Why the fuss about 0.5°C?

An essential part of the COP experience are it’s side events, ranging from official UNFCCC plenary sessions to NGO panels, training workshops, local museum tours and demonstrations. It is impossible to even visit a significant fraction of these, so I have attended a rather random subset of them.

First, I went to an official IPCC plenary session: Not surprisingly, a central theme to this year’s COP has been SR15, the IPCC’s 1.5C report that was timely published on Oct 8. Limiting global warming to 1.5 instead of 2C might sound arbitrary, however, here’s a number of compelling reasons to do so: 

  • Several hundred million fewer people will be exposed to climate-related risks and poverty by 2050, with 50% fewer people being exposed to water shortages
  • Average sea level rise will be 10cm less by 2100 (note that this has profound influence on groundwater supplies in coastal areas, such as Miami – as well as areas prone to flooding, such as Bangladesh)
  • crop yields (wheat, maize etc) will shrink by 1-4% less
  • Insects will lose 50% fewer of their geographically inhabitable regions (this may have profound effects for agriculture as well)
  • 30-10% of coral reefs will be preserved (but 99% will die at 2C)

 To add to this, the WHO just published a health report on 1.5C, which estimates that the accompanying reduction in air pollution alone would save 1 million lives a year globally by 2050. It is estimated that the 15 most polluting countries forfeit 4% (ca. $2.8Tr) of their GDP due to air pollution-related health issues, while limiting warming to 1.5C would cost 1% of global GDP (clocking in at ca. $0.8Tr). As such, WHO sees climate change mitigation as an economic opportunity, not a cost.

The WHO report also re-emphasises the crucially important relationship between climate change, health, environmental pollution, sustainable land use and preservation of biodiversity: Healthy humans require access to clean air, safe drinking water, nutritious food supply and safe shelter. Global warming puts all of these at stake individually, but also leads to combined effects: E.g. cattle health, and thus food security, is disproportionally endangered if water shortages occur concurrently with rising temperatures.

Or, as a quick summary for process fetishists: We can as well trash most of the 2030 Sustainable Development Goals immediately if we are not prepared to step up our ambitions in fighting climate change.

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