For Ontario farmers, summer 2007 signified drought

Though drought conditions across the Great Lakes basin were not that extreme, south-central Ontario experienced near-record low rainfall and cereal crops will likely be affected

by HENRY HENGEVELD

The summer of 2007 was great for Ontario vacationers – at least as far as the weather goes. Lots of sunshine and heat, relatively little rain (particularly on weekends) and a general absence of significant extreme storm events. 

According to Environment Canada’s statistics, temperatures in the Great Lakes-St. Lawrence basin this summer were actually quite close to normal – only about 0.5 C warmer than the long-term average.

There were, of course, lots of sweaty days when maximum temperatures crept into the uncomfortable 30 C+ range. Toronto experienced 22 of these (compared to the norm of eight), while Windsor sweltered through 28 “hot” days. However, this was still a far cry from the torrid summer of 2005, when temperatures at Pearson International Airport reached or exceeded 30 C a total of 38 times. 

While vacationers may have relished the extended period of dry weather, most Ontario farmers didn’t. For them, the real Ontario weather story this summer related to the ‘D’ word – drought! 

But, when averaged across the entire Great Lakes Basin, the drought conditions were actually not that extreme. Average deficit in rainfall was only about 16 per cent below the long-term norm, the eighth driest since 1948. However, much of south-central Ontario, particularly the region between Chatham and Peterborough, experienced near-record low precipitation during the three months of June to August. At the Pearson airport, for example, the 112 millimetres of rain that fell was about half the norm, and the lowest in almost 50 years.

The effect of such drought on most people within the non-farming community is primarily one of inconvenience. Often, it just means daily watering of the garden or flower beds and, if you dislike brown lawns, regularly sprinkling the yard. However, for farmers without irrigation systems, it is far more than an inconvenience.

Early indications are that the combined impact of low rainfall and high evaporation caused by sunny skies on cereal crops across southern Ontario farmland is likely to be far less tolerable. While the final results will also depend on how much rain falls in early fall, it appears unlikely that the good crop yields of the last few years will recur this year.

The drought has also added to concerns about dropping water levels in the Great Lakes. As of the end of August, levels in Lake Superior had dropped to 54 centimetres below the long-term average, reaching the lowest values since records began in 1918. Levels in Lake Huron, while not yet down to the record low set in 1964, were also well below normal – and are still dropping. By comparison, levels in Lakes Erie and Ontario were only modestly below long-term means, the latter partly because of flow regulations in the St. Lawrence Seaway system. 

The summer’s weather across the rest of Canada was relatively uneventful. While almost all of the country was warmer than normal, only parts of the Arctic and the Prairies experienced unusually warm temperatures, although not outrageously so.

Likewise, the only other significant precipitation anomalies were the very wet conditions in the normally dry western part of the Northwest Territories and the drought in the southern Prairies. The former was a result of a major precipitation event in early summer, the latter a spill-over northward of a major drought in the American west. Few other major weather events were sufficiently serious to attract significant media attention. 

While the summer’s weather may have been relatively benign for most Canadians, it was less gentle in other parts of the world. Global temperatures continue to rise, with average temperatures for the first seven months of the year being the second highest on record, surpassed only by 1998. American tropical storm forecasters had also predicted that the warm ocean temperatures would create an unusually high level of hurricane activity in the Atlantic Ocean this year.

By early September, two extremely powerful category 5 hurricanes had already roared their way through the Caribbean Islands and into Central America, and several more modest ones had added their effects. Hurricane Dean passed though in mid-August, hitting Mexico as a category 5 storm (the most intense category) and leaving 40 deaths in its wake.

The second, dubbed Felix, also reached the category 5 level, and resulted in at least 98 deaths, mostly in Honduras and Nicaragua. Before Felix had dissipated, a somewhat weaker Hurricane Henrietta had arrived in the Gulf region, dumping copious amounts of rain in the southern United States and Mexico. It caused another 10 fatalities.

As usual, droughts and heat were also major topics on the world’s weather scene this summer. Near to home, a prolonged heat wave and drought in the central and southeast United States caused soil moisture levels there to drop to extreme lows. Regional crops have been severely damaged. Drought conditions also persisted in the western U.S. 

Meanwhile, southern Europe continued to feel the effects of the hot, dry winds blowing in from the Sahara. Countries along the northern Mediterranean were significantly affected. In particular, during August, arsonists igniting the tinder-dry forests in Greece caused massive forest fires that resulted in more than 60 fatalities.  

Other regions of the world received far too much rain. The United Kingdom and central Europe had one of their wettest summers on record. Asia was also hit hard. Heavy rain across parts of China during June and July generated devastating floods and landslideswhich affected about 500,000 people and caused extensive loss of property. 
Likewise, flooding due to intense July rainfall across eastern and northeastern India caused dislocation and hardship for more than a million people. Pakistan, Nepal and Indonesia were also hit hard with flooding.

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