climate Change Communication, category: blogs]

Titanic

The Titanic system on the brink to experience a perturbation higher than its resilience

The Earth’s climate is the result of the interaction of several different components affected not only by the greenhouse effect but also by the influence that this effect has on its diverse components. We are looking at a system composed of different subsystems, each one with its own way of responding to the perturbations it undergoes. If we were able to know, mathematically, the laws of behavior (equations) of those subsystems, and the (mathematical) equations governing the mutual interrelations between those subsystems, the application of the (mathematical) laws from systems theory would allow us to know (mathematically) the behavior of the whole system: the climate system.

These effects of a component which, in turn, cause perturbations to another component to which it is related (for instance, the diminishing extent of white ice uncovers darker ocean or terrestrial areas: they reflect much less sunlight, so the new surfaces warm much more than if the greenhouse effect was acting alone without this added forcing) are a characteristic of feedback systems. It can be (mathematically) showed that these kinds of systems exhibit, in their operation, some behaviors that aren’t intuitive at all:

  • A delay between the effect and the cause
  • Exponential behavior (non proportional)

A very particular trait of the climate system, moreover, is its very slow evolution when compared to our atavist modes of planning and reaction.

The ‘systemic’ analogy between the Earth’s climate dynamics and the famous ship Titanic seems to me very useful in assessing the behavior of a feedback system when it is forced by a perturbation that exceeds its robustness. The film, directed by James Cameron in 1997, has the virtue of being the second highest-grossing film of all time, so the metaphor can be significant for most people.

Some of the analogies one can establish are described next:

We can think of the system Titanic + ocean as an analogy of the Earth’s climate system.

We can think of the Titanic as a ship generally considered unsinkable, in the same fashion humans, at least in their great majority, suffer from the prejudice that the climate system is always stable.

We can, also, imagine that the capacity for resistance (‘resilience’, ‘robustness’) of those systems is being forced. In the case of the Titanic, the captain, Edward John Smith, accepts to force the engines, setting the maximum speed as the cruise speed. In the climate system, this forcing is termed ‘radiative’ and, to our knowledge, we are forcing it at a speed never before experienced in the planet’s geological history.

We can also suspect the motives for this kind of behavior. The Titanic forced its engines and structure to break the crossing’s speed record; we humans, in forcing the Earth radiatively, are swiftly generating, through our unbridled consumption, weatlh standards (wellbeing?) never reached before.

The Titanic, given its inertia (and excessive speed), can’t avoid the killer iceberg despite having spotted it minutes earlier. The Earth also has its inertia: even if we took dramatic measures today to reduce, or even eliminate, all harmful emissions, it would take at least decades before the levels of greenhouse gases cease to force the climate. And centuries, more likely millennia, before the climate system could return back to the stable state as we know it.

The forcing intensity is one of my preferred analogies. In the Titanic, after the collision with the iceberg and the damage report in hand, Thomas Andrews, the chief engineer, reports, in dismay, to the captain:

Water… fourteen feet above the kill in ten minutes …  in the forepeak, in all three holds and in boiler room six … That’s five compartments. She can stay afloat with the first four compartments breached, but not five. Not five! As she goes down by the head … The water will spill over the tops of the bulkheads, from one to the next .. back, and back. There’s no stopping it … The pumps buy you time, but minutes only … From this moment, no matter what to do, Titanic will founder.

Andrews stares at the ship constructor, who had commanded to run at maximum speed convinced that… this ship can’t sink!

– She’s made of iron, sir. I assure you: she can! And she will! It is a mathematical certainty.

El ingeniero jefe del Titanic, Thomas Andrews informa, consternado, al armadorIf only four cabins had been flooded, Andrews could have managed to block the water flow or to set up an emergency team to, at least, pump out an amount equal to that of the incoming water. But being five the cabins affected, this solution turned out to be impossible.

The system’s stability threshold had been exceeded, a point of no return had been crossed. The system had lost its equilibrium and it was no longer possible, from the ship, to maintain or re-establish its equilibrium on the water. The threshold had been crossed beyond which any incoming water had such an effect as to cause, in turn, a yet greater amount of incoming water. One of those effects-cause is, for instance, the ship’s increasing inclination.

In the Earth’s climate system something similar occurs. Once atmospheric greenhouse gas concentrations cross a certain threshold, the Earth ”ship” triggers mechanisms that are beyond human control. Those mechanisms prompt, in turn, an even higher increase of the greenhouse gas concentration, and so on. It’s the effect commonly known as vicious circle, technically called positive feedback.

The greater the GHG concentration, the greater the Earth’s average temperature and, beyond a certain point, this implies more GHG emissions. Not only anthropogenic but also ‘natural’ emissions, now from the Earth itself, the latter due to the interaction of the climate system with the carbon cycle.

It is not possible to know the precise GHG concentration that will move/push us past the point of no return, although we know we are (at least) approaching its value and that, either we have already gone beyond it, or we are on the brink of doing so very soon. When?

We find a new, slightly bloodier, analogy in the response time of both systems. In the Titanic:

How long? – asks the captain, dismayed -. “One hour. Two at most.” – answers Andrews.

From the impact with the iceberg and the flooding of the fifth cabin, to the complete sinking of the ship – and new stabilization on the seafloor – some time elapses. Two hours, at most. Again, some time elapses between the moment when the GHG concentration exceeds the critical threshold, the climate system enters the instability zone and the Earth finds a new stable state, very different from the present: undoubtedly, an unrecognizable planet. Of course, much less hospitable.

Through the Titanic we can also grasp what a system’s exponential behavior means. At the start, we get the impression the ship capsizes in a proportional way with respect to the time since the perturbation. But later, the acceleration of the sinking phenomenon becomes evident. In the case of the Earth, always with average values formally measured, from 1850 to 2000 the temperature rise has also been roughly proportional.

Nevertheless, this is a false impression. Going back decade upon decade we find a slightly slower evolution, except in the aftermath of World War II. Sure enough, for many years the lack of regulation to coal-fired power plants allowed a continuous emission of solid particles (aerosols). Some of those particles partially intercept the solar flux, causing a temporary cooling and thus mask the background warming in process. In fact this effect still remains nowadays. It is known as ‘global dimming’.

An (almost) last analogy can be established concerning the individuals. On the Titanic, a well-informed minority knew very soon what would happen. They had the knowledge that, mathematically, the Titanic would sink. The rest of the passengers were in the party. The first to be informed were the elites, the first-class passengers. On Earth, no doubt the elites, well-informed by the scientific community (which is analogous to the Titanic’s chief engineer) do know it, even if some of them have been resistant to believe this level of alarm and some still don’t want to believe it.

Those who don’t believe it at this point in time do so because they are simply unable to. They are prisoners of their ideology which prevents them from abjuring some prejudices they hold unshakable: self-regulating markets, minimal government to avoid disturbing corporations, literal faith in the Bible, a myriad of atavisms… Not to forget those who do know it but live on merrily pretending they don’t: remember some radio and TV lunatics.

I said it was ‘almost’ the last analogy, but only for one reason. We arrived, in this metaphor, to the present time. I let the reader imagine analogies to come: what is the meaning of the lifeboats and its number, or whether the Titanic had too much passengers. What happens when a lifeboat can hold more people but they can’t be admitted out of fear everyone will show up, even those who already considered themselves saved? What analogy can the reader establish about the distant ship which was asked for help, but was too distant to avoid the death of the majority of passengers?

Una hora. Dos, como muchoBut… wait a moment.

Why did the chief engineer say: ‘one hour… two at most?’ Why didn’t he specify an exact figure in order to plan with higher precision? That’s because the scientific calculus and method generate truths, but some margin of uncertainty always remains for at least one variable (even if it can be limited within margins of probability, often approaching virtual certainty); especially when dealing with predictions. Andrews delimited the uncertainty: One hour. Two at most. And so it was.

Make no mistake: if everything continues business as usual, the Earth sinks. Completely. We are left with the uncertainty to know when. Something we already know: the crash with the iceberg has happened. To sink: 20-30 years, 50 at most for a monumental collapse. The Climate Crunch, The Perfect Storm. Some respected voices announce, at the end of the century, a survival of just 5% of human beings, living near the poles.

To know what this uncertainty margin is, follow this blog. Science isn’t settled on this particular point, but never before has this amount of effort and resources been applied to scientific research as today in the field of global warming. Tens of thousands of people, fully qualified, all over the world, are working hard on it, with a sense of urgency hard to describe. The challenge is immense. What’s at stake, precisely, are you and me. And billions more.

Acknowledgement

Special thanks to climate activist Arne Perschel for his unvaluable revision of my Spanish to English translation and the suggestions that improved the text.

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