Ragweed set to continue its march to make more misery for hay fever suffers as the climate continue to warm. Photo credit: hounddiggity via Flickr.

By Anders Lorenzen

We have entered the annual period, which millions of allergy sufferers across the planet dread: pollen season. Research conducted in recent years has found that due to climate change that period could become longer, and include more severe and prolonged symptoms. On top of this, new plant species can thrive where not possible before, introducing new kinds of pollen to an area. Today it is estimated that, worldwide, around 400 million people suffer from some kind of hayfever.

Ragweed the main cause of the pollen season increase

The Asthma and Allergy Foundation of America (AAFA) are clear about what a warming world means for sufferers: ‘As global temperature and CO2 levels rise, plant pollination cycles have become longer and more intense, with record pollen counts becoming routine. This was seen in the U.S. where record temperatures went hand-in-hand with record pollen counts, and with that, record allergy suffering. While warm temperatures and high CO2 are the ideal growing conditions for all plants, allergenic plants, such as grasses and weeds, are the fastest growing and most adaptable so they will receive the most benefit. The success of these plants will mean increased symptoms among those living with allergies.’

Due to climate change, the whole plant environment is changing, AAFA notes: ‘besides plants, the warming climate will also have an impact on the distribution of insects, especially allergenic ones such as wasps and fire ants. With the extended warm seasons, wasps are coming out earlier and staying out longer, increasing the chances that allergic patients will encounter them. In addition, the distribution of fire ants appeared to be limited to the southern U.S. due to the freezing of the ground in the northern states. However, as the country gradually warms, less and less of this ground will experience extensive freezing, clearing the way for their upward expansion.

And the US government body, the Environmental Protection Agency (EPA) have conducted research highlighting the staggering increase in ragweed across US and Canadian states. Looking at data between 1995 – 2015, and in states ranging from north to south, the extension of the ragweed pollen season ranged from 5 all the way to 25 days. Only one state noted a decrease, of 1 day.

Ragweed on the rise in Europe

In Europe, the outlook is not much brighter. A study last year from the University of East Anglia, UK, concluded that the very same pollen will result in a doubling of hayfever sufferers by 2050 to 77 million, up from today’s 33 million.

Ragweed originates from North America where a quarter of the US population suffers from it. It is believed that it is now spreading fast across Europe, particularly in the north as that is the region in Europe which is warming fastest. Hayfever sufferers will be dismayed to learn that ragweed is hard to control and is a particularly invasive species. A single plant could produce a billion pollen particles per season. Added to this, high levels of carbon dioxide (CO2) will spur it on further. The wind will pick up the seeds and mix them with air pollution particles making it a perfect storm for hay fever and asthma sufferers alike.

Ian Lake from the University of East Anglia, one of the scientists who lead the study, says that ragweed pollen normally peaks in the late summer, but the new models predict that warmer climates and delayed frosts will extend this into the autumn, possibly as late as mid-October in some regions. More pollen in the air, which could also be drier in some countries due to drought, is altering the surface of the pollen and therefore its potential to trigger allergies could also make hay fever symptoms more severe.

Of course, you can take medication to limit the symptoms of hayfever, but as the season has extended and will continue to extend further due to a warming climate doing so will be more costly. The increased severity of symptoms casts doubt on the current medications ability to compensate. So could the vocal voice for action on climate change get a whole new set of members in those who suffers from pollen allergies?