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Manitoba's climate
Click the links below for charts showing how average temperatures have changed in Winnipeg in each season from 1872 to now:
Each point on each chart shows the average (mean) temperature value for the same three months of each year.
Global dimming
In the charts for three of the four seasons there is a period of warming, followed by a period of slight cooling and then more warming.
Scientists believe the cooling period was largely due to other pollution called "aerosols", such as sulphur dioxide, that shaded the earth.
This effect is most evident in the graph for winter.
Acid rain
Smog and acid rain in the 1970s were mostly caused by nitrogen oxides and sulphur dioxide from cars and coal-fired power plants.
These caused global dimming.
After laws required catalytic converters on cars and scrubbers on coal plants, the clouds of pollution has reduced and the earth has gone back to warming up again.
