Toronto - what happened to 1.5 degrees?

Some time ago, I posted my calculations on the difference between Canada and Ontario's published emission reduction targets and what they should be if we were to keep our cumulative emissions under the carbon budgets documented by the Intergovernmental Panel on Climate Change (IPCC). 

In the following discussion the carbon budgets are for a likely (> 66%) chance of remaining below 1.5 and 2 degrees C.

Since then I have performed the same calculations for Toronto.

Toronto's Climate Change Action Plan has the following targets based on 1990 levels of approximately 22 million tonnes per year, city-wide, are:

  • 6 percent by 2012 (1.32 MtCO2e)
  • 30 percent by 2020 (6.6 MtCO2e)
  • 80 per cent by 2050 (17.6 MtCO2e)

If we follow Toronto's plan, by around 2037 we will exceed Toronto's fair share of the carbon budget for remaining below a 2 degrees C temperature increase.​ We are already close to the carbon budget for remaining under 1.5 degrees C.


Red line - the carbon budget for a chance of remaining under 3C

Orange line - the carbon budget for a chance of remaining under 2C

Green line - the carbon budget for a chance of remaining under 1.5C

Blue line - Toronto's cumulative emissions if we use Toronto's plan


Toronto's share of the global population is 0.03%. If we use population sharing (also referred to as Equity), our budget will be approximately 394 MtCO2e to remain under 2 degrees C.

If we reduce Toronto's emissions by approximately 0.6 Mt CO2e each year our targets should be as follows:

  • 2020 28%
  • 2030 54%
  • 2040 80%
  • 2050 100%

If we do this, Toronto will have achieved zero carbon emissions before 2050 and not exceeded our fair share of the global carbon budget for keeping the termperature increase around 2 degrees C.

The possible targets for remaining below the given temperatures are in this table (compared to 1990 emissions)

Toronto Plan
Carbon Budget < 2 degrees C
2020   28%
2030 30% 54%
2040   80%
2050 80% 100%


If you are interested in more details of my calculations, I have posted them on is external).