Climate forcing and the threats of feedback mechanisms

While we tend to plan for the future based on current climate inputs and observations, we should also look ahead and take into consideration the dramatic turn of events that could result from positive feedback mechanisms.

A brief overview of feedback mechanisms

Feedback mechanisms are processes which are the direct consequences of other events. Basically, there are two types of feedbacks: positive feedbacks which amplify the on-going trends and negative feedbacks which soften them. As an illustration, two examples of simple feedback mechanisms are given below:

Positive feedback: The warmer the climate (e.g. heat waves), the more energy we consume (e.g. air conditioning), the more GHGs are emitted and therefore the warmer the climate will get. We tend to forget that human behaviour in response to a changing world is in fact a powerful feedback mechanism.

Negative feedback: The warmer the climate; the more water vapour in the atmosphere at any given time; the more clouds which have white surfaces reflective of incoming solar radiations; the cooler the temperatures. Note however that water vapour is also a strong greenhouse gas and therefore also has a positive feedback effect.

Natural equilibrium versus destabilisation

Over billions of years of Earth history, the planet has been subject to a series of dramatic events. In between such events, systems on Earth have reached equilibriums which are governed by closed loop systems and a balance between positive and negative feedback mechanisms.

The current trend however is for human activities to modify some of these natural equilibriums by increasing disorder in the Earth systems.

Many signs of upcoming changes from positive feedbacks are already highly noticeable and measurable (e.g. release of methane gas from the melting permafrost; sea ice melt exposing darker ocean surfaces in the Arctic…). All seem to indicate that positive feedback mechanisms are on the rise and will intensify throughout the century, largely overtaking negative feedback effects which would normally act as a buffer in the systems.

The uncertainty

Most climate models (which shape policy decisions) are based on predictions which account for a range of inputs such as emissions scenarios (global amount of GHGs emitted); however few if any seriously consider how systems will evolve when feedback mechanisms are added into the equation.

The main reason is that systems are incredibly complex. Modelling some of these impacts is proving very difficult, especially certain aspects such as atmospheric water vapour that have both positive and negative feedback effects.

However, reasoning on logical deductions and how systems are likely to react should lead the way to anticipation and a more cautious approach. Some of these positive feedbacks really have the potential to shift the situation from currently alarming to dramatic and irreversible in a short time.

Citing David Suzuki: “We are playing Russian roulette with features of the planet’s atmosphere that will profoundly impact generations to come. How long are we willing to gamble?”

An unwanted but possibly unavoidable solution

If positive feedbacks become a factor as predicted by many climate scientists, our only option may end up being deliberate human negative feedback on a massive scale. We may be forced to attempt to counter warming trends through technological inputs, the most extreme of these actions being  Earth Engineering.

Earth Engineering, which is the process of humans voluntarily modifying natural systems on a global scale, is however not without serious consequences and is often considered a last resort.

It may seem like science-fiction but ideas such as injecting sulphur compounds into the upper atmosphere; producing artificial fine clouds on a large scale; fertilising oceans to absorb carbon dioxide; deploying a reflective membrane in the Artic or even sending millions of small mirrors into space to divert the sun rays are ideas which have been proposed and seriously considered to cool down the Earth.

The business case

However, in addition of being extremely risky, all of these engineering measures are also astronomically expensive and far more costly than mitigation measures such as cutting down current GHG emissions and shifting to a low carbon economy.

It is clear from an economical point of view that the cost of dealing with the consequences of climate change will far exceed the cost of mitigating it. This argument has been given over and over again by some leading economists (e.g. The Stern report).

Furthermore we should act fast because we are running out of time. Indeed, because GHGs remain in the atmosphere for extended periods of time, they have been accumulating. We are reaching the point of no return after which the current focus on reducing GHG emissions will no longer make much difference on the outcome (i.e. even the smallest effects will already be dramatic).

Once this point is passed, the next step will probably be to try to remove certain GHGs from the atmosphere on a large scale (which may simply take too long) followed by the final option of earth engineering.

The more we wait, the more extreme and outlandishly expensive the solutions become.

We are truly racing against time and need to intensify our efforts of cutting down GHG emissions through the deployment of renewable energy; shifting away from fossil fuels and intensifying research to come up with new technological and society solutions.

These actions are the ingredients we need to fuel a new economic revolution based on a low carbon economy. The threat of positive feedbacks should be seen as yet another argument to renew our efforts.

Sylvain Richer de Forges is head of sustainability at Siloso Beach Resort.

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