Future of the human climate niche
The paper presents a data-backed analysis of the extreme Mean Annual Temperature (MAT) changes in the next half a century as a result of anthropogenic climate change. These severe changes will predominantly occur in the global south resulting in almost 3.5 billion people experiencing a mean temperature of around 29.0 °C. The human experience temperature will be 2.3 times of this actual temperature due to faster warming of land than oceans. This range of temperature is currently only found in a few areas of the Sahara. The limited temperature range within which humans and food production have thrived for the last 6000 years is ∼11 °C to 15 °C. This human niche, as the authors call it, will be limited to only a narrow zone in the northern hemisphere by the end of this century unless we radically adapt. This will have serious implications for not just global migration but also national political and security issues. Immediate action at unprecedented scales needs to be mobilised to firstly, mitigate climate change and secondly, to create targeted policies for rapid climate adaptation in the affected areas.
Cost of climate inaction
One of the most compelling arguments for climate action has to do with the cost of climate inaction. Several studies have calculated the social cost of carbon (SCC) - economic impacts of per tonne of carbon released into the atmosphere. The global median costs per tonne of CO2 emissions is more than $400 according to one study (study 1), whereas cumulative costs stand at $16 trillion per year at 2017 CO2 levels. The study also estimates the geographical distribution of SCC. While India, Brazil and China top the list of countries most affected by climate change, the economic costs are substantial in other developing countries, too. Additional studies have warned that these amounts are likely to be an underestimation, as they exclude uncertain and unpredictable impacts (study 2, study 3). Further, SCC remains strictly an economic indicator and does not account for the social fallout of climate change impacts, such as migration and armed conflict.