Allergy season is now starting earlier thanks to climate change

A person uses a handkerchief while standing near a flowering tree.

A person uses a handkerchief while standing near a flowering tree. (Getty Images)

Spring seemed to come early this year across much of the United States, and nearly everyone with seasonal allergies took notice. As climate change causes winters to get warmer and plants to begin blooming earlier, studies have shown that the pollen that triggers allergy symptoms is arriving earlier than in decades past.

Here’s a look at how warmer winters lead to a longer growing season for plants and how it affects millions of Americans with hay fever.

A warm, wet winter in the eastern United States

Skiers on artificial snow wear T-shirts.

Skiers on artificial snow wear T-shirts on a day of record-breaking warm temperatures, at Liberty Mountain Resort in Fairfield, Pennsylvania, on Feb. 23, 2023. (Kevin Lamarque/Reuters)

“February continued the unusually mild start to 2023, with much of the eastern U.S. experiencing record or near-record warm temperatures,” the National Oceanic and Atmospheric Administration (NOAA) said.

“The average temperature in the contiguous U.S. last month was 36.5 degrees F, 2.7 degrees above the 20th century average, and was in the warmest third of the 129-year climate record,” the agency said in a report. which was released last week.

Virginia had recorded the warmest February on record. Eight other states east of the Mississippi River had their second-warmest February on record, and three had their third-warmest.

There was an exception, however: Six western states — Arizona, California, Colorado, Idaho, Nevada and Oregon — experienced colder than usual February temperatures this year.

While there is one more week of winter on the astronomical calendar, which is based on the Earth’s position relative to the sun, “meteorological winter” refers to the coldest three months of the year and is considered December-February.

NOAA reported last week that the average meteorological winter temperature was 2.7 degrees warmer than the 20th century average, making it the 17th warmest meteorological winter on record. Massachusetts had its warmest winter on record, and seven states in the Northeast, the Appalachians and the Upper Midwest experienced their second warmest winter on record. Another 21 states had one of their 10 warmest winters.

Overall average winter precipitation for the December-February meteorological winter of 2022-2023 has been 0.90 inches above the historical average so far. Wisconsin had its wettest winter on record, and another six states had one of their 10 wettest winters. Studies have shown that more rainfall during a plant’s growing season leads to earlier and faster growth.

An early bloom in the eastern half of the country

Purple lagers in bloom.

Flowers bloom during a lull between storms near Wheeler Ridge, California (David McNew/Getty Images)

“Observers are reporting very early offshoots of the common lilac in Pennsylvania, the brilliant yellow blossoms of forsythia in Maine and witch hazel in New York,” USA Today reported late last week. A study of data from more than 140 years at the Missouri Botanical Garden found that pansies respond to increased rainfall and warmer temperatures by budding earlier, the paper reported.

“I’m sitting outside on March 7 and all my daffodils are blooming, and it’s ridiculous,” Lois Krauss, a local environmentalist in Westfield, NJ, told Yahoo News.

The National Phenology Network, which tracks the arrival of spring by tracking the blooms of plant species native to the country that are typically among the first to sprout leaves, such as honeysuckle and lilacs, reported in late February that the leaves are the earliest germinated they once had in parts of the eastern U.S. In New York City, buds appeared 32 days earlier than the historical average.

“Spring leaves continue to spread north, arriving several days to weeks earlier than average (the 1991-2020 period) across much of the Southeast, lower Midwest, and mid-Atlantic. Kansas City, MO is 9 days early, Nantucket, MA is 35 days early,” the National Phenology Network reported Monday. The group added that “Spring blooms have also arrived in Southern states, days to weeks early in the Southeast,” including 22 days early in Norfolk, Virginia.

“It’s a little disturbing. It’s definitely something that’s out of the bounds of when we would normally expect spring,” Teresa Crimmins, the director of the National Phenology Network and an environmental scientist at the University of Arizona, told the Guardian, related to the early blooms. “It may not be surprising given the trajectory our planet travels, but it’s surprising when you experience it.”

However, this does not apply to the entire country. “The West is a mix of early and late,” the group noted. “Southwest UT is days to over a week late and Portland, OR is 2 days late…Spring Bloom is 10 days late in Las Vegas, NV.”

A new report from Climate Central, a nonprofit climate research organization, analyzed temperature data for 203 U.S. cities since 1970, to measure the length of the growing season for plants — the stretch between the last freeze in or before spring and the first of the next fall or winter. The group found that 85% of cities have longer growing seasons than in 1970. On average, the frost-free season grew the most in the west, 27 days, followed by the southeast (16 days), the northeast (15 days). , South (14 days) and Central US (13 days).

“Because of climate change, we are now seeing an earlier and longer growing season for plants, which naturally make pollen, which is the enemy of many Americans who suffer from pollen allergies — and also mold allergies,” Lauren Casey, a meteorologist with Climate Central, told CNN. “Pollen can also trigger an asthma attack, which is of course much more serious for people who suffer from asthma.”

Warmer weather, heavier rainfall and early flowering are consistent with climate change

People walk and drive along a path.

In unseasonably warm temperatures, people walk and ride along the Rockingham Recreational Rail Trail in Salem, NH (Charles Krupa/AP)

While the weather will always vary from year to year, temperatures have risen consistently since 1880, averaging 0.14 degrees Fahrenheit due to climate change, the federal government said. The average temperature on Earth has increased by 2 degrees Fahrenheit since the industrial revolution due to increased concentrations of greenhouse gases such as carbon dioxide in the atmosphere.

“Winter is getting warmer,” Matthew Barlow, a climate science professor at the University of Massachusetts Lowell, told Yahoo News. As a result, the duration of cold weather is getting shorter on both sides.

Climate change also leads to more precipitation. “As average temperatures rise at the Earth’s surface, more evaporation occurs, which in turn increases overall precipitation,” the Environmental Protection Agency (EPA) explains. “Therefore, a warming climate is expected to increase precipitation in many areas. Since the early 1900s, precipitation in the contiguous 48 states has increased by an average of 0.20 inches per decade, according to the EPA.

It’s not just climate change that’s contributing to the early sprouting. The carbon dioxide emissions that cause climate change also encourage earlier and faster plant growth. Since plants take in carbon dioxide when performing photosynthesis, higher atmospheric concentrations of carbon dioxide speed up that process.

“Carbon dioxide (CO2) is not only the main global warming gas, but can also be considered a plant food – it is the source of carbon needed to make sugars during photosynthesis,” explained a 2016 research paper in the journal Environmental Health Perspectives. “When exposed to warmer temperatures and higher CO2 levels, plants grow more vigorously and produce more pollen than they otherwise would.”

Earlier, faster plant growth causes an earlier, more severe allergy season

Woman blowing her nose with a tissue.

Woman blowing her nose with a tissue. (Getty Images)

Seasonal allergies, also known as “hay fever,” are caused by allergic reactions to plant pollen and airborne mold spores. As higher concentrations of CO2, higher temperatures and heavier precipitation contribute to earlier and faster plant growth, the allergy season is lengthened and exacerbated.

For example, Atlanta “saw pollen counts rise to ‘extremely high’ levels on March 6, the earliest in 30 years,” Forbes recently reported.

The Washington Post reported in mid-February that “unusually high winter temperatures have led to a historically early and intense tree pollen explosion,” in the nation’s capital. DC’s first high pollen count in trees came on Feb. 8, marking the third-earliest recorded high pollen count, and the third such occurrence since 2017.

A number of studies in recent years have identified longer and more intense pollen seasons as a result of climate change.

QA 2021 paper published in the Proceedings of the National Academy of Sciences between 1990 and 2018 of 60 pollen counting stations in the United States and Canada found a 21% increase in pollen concentrations and a 10-day longer average pollen season over time from the period of 38 years.

“Trend data suggest that the prevalence of asthma, including forms of the disease caused by pollens, molds and other allergens, is increasing,” reported a 2016 article in the journal Environmental Health Perspectives.

For many, allergies are just a minor nuisance, but for asthmatics, it can be deadly, as allergies are a leading cause of asthma attacks.

Eighty-one million Americans, including about 26% of adults and 19% of children, had a diagnosis of asthma as of 2021, according to the Asthma and Allergy Foundation of America.

While some treatments for allergies exist, including antihistamines and allergy shots, none are 100% effective, and some are quite expensive or time-consuming. Ultimately, environmental and public health advocacy groups are advocating for reducing greenhouse gas emissions to limit the severity of climate change.

“We are already experiencing the effects of climate change with every breath we take in the spring,” William Anderegg, an associate professor of biology at the University of Utah, told NPR last year. “Addressing climate change is really important for people’s health.”

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