The map shows the value for the selected climate variable or index for one of three 30-year time periods: the recent past (1976-2005), the immediate future (2021-2050) and the near future (2051-2080). Future projections are calculated using two possible greenhouse gas emissions scenarios that result in more or less severe levels of climate change.
Emissions continue to increase at current rates, leading to higher emissions that cause more severe warming.
This is the "business as usual" scenario, and assumes that world greenhouse gas emissions continue to increase at current rates through the end of the century. This large amount of greenhouse gas emissions results in more severe global warming. This is also called the "high carbon" future, and is based on the RCP8.5 emissions scenario.
Greenhouse gas emissions slow, peak mid-century, and then drop rapidly, leading to lower emisions that cause less severe warming.
This scenario assumes that greenhouse gas emissions increase until about 2050 and then rapidly decline. This decline in emissions leads to less severe global warming than the alternative “business as usual” or high carbon scenario. This is also called the "low carbon" future, and is based on the RCP4.5 emissions scenario.
The benefits of reducing emissions
On the Climate Atlas map, you can choose between the scenarios using the “Climate Change” switch that selects “more” or “less” climate change. If you use the “Find local data” page or follow a “detailed climate data” link from the map sidebar, you can select RCP8.5 or RCP4.5 scenario in the form on the data page.
Comparing the two possible scenarios demonstrates the importance of taking climate action. For example, these images show the projections for the number of very hot days in southern Ontario for the recent past and for 2051-2080 under the high carbon and low carbon scenarios.
The high carbon scenario clearly shows much more warming taking place over a much larger area. The low carbon future is still warmer than the past conditions Ontarians are used to, but it’s a whole lot less severe.
The difference between these possible futures tells us how important it is to take action. Only reducing greenhouse gas emissions can make the difference between these possible climate futures.