What’s in a Number? Why 1.5°C Matters

A multi-cultural group of people are seated at a table looking at laptops and books. In the foreground, models of wind turbines can be seenThough climate change has been part of the global discourse for some time, the international community has been slow to react to the environmental crisis. This reluctance to act may be attributed in part to the ambiguous nature of climate change: How do we know the climate is really changing? What does a change in temperature have to do with international relations? What specific actions would prevent climate change anyway?

To begin to answer some of those questions, the United Nations Framework Convention on Climate Change (UNFCCC) invited the Intergovernmental Panel on Climate Change (IPCC) to prepare a report on the topic in 2015 when the Paris Agreement was adopted.

The subsequent report, titled Global Warming of 1.5°C, an IPCC special report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty, is a comprehensive report on the scientific and political effects of a global 1.5°C (34.7°F) increase in temperature.

Hoesung Lee, Chair of the IPCC, stated that

“With more than 6,000 scientific references cited and the dedicated contribution of thousands of expert and government reviewers worldwide, this important report testifies to the breadth and policy relevance of the IPCC[.]”

Chapter Three of the report, which focuses on human and natural systems, provides many examples of the consequences of a 1.5°C increase in temperature, including:

  • A reduction of crop yields and nutritional content in the following regions: West Africa, Southern Africa, South-East Asia, and Central and South America.
  • An increase in poverty and disadvantage for populations dependent on agricultural production.
  • An increase in heat-related mortality and morbidity, especially in urban areas due to urban heat islands.

This report is both a warning and a call to action. Some of the measures needed to mitigate the effects of global warming are already in place, albeit at a smaller scale than necessary. The intent of this report is to inform policymakers’ efforts to continue to mitigate the effects of global warming.

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