Pollen season is getting longer and more intense with climate change – here’s what allergy sufferers can expect in the future

Ragweed pollen, instigator of headaches and itchy eyes across the U.S. Bob Sacha/Corbis Documentary via Getty Images

by Yingxiao Zhang, University of Michigan and Allison L. Steiner, University of Michigan

Brace yourselves, allergy sufferers – new research shows pollen season is going to get a lot longer and more intense with climate change.

Our latest study finds that the U.S. will face up to a 200% increase in total pollen this century if the world continues producing carbon dioxide emissions from vehicles, power plants and other sources at a high rate. Pollen season in general will start up to 40 days earlier in the spring and last up to 19 days longer than today under that scenario.

As atmospheric scientists, we study how the atmosphere and climate affect trees and plants. While most studies focus on pollen overall, we zoomed in on more than a dozen different types of grasses and trees and how their pollen will affect regions across the U.S. in different ways. For example, species like oak and cypress will give the Northeast the biggest increase, but allergens will be on the rise just about everywhere, with consequences for human health and the economy.

6 maps showing differences in how types of plant pollen seasons will change. Ambrosia, better known as ragweed, has the greatest increase.
The maps on the left show the recent average pollen season length in days for three types of plants: platanus, or plane trees, such as sycamores; betula, or birch; and ambrosia, or ragweed. The maps on the right show the expected changes in total days by the end of the century if carbon dioxide emissions continue at a high rate. Zhang and Steiner, 2022

If your head is pounding at just the thought of it, we also have some good news, at least for knowing in advance when pollen waves are coming. We’re working on using the model from this study to develop more accurate local pollen forecasts.

Why pollen is increasing

Let’s start with the basics. Pollen – the dust-like grains produced by grasses and plants – contains the male genetic material for a plant’s reproduction.

How much pollen is produced depends on how the plant grows. Rising global temperatures will boost plant growth in many areas, and that, in turn, will affect pollen production. But temperature is only part of the equation. We found that the bigger driver of the future pollen increase will be rising carbon dioxide emissions.

The higher temperature will extend the growing season, giving plants more time to emit pollen and reproduce. Carbon dioxide, meanwhile, fuels photosynthesis, so plants may grow larger and produce more pollen. We found that carbon dioxide levels may have a much larger impact on pollen increases than temperature in the future.

Dust-like pollen falls from pine cones
Cones on a Norway Spruce in Virginia release pollen. Famartin/Wikimedia, CC BY-ND

Pollen changes will vary by region

We looked at 15 different pollen types, rather than treating all pollen the same as many past studies have.

Typically, pollination starts with leafy deciduous trees in late winter and spring. Alder, birch and oak are the three top deciduous trees for causing allergies, though there are others, like mulberry. Then grasses come out in the summer, followed by ragweed in late summer. In the Southeast, evergreen trees like mountain cedar and juniper (in the cypress family) start in January. In Texas, “cedar fever” is the equivalent of hay fever.

We found that in the Northeast, pollen seasons for a lot of allergenic trees will increasingly overlap as temperatures and carbon dioxide emissions rise. For example, it used to be that oak trees would release pollen first, and then birch would pollinate. Now we see more overlap of their pollen seasons.

How pollen season spreads across the U.S. over one year. Yingxiao Zhang and Allison Steiner.

In general, pollen season will change more in the north than in the south, because of larger temperature increases in northern areas.

Southeastern regions, including Florida, Georgia and South Carolina, can expect large grass and weed pollen increases in the future. The Pacific Northwest is likely to see peak pollen season a month earlier because of the early pollen season of alder.

Silver lining: We can improve pollen forecasting

Most pollen forecasts right now provide a very broad estimate. Part of the problem is that there aren’t many observing stations for pollen counts. Most are run by allergy clinics, and there are less than 100 of these stations distributed across the country. Michigan, where we live, doesn’t have any.

It’s a very labor-intensive process to actually measure different types of pollen. As a result, current forecasts have a lot of uncertainties. These likely are based in part on what a station has observed in the past and the weather forecast.

A person's hands jostle a pine branch to collect pollen
Pollen sampling for regional forecasts can be labor-intensive. HelenaAnna/Wikimedia, CC BY-ND

Our model, if integrated into a forecasting framework, could provide more targeted pollen forecasts across the country.

We can estimate where the trees are from satellite data and on-the-ground surveys. We also know how temperature influences when pollen comes out – what we call the phenology of the pollen. With that information, we can use meteorological factors like wind, relative humidity and precipitation to figure out how much pollen gets into the air, and atmospheric models can show how it moves and blows around, to create a real-time forecast.

All of that information allows us to look at where pollen might be in space and time, so people dealing with allergies will know what’s coming in their area.

We’re currently talking with a National Oceanic and Atmospheric Administration lab about ways to integrate that information into a tool for air quality forecasting.

Dozens of round, spiky pollen grains attached to a plant
Ragweed pollen grains, magnified and colorized. Bob Sacha/Corbis Documentary via Getty Images

There are still some unknowns when it comes to long-term pollen projections. For example, scientists don’t fully understand why plants produce more pollen in some years than others. There’s not a good way to include that in models. It’s also not fully clear how plants will respond if carbon dioxide levels go through the roof. Ragweed and residential trees are also hard to capture. There are very few ragweed surveys showing where these plants are growing in the U.S., but that can be improved.

Pollen levels are already on the rise

A study in 2021 found that the overall pollen season was already about 20 days longer in North America than it was in 1990 and pollen concentrations were up about 21%.

Increasing pollen levels in the future will have a much broader impact than a few sniffles and headaches. Seasonal allergies affect about 30% of the population, and they have economic impacts, from health costs to missed working days.

Yingxiao Zhang, Ph.D. Student in Atmospheric Science, University of Michigan and Allison L. Steiner, Professor of Atmospheric Science, University of Michigan

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Nanoplastics should be included in existing regulatory frameworks

Read the full story from the University of Eastern Finland.

In a viewpoint article published in Environmental Science & Technology yesterday, researchers address regulatory concerns related to intentionally produced nanoplastics and outline how the inclusion of the three above-mentioned policy and legislative processes could impact the future regulation of nanoplastics. The discussion in the paper is about whether nanoplastics could be classified as microplastics, nanomaterials, or polymers for regulatory purposes.

Funding opp: Drivers and Environmental Impacts of Energy Transitions in Underserved Communities

Applications due: Apr 28, 2022
For more information and to apply.

The U.S. Environmental Protection Agency (EPA), as part of its Science to Achieve Results (STAR) program, is seeking applications proposing community-engaged research that will address the drivers and environmental impacts of energy transitions in underserved communities. For purposes of this competition and the evaluation of applications, “underserved communities” refers to populations sharing a particular characteristic, as well as geographic communities, that have been systematically denied a full opportunity to participate in aspects of economic, social, and civic life, including people of color, low income, rural, tribal, indigenous, and other populations that may be disproportionately impacted by environmental harms and risks.

Applicants for regular awards should address at least two of the five research areas described below; and early career applicants should address at least one of the five research areas. Applications not addressing the minimum number of research areas may not be rated as highly as those that do. Applications should clearly indicate which research area(s) the application is addressing. Applications addressing more research areas will not necessarily be rated more highly than those that address fewer research areas.

Applicants for regular awards are strongly encouraged to approach the research areas from a multi-disciplinary perspective (e.g., including both social and natural science disciplines).
While the proposed research may focus on a specific geographic (e.g., rural and urban areas), socioeconomic, demographic, governmental (e.g., tribal), or other contexts, and recognizing that each community may have its unique set of contexts, research addressing how the results could be applied or generalized to other locations, demographic groups, etc., or linked to broader theoretical frameworks is encouraged.

In addressing each of the research areas below, applicants are strongly encouraged to consider the resiliency of future energy systems, impacted communities and/or tribes, and policy frameworks. Resiliency is the capacity to adapt to and to recover from unexpected and changing conditions or a range of shocks and stresses. Applicants are encouraged to consider how energy system transformations affect the resiliency of systems that produce and consume energy and the resiliency of populations and ecosystems with respect to public health and environmental risks, including risks that are anticipated to increase due to climate change.

Research areas

  1. How might air quality, the environment, and public health in underserved communities be improved through the large-scale transformation of the energy sector (e.g., wide-spread adoption of renewable energy sources and energy efficient technologies, electrification of transportation services, and household energy use) while minimizing potential negative impacts (e.g., from disuse or abandonment of obsolete fossil energy infrastructure)? How can existing or new data sources and methods be used to measure impacts and track progress?
  2. What approaches or strategies can be employed during and after energy transitions to meet the goals of improving air quality and reducing other environmental health burdens while meeting the energy and mobility needs of underserved communities? How do these approaches impact air quality and health burdens over time as the energy system evolves? How can existing or new data sources and methods be used to measure progress towards these goals?
  3. How do socioeconomic, cultural, behavioral, institutional, and systems factors drive individual and household decisions regarding the adoption of renewable energy sources, energy-efficient technologies and building modifications, and new transportation modes in underserved communities? What are the barriers and enablers of adoption? How do behavioral responses influence the effectiveness of strategies and policies aimed at achieving energy savings and greenhouse gas emission reduction goals?
  4. How do socioeconomic, organizational, and institutional factors affect decisions at the organizational, governmental and community levels regarding the adoption and diffusion of renewable energy sources, energy-efficient technologies, building modifications, and new transportation modes in underserved communities?
  5. What multi-pollutant and/or multi-sectoral approaches could be effective at the community, state, or national level in achieving climate, air quality, and other environmental goals in ways that maximize potential positive impacts and minimize potential negative impacts to underserved communities arising from such large-scale transformation? How can existing or new data sources and methods be used to measure these goals?

Granholm announces $3M for net-zero carbon research at HBCUs

Read the full story from the Associated Press.

U.S. Energy Secretary Jennifer Granholm on Thursday announced that $3 million in federal funding would be directed toward historically Black colleges and universities, and other minority serving institutions, for research she said will further the Biden administration’s goals of carbon neutrality and help strengthen a pipeline from those schools into energy-related jobs.

Looking to reduce emissions, apparel makers turn to their factories in the developing world

Read the full story at Inside Climate News.

Solar projects in Vietnam by a South Korean manufacturer for leading brands like Under Armor and Victoria’s Secret represent a small start for an industry whose emissions may eclipse those of shipping and aviation.

Your standard environmental site assessment may still be skipping over PFAS

Read the full story at JD Supra.

With all the attention on PFAS over the past few years, you might assume that your standard Environmental Site Assessment would assess the possibility that the property you’re buying has been impacted by PFAS, the “forever chemicals” that are on their way to being regulated by the Federal Government in parts per trillion (and are already regulated in such minute concentrations in many states).

But, as Inside EPA reports, because PFAS are not yet “hazardous substances” according to Federal law, the current ASTM standard for Environmental Site Assessments doesn’t cover them.

That means you need to make sure your site assessment professional adds PFAS to its scope of work.

Tree planting is booming. Here’s how that could help, or harm, the planet.

Read the full story in the New York Times.

Reforestation can fight climate change, uplift communities and restore biodiversity. When done badly, though, it can speed extinctions and make nature less resilient.

EPA plans sweeping regulatory strategy for power plants covering air, water and land pollution

Read the full story from Utility Dive.

The Environmental Protection Agency is preparing to issue a series of proposals covering air, water and waste pollution from power generators, especially coal-fired power plants, EPA Administrator Michael Regan said Thursday.

The pending actions will give the power sector increased certainty around where it makes the most sense to invest: upgrading existing power plants or retiring them to focus on new forms of generation, Regan said at the CERAWeek energy conference in Houston.

“We’re looking at a full suite of opportunities that marry a range of EPA authorities,” Regan said. “We don’t have to overly rely on any one policy or rulemaking to achieve our mission and ensure affordable and reliable energy.”

Surveying the BECCS Landscape

Download the document.

Surveying the BECCS Landscape is the first report in the series Bioenergy with Carbon Capture and Storage: Sowing the Seeds of a Negative-Carbon Future. Producing nine key findings through a literature review of more than 300 sources, this report establishes the challenges and opportunities associated with growing a BECCS industry, lining up future areas of deeper study.

How oil companies rebranded deceptive climate ads as ‘free speech’

Read the full story in The Guardian.

In two dozen climate liability cases, companies are arguing that their public statements about climate change are not ‘deceptive’ so much as persuasive – and protected free speech