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Climate Change is Increasing Seasonal Allergies

Each spring, blooming flowers and trees are a hallmark of the season’s warmer weather. But their pollen is aggravating for people suffering from seasonal allergies, and can be downright dangerous for people with asthma. In fact, around this time each year, web searches soar for things like “pollen,” “allergies,” and “Claritin.” And this year is no different. During the past few weeks, Google web searches for “pollen” have been rising, as illustrated in the interactive graphic below.

Click here for a high resolution static version

Allergy related Google search trends show how the timing of allergy season varies from year to year, depending largely on spring weather. Years with mild winters, like 2007, 2010, and 2012, saw searches for “pollen” peak earlier and higher than other years. Those big spikes can give us a glimpse of what allergies will be like in the future. As climate change brings spring earlier and earlier, we can expect that seasonal allergies — and the web searches they inspire — will only worsen.

In fact, there is evidence that warmer temperatures have already begun to affect pollen seasons, causing them to start earlier and last longer. A 2011 study from the U.S. Department of Agriculture showed that since 1995, the ragweed pollen season has grown longer — as much as 13-to-27 days longer — across much of the U.S. In the spring, pollen from flowering trees causes most allergies, and already trees are blooming days, or even weeks, earlier now than they did several decades ago.

Not every year will have an earlier pollen season than the one before, since the variability of weather patterns will bring surprises, such as this year’s ongoing cold and snowy March. That is clear when you look at Google trends. In 2012, January-March temperatures were the warmest on record for the U.S., and the allergy season hit hard and early. By comparison, this year, the pollen season has been delayed. But studies looking over decades of plant growth and pollen trends show that, overall, the trend will be toward earlier and longer pollen seasons.

And climate models predicts that over the next several decades spring will continue to creep forward, particularly in northern regions of the U.S., which are likely to see more dramatic winter and spring warming trends, which will extend the length of pollen seasons even more.

And it’s not just the warming temperatures and earlier onset of spring that are affecting pollen production. All the CO2 being added to the atmosphere by burning fossil fuels is also compounding the problem. CO2 helps stimulate plant growth, and several recent studies have shown that when plants are exposed to more CO2, they tend to produce more pollen.

In combination, more pollen and longer pollen seasons are more than just an inconvenience. According to the National Climate Assessment, the pollen-related affects of climate change can “diminish productive work and school days.” And for anyone already suffering from seasonal allergies, their misery doesn't need any more company.

Related Content
Spring May Arrive Five Weeks Earlier by 2100, Study Finds
State-by-State Look at How Early Spring Has Arrived
Pollen Searches are on the Rise
Flora and Fauna Feel the Effects of an Early Spring
Sniffle, Snort, Achoo! Allergy Season is Extending, Scientists Find


By Dave (Basking Ridge, NJ 07920)
on March 27th, 2013

Spring time clearly dominates the timing of allergy season, but I also suspect that the relationships between climate change and allergies could be or get quite complicated in detail. For instance, the regional impacts of climate change vary and must act to alter not only the timing but also ultimately the types, or spectrum, of regionally generated airborne allergens, pollen types, molds, dust and so on. On top of that, large scale changes in winds and wind patterns due to climate change trends including perhaps also changes in precipitation must also tend to impact the transport and downwind distribution and timing of airborne allergen concentrations. Here for instance I’m thinking of the well reported increase in the severity and incidence of allergies and asthma in the Caribbean and its link to the increased transport of Saharan dust into that region.

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By Steve Rodgers
on June 21st, 2013

I always have horribel seasonal allergies. The people good people at NYC allergy really cleared me up tho! I couldnt believe it. It was like the spring time had no effect on me.

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