Why is the content of this map important?
Air pollution due to particulate matter affects human morbidity and mortality. Changes in natural emissions of desert dust and in dispersion conditions potentially affect the way particulate matter is emitted or transported. It is therefore important to understand the effect of a +2°C global warming on particulate matter concentrations, and how related changes compare with those obtained from emission abatement policies.
A higher PM2.5 concentration leads to a higher mortality risk and loss of life expectancy. Some compounds of particulate matter such as soot induce warming while others such as sulphates induce an albedo effect and hence climate cooling.
Which sectors are affected by this result?
Particulate matter affects human health, visibility and the climate system itself.
What is shown on the maps?
These maps show the simulated PM2.5 concentration values for (i) the reference period and (ii) the future climate period when a +2°C global warming is reached. PM2.5 are particles smaller than 2.5 micrometers. Particulate matter concentrations are in microgram per cubic meter (μg/m3 ). For the future period, changes in air pollutant emissions are also taken into account that indicate changes are due to both, emission and climate change. In contrast, maps showing the climate change signal for a +2°C global warming only show the effect of climate change i.e., air pollutant emissions are fixed.
Details and further information:
The results are based on simulations from global, regional climate, air quality, and health impact assessment models. Based on these four suites (CHIMERE, EMEP, MATCH, MOCAGE), we have found that a climate under a +2°C global warming modifies the near-surface atmospheric composition of air pollutants in Europe. This is due to several reasons such as changes in weather variables (temperature, precipitation, water vapour, atmospheric flow, boundary layer turbulence) and to biogenic emissions (dust, sea salt, biogenic volatile organic compounds). We have identified areas where changes are robust, where 3 of the 4 models give a change with the same sign. However the changes remain small.
For air pollution, four different model chains, from global to regional climate and chemistry-transport models (CTM) have been used. These CTMs are: CHIMERE, EMEP, MATCH and MOCAGE.
Two types of experiments have been conducted: (1) simulations with an air pollutant emissions reduction scenario and climate change. (2) simulations with constant air pollutant emissions and climate change.
To represent climate change simulations have been conducted for the +2°C global warming period following the RCP4.5 scenario. To represent changes in air pollutant emissions data for current (2005) and future (2050) air pollutant emissions were taken from the ECLIPSE v5 Current Legislation emissions database.
The ensemble consists of 4 simulations for each of the experiments.
Robert Vautard
Centre national de la recherche scientifique (CNRS-IPSL), France