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The Science of Climate Change

Climate science represents a consilience of inductions that combines a convergence of evidence from multiple data streams. Anthropogenic climate change is supported by studies from fields as diverse as geophysics, meteorology, geology, oceanography and paleoclimatology. However the risks of global warming extend far beyond those related to increase global surface temperature with a 60% decline in biodiversity reported since 1970 leading to the risk of the Eremocine or the age of loneliness, (Wallace-Wells, 2019). The scientific evidence for AGW is no longer contestable and yet commensurate global action to mitigate emissions lags significantly behind the overwhelming empirical evidence resulting in a response gap that threatens to cause enduring and unnecessary suffering to those who have contributed and benefitted least from industrialization related emissions. The IPCC currently recommend the safe operating limits of global warming are to be achieved by keeping temperature to 1.5C above preindustrial levels. The fact that even after the Paris accord commitments we are on track for an increase of 3.2C should concentrate the minds of all stakeholders.

The Scientific Consensus

Much of the historical contention around the empirical evidence for climate change centered around what constituted the scientific method. In fact there is no singular scientific method but rather a variety of processes that vary in their emphasis from how data is gathered and interpreted (induction, deduction and abduction) to how scientists are influenced in the process of investigation (theory dependent observations and motivated reasoning). However all methodologies share some core constructs including that the data should form hypotheses that have superior explanatory power and predictive utility, that they are parsimonious in their reasoning and that they are falsifiable, (Chalmers, 2013). The communal aspect of science ensures that individual biases and predilections are exposed and countered through the process of publication scrutiny and peer review.  The fact that climate scientists across the spectrum has arrived as such a unanimous consensus regarding AGW is one of the remarkable aspects of the climate change paradigm. However it’s important to emphasise that this is an outcome of the scientific method rather than a process. Nevertheless the outcomes of the cumulative investigation into climate change are compelling. A study of nearly 12000 scientific papers on AGW concluded that 97% of the authors supported the hypothesis that human activity was significantly contributing to global warming, (Cook et al, 2016). Furthermore, more than 110000 scientists recently signed an article declaring a climate emergency and citing 15 planetary indicators in support including fossil fuel subsidies, CO2 emissions, world GDP, deforestation and energy consumption, (Ripple et al, 2020).

Risk Estimation and Scientific Predictions

One of the frequent criticisms of climate change research is that it is alarmist and tends to overestimate the risk of AGW.  Such claims demand empirical investigation and the accuracy of historical predictions has been reviewed by Brysse et al (2012). A significant proportion of the scientific evidence for the future adverse impacts of global warming comes from scientific modeling that uses current trajectories in key variables to predict future outcomes. Given that this modeling has been undertaken now for more than two decades we have to opportunity to test the veracity of the models and their capacity to accurately predict future trends. Rather than over-estimating risk, the review found the converse was true with scientists consistently underestimating the levels of atmospheric greenhouse gases, ice flow degradation and ocean temperature increase. The authors attribute this under-estimation of risk to the scientific norms of restraint, conservatism and dispassionate objectivity.

Planetary Boundaries

One of the critical components to developing a model of climate change leadership is the recognition that all leadership operates within the finite limits of the ecosystem, (See Leadership Matters section). These planetary boundaries have been developed as a means of linking the continued evolution of human societies with the finite nature of the Earth’s resources, (Steffen et al, 2015). These nine critical boundaries include land use, ocean acidification, atmospheric contamination, ozone depletion, biosphere integrity and climate change and have subsequently been incorporated into economic models of sustainability, (Raworth, 2018) and the UN sustainable development goals. Currently four of the planetary processes are already in the global risk zone and all boundaries have profound implications for the future of sustainable corporations. The boundary or safe operating level for CO2 is 350ppm whereas current levels are around 410ppm, the highest for 800000 years.

Fig 1: The 9 Planetary boundaries (Rockstrom et al, 2009

Broader implications of Climate Change

What are the broader implications of climate change? Multiple authors have suggested that unchecked, AGW could cause societal and environmental collapse (Turner, 2014). In a review of the causes of societal collapse over the last 5000 years, Motesharrei et al, (2014) created a model that predicted the decline of civilizations across the centuries. Their research discovered two social features that predicted the decline and collapse of historical civilizations – the economic stratification of societies into elites and commoners and the unsustainable use of resources. Only a rapid reduction in resource consumption and a fairer distribution of those resources led to avoidance of societal collapse in their modeling. The lack of empirical evidence for the decoupling of economic growth and resource consumption (Hickel & Kallis, 2019) suggests that as long as economic growth remains the primary metric of social progress, the prospect of collapse is real and increasing. What does it take to maintain the current social complexity we enjoy via the globalized economy? According to a recent review of the factors involved in social evolution, social complexity emerges as the single predictive factor, (Turchin et al, 2017). In a review of 414 societies spanning the last 10000 yrs, the authors concluded that many of the factors involved in social evolution correlate and suggest the presence of a single organising principle. However complexity comes at a significant economic cost and beyond fossil fuels, it is unclear what will support the model unless there is a radical and imminent transition to renewable energy, (Diamond, 2020).

The limits of adaptation

The “business as usual” model seeks to focus on adaptation to the inevitability of climate change rather than the more challenging issue of mitigation and emissions reduction (Link  Business matters). This preference makes significant demands on the human capacity to adapt, survive and thrive in an ecological context that may look radically different to what we experience today. But what if we are reaching the limits of psychological and physical adaption? There is convergent evidence that humans may be reaching their peak adaptive capacity in a number of areas that challenges the notion that adaptation alone will be sufficient to address the challenges of AGW, (Marck et al, 2017). In the areas of sport, health and lifespan there are suggestions of a plateauing in performance that indicates we may be approaching the biological ceiling of performance and that environmental degradation may impose downward pressure of these limits.


Brysse, K., Oreskes, N., O’Reilly, J., & Oppenheimer, M. (2013). Climate change prediction: Erring on the side of least drama?. Global environmental change23(1), 327-337.

Chalmers, A. F. (2013). What is this thing called science?Hackett Publishing.

Cook, J., Oreskes, N., Doran, P. T., Anderegg, W. R., Verheggen, B., Maibach, E. W., … & Nuccitelli, D. (2016). Consensus on consensus: a synthesis of consensus estimates on human-caused global warming. Environmental Research Letters11(4), 048002.

Diamond, J. (2019). Upheaval: How nations cope with crisis and change. Penguin UK.

Hickel, J., & Kallis, G. (2020). Is green growth possible?. New Political Economy25(4), 469-486.

Marck, A., Antero, J., Berthelot, G., Saulière, G., Jancovici, J. M., Masson-Delmotte, V., … & Toussaint, J. F. (2017). Are we reaching the limits of homo sapiens?. Frontiers in physiology8, 812.

Motesharrei, S., Rivas, J., & Kalnay, E. (2014). Human and nature dynamics (HANDY): Modeling inequality and use of resources in the collapse or sustainability of societies. Ecological Economics101, 90-102.

Raworth, K. (2018). Doughnut economics: seven ways to think like a 21st-century economist. Chelsea Green Publishing.

Ripple, W., Wolf, C., Newsome, T., Barnard, P., Moomaw, W., & Grandcolas, P. (2019). World scientists’ warning of a climate emergency. BioScience.

Rockström, J., Steffen, W., Noone, K., Persson, Å., Chapin III, F. S., Lambin, E., … & Nykvist, B. (2009). Planetary boundaries: exploring the safe operating space for humanity. Ecology and society14(2).

Steffen, W., Richardson, K., Rockström, J., Cornell, S. E., Fetzer, I., Bennett, E. M., … & Folke, C. (2015). Planetary boundaries: Guiding human development on a changing planet. Science347(6223).

Turchin, P., Currie, T. E., Whitehouse, H., François, P., Feeney, K., Mullins, D., … & Mendel-Gleason, G. (2018). Quantitative historical analysis uncovers a single dimension of complexity that structures global variation in human social organization. Proceedings of the National Academy of Sciences115(2), E144-E151.

Turner, G. (2014). Is global collapse imminent? An updated comparison of the Limits to Growth with historical data. MSSI Research paper4, 21.

Wallace-Wells, D. (2019). The uninhabitable earth: A story of the future. Penguin UK.