Weather: 2008 - a year of heavy Ontario precipitation and unprecedented shrinking of Arctic ice

Monday, March 2, 2009

Records were broken for precipitation in many parts of Ontario. But perhaps most worrying is that Arctic ice is disappearing much faster than anticipated

by HENRY HENGEVELD

David Phillips, Environment Canada's senior climatologist, has selected the heavy rains and snowfall of 2008 as the most significant weather story for Ontario for the year. 

That shouldn't come as a big surprise to any of us. Pearson International Airport, for example, normally gets a total amount of about 793 millimetres of precipitation per year. Its previous record high, established in 1977, was 971 millimetres. This year, it reached 1,050 millimetres – 32 per cent higher than the average, and eight per cent above the previous record.

Many other Ontario communities experienced similar record-breaking amounts. The net result was annual precipitation across the Great Lakes Basin for 2008 some 20.4 per cent above normal – the wettest year since national record-keeping began in 1948. 

Of course, all that snow and rain has some pluses. It helped greatly to recharge depleted groundwater reserves and lake levels. Although water levels for Lake Superior and Lake Huron remained 21 and 32 centimetres below the long-term average, by the end of 2008 those for Lake Erie and Lake Ontario had risen to above normal
levels. Ski resort operators and snowmobile clubs were also delighted with the extended seasons and the depth
of snow packs.

With all that cleansing summer rain, air quality across the province was one of the best in many years. Lawns were lush, and gardens and trees flourished. Forest fires were few and far between. Even farm crops, despite the heavy summer rainfall amounts, fared remarkably well, largely because the rain came in large bursts interspersed with plenty of sunshine. 

On the down side, the regular and often intense rains this summer caused local floods, created ground conditions often too soft for field work and spoiled a lot of outdoor summer recreational activities. In July, for example, Sarnia had at least a trace of rain every single day of the month. During the year, Hamilton experienced thunderstorms on 28 days, well above the average of 16 days. A few of these storms generated heavy hail that caused considerable damage in the region.

Snowstorms during the winter months brought their own challenges. Contractors and operators experienced a lot of sleepless nights and tiresome days while diligently trying to keep our roads, driveways and parking lots cleared and salted.  In most municipalities, the cost for these services made a mockery out of budgets. The Greater Toronto region alone spent an estimated $80 million for snow removal in 2008.

At least, Ontarians had little to complain about with regard to seasonal temperatures. While we had a few unusually cold and warm days here
and there during the year, average thermometer readings for Ontario farmland were only slightly (about
0.4 C) above normal. 

Across the rest of Canada, most regions also experienced average annual temperatures within a half degree of normal values. The exceptions were most of the Arctic (0.8 to 1.5 C above normal) and the Atlantic provinces (0.7 C above normal). These regions helped push the national mean temperatures to 0.7 C above normal, making 2008 the 16th warmest year on record since 1948.

Meanwhile, large areas of drought in some areas of Western Canada largely offset the precipitation excesses in the east. Hence, precipitation averaged only modestly above normal (4.6 per cent). 

However, within these averages, each region experienced its own customized weather drama. For B.C., it was the cool summer, the wet north, dry south and, during December,  unusual heavy snow falls along the coast. Not geared for the white stuff like the rest of us, west coasters had to cope with clogged airports (particularly during the days leading up to Christmas), uncleared roads, numerous road accidents and many people unable to get to work. That's not supposed to happen in mild, coastal B.C.!

The Prairies, for their part, experienced a large number of hailstorms which generated crop insurance claims exceeding $225 million. Drought once again hit the southern Prairies, and intense cold periods, reminiscent of some of the harsh winters of decades ago, came back to haunt the region.

In late January, the thermometer dipped below -40 C across all three provinces. A repeat performance occurred in mid-December. Quebec and the Atlantic provinces, in addition to getting much of the same heavy precipitation as Ontario, got whacked with downpours and high winds associated with four major tropical storms, including the remnants of Hurricanes Hanna, Ike and Kyle. As a result, most of eastern Canada also experienced annual precipitation levels more than 20 per cent above normal.

Perhaps the most worrisome climate anomalies, however, occurred in the Arctic. The volume, extent and duration of ice cover covering Arctic waters have been progressively shrinking over the past decade. By the end of this summer's melt season, the volume was the lowest ever recorded, despite the relatively cold winter in 2007-08.

Researchers indicate that the unprecedented shrinkage of Arctic sea ice is the accumulated response to the combined effects of several years of enhanced drift of old Arctic ice into the Atlantic Ocean, a persistent, year-round warming across the North and a dramatic transformation of the ocean surfaces from a highly reflective white snow or ice to dark, heat-absorbing sea water.

Such changes are generally consistent with what we can expect as a result of climate change, but appear to be coming much earlier than anticipated. Experts worry that the processes that maintain ice cover in the North may have already passed a critical no-return threshold, and that the Arctic Ocean could be completely ice free in late summers within the next 10 years. That means that there would no longer be any significant amount of hard multi-year ice remaining, and that winter ice would remain relatively thin and weak – good news for ice transportation, but not for the polar bear or for weather around the world.

The changing global pressure and wind patterns that would result from an ice-free Arctic Ocean would significantly alter jet stream patterns and change Northern Hemisphere – and possibly global – storm tracks. The impact on our weather behaviour will likely make our recent wacky weather seem trivial.  

Finally, a brief synopsis of global weather news for the year. Despite the effects of La Niña (which usually brings somewhat cooler weather to the globe) during much of the year, preliminary results indicate that 2008 was about 0.3 C above the long-term average, making it the tenth warmest year since 1850.

Munich Re, in its year-end report, also notes that the year was another bad one for the insurance industry. They estimate total losses due to natural disasters to be about $200 billion US (compared to $82 billion in 2007), of which about $45 billion was insured.  For the insured losses, the impacts of hurricanes in the Caribbean and the United States topped the list at more than $20 billion.

The greatest human disaster caused by weather events was the flooding in Myanmar due to Cyclone Nargis, where almost 85,000 people lost their lives. 
And that, in brief, was the way it was in 2008. BF

Henry Hengeveld is Emeritus Associate, Science Assessment and Integration Branch/ACSD/MSC, Environment Canada.