Why is 1.5°C so important?

Illustration from FAQ1.2, summary of FAQs in IPCC AR5

At the decade 2006-2015, human activity had caused the global average temperature had increased by 0.87°C (+/-0.12°C) compared to pre-industrial times (1850-1900).

In 2015 a majority of the counties in the world gathered in Paris to discuss what to do with the climate crisis. The outcome of this meeting organized by the United Nations Framework Convention to Combat Climate Change (UNFCCC) was a commitment to limit global temperature rise to 1.5°C. So, the question is, why did the countries decide on a limit of global temperature rise of 1.5°C?

The actual agreement stated: ‘holding the increase in the global average temperature to well below 2°C above pre-industrial levels and pursuit efforts to limit the temperature increase to 1.5°C above pre-industrial levels’.

An extensive review of the long-term global goals conducted by experts and representatives from UNFCCC concluded that in some vulnerable ecosystems, high risks are projected even at a warming of 1.5°C. This led to the decision to not stop at 2°C as the defense line, but to strive towards a goal of keeping the temperature increase to below 1.5°C.

A key reason for a lower limit is that already at an increase of global average temperature with 1.5°C from pre-industrial levels the expected impacts are so extensive that there is a limited capacity to adapt to its impacts. This is particularly the case in developing and island countries.

This is why limiting the increase of global average temperature to less than 1.5°C is so important, a majority of developing and island nations will not be able to cope with the changed conditions that this warming will bring. The effect of these countries not coping is likely to be massive migration from these nations, to areas less affected by the direct impacts of climate change.


The text is a reflection based on the Frequently Asked Questions (FAQ1.2) extracted from chapter 1 of IPCC’s fifth assessment report.

You can download the entire FAQ document here.

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