The scientific evidence is clear: the Earth’s climate is warming. Since the 1950s, many of the observed changes are unprecedented over decades to millenniaFootnote1. In Canada, these changes include rising temperatures, shifting rainfall patterns, and increases in certain types of hazardous weather.
Climate change is primarily attributed to the accumulation of greenhouse gases (GHGs), which traps heat in the atmosphere and causes a warming effect. This warming effect depends on the total amount of GHGs accumulated in the atmosphere, the time that they remain in the atmosphere, and each GHG’s capacity to trap heat. In 2014, the Intergovernmental Panel on Climate Change (IPCC) concluded that “it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century”.
Based on the IPCC Fifth Assessment Report’s mitigation scenario, limiting the average global temperature increase to likely less than 2°C relative to pre-industrial levels, in line with the goal of the Copenhagen Accord, will require that global GHG emissions be reduced by 40% to 70% below 2010 levels by mid-century and that emissions be decreased to near zero in the long term. To keep warming likely below 2oC, cumulative global emissions of carbon dioxide must be limited to approximately one gigatonne of carbon, half of which has already been emitted. Under this scenario, temperature in Canada is projected to rise by approximately 4.0oC. Under the highest emissions scenario, which assumes that global annual GHG emissions continue to rise throughout the 21st century, average global temperature is projected to rise by 5.6oC by 2100. However, temperature in Canada is projected to rise by 9.5oC.
While impacts including temperature rise are projected to vary by region, GHGs are distributed throughout the Earth’s atmosphere. As a result, emissions reductions efforts that are undertaken contribute to addressing this global challenge, irrespective of where they are taken (either within or beyond any one country’s national borders). This underscores the importance of coordinated global action to address climate change.
Explanation:
Why is it important?
Climate science provides facts about climate change, enables understanding of the causes, and makes projections about future climate conditions. Scientific methods and processes such as scientific research, monitoring, modeling and assessment inform evidence-based decision making by providing policy makers with credible and relevant information. Climate science contributes to building effective domestic climate change strategies and mitigation measures, and informs international policy (e.g., selection of emission targets and policy options).
Answers & Comments
Answer:
Climate Change Science
What is the issue?
The scientific evidence is clear: the Earth’s climate is warming. Since the 1950s, many of the observed changes are unprecedented over decades to millenniaFootnote1. In Canada, these changes include rising temperatures, shifting rainfall patterns, and increases in certain types of hazardous weather.
Climate change is primarily attributed to the accumulation of greenhouse gases (GHGs), which traps heat in the atmosphere and causes a warming effect. This warming effect depends on the total amount of GHGs accumulated in the atmosphere, the time that they remain in the atmosphere, and each GHG’s capacity to trap heat. In 2014, the Intergovernmental Panel on Climate Change (IPCC) concluded that “it is extremely likely that human influence has been the dominant cause of the observed warming since the mid-20th century”.
Based on the IPCC Fifth Assessment Report’s mitigation scenario, limiting the average global temperature increase to likely less than 2°C relative to pre-industrial levels, in line with the goal of the Copenhagen Accord, will require that global GHG emissions be reduced by 40% to 70% below 2010 levels by mid-century and that emissions be decreased to near zero in the long term. To keep warming likely below 2oC, cumulative global emissions of carbon dioxide must be limited to approximately one gigatonne of carbon, half of which has already been emitted. Under this scenario, temperature in Canada is projected to rise by approximately 4.0oC. Under the highest emissions scenario, which assumes that global annual GHG emissions continue to rise throughout the 21st century, average global temperature is projected to rise by 5.6oC by 2100. However, temperature in Canada is projected to rise by 9.5oC.
While impacts including temperature rise are projected to vary by region, GHGs are distributed throughout the Earth’s atmosphere. As a result, emissions reductions efforts that are undertaken contribute to addressing this global challenge, irrespective of where they are taken (either within or beyond any one country’s national borders). This underscores the importance of coordinated global action to address climate change.
Explanation:
Why is it important?
Climate science provides facts about climate change, enables understanding of the causes, and makes projections about future climate conditions. Scientific methods and processes such as scientific research, monitoring, modeling and assessment inform evidence-based decision making by providing policy makers with credible and relevant information. Climate science contributes to building effective domestic climate change strategies and mitigation measures, and informs international policy (e.g., selection of emission targets and policy options).