Poorly diversified? That's just a myth not backed by the facts. As a percent of GDP, it's 3rd at 8%:
12.34 Real estate and rental and leasing
10.86 Manufacturing
07.96 Mining quarrying and oil or gas extraction
07.03 Health care and social assistance
06.90 Public administration
06.55 Finance and insurance
05.41 Wholesale trade
05.41 Retail trade
05.38 Educational services
05.21 Professional scientific and technical services
Apparently what my previous response had in brevity, it lacked in depth.
In response
Music Lover, your statistics both highlight my point and give an incomplete total picture.
Yes, oil, gas and mineral extraction make up 8% or 1/12 of the entire economy, as measured by GDP. That is a very large percentage, particularly because the price of crude oil can swing by 50% or more in just a few months. That kind of a swing can be the difference between the economy growing by ~1% and a recession. Few other industries can have that dramatic of a change in that short amount of time.
Now, showing oil and gas extraction as a % of the GDP is only part of the picture. Oil and gas make up about 15% of all of Canada's
exports (and that percentage has been increasing steadily since the 1980s). A drop in global demand and/or prices, particularly overseas (where almost all of Canada's oil is shipped) creates a large trade imbalance. To further complicate matters, Canada is in the odd situation where it both exports (about 1.6MM bbl) and imports (about 0.8MM bbl) huge amounts of oil given there are only ~35MM people living here.
So yes, our economy here in Canada is heavily influenced by all things Oil.