New research shows the global average of mild weather days will drop, with dramatic declines for some, increases for others
As scientists work to predict how climate change may affect
hurricanes, droughts, floods, blizzards and other severe weather,
there’s one area that’s been overlooked: mild weather. But no more.
NOAA and Princeton University scientists have produced the
first global analysis of how climate change may affect the frequency and
location of mild weather – days that are perfect for an outdoor
wedding, baseball, fishing, boating, hiking or a picnic. Scientists
defined “mild” weather as temperatures between 64 and 86 degrees F, with
less than a half inch of rain and dew points below 68 degrees F,
indicative of low humidity.
Knowing the general pattern for mild weather over the next decades is
also economically valuable to a wide range of businesses and
industries. Travel, tourism, construction, transportation, agriculture,
and outdoor recreation all benefit from factoring weather patterns into
their plans.Tropics to lose milder days
The new research, published in the journal Climatic Change, projects that globally the number of mild days will decrease by 10, or 13 percent, by the end of the century because of climate warming from the buildup of human-caused greenhouse gasses in the atmosphere. The current global average of 74 mild days a year will drop by four days by 2035 and 10 days by 2081 to 2100. But this global average decrease masks more dramatic decreases in store for some areas and increases in mild days in other regions.
“Extreme weather is difficult to relate to because it may
happen only once in your lifetime,” said first author Karin van der
Wiel, a Princeton postdoctoral researcher at NOAA’s Geophysical Fluid
Dynamics Laboratory (GFDL) located on the university’s Forrestal Campus.
“We took a different approach here and studied a positive
meteorological concept, weather that occurs regularly, and that’s easier
to relate to.”
Scientists predict the largest decreases in mild weather
will happen in tropical regions because of rising heat and humidity. The
hardest-hit areas are expected to be in Africa, Asia and Latin America,
where some regions could see 15 to 50 fewer days of mild weather a year
by the end of the century. These are also areas where NOAA and partner research
shows economic damages due to climate change. The loss of mild weather
days, especially during summer, when they can serve to break up extended
heatwaves, also could significantly affect public health.
Parts of U.S., Canada, northern Europe to gain milder days
People living in the mid-latitudes, which include much of the United States, as well as many mountainous areas around the world, will gain mild weather days on average, the new study found. The biggest winners will include communities along the border with Canada in the Northeast, Midwest and Northwest, as well as many parts of Canada.
Other areas projected to gain as much as 10 to 15 days more
annually of mild weather by the end of the 21st century include parts
of England and northern Europe, and Patagonia in extreme southern South
America. In some of these areas, mild weather will drop during
increasingly hot and humid summers but become more plentiful in fall,
winter and spring as winters warm and the shoulder seasons last longer.
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| This map shows the change in the annual number of mild days across the globe from the period of 1986-2005 to the period from 2081-2100. Areas of blue are expected to experience an increase in mild days while areas of brown are expected to see a decline in those days. (Van der Wiel/ NOAA/ Princeton) |
“We believe improving the public understanding of how
climate change will affect something as important as mild weather is an
area ripe for more research and more focused studies,” said Sarah
Kapnick, a physical scientist at NOAA’s GFDL and co-author. “Predicting
changes in mild weather is not only important to business and industry,
but can also contribute to research on the future of physical and mental
health, leisure and urban planning.”
Links
- Shifting patterns of mild weather in response to projected radiative forcing
- A top-down approach to projecting market impacts of climate change
- Research to measure cost of climate change, improve prediction of severe weather
- Playing hide and seek with El Niño
- El Niño/Southern Oscillation and greenhouse warming
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