Elliot:
Have you had a chance to look at the information for our project yet, Beth?
Beth:
I've had a look at most of the stuff on the relationship between climate change and allergies and at the role played by pollen from flowering plants and trees.
Elliot:
The main message is that seasonal allergies seem to be getting worse.
Elliot:
In just the last 20 years, the amount of pollen that's produced by the flowers on birch trees has tripled, and one in four people suffers from either hay fever or asthma, which is triggered by pollen.
Beth:
I read something about allergy sufferers being more likely to have a vitamin D deficiency because we no longer take cod liver oil as a vitamin supplement, like many people used to do in the 1950s in Britain.
Beth:
And since then, allergies have quadrupled in most European countries, but it was only in Britain that cod liver oil was so popular, so that argument doesn't really make sense.
Elliot:
No, it doesn't seem that relevant.
Beth:
What seems to be happening now is that an increasing number of people are getting their first attack in their 40s and 50s.
Elliot:
That must be because of the link with climate change causing rising temperatures.
Elliot:
But CO2 levels are seriously affecting pollen counts too.
Beth:
As much as milder winters?
Elliot:
CO2 helps stimulate plant growth, and several recent studies have shown that when plants are exposed to more CO2, they produce more pollen.
Beth:
So people might experience more severe allergic symptoms in future?
Beth:
And another factor is that the pollen season is changing.
Elliot:
Scientists are predicting spring will come five weeks earlier, by 2130.
Beth:
That's in the long term.
Beth:
But that doesn't mean that spring will come earlier every year.
Beth:
Look at last winter.
Beth:
That was really cold until March, and the pollen season was delayed.
Beth:
Whereas this year, spring came earlier and lasted longer.
Elliot:
And another thing we should mention is ragweed.
Beth:
As an example of a plant species moving into new areas as a result of climate change.
Elliot:
In the US, it's already the major allergen, affecting millions of people in August and September.
Elliot:
But we're starting to see it grow in Europe for the first time, which is really worrying because it's so allergenic.
Beth:
The problem with tree pollen is also worse in cities because there are so many hard surfaces around, and the pollen doesn't get absorbed so much, just stays in the air.
Elliot:
Wasn't the pollen shown to be three times higher in one city?
Beth:
So because of this, many cities have started to ban the planting of certain types of trees.
Beth:
So shall we look at the different data tables for seasonal changes for pollen in Europe?
Elliot:
But I think we should just focus on the trees and plants, which we have the most data for.
Elliot:
So that's oak trees and birch trees and grass.
Beth:
Yes, that makes it more manageable.
Beth:
Shall we go through the data for each country in detail and pick out anything interesting?
Elliot:
So, starting with Austria.
Elliot:
Well, here we've only got data for birch pollen.
Elliot:
I wonder why there's no data for oak or grass?
Beth:
It would be interesting to compare with neighbouring countries.
Beth:
The picture in France is unusual.
Elliot:
Yes, the pollen season starts earlier for both oak and birch, but it doesn't start any earlier for grass.
Elliot:
I wonder why that is?
Elliot:
In the Netherlands, we've got complete data for all three plants.
Beth:
So what does it show?
Beth:
Grass and birch pollen are only starting a few days earlier, but oak pollen is starting much earlier, 18 days in fact.
Beth:
There's not such a big difference in other countries.
Elliot:
Switzerland's an interesting case.
Elliot:
The pollen season starts here earlier than in the past for oak, birch and grass.
Beth:
Yeah, from 21 days to 14 days earlier.
Elliot:
The UK shows a different picture again.
Beth:
Here the problem is that wet summers have extended the grass pollen season from five weeks to eight weeks, which is bad news for allergy sufferers.
Elliot:
Well, I think we should have another look...
