Longer heat waves, heavier smog go hand in hand with climate change

(credit: MIT News)

Exposure to high levels of airborne pollutants is an ongoing problem, as is exposure to extreme temperatures. If these two overlap, then it's possible that the health impacts will be greater. A recent paper published in PNAS uses 15 years of climate observations in the US and Canada to show that the two problems do indeed cluster together and occur in overlapping, large-scale episodes. The largest of these episodes has the hottest temperatures and the highest level of pollution.

The authors used both surface station and meteorological data from the years of 1999 to 2013. They divided this data into one-degree squares. Then they carefully gridded daily Earth surface values for ozone, particulate matter (as a proxy for air quality), and temperature, and they identified climatologically extreme events.

In this analysis, they saw that extreme weather and pollution events clustered into multi-day episodes that tended to be spatially connected. This means that the episodes typically affected grid squares that were adjacent to each other or contiguous. The researchers saw that the weather tended to drive several types of extreme events at once, with problems often coinciding or happening adjacent to each other in either space or time.