With the adoption of the 2015 Paris Agreement, 194 world countries committed to keep global warming well below 2°ͦC compared to pre-industrial levels, and to strive to limit it to 1.5°C.
However, countries’ mitigation actions, as pledged in their national climate plans – or nationally determined contributions (NDCs) in the UNFCCC lingo – currently fall short of this ambition.
The aggregate effect of NDCs could lead to a warming of between 2.6 and 3.1°C by the end of the century, and thus lead to an increase in the severity and/or frequency of deadly and costly hydro-meteorological hazards.
While the COP26 was postponed to November 2021, countries are nevertheless requested to communicate new or updated NDCs by the end of this year.
The recently published paper “Will the Paris Agreement protect us from hydro-meteorological extremes?” provides a powerful indication of why more ambitious action on mitigation is needed to avoid the most dangerous consequences of climate change.
The JRC-led study, published in Environmental Research letters, performs the first-ever combined assessment of global population exposure to hydro-meteorological extremes such as floods, droughts, and heat waves.
Several studies have already shown how an increase in average temperature can deeply influence some natural phenomena, producing different effects depending on the geographical areas considered.
However, these phenomena are usually evaluated individually.
An analysis that takes them all into account together can help understand the overall risk involved and, therefore, improve long-term projections of their evolution.
The paper provides a first comprehensive assessment of global population exposure to hydro-meteorological extremes—floods, drought and heatwaves—under different global warming targets.
It shows how limiting a rise in temperature to 1.5 and 2°C, in line with the goals of the Paris Agreement, could substantially decrease the share of global population impacted, compared to a 3°C scenario.
The evaluation was conducted by analysing different aspects of the combination of floods, droughts and heat waves, taking into account their intensity, duration, frequency and geographical distribution.
Results were then combined using the population projections of one of the forecast scenarios used by the Intergovernmental Panel on Climate Change (IPCC), the United Nations body for assessing the climate change science.
The authors were thus able to show that, in a 2°C compared to a 3°C world, population exposure would drop by more than 50%, in Africa, Asia and the Americas, and by about 40% in Europe and Oceania.
A 1.5°C stabilisation would further reduce exposure of about an additional 10% to 30% across the globe.
The authors highlighted some limitations of their analysis. For example, it was not possible to analyse the effects of events occurring simultaneously; nor was it possible to take into account the vulnerability of populations, a fundamental parameter for risk assessment.
However, the results provide a strong indication of the benefits that meeting the objectives of the Paris Agreement would bring in terms of significantly reducing in the share of global population exposed to hydro-meteorological extremes.
- 26 november 2020