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Monique Keiran: Allergic to pollen? Get used to it

Victoria is a year-round allergy town. If mould and wood smoke aren’t causing itchy eyes, runny noses, scratchy throats and sneezing among residents in fall and winter, then pollen and dust do the honours in spring and summer.
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A bumblebee gathers pollen from lantana flowers on the State Capitol grounds in Raleigh, N.C., in a September 2015 file image. Lantana offers many color choices, and the vibrant tones of red, orange and pink are especially beautiful. (Chris Seward/Raleigh News & Observer/TNS)

Victoria is a year-round allergy town. If mould and wood smoke aren’t causing itchy eyes, runny noses, scratchy throats and sneezing among residents in fall and winter, then pollen and dust do the honours in spring and summer.

But pollen appears to be extending its season on duty. According to data released by London Drugs and Canadian airborne allergen-monitoring firm Aerobiology Research Laboratories, the length of allergy season in Canada has increased by more than six months in the past decade. Here on the south coast, grass-pollen season is almost one month longer than it was in 2006, and dock-weed-pollen season is 203 days longer.

The cause for the extended open season on pollen allergies, say Aerobiology’s researchers, is climate change. Data on pollen presence and abundance from across Canada indicate plants are flowering sooner and longer each year than they did just 10 years ago.

Plants respond to both intensity of sunlight and temperatures. As seasonal temperatures have climbed in recent years, seasonal sunlight intensity remains steady. The size of Earth’s orbit around the Sun hasn’t changed appreciably in the past 100 years. The sun continues to rise on, for example, May 30, about the same time and the same place on the horizon every May 30.

What has changed, however, is weather. Milder winter temperatures in recent years — this year in the Interior being an exception — have brought more sunny and warm days both earlier and later in the year.

In areas where prolonged winter ice and snow are normal, early warm temperatures cause the ground to warm and melt earlier, which allows it to absorb snow melt or rain. The combination of warm air, warm ground and water in the soil can trigger some plant species to shake off their winter dormancy and spring into growth and reproduction.

Some plants might react to the changes more tentatively. For example, local forest researchers documented a timing disconnect between the budding of native evergreens on Vancouver Island and the hatching of a species of caterpillar that relies on those trees’ tender young needles for food. Insect life-cycle events typically are attuned more tightly to temperature than trees are, so when warming ocean currents brought springtime weather to our shores earlier than usual, the bugs hatched well before their buffet was served.

The changing environment might affect plants that we’ve imported from elsewhere more strongly. Having evolved hand-in-hand with warmer climates and earlier springtimes, the internal clocks of these garden specimens might be triggered by the warmer seasonal temperatures we’ve seen in recent years.

Here, many of our local plants seem as keyed to availability of water as to sunlight and warmth. Lack of water is rarely an issue on the coast in late winter and early spring, but it often becomes limiting during the summer.

The iconic Garry oak, for example, is often one of the last trees to bud and leaf out, even in warm springs — which suggests it is keyed more strongly to sunlight cues than to warmth or water. It is, however, also one of the first to lose its leaves at the end of the season — unlike some non-native green and white oaks that have been known to remain leafy and green right into January, which might be springlike compared to the parts of Europe to which these trees are native.

The drier the summer, the earlier the Garry oak leaves dry and brown up on the tree.

Indian plum seems to take its cue from temperature, as it is often one of the region’s first native shrubs to bloom after a mild winter. It gets its blossoms out before the competition can waylay the early-season pollinators, which take their cue from temperature. The native plum also seems well adapted to survive the area’s dry summers, often turning yellow and going dormant as early as July if it encounters drought.

Fortunately, few people are allergic to all types of pollen. Each reacts to his or her own unique immune-system triggers, be they pollen from ragweed or grass, oak or alder, or spruce or Douglas fir.

To find out which pollens are most prevalent in Victoria’s air today, check out Aerobiology’s three-day pollen forecast at the Weather Channel.