In February 2022, as we were pulling together the first drafts of the paper, Quantifying the Human Cost of Global Warming, the White House Office of Science and Technology Policy [OSTP] brought together a virtual roundtable of natural and social scientists to “discuss the scientific understanding of why arguments for delaying climate action are appealing and how they can be countered effectively”.
Then Head of OSTP and Deputy Assistant to the US President, Dr Alondra Nelson, opened the meeting by referencing “forces hostile to climate action - running the gamut from self-interest and short-term thinking, to deliberate disinformation campaigns that are as insidious as they are invidious”.
COP26 had failed to move things beyond a situation where global warming is projected to exceed 2.7˚C by the end of the century and COP27 witnessed no significant advance on this scenario either while, according to a report published in December by Christian Aid, 2022 saw a spate of extreme weather events in which 10 climate disasters cost more than $3 billion USD each.
The costliest in financial terms, Hurricane Ian, incurred damages across the USA and Cuba in excess of $100 billion USD whilst, in human terms, the Pakistan floods killed more than 1700 people, displaced more than 7 million and drove up to 15 million people into poverty, according to World Bank estimates.
Global commitments on climate finance, however, continue to fall short of the $100 billion/year promised by the world’s richest nations in Copenhagen in 2009, indicating a growing deficit that continues to push the escalating burden of climate impacts onto those who are most vulnerable and least responsible for causing climate change.
The question of how best to quantify this rising inequality in order to strengthen future policymaking has been at the forefront of our thinking whilst conducting this study.
Pakistan, for example, the eighth most climate vulnerable country in the world, according to the Global Climate Risk Index, is responsible for around 0.3% of all greenhouse gas emissions (as compared with the USA at 24.2%). The 2022 floods there incurred economic damages, according to the World Bank, of around $30 billion USD but the country was able to access only $5.6 billion USD in insurance payments and $9 billion USD in international aid.
Pakistan’s own reserves total just $4.5 billion USD and as of 9 May 2023, the credit ratings agency, Moody’s Investor Service, identified the country as being at risk of defaulting on existing debt payments without the intervention of an IMF bailout that to-date has not been agreed.
The scenario points towards what UN Special Rapporteur Philip Alston described, presenting his 2019 report on climate change and poverty, as a coming “climate apartheid”, “where the wealthy pay to escape overheating, hunger and conflict while the rest are left to suffer”.
Quantifying the Human Cost of Global Warming responds at the level of the climate model by acknowledging, first, how systems that have underpinned the economics of climate change and guided policy and government decision-making have often reinforced this dynamic by (1.) emphasising the projected cost of climate change in monetary and not primarily human terms, (2.) therefore placing a greater value on climate impacts suffered by the rich than the poor and (3.) placing greater value on current over future generations (because future damages are subject to economic discounting).
2018 Nobel Prize Winner, William Nordhaus’s DICE model, which continues to exert a dominant influence, is exemplary of this approach. Having evolved through successive iterations since the 1990s, it has driven the quest to establish appropriate figures for the social cost of carbon, most notably in the US since the time of the Obama administration.
Yet the 2007-DICE model, by placing greater value on centres of wealth than on human suffering, calculated the social cost of reducing carbon emissions in line with 1.5˚C targets as being more than $14 trillion USD greater than the cost of taking no action at all, whilst the 2016-DICE model calculated that an optimal carbon tax would limit global warming to 3.5˚C not 2.5˚C by the year 2100.
In both scenarios we are presented with figures that gravely underestimate the human costs of climate breakdown, invisibilising victims of climate impacts in a way that would encourage any company board or cabinet body to think twice before ruling out an approach to climate action that took its time.
This delayism, that has become an orthodoxy of contemporary climate governance and its crisis of inaction, in many ways derives from this use of the model that has encouraged us to see the world and our future in this way.
By contrast, our approach to the quantification of climate impacts starts out from the principle that the lives of all humans, whether rich or poor, young or old, should be valued equally and this approach yields radically different numbers and a very different perspective on the value of urgent action when faced with the crisis of global warming.
By comparing projected movement in the human climate niche with movement in the global population, we have found that the projected rise of 2.7˚C by 2100, for example, (the likely outcome of existing policy commitments) stands to leave two billion people – more than one fifth of humanity – exposed to dangerous levels of heat (in a situation where around 60 million people are already exposed in this way).
In this scenario, limiting warming to 1.5˚C would leave only 5% of the human population exposed, saving a sixth of humanity compared with warming of 2.7˚C, while the worst-case/no-action scenarios of 3.6˚C or even 4.4˚C global warming could put half of the world’s population outside the human climate niche, posing an “existential threat”.
Clearly, these metrics do not lead us to conclusions that no action would be in any way cost-beneficial compared to limiting global warming to 1.5˚C. Instead they underline the enormous value of early and decisive action to reduce carbon emissions whilst also pointing us towards the profound inequalities that characterise the distribution of both impacts and responsibility for causing climate change that will also need to be addressed in the design of collective solutions.
Of the two billion people displaced outside the human climate niche at 2.7˚C, for example, more than 600 million of them are projected to be in India and more than 300 million in Nigeria in a situation where per capita emissions in these countries are less than half the global average.
The inequality remains as stark when considered in relation to future generations since we find that 3.5 global average citizens and 1.2 average US citizens currently emit enough carbon in their lifetimes to expose one future person, a person who is statistically most likely to be black or brown, to unprecedented heat. In the words of the poet, June Jordan, “it would be something fine if we could learn how to bless the lives of children.”
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