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Ice floats in Slidre Fjord outside the Eureka Weather Station on Ellesmere Island, Nunavut, in this file photo from July 2006. ((Jeff McIntosh/Canadian Press))

Temperatures soared to record highs in the High Arctic in July, stunning Environment Canada's senior climatologist.

David Phillips said a heat record was broken last month in Eureka on Ellesmere Island. A similar record was almost broken further up the island at Alert, Canada's most northerly place.

"Boy, there are some real head-shakers. I look at Eureka — I mean, it is probably almost as far north as you can get — and we saw temperatures of, you know, up to almost 21 C," Phillips told CBC News.

"It's been just absolutely balmy."

Phillips said Eureka went up to 20.9 C on July 14, breaking the record of 20.7 C from July 23, 2007. Environment Canada started recording weather at the Eureka weather station in 1947.

Normal high around 8 C

He added that Eureka has seen temperatures between 17 C and 20 C on several days in July.

"At this time of the year, you should see highs of about perhaps maybe closer to about 8 C, and these are temperatures that are, you know, 12 to 15 degrees warmer than normal," he said.

Temperatures in Alert went up to 18.6 C in late July. Phillips said that did not break the July record set in 1956, when the mercury hit 20 C there.

Greg Henry, a researcher who has studied plants on the tundra on eastern Ellesmere Island for almost 30 years, said he has noticed major weather changes in the area since the mid-1990s.

Henry, a geography professor at the University of British Columbia, said he's noticed rainstorms instead of snowstorms in the middle of July. His team recently worked outside in T-shirts and shorts when the bugs weren't too bad, he added.

"At Alexander Fiord this year, I think we probably hit pretty close to 19 C on a number of days," he said.

"We had glorious weather of no clouds for about 2½ weeks, and we've had these sort of warm summers now for the last eight or nine years."

Plants growing taller, bigger

The warmer weather has also meant plants are growing taller and faster, and blooming earlier, in the High Arctic, Henry said.

He said that over the past 28 years, annual temperatures have risen by almost 3 C. That has led to denser vegetation both on wetlands and on drier land, especially an evergreen shrub known as the Arctic white heather.

"In both cases there was two times and greater weight of plants, so the biomass has increased by two to five times above the ground," he said.

"And below ground in the wetland, we found 10 times the increase in biomass over that ... 28 years."

Henry said researchers are noticing more woody shrubs across tundra systems around the world, matching observations by Inuit.

Henry said he is also noticing the permafrost is melting, and there is a lot of erosion and slumping along one of the rivers.

With files from the CBC's Patricia Bell