In Layman’s Terms: Ignition Point

Editor’s Note: On 4th November 2016, the Paris Agreement on Climate Change entered into effect. It’s aim is “to hold the increase in the global average temperature to well below 2°C above pre-industrial levels”. Here, NESSE Member Simon Rauch describes the risk of climate change on the basis of an example from chemical reaction engineering.

For the construction and operation of a reactor for an exothermic reaction, the consideration of the ignition behaviour is a fundamental issue. While the heat removal (WAG) proceeds linear, the heat production (WEK) is strongly non-linear. This results from the self-reinforcing effect of exothermic reactions. The higher the temperature is, the faster the reaction runs. A faster reaction produces more heat, which increases the temperature. If the heat production exceeds the heat removal, the ignition point is reached (4) and it comes to a runaway. At this point, the temperature in the reactor rises, until another stable operating point is reached (8).

untitledIn the best case, the reactor is designed for the new operating conditions. Often neglected by this calculation is the influence of the solvents, which will be in huge excess compared to the reactant. In the case of the transgression of a critical point, the thermal combustion of the solvent starts and much more energy is released. This is a situation which is difficult to handle.

I want to use my knowledge of this behaviour to describe what is happening to our planet and climate. In this case, our solvent is the carbon that is cryopreserved in form of dead biomass by permafrost. The ratios are similar. Every year, humankind emits 6.5 gigatonnes (gt) of carbon. Around 770 gt of carbon are still stored as oil and mainly coal in the ground. The entirety of all living plants contains 650 gt of carbon and the atmosphere contains 730 gt. In the permafrost soils of the northern latitudes there are assumingly 1600 gt of carbon fixed. With a rising global temperature, there is the danger that this carbon is released in the atmosphere as carbon dioxide or methane, which is even worse. This depends on the humidity of the ground.  Those emissions reinforce the greenhouse effect, whereby the process enforces itself. Additionally, the microbes produce heat during the degradation of the biomass, which increases the soil temperature.

If only a small amount of that carbon is released to the atmosphere, the Paris Agreement on Climate Change will be nullified and the 2°C limit will not be achievable. This issue is one of the tipping points of the climate and eco system, the ignition point of our planet. There are related processes, such as the ice-abledo feedback. A higher partial pressure of CO2 in the Atmosphere also contributes to acidification of the oceans, which is a big problem on its own.

The behaviour of permafrost soils concerning increasing temperatures is not investigated very well at the moment. Scientists just start to examine these processes and connections; therefore we have to deal with uncertainties.  According to the US-American geologist Laurence C. Smith, we need at least ten years to attain a solid scientific consensus. But do we have the time to wait?

A non-linear and stochastic chain of effects is one of the four characteristics of systemic risks. Those are complex, uncertain and ambivalent. The other three characteristics are related to climate change:

  1. Climate risks are global in character, it doesn’t matter where and by whom greenhouse gases are emitted. Each individual, you and me, contributes to this problem in a small amount, but combined, we cross the boundary. The negative, and maybe positive, effects occur globally.
  2. Climate risks are tightly connected with other economic and social crises phenomena. They enforce droughts, floods and famines, but also increase the possibility and potential of extreme weather events. A rising sea level endangers coastal areas. For a better overview, I recommend the Global Risks Interconnection Map, developed at the World Economic Forum in Davos.
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  3. Climate risks are underestimated and do not lead to a change of our behaviour. Until the present moment, the emission increase almost continuously, together with the risk of a climate change. Those changes occur insidious, which is a problem for our perception that is evolutionary focused on sudden changes and dangers. Thanks to the cognitive dissonance reduction, we don’t have mental stress, when we violate our own moral values and contribute to greenhouse gas emissions. What is your carbon foot print?

When we want to achieve sustainability, the transition doesn’t only depend on new and more efficient technologies, we also need a change of our behaviour and habitus. Otherwise rebound effects might compensate all the saving, achieved by an intensified production.

That’s why, I want to finish with a quote by Mahatma Gandhi:
“As human beings, our greatness lies not so much in being able to remake the world – that is the myth of the atomic age – as in being able to remake ourselves”

How we can remake ourselves, will be the content of another article.

This article is mainly based on the books “Chemical Technology” by Dr. Peter Wasserscheid / Dr. Andreas Jess (source of the picture), “The World in 2050 – Four Forces Shaping Civilization’s Northern Future” by Dr. Laurence C Smith, and “Das Risikoparadox – Warum wir uns vor dem Falschen fürchten” by Dr. Ortwin Renn (sadly there is no English translation).