Disastrous duo: Heatwaves and droughts
Climate change at the heart of more frequent and intense dry and hot
extremes in recent decades
Date:
September 28, 2020
Source:
McGill University
Summary:
Simultaneous heatwaves and droughts are becoming increasingly
common in western parts of the Unites States, according to a new
study. Periods of dry and hot weather, which can make wildfires
more likely, are becoming larger, more intense, and more frequent
because of climate change.
FULL STORY ========================================================================== Simultaneous heatwaves and droughts are becoming increasingly common
in western parts of the Unites States, according to a new study led
by researchers from McGill University. Periods of dry and hot weather,
which can make wildfires more likely, are becoming larger, more intense,
and more frequent because of climate change.
==========================================================================
In a study published by Science Advances, the researchers analyzed heat
and drought events across the contiguous United States over the past
122 years.
They found that combined dry and hot events have not only increased
in frequency, but also in size geographically. Where such events were
once confined to small parts of the United States, now they cover whole regions, such as the entire west coast and parts of the Northeast and Southeast.
"Dry-hot events can cause large fires. Add wind and a source of ignition,
and this results in 'megafires' like the 2020 fires across the west coast
of the United States. Drought and record-breaking heatwaves, coupled with
a storm that brought strong winds and 12,000 lightning events in a span of
72 hours, caused more than 500 wildfires," says lead author Mohammad Reza Alizadeh, a PhD student under the supervision of Professor Jan Adamowski
in the Department of Bioresource Engineering at McGill University.
The researchers also found that dry and hot weather
events are intensifying, with longer periods of drought and
higher temperatures. These dual "dry-hot extremes" are not only self-intensifying -- more heat causes more drought and vice versa --
but are also self-propagating, meaning they are able to move from region
to region. "As increased temperatures are driving and expanding aridity, droughts and heatwaves move from one region to downwind regions," says Alizadeh. These extremes can be particularly damaging for agricultural production and ecosystems, they warn.
According to the researchers, the trigger for these hot-dry events
is shifting.
Looking back at the catastrophic Dust Bowl of the 1930s, they explain
that the dust storms were driven by a lack of rainfall coupled with poor
land management practices. In recent decades, however, dry-hot disasters
are driven more often by excess heat than a lack of rainfall.
The future will bring us more of these disasters, if the current warming
trends continue, the researchers caution. They suggest their findings
could be used to inform climate mitigation and adaptation efforts. "We
need to understand how things are changing in order to adapt," says
Professor Jan Adamowski.
========================================================================== Story Source: Materials provided by McGill_University. Note: Content
may be edited for style and length.
========================================================================== Journal Reference:
1. Mohammad Reza Alizadeh, Jan Adamowski, Mohammad Reza Nikoo, Amir
AghaKouchak, Philip Dennison, Mojtaba Sadegh. A century of
observations reveals increasing likelihood of continental-scale
compound dry-hot extremes. Science Advances, 2020; 6 (39): eaaz4571
DOI: 10.1126/ sciadv.aaz4571 ==========================================================================
Link to news story:
https://www.sciencedaily.com/releases/2020/09/200928152922.htm
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