Category Archives: sustainability

We are ecosystem engineers

Decorative photograph of common cuscusHumans have been ecosystem engineers since the Pleistocene, more than 12,000 years ago.  There is evidence of a tree-dwelling possum, the common cuscus, being introduced to the Solomon Islands from New Guinea more than 20,000 years ago as a game species [1].  The ecosystem is a complex system and there are unintended consequences of our engineering.  For instance, the burning forests and grasslands about 8,000 years ago changed reflectivity and absorption of heat in parts of Eurasia which altered the pattern of monsoons in India and parts of South East Asia.  The palaeobiologist, Thomas Halliday has suggested that we are such effective ecosystem engineers that is impossible to think about a pristine Earth unaffected by human biology and culture [2].  The challenge now is to re-engineer the ecosystem so that it remains habitable.  This involves handling the complexities of  the ecosystem, human society and their interactions.  The philosopher, Nabil Ahmed has written, in the context of his native Bangladesh, that it is impossible to differentiate between land and rivers, human population, grains and forests, politics and markets because they all coalesce as a single entity resulting from the legacy of interaction between politics and natural actors [3].  Everything is interconnected – more than we realise.

References

[1] Abate RS & Kronk EA, Climate change and indigenous peoples: the search for legal remedies Cheltenham UK: Edward Elgar, 2012.

[2] Halliday T, Otherlands: A world in the making, London: Allen Lane, 2022.

[3] Ahmed N, Entangled Earth, Third Text, 27:44-53, 2013.

Image: Exhibit in the Museo Civico di Storia Naturale di Genova, Via Brigata Liguria, 9, 16121, Genoa, Italy; by Daderot, CCO 1.0 licence

Ice caps losing water and gravitational attraction

Map of the world showing population density is greater in the regions furthest from the polesI have written previously about sea level rises [see ‘Merseyside Totemy‘ on August 17th, 2022 and ‘Climate change and tides in Liverpool‘ on May 11th, 2016] and the fact that a 1 metre rise in sea level would displace 145 million people [see ‘New Year resolution‘ on December 31st, 2014].  Sea levels globally have risen 102.5 mm since 1993 primarily due to the water added as a result of the melting of glaciers and icecaps and due to the expansion of the seawater as its temperature rises – both of these causes are a result of global warming resulting from human activity.  I think that this is probably well-known to most readers of this blog. However, I had not appreciated that the polar ice caps are sufficiently massive that their gravitational attraction pulls the water in the oceans towards them, so that as they melt the oceans move towards a more even distribution of water raising sea levels further away from the icecaps.  This is problematic because the population density is higher in the regions further away from the polar ice caps, as shown in the image.  Worldwide about 1 billion people, or about an eighth of the global population, live less than 10 metres above current high tide lines.  If we fail to limit global warming to 1.5 degrees Centigrade and it peaks at 5 degrees Centigrade then the average sea level rise is predicted to be as high as 7 m according to the IPCC.

Image: Population Density, v4.11, 2020 by SEDACMaps CC-BY-2.0 Creative Commons Attribution 2.0 Generic license.

Source: Thomas Halliday, Otherlands: A World in the Making, London: Allen Lane, 2022

Storm in a computer

Decorative painting of a stormy seascapeAs part of my undergraduate course on thermodynamics [see ‘Change in focus’ on October 5th, 2022) and in my MOOC on Thermodynamics in Everyday Life [See ‘Engaging learners on-line‘ on May 25th, 2016], I used to ask students to read Chapter 1 ‘The Storm in the Computer’ from Philosophy and Simulation: The Emergence of Synthetic Reason by Manuel Delanda.  It is a mind-stretching read and I recommended that students read it at least twice in order to appreciate its messages.  To support their learning, I provided them with a précis of the chapter that is reproduced below in a slightly modified form.

At the start of the chapter, the simplest emergent properties, such as the temperature and pressure of a body of water in a container, are discussed [see ‘Emergent properties’ on September 16th, 2015].  These properties are described as emergent because they are not the property of a single component of the system, that is individual water molecules but are features of the system as a whole.  They arise from an objective averaging process for the billions of molecules of water in the container.  The discussion is extended to two bodies of water, one hot and one cold brought into contact within one another.  An average temperature will emerge with a redistribution of molecules to create a less ordered state.  The spontaneous flow of energy, as temperature differences cancel themselves, is identified as an important driver or capability, especially when the hot body is continually refreshed by a fire, for instance.  Engineers harness energy gradients or differences and the resultant energy flow to do useful work, for instance in turbines.

However, Delanda does not deviate to discuss how engineers exploit energy gradients.  Instead he identifies the spontaneous flow of molecules, as they self-organise across an energy gradient, as the driver of circulatory flows in the oceans and atmosphere, known as convection cells.  Five to eight convections cells can merge in the atmosphere to form a thunderstorm.  In thunderstorms, when the rising water vapour becomes rain, the phase transition from vapour to liquid releases latent heat or energy that helps sustain the storm system.  At the same time, gradients in electrical charge between the upper and lower sections of the storm generate lightening.

Delanda highlights that emergent properties can be established by elucidating the mechanisms that produce them at one scale and these emergent properties can become the components of a phenomenon at a much larger scale.  This allows scientists and engineers to construct models that take for granted the existence of emergent properties at one scale to explain behaviour at another, which is called ‘mechanism-independence’.  For example, it is unnecessary to model molecular movement to predict heat transfer.  These ideas allow simulations to replicate behaviour at the system level without the need for high-fidelity representations at all scales.  The art of modelling is the ability to decide what changes do, and what changes do not, make a difference, i.e., what to include and exclude.

Source:

Manuel Delanda Philosophy and Simulation: The Emergence of Synthetic Reason, Continuum, London, 2011.

Image: Painting by Sarah Evans owned by the author.

Global citizenship in the context of COP27

About five years ago I wrote a long piece for the Citizens of Everywhere project and also published it on this blog [see ‘We are citizens of the world‘ on April 5th, 2017].  One theme of the essay was the way in which scientists and engineers work as part of a global community contributing to, and exploiting, a shared knowledge and understanding of natural and manufactured phenomena; and in this process, as global citizens, we are relatively unaware and uninfluenced by the national boundaries drawn and fought over by politicians and leaders.  Engineers frequently draw boundaries to define a system for analysis [see ‘Drawing boundaries‘ on December 19th, 2012] but we understand that they do not exist in reality so energy and, sometimes, matter can flow across them.  Similarly, national boundaries are man-made constructs, occasionally existing in physical reality such as the Berlin Wall, but usually only on a map.  Most people would like to be able move freely around the world; however, we are often restricted from crossing borders by the location of our mother when she gave birth to us.  Gaia Vince in her book, Nomad Century: How to Survive the Climate Upheaval, has suggested that assigning nationality based on your birthplace is arbitrary and instead we should have a universal UN citizenship with a national affiliation.  This might be one small step towards achieving peaceful mass migrations from uninhabitable zones created by major changes in the Earth’s climate.  There could be 1.5 billion environmental migrants by 2050 according to the UN’s International Organisation for Migration – that’s one in five people!

As I have argued before [see ‘Planetary Emergency‘ on February 20th, 2019], our politicians need to stop arguing about borders and starting worrying about the whole planet not just at COP27 but in everything they do. We are all in this together and no man-made border will protect us from the impact of making the planet a hostile environment for life.

Source: Anjana Ahuja, Acclimatising to crisis, FT Weekend, 27 August/28 August 2022.