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Seasonal allergies spiking earlier due to rising global temperatures

As our planet warms, allergy season is starting earlier and lasting longer, with pollen counts in the US already reported to be at ‘extremely high’ levels.

Despite my preference for the hotter months of the year, whenever winter finally ends and spring rolls around, I’m usually filled with dread by what’s to come.

As a long-time sufferer of hay fever, better weather means a bitter sweet amalgamation of actually enjoying the outside and being forced to avoid it at all costs, unless I want my head to feel as though it’s on the verge of exploding.

Unfortunately, until we combat the climate crisis, this is looking to get a whole lot worse.

Due to rising global temperatures, allergy season is starting earlier, lasting longer, and pollen counts are on the up, leading to much worse symptoms for some and new ones altogether for others.

According to scientists, this trend is projected to increase as our planet warms and won’t abate or be reversed without substantial action to reduce carbon emissions worldwide.

‘The intensity of the symptoms has increased, which means what used to be responsive to maybe just one pill used sporadically now requires absolutely an allergy pill but also a nasal anti-inflammatory steroid spray as well,’ says Dr John Costa, medical director of allergy and clinical immunology at Brigham and Women’s Hospital.

‘You get an increased volume of plant material because the conditions of moisture and warmth are conducive to greater plant growth, and the greater plant growth means that we are going to have more pollen.’

In other words, carbon dioxide is used during plant photosynthesis, so when there’s an abundance of it in the atmosphere paired with warmer temperatures, more plants grow and produce higher amounts of pollen.

The most drastic changes can be seen in the US, where 81 million people were diagnosed with hay fever in 2021. Allergy season increased by 20 days and pollen concentration increased by 21% between 1990 and 2018.

Pollen counts climbed to ‘extremely high’ levels in Atlanta on Monday, the earliest it has done so in 30 years of record-keeping. By Tuesday, the tree pollen count had doubled.

A report by Climate Central analysed how rising temperatures have affected allergy season in 203 US cities since 1970.

It found that growing season – the period between the last freeze in spring to the first freeze of autumn – is lasting 16 days longer in the southeast, 15 days longer in the northeast, 14 days longer in the south, and 27 days longer in the west.

‘Those areas are where the springtime is warming pretty extensively, but there is also a lot that we don’t fully understand about why in particular those areas are seeing the biggest trends,’ says William Anderegg, director of the Wilkes Center for Climate Science and Policy at the University of Utah.

‘Planning for the next five, 10, 15 years, we should expect pollen seasons to continue to get worse.’

That is, as Anderegg explains, if we stop relentlessly churning out greenhouse gases at the rate we currently are – and fast.


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