Climate Change Has ‘Worsened’ North America’s Pollen Season
By Ayesha Tandon
The research, published in the journal Proceedings of the National Academy of Sciences (PNAS), concludes that the North American pollen season is now starting 20 days earlier and lasting eight days longer than in 1990. Climate change is responsible for roughly half of these changes, the study says.
The study also finds that climate change is a "significant contributor" to a 21% increase in pollen levels since 1990. The authors note that the increase in tree pollen levels is bigger than the increase in either grass or weed pollen.
"Climate change is already worsening pollen seasons," the lead author of the study tells Carbon Brief, adding that this is "bad news for people with respiratory health problems."
'Worsening' Pollen Seasons
Pollen is a powdery substance that is released into the air by plants, such as grasses, weeds, and trees. Pollen grains float through the air – if they land on another plant of the same species, they can fertilize it to produce seeds for a new plant.
Plants only release pollen into the air throughout the warm "pollen season". For the US, this begins – depending on the state – around February and continues throughout the summer.
Research shows that warmer temperatures and higher CO2 levels can shift pollen seasons and increase pollen levels. However, this study is the first to calculate the contribution of climate change to historical pollen data trends, lead author Dr William Anderegg from the University of Utah tells Carbon Brief:
"The central new aspect of this study is a detection of a 'fingerprint' of climate change on pollen trends in the US and Canada and in attributing how much of these trends is likely due to climate change."
To determine the impact of climate change on the pollen season, the team analyzed pollen records from 60 cities in the US and Canada from 1990–2018. The data are shown below.
The map on the left shows changes in pollen level – in other words, how much pollen the air is carrying. Red circles indicate rising pollen levels over time and blue circles indicate falling levels. Circle size corresponds to how many years of data were available – larger circles mean more years of data are used.
Similarly, the figure on the right shows changes in the start date of the pollen season. Red circles indicate an earlier start date and blue circles indicate a later start date.
Pollen data from 60 stations in the US and Canada. Changes in "pollen integral" (top) and changes in pollen season start date (bottom). Red circles indicate higher pollen levels and earlier start dates, respectively. Circle size is proportional to the number of years of data at each station. Source: Anderegg et al. (2021).
The study also shows that the North America pollen season has become around eight days longer and has also shifted to start around 20 days earlier. This suggests a "seasonal shift of pollen loads to earlier in the year," according to the paper.
The authors find that between 1990-2018 the average annual pollen level increased by 21%. The map shows that the largest, most consistent increases were seen in Texas and the midwestern US.
There are three main types of pollen that can cause allergic reactions in humans, such as hayfever – "tree pollen," "grass pollen" and "weed pollen". Many people are more allergic to some types than others.
The impacts of climate change are different for different plants, so the authors analyzed pollen trends for each of these three plant types individually. They found that, of the three main plant types, the biggest increase in pollen level is from tree pollen.
The longer pollen season and the higher levels of pollen in the air means that peoples' exposure to allergenic pollen has "increased significantly" over recent decades, the paper notes. Anderegg adds that this is "bad news" for those with respiratory health problems and that it is "likely to get worse in coming decades."
Dr Claudia Traidl-Hoffman from the Technical University of Munich, who was not involved in the study, tells Carbon Brief that "allergies are the most common chronic inflammatory diseases and will be further fueled by climate change."
Climate Changes 'Worsens' Pollen Seasons
As well as analyzing changes in the pollen season, the authors determined how much climate change contributed to these trends.
To do this, the authors tested a range of annual and seasonal climate variables, including temperature, rainfall, frost days and atmospheric CO2 level. These analyses were run on 22 Earth system models from the fifth and sixth Coupled Model Intercomparison Projects (CMIP).
The study finds that average annual temperature is the strongest predictor of changes to annual pollen level, spring level, pollen season length and pollen season start date.
Anderegg tells Carbon Brief that temperature is a "key determinant" in plant development and that "a longer growing season due to climate change appears to mean a longer pollen season."
Dr Thanos Damialis from the University Centre for Health Sciences at University Hospital Augsburg, who was not involved in the study, tells Carbon Brief how climate change can affect pollen production:
"Land eutrophication and increased temperatures, along with higher urbanity and anthropogenic emissions – such as nitrogen dioxide – are known to have a multiple effect on plants: they produce more biomass, more flowers, the plant produces more pollen, which all result in more airborne pollen in urban environments."
The figure below shows the contribution of climate change to annual pollen level (dark red), spring pollen level (light red), pollen season start date (dark green) and pollen season length (light green). For each of these factors, two different time periods are shown – 1990-2018 and 2003-2018. The black line shows the model average.
Impact of climate change on annual pollen level (dark red), spring pollen level (light red), pollen season start date (dark green) and pollen season length (light green). Source: Anderegg et al (2021).
The study concludes that climate change is responsible for roughly 50% of the changes to the pollen duration and start time, and 8% of the changes to pollen level.
The authors note that the impact of climate change is more significant in spring than annually due to a "seasonal compensation" effect, whereby a decrease in summer pollen levels could lower the annual average.
The figure above also shows that the influence of climate change on pollen seasons has become larger over time. For example, the study finds that between 1990-2018 climate change was responsible for between 35-66% of the shift in pollen start date. However, between 2003-2018, it contributed to between 45-84% of this shift.
These findings suggest that the impact of climate change on the pollen season is getting stronger over time, the authors say.
The paper notes that the increase in monitoring stations in recent years could also have influenced this result. However, the authors add that the results are robust when "sensitivity analyses" are conducted around the number of stations included and the longevity of station observations.
Traidl-Hoffman says the study is of "utmost importance" for investigating the impacts of climate change on health. She tells Carbon Brief:
"Climate change is impacting enormously on our health and allergic diseases are in the first line of importance."
Reposted with permission from Carbon Brief.
- 35 Worst Cities (and the Worst State) for Asthma and Allergy ... ›
- Pollen Is Getting Worse, but You Can Make Things Better With ... ›
- It's Official: Climate Change Worsens Global Pollen Season ... ›
- January Warm Spells, March Freezes: How Plants Manage the Shift From Winter to Spring - EcoWatch ›
- New Clues Help Monarch Butterfly Conservation Efforts - EcoWatch ›
- Monarch Butterflies Will Be Protected Under Historic Deal - EcoWatch ›
EcoWatch Daily Newsletter
California faces another "critically dry year" according to state officials, and a destructive wildfire season looms on its horizon. But in a state that welcomes innovation, water efficacy approaches and drought management could replenish California, increasingly threatened by the climate's new extremes.
- Remarkable Drop in Colorado River Water Use Sign of Climate ... ›
- California Faces a Future of Extreme Weather - EcoWatch ›
Wisdom the mōlī, or Laysan albatross, is the oldest wild bird known to science at the age of at least 70. She is also, as of February 1, a new mother.
<div id="dadb2" class="rm-shortcode" data-rm-shortcode-id="aa2ad8cb566c9b4b6d2df2693669f6f9"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1357796504740761602" data-partner="rebelmouse"><div style="margin:1em 0">🚨Cute baby alert! Wisdom's chick has hatched!!! 🐣😍 Wisdom, a mōlī (Laysan albatross) and world’s oldest known, ban… https://t.co/Nco050ztBA</div> — USFWS Pacific Region (@USFWS Pacific Region)<a href="https://twitter.com/USFWSPacific/statuses/1357796504740761602">1612558888.0</a></blockquote></div>
By Hui Hu
Winter is supposed to be the best season for wind power – the winds are stronger, and since air density increases as the temperature drops, more force is pushing on the blades. But winter also comes with a problem: freezing weather.
Comparing rime ice and glaze ice shows how each changes the texture of the blade. Gao, Liu and Hu, 2021, CC BY-ND
Ice buildup changes air flow around the turbine blade, which can slow it down. The top photos show ice forming after 10 minutes at different temperatures in the Wind Research Tunnel. The lower measurements show airflow separation as ice accumulates. Icing Research Tunnel of Iowa State University, CC BY-ND
While traditional investment in the ocean technology sector has been tentative, growth in Israeli maritime innovations has been exponential in the last few years, and environmental concern has come to the forefront.
theDOCK aims to innovate the Israeli maritime sector. Pexels<p>The UN hopes that new investments in ocean science and technology will help turn the tide for the oceans. As such, this year kicked off the <a href="https://www.oceandecade.org/" target="_blank" rel="noopener noreferrer">United Nations Decade of Ocean Science for Sustainable Development (2021-2030)</a> to galvanize massive support for the blue economy.</p><p>According to the World Bank, the blue economy is the "sustainable use of ocean resources for economic growth, improved livelihoods, and jobs while preserving the health of ocean ecosystem," <a href="https://www.sciencedirect.com/science/article/pii/S0160412019338255#b0245" target="_blank" rel="noopener noreferrer">Science Direct</a> reported. It represents this new sector for investments and innovations that work in tandem with the oceans rather than in exploitation of them.</p><p>As recently as Aug. 2020, <a href="https://www.reutersevents.com/sustainability/esg-investors-slow-make-waves-25tn-ocean-economy" target="_blank" rel="noopener noreferrer">Reuters</a> noted that ESG Investors, those looking to invest in opportunities that have a positive impact in environmental, social and governance (ESG) issues, have been interested in "blue finance" but slow to invest.</p><p>"It is a hugely under-invested economic opportunity that is crucial to the way we have to address living on one planet," Simon Dent, director of blue investments at Mirova Natural Capital, told Reuters.</p><p>Even with slow investment, the blue economy is still expected to expand at twice the rate of the mainstream economy by 2030, Reuters reported. It already contributes $2.5tn a year in economic output, the report noted.</p><p>Current, upward <a href="https://www.ecowatch.com/-innovation-blue-economy-2646147405.html" target="_self">shifts in blue economy investments are being driven by innovation</a>, a trend the UN hopes will continue globally for the benefit of all oceans and people.</p><p>In Israel, this push has successfully translated into investment in and innovation of global ports, shipping, logistics and offshore sectors. The "Startup Nation," as Israel is often called, has seen its maritime tech ecosystem grow "significantly" in recent years and expects that growth to "accelerate dramatically," <a href="https://itrade.gov.il/belgium-english/how-israel-is-becoming-a-port-of-call-for-maritime-innovation/" target="_blank" rel="noopener noreferrer">iTrade</a> reported.</p><p>Driving this wave of momentum has been rising Israeli venture capital hub <a href="https://www.thedockinnovation.com/" target="_blank" rel="noopener noreferrer">theDOCK</a>. Founded by Israeli Navy veterans in 2017, theDOCK works with early-stage companies in the maritime space to bring their solutions to market. The hub's pioneering efforts ignited Israel's maritime technology sector, and now, with their new fund, theDOCK is motivating these high-tech solutions to also address ESG criteria.</p><p>"While ESG has always been on theDOCK's agenda, this theme has become even more of a priority," Nir Gartzman, theDOCK's managing partner, told EcoWatch. "80 percent of the startups in our portfolio (for theDOCK's Navigator II fund) will have a primary or secondary contribution to environmental, social and governance (ESG) criteria."</p><p>In a company presentation, theDOCK called contribution to the ESG agenda a "hot discussion topic" for traditional players in the space and their boards, many of whom are looking to adopt new technologies with a positive impact on the planet. The focus is on reducing carbon emissions and protecting the environment, the presentation outlines. As such, theDOCK also explicitly screens candidate investments by ESG criteria as well.</p><p>Within the maritime space, environmental innovations could include measures like increased fuel and energy efficiency, better monitoring of potential pollution sources, improved waste and air emissions management and processing of marine debris/trash into reusable materials, theDOCK's presentation noted.</p>
theDOCK team includes (left to right) Michal Hendel-Sufa, Head of Alliances, Noa Schuman, CMO, Nir Gartzman, Co-Founder & Managing Partner, and Hannan Carmeli, Co-Founder & Managing Partner. Dudu Koren<p>theDOCK's own portfolio includes companies like Orca AI, which uses an intelligent collision avoidance system to reduce the probability of oil or fuel spills, AiDock, which eliminates the use of paper by automating the customs clearance process, and DockTech, which uses depth "crowdsourcing" data to map riverbeds in real-time and optimize cargo loading, thereby reducing trips and fuel usage while also avoiding groundings.</p><p>"Oceans are a big opportunity primarily because they are just that – big!" theDOCK's Chief Marketing Officer Noa Schuman summarized. "As such, the magnitude of their criticality to the global ecosystem, the magnitude of pollution risk and the steps needed to overcome those challenges – are all huge."</p><p>There is hope that this wave of interest and investment in environmentally-positive maritime technologies will accelerate the blue economy and ESG investing even further, in Israel and beyond.</p>
- 14 Countries Commit to Ocean Sustainability Initiative - EcoWatch ›
- These 11 Innovations Are Protecting Ocean Life - EcoWatch ›
- How Innovation Is Driving the Blue Economy - EcoWatch ›