Another record-setting year for world weather

Monday, February 28, 2011

2010 tied 2005 as the warmest on record, resulted in a new low for Arctic Ocean ice volume and, thanks to La Niña, generated some devastating weather events around the world. But, for Ontario farmers, it was relatively benign

by HENRY HENGEVELD

El Niño and La Niña appear to have been two of the key global weather makers of 2010.

The year began with a continuation of moderate El Niño conditions that dominated much of the later part of 2009.  By early spring of 2010, however, the warm pool of El Niño surface waters in the eastern tropical Pacific Ocean had once again shifted westward, to be replaced by cooler than normal waters from the deeper ocean. The area and intensity of this surface cooling increased during the summer, ending up in full-blown La Niña conditions by fall. 

However, it appears that the cooling effect of La Niña came too late in the year to significantly reduce average annual global surface temperatures. By mid-January, American climate data analysts announced that 2010 had tied 2005 as the warmest year ever recorded in more than 163 years of global record keeping.

The mid-year El Niño/La Niña flip-flop also caused some dramatic changes in global wind circulation patterns and the distribution of heat and precipitation across the planet.  These changes, in turn, contributed to some bizarre and devastating events around the world, particularly intense cold and warm anomalies, and intense rainfall events. 

For example, a wide-scale catastrophic heat wave, estimated to be the most severe of the past millennium, pushed its way across Russia and neighbouring countries in early July and stayed there until September. In some regions of central Russia, daily maximum temperatures exceeded 30 C for two months on end. Forest fires raged in many locales, and at least 56,000 people died as a result of heat and air pollution, making it the most deadly natural disaster in Russia's history.

At the same time, extreme monsoon rainfall flooded up to one-quarter of Pakistan, the worst flood in its history. Property losses caused by the flood waters are estimated at $9.5 billion, an extremely high amount for Pakistan's emerging economy. Heavy floods also occurred in China. Then, towards year's end – and continuing well into 2011 – extreme floods swamped much of northeastern Australia. In sharp contrast, severe droughts ravaged large areas of sub-Saharan Africa and the Amazon Basin. 

Although relatively benign in terms of human impacts, the hurricane season in the North Atlantic was also one of the severest of the past century in the number and intensity of storms. Altogether, there were 19 named tropical cyclones. Twelve of the storms attained hurricane strength, with five of these falling into the top hurricane categories (wind speeds over 178 kilometres an hour).

In its year-end report, the major international reinsurance company, Munich Re, noted that the above events were only a few of the many significant natural disasters across the globe during the year – 950 in all. Overall losses from these disasters amounted to around $130 billion, of which approximately $37 billion was insured.

This makes 2010 one of the six most costly years for the insurance industry since 1980. Loss of human life during these disasters, estimated at 295,000, was also unusually high.  However, although 90 per cent of the disasters were weather-related, a significant part of these losses (economic and human) were related to several major earthquakes, particularly that in Haiti (overall losses of $30 billion, insured losses of $8 billion and some 220,000 deaths).  

Across Canada, one of the major weather stories of 2010 was the record-setting heat.  Environment Canada's preliminary analyses indicate that 2010 was the warmest year on record since nationwide records began in 1948 – about three degrees above normal. All parts of the country were above normal, with most of Nunavut and northern Quebec recording anomalies of 4 C and higher. This result was of little surprise, since both spring and winter seasons had also been the warmest on record (4.0 and 4.1 C above normal, respectively), while summer was the third warmest on record and autumn the second warmest. 

Long-term trends indicate that average annual temperatures across Canada have now warmed by 1.6 C over the last 63 years.

One of the most visible victims of the warm temperatures heat was the 2010 Olympic and Paralympic Winter Games. For 40 consecutive days between Jan. 8 and Feb. 16, the average temperature at Vancouver stayed above 5.2 C, dramatically breaking all previous records.

Furthermore, in the 50 days prior to the opening ceremonies, Vancouver experienced no snow, but a total of 247.2 millimetres of rain. It took armies of workers to bring in snow from elsewhere to counteract these El Niño-related setbacks and save the day for what ultimately became a very successful event.

In the Great Lakes region, average temperatures for the year were 1.9 C above normal, only a little below the record set in 1998. Surface water temperatures in the Great Lakes also set new records. By mid-August, surface temperatures on Lake Superior were a remarkable 8 C above normal. Meanwhile, over parts of Lake Ontario, surface temperatures peaked at 24 C, while Lake Erie's reached 27 C.

However, 2010 was a relatively benign year for Ontarians when it came to extreme weather. There were, of course, some heavy thunderstorm and rainfall events. One such event in southern Ontario in mid-March caused about $20 million in flood-related damages.

Some 10 tornadoes touched down in various spots during the summer, but most were relatively weak category F1 and F2 storms, causing only minor and localized damage and, fortunately, no loss of life.

The province's most notable extreme weather events may well be the December snow storms. The first of these hit the Strathroy-London-St.Thomas area hard. Snow blowing in from the open waters of Lake Huron began to fall on the region on Dec. 4 and kept coming almost continuously for five days. By the time it was over, London had received 75 cm of snow, and other locales in the center of the storm more than twice that amount.

The second event came about 10 days later, bringing much of southwestern Ontario to a virtual standstill for a day. Particularly hard hit were regions near Sarnia and Strathroy, where blinding blizzard conditions on Dec. 15 stranded some 300 motorists along Highway 402.

Other parts of Canada also experienced weather-related events to add to local folk lore.  For example, the hardy folks of Newfoundland and Labrador, although well acquainted with foul weather, were surprised at the record-setting destruction caused there by Hurricane Igor. While insured losses totalled about $65 million, estimated non-insured losses may exceed twice that amount. 

On July 12, Calgarians were also greeted with an intense hailstorm that dumped stones up to baseball size on the city and surrounding farmlands. Insured property and crop damages are estimated at $400 million. 

In the north, minimum Arctic sea ice cover dropped to 4.76 million square kilometres by mid-September. While not as low as coverage in 2007, the ice that was present was thinner, resulting in a new record low for total Arctic Ocean ice volume. Environment Canada's Canadian Ice Service experts also noted that total summer ice cover in the Canadian sector of the Arctic was seven per cent lower than the previous lowest extreme of the past 40-some years of record keeping. However, despite these anomalies, many Canadians would agree that 2010's weather wasn't that hard to take.

For most of us, mild winters are most welcome. Furthermore, the summer in central and eastern Canada was relatively warm and largely smog-free, with mild conditions continuing well in the fall.

Farmers I talk to also seem content. In Ontario, the early spring meant an early start to planting and the onset of growth, while timely rains, lots of sunshine and above normal heat units meant good growth conditions. May 2011 be as good! BF

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