Things aren’t as frosty as they used to be, and it means that you might be sneezing more.
Climate Central – an independent group of scientists and communicators who research our changing climate – recently released a report that found rising temperatures are resulting in more freeze-free days every year in 83% of 197 cities surveyed. In these 164 cities, freeze-free days have lengthened by 19 days on average since 1970.
These are the 10 cities with the most significant increase in freeze-free days:
1. Reno, Nev. (95 days)
2. Las Cruces, N.M. (65 days)
3. Medford, Ore. (61 days)
4. Boise, Idaho (51 days)
5. Tupelo, Miss. (50 days)
6. Missoula, Mont. (48 days)
7. Myrtle Beach, S.C. (48 days)
8. El Paso, Texas (47 days)
9. Toledo, Ohio (45 days)
10. Eugene, Ore. (40 days)
A full list of the cities can be downloaded here.
“All nine major U.S. climate regions have seen their freeze-free growing seasons lengthen by at least 11 days on average since 1970,” Climate Central said. “Among regions, the freeze-free season lengthened by more than two weeks on average in: the Northwest (26 more days); the Southeast and Northeast (15 more days, respectively); and the Upper Midwest (14 more days).”
What does a decrease in freeze days have to do with allergies?
With fewer freeze days, plants have more time to grow and release pollen. Per the U.S. Centers for Disease Control and Prevention, pollen is “the grains or tiny seeds of flowering plants, trees, and grasses,” that can be carried on the wind. For people with allergies, pollen can cause symptoms such as runny nose, stuffy nose, sneezing, red and watery eyes, eye swelling and itchiness of the nose, ears, eyes and mouth.
“When someone has allergies, their immune system makes an antibody called immunoglobulin E (IgE). These antibodies respond to allergens,” explained the Asthma and Allergy Foundation of America. “The symptoms that result are an allergic reaction.”
While some allergy symptoms are uncomfortable but not serious, others can be life-threatening.
“Trouble breathing and swelling in your mouth or throat… may be a life-threatening reaction called anaphylaxis,” said the Asthma and Allergy Foundation of America.
According to the National Library of Medicine, pollen rarely causes anaphylaxis. However, it can trigger asthma.
“Longer and more intense pollen seasons can have serious consequences for people with respiratory illnesses like asthma – particularly for children,” said Climate Central. “Around 19% of children in the U.S. suffer from seasonal allergies,” and 6.5% of children suffer from asthma with allergic asthma being the most common.
Asthma is a chronic condition in which airways can become inflamed and narrowed, said the National Heart Lung and Blood Institute. When these airways are inflamed, it is harder for air to flow out of them. In some cases, asthma attacks can be fatal.
Even less severe allergy symptoms can “affect children’s quality of life including school performance, mood, and sleep in adolescents aged 10-19 years,” per Climate Central. Last spring, Audacy reported on research linking seasonal allergies to an increased risk for anxiety and depression.
More than 100 million people in the U.S. live with these allergies, according to the Asthma and Allergy Foundation of America.
What role does climate change play?
“Earlier springs, longer pollen seasons, and worse seasonal allergies are all linked to our warming climate,” said Climate Central.
A recent study cited by the group found that human-caused warming was a primary driver of North American pollen seasons since 1990. Elevated CO2 levels decrease freeze days, elongating spring.
To determine the start of spring, the National Phenology Network gathers data about early season events in plants, such as first leaves and first blooms.
As of Monday, it said there had been a slow start to spring in the southern part of the U.S. this year. However, it added that “spring is spreading more quickly now across the central part of the country,” with the season starting six days early in Billings, Mont., 15 days early in Kalamazoo, Mich., and four days early in Providence, R.I., compared to a long-term average of 1991 through 2020.
“The Sacramento Valley, coastal areas of Northern California, Oregon, and Washington, and parts of the Great Plains and southern Midwest are seeing the earliest spring leaf out on record,” said the National Phenology Network.
In particular, Climate Central said carbon pollution from coal, oil and natural gas is driving climate changes linked to reduced frost and allergies. Citing an analysis from the U.S. Environmental Protection Agency, it said that continued warming could worsen allergies for future generations of children.
“The analysis found that 2°C (3.6°F) of warming could result in a 17% annual increase in asthma-related emergency room visits among children due to pollen exposure, relative to baseline conditions (1986-2005), Climate Central said. “Projected increases were largest in Indiana, Kentucky, Ohio, Vermont, and West Virginia.”
Already, oak pollen exposure disproportionately impacts Hispanic, Asian, and Black children, as well as low-income, limited English-speaking, and uninsured children, said the EPA.