‘Hothouse Earth’ and possible trajectories for humanity and the planet

Ayushi Uppal writes: While the concept of Anthropocene remains contested, there is consensus on the human-led changes to the climate and the need for intervention. Humanity must create a pathway from a possible ‘Hothouse earth’ to a ‘Stabilized Earth’ state, where human activities create biogeophysical feedbacks that sustain the Earth System within the planetary threshold.

Anthropocene and the ‘Hothouse Earth’ phenomenon

Ayushi Uppal

The idea of the ‘Anthropocene’ as a geological epoch was proposed by Paul Crutzen in 2002. It is suggested to follow the Holocene Epoch, marked by agriculture, settled communities, and technological and social development of human societies. The Anthropocene marks humanity as a geological force, impacting the Earth Systems significantly and causing a change in the stratigraphic composition and geological relations. Earth Systems can be studied in terms of trajectories of states separated by thresholds. These thresholds are governed by various geological processes, relations, and feedbacks.

The Earth systems have changed dramatically in the past as well. About 1.2 million years ago, studies suggest rise of sea-level about six meter above today’s due to melting of glaciers, but animals and man-kind simply migrated according to the shore. It is also suggested by scientists that conditions like the Hothouse Earth, high carbon di-oxide levels, were seen about 100 million years ago, when dinosaurs inhabited the polar regions. But, these conditions were a result of bio-geological forces.

The Earth System can be understood with the help of Figure 1 mapping the dynamics of the earth systems. The system was in the glacial-interglacial loop for 1.2 million years, until Holocene, marking the end of ‘ice age’, as known to lay man. The general consensus is that Industrial Revolution marked the onset of Anthropocene, with the realization of the potential of fossil fuels. But, according to some theorists, it was the manipulation of fire that led the path to Anthropocene, as it marked control of energy.

Regardless, it led to an era of human domination, based on high carbon economic growth and exploitative use of resources. It is characterized by the emission of greenhouse gases, biosphere degradation, and rapid climate change. The Paris Agreement witnessed signatories agreeing to stall temperature rise to 1.5 degree celsius over pre-industrial temperatures as the rise of temperature to two degrees higher marks a threshold, when crossed is characterized by biogeophysical feedbacks that could define the path to Hothouse Earth effect. While it is difficult to be certain of planetary thresholds, geologists believe that further increase in temperature could lead to a tipping cascade, activating tipping elements that raise the temperature higher leading to the irreversible path to Hothouse Earth. This is marked as point B in figure one. Beyond this, positive biogeological feedback could control the Earth Systems and be the driver of change, outside the realm of human intervention and irreversible.

Transition to Hothouse Earth is fatal to health, economies, political systems, and ultimately, habitability. Agricultural production and water supply will be severely impacted by the climate, and can lead to severe regional drought, flood deltaic environments, global migration, resettlement, decrease in agricultural production, increasing disparities between rich and poor, among other consequences.

This theory changes the narrative of climate change to a ‘sociogenic’ factor, a result of social relations of humanity, thus de-naturalizing a biogeological process. The concept is ‘renaturalized’ by the explanation that manipulation of carbon and resources is a part of evolution, and innate to humans. This is contested by theorists who prefer to term the epoch as ‘Capitolegenic’, and is against the sweeping universality, as not all humans are responsible for harmful emissions and factors causing irreversible change. This challenges the species wide blanketing as geological forces. It is a marxist understanding of Anthropocene and its implications, identifying agents such as multinationals and corporates that need intervention.

While others, like Swanson, Bubandt, and Tsing, critique the Anthropocene as a concept to challenge the current pattern of growth and the future economic and socio-political scenario. Stratigraphers like Whitney Autin critique the idea on the basis of the lack of evidence of any change in the rock strata. The examination of planetary boundaries is beyond the capacity of human agency at this stage of scientific and technological progress. Geophysical change cannot be determined on the basis of a slight margin or a tipping point according to this school of thought.

While the concept of Anthropocene remains contested, there is consensus on the human-led changes to the climate and the need for intervention. In order to prevent this humanity must create a pathway to ‘Stabilized Earth’ state, where human activities create biogeophysical feedback that sustain the Earth System within the planetary threshold. This requires humans to adapt to the Earth system and engage in active planetary stewardship, rather than being an external geological force driving change. Reduction in emissions of greenhouse gases, creation of carbon sinks or conservation of biomes, and keeping the energy balance in check, are some of the urgent actions that need to be taken as a global community.

References

Stromberg, Joseph. “What is the Anthropocene and are we in it?.” Smithsonian Magazine (2013).
Malm, Andreas, and Alf Hornborg. “The geology of mankind? A critique of the Anthropocene narrative.” The Anthropocene Review 1, no. 1 (2014): 62-69.
Moore, Amelia. “The Anthropocene: A critical exploration.” Environment and Society 6, no. 1 (2015): 1-3.
Steffen, Will, Johan Rockström, Katherine Richardson, Timothy M. Lenton, Carl Folke, Diana Liverman, Colin P. Summerhayes et al. “Trajectories of the Earth System in the Anthropocene.” Proceedings of the National Academy of Sciences 115, no. 33 (2018): 8252-8259.
Zalasiewicz, Jan . “Hothouse Earth: our planet has been here before – here’s what it looked like.”Down to Earth (2018)https://www.downtoearth.org.in/news/forests/hothouse-earth-our-planet-has-been-here-before-here-s-what-it-looked-like-61388

The writer is pursuing a Master’s in Public Policy National Law School of India University Bangalore

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