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Cherry Blossoms blooming in spring

Sneezing More This Spring? Thank the Climate Crisis.

It's not just you.


You’re itchy, you’re sneezy, your nose is dripping – it’s that time of year. The plight of seasonal allergies takes hold every time you dare step outside. But did you know that, depending on where you live, climate change could be making allergy season even worse?

How Does it Work?

You’ve heard it from us before: The planet is heating up. And as scientists at the University of Michigan note, rising global temperatures can “boost plant growth in many areas, and that, in turn, will affect pollen production.” More pollen production, as any allergy sufferer will understand instantly, means more floating catalysts for itches, sneezes, and more.

It gets worse. Higher temperatures will also lengthen the growing season and provide plants more time to release pollen. Rising temperatures, however, are only one piece of the puzzle.

Atmospheric CO2 also plays a role. Carbon dioxide is one of the key ingredients for photosynthesis, and in a world of increasing carbon pollution pumping out of smokestacks and tailpipes, plants may grow “larger and produce more pollen.” One study found that rising carbon dioxide emissions may be the biggest driver of pollen increase in the future, playing an even larger role than increasing temperatures.

Allergy Season Keeps Getting Longer

The net result that is that, in general, pollen season is getting longer. According to the USA National Phenology Network, depending on the region, the first leaves and blooms of spring are arriving days to weeks earlier than average across the US. Warmer temperatures contributing to an earlier spring combined with “longer periods of freeze-free days mean that plants have more time to flower and release allergy-inducing pollen,” according to Climate Central.

Since the beginning of the 20th century, the average length of the growing season in the contiguous 48 states has increased by more than two weeks. Which can mean two more weeks of allergies.

One study published in the Proceedings of the National Academy of Sciences found that between 1990 and 2018, North American pollen seasons started on average 20 days earlier, lasted 10 days longer, and included 21% more pollen.

The study also found that anthropogenic – i.e. human-caused – warming contributed to approximately half the change in when pollen season began and approximately 8% to the increase in pollen concentrations during the period.

Pollen is Increasing Overall, But It Varies

Not only is pollen season getting longer, but there’s also more of it in the air. We already know that rising temperatures and carbon emissions are a huge part of it: Plant growth is being stimulated and plants are releasing more pollen as a result.

Researchers at the University of Michigan found that if we continue to produce high levels of greenhouse gas emissions, the US faces a whopping 200% increase in total pollen by the end of the century.

Of course, where you live factors in, too. According to the study, in the US at least, it is likely the pollen season will be affected more in northern states than southern ones as a result of larger increases in temperature.

However, that's just the general trend. The region-by-region picture becomes much more complicated as some areas may be more impacted due to the kinds of tree and planet species that grow there. For example, the study forecasted that the Pacific Northwest’s pollen season could begin an entire month earlier due to the early pollination of the alder tree.

In addition to pollen, fungal spores – both indoor and outdoor – can also become intensified by the climate crisis. Molds are a kind of fungal growth that spread through “tiny airborne spores” and can – in addition to pollen – contribute to seasonal allergies.

According to the Environmental Protection Agency (EPA), “changes in the amount of outdoor air pollutants can also affect indoor air quality … Mold, dust mites, bacteria, and other indoor pollutants may increase as climate change-related precipitation and storms increase.”

Extreme flooding or drought may impact fungal spores in indoor air. Heavy precipitation could contribute to fungal spores in indoor air due to increased dampness.

For example, the devastating flooding resulting from hurricanes Katrina and Rita in New Orleans, Louisiana, in 2005, “promoted heavy microbial and mold growth, with levels of indoor molds, endotoxins, and fungal glucans similar to levels found in agricultural environments and at levels associated with adverse respiratory health effects.

What are the Health Risks?

It’s more than just sneezing. Allergens can also worsen or result in asthma, and pollen exposure has been connected to asthma attacks and increases in “hospital admissions for respiratory illness,” according to the Centers for Disease Control and Prevention (CDC). Indoor mold growth can also worsen respiratory conditions for people with asthma or mold allergies.

Air pollution – which is known to increase the risk and severity of asthma – can make matters even worse and interact with allergens in ways that exacerbate both of their negative effects. For example, particles from diesel exhaust can increase the amount of time allergens stay in the body, and when ground level ozone pollution levels are high, smaller amounts of ragweed can “trigger an asthmatic or allergic response.

Like so many of the wide-ranging consequences of climate change, the impacts are unequally – and inequitably – distributed. Poor communities and communities of color are often hit the hardest by both air pollution and the health conditions that stem from breathing in hazardous air.

Let’s Take Action

It’s clear: The impacts of the climate crisis on the air we breathe aren’t just a seasonal nuisance. While our allergies will get worse, the climate crisis has devastating repercussions all over the world – and our most vulnerable communities bear the brunt of its health impacts.

There’s plenty that we can do to reduce air pollution. We also have a narrowing window to take bold climate action to slash our emissions and fight rising temperatures. But we need you with us. Help us fight for the just, clean energy future that we desperately need and learn what you can do by joining our digital community of advocates around the world today.