What is the Local News Data Hub?
The Local News Data Hub is committed to i) shoring up local journalism across Canada by supplying newsrooms with data-based stories ii) training student data journalists and iii) providing support to individual journalists and news organizations that require assistance with data analysis for their reporting projects.
The Data Hub’s reporting team, consisting of student data journalists and student data analysts supervised by faculty at X (also known as Ryerson) University, identifies government and other data with the potential to generate local stories. Once a dataset is identified and the basic reporting is done, the Data Hub team writes a story template and the code necessary to populate the template with data for specific communities. The local stories produced using this application of automated journalism are then posted on the LNDH website and also shared with the Canadian Press wire service for distribution to CP clients across the country. Find out more about the Local News Data Hub here.
Introduction and background
The Local News Data Hub’s goal with this project was to produce national and local stories on how climate change will alter winter cold and summer heat in Canadian communities in the coming decades.
The dataset for this series uses five climate change variables that paint a picture of winters with fewer cold days, when temperatures fall below freezing, and summers with more hot days, when temperatures soar above 30 C. The analysis compared the five climate change variables for the period 1951-80 to the period 2051-80.
The stories are based on data that are publicly available from ClimateData.ca, a federally funded collaboration involving scientists from Environment Canada and Climate Change Canada, the Computer Research Institute of Montreal, the Pacific Climate Impacts Consortium, the Prairie Climate Centre, HabitatSeven and Ouranos. We were advised on definitions and other technicalities related to the data by federal climate scientists Trevor Murdock, who manages the data and products office at the Canadian Centre for Climate Services, and his colleague Carrington Pomeroy.
“Canadian communities are experiencing the impacts of climate change on their infrastructure, health and well-being, cultures and economies and…these impacts are also threatening ecosystems and the important services they provide,” says Murdock, who oversees ClimateData.ca. “We know for certain that climate change is happening and that the historical climate is not a good indicator of future climate. This means we must make use of estimates of future conditions.”
The ClimateData.ca projections, Murdock noted, are based on “the most rigorous, evidence-based, peer-reviewed methods – namely numerical simulations of the climate system, which have been actively developed for over six decades and are the basis for estimations of future climate in the Intergovernmental Panel on Climate Change.”
The release of the stories was timed to coincide with the 26th UN Climate Change Conference of the Parties (COP26), scheduled for Oct. 31 to Nov. 12, 2021 in Glasgow, Scotland. The meeting was billed as an opportunity for countries that signed the 2015 Paris Agreement to commit to a more aggressive timetable for reducing greenhouse gas emissions – one that would come closer to achieving the agreement’s goals.
In the Paris Agreement, countries committed to limiting global warming by 2030 to below 2 C or as close as possible to 1.5 C. The longer-term objective set out in the accord is to reduce greenhouse gas emissions caused by humans to zero by 2050. A report by the United Nations Environment Program published just before the Glasgow conference started, however, warned that the world is far from achieving those goals. Even with new national climate pledges from Canada and other countries, the Emissions Gap Report 2021 said the world is headed for a temperature rise of 2.7 C by the end of the century that will “lead to catastrophic changes in the Earth’s climate.”
The report went on to say that “to keep global warming below 1.5 C this century, the aspirational goal of the Paris Agreement, the world needs to halve annual greenhouse gas emissions in the next eight years.”
Climate Change: Long-term continuous increase or decrease of any of the statistics over 30 years (mean, variability, extreme) of climatic variables such as temperature and precipitation.
COP26: A two-week United Nation climate change conference held in Glasgow, Scotland from Oct. 31 to Nov. 12, 2021. Since the commitments laid out in the 2015 Paris Agreement are insufficient to limit global warming to 1.5 C by 2030, the meeting was billed as an opportunity for countries to update their emissions pledges.
Days with Tmin < 0 C (Frost days): Describes the number of days when the coldest temperature of the day is lower than 0 C. The number of frost days is an indicator of the length and severity of the winter season. Locations with a high number of frost days likely have a short growing season because frost is harmful to many plants.
Days with Tmin < -15 C: Describes the number of days where the lowest temperature of the day is colder than -15 C. Cold temperatures affect health and safety, determine what plants and animals can live in the area, limit or enable outdoor activities, define how buildings and vehicles are designed, and affect transportation and energy use.
Days with Tmin < -25 C: Describes the number of days where the lowest temperature of the day is colder than -25 C. Cold temperatures affect health and safety, determine what plants and animals can live in the area, limit or enable outdoor activities, define how buildings and vehicles are designed, and affect transportation and energy use.
Days with Tmax > 30 C: Describes the number of days where the daytime high temperature is warmer than 30 C. High temperatures determine if plants and animals can thrive, limit or enable outdoor activities, define how buildings and vehicles are designed, and shape transportation and energy use. When temperatures are very hot, people – especially the elderly – are much more likely to suffer from heat exhaustion and heat stroke. Many outdoor activities become dangerous or impossible in very high temperatures.
Ensemble: Term used to refer to the complete set of climate simulations or climate scenarios used for a given study. Because no one model can be considered best, it is standard practice in climate change studies to use the outputs of many models when studying the projected changes. Consequently, ensemble is usually a synonym for the term multimodel ensemble.
Maximum one-day total precipitation: Describes in millimetres the largest amount of precipitation (rain and snow combined) that falls within a single 24-hour day for the selected time period. This index is commonly referred to as the wettest day of the year. Very high one-day precipitation totals could be the result of intense, but short-lived precipitation events such as thunderstorms, or may be due to precipitation occurring steadily over the course of the day. Short duration, high intensity precipitation events may lead to flash flooding, particularly in urban areas where storm drains may be overwhelmed. Heavy snowfall events can cause damage to buildings and disrupt transportation services.
Paris Agreement: The 2015 Paris Agreement committed countries to limiting global warming by 2030 to below 2 C and ideally 1.5 C. The longer-term objective set out in the agreement is to reduce greenhouse gas emissions caused by humans to zero by 2050.
Projection (climate projection): Projections represent the future portion of climate model simulations that take into account an emissions scenario. Scenarios are based on assumptions about future socioeconomic and technological developments that may or may not be realized and thus are subject to uncertainty.
*Definitions for this section are based on information from the glossary of ClimateData.ca.
The data source
The ClimateData.ca portal makes climate projections and historical data publicly available with a view to helping Canadians understand what the future looks like under various emissions scenarios. Projections also help with climate change adaptation planning.
To get the best possible projection for what the future might look like, data on the site are based on an ensemble of 24 climate models. Although all of these climate models use well established principles to simulate the climate, they each have strengths and weaknesses and therefore produce different projections. Since there is no single “right model,” ClimateData.ca uses an ensemble of all 24 to generate projections.
These projections are expressed as a range. The low end of the range is represented by the 10th percentile, which indicates a value that is lower than all but 10 percent of the ensemble. The high end of the range is represented by the 90th percentile, which indicates a value that is higher than 90 percent of the ensemble. The 50th percentile is the middle value of the range, or the median of the ensemble. You can read more about ranges in climate change projections here.
Each of the original 24 climate models simulates the climate covering the historical period 1950-2005 and for plausible future years between 2006-2100 based on three emissions scenarios representing different atmospheric concentrations of greenhouse gases.
The three emissions scenarios
RCP 8.5, the high emissions scenario, assumes that greenhouse gas concentrations will continue to increase at approximately the same rate as they are increasing today and that the increases will continue well after 2100. This pathway results in the most severe global warming and climate change.
*RCP 4.5, the moderate emission scenario, assumes greenhouse gas emissions will continue to rise until about 2040 albeit much more slowly than at the current rate. After that they will start to decrease, so that by the end of the century emissions will be about half of what they are now. This pathway is both more ambitious than global attempts at reducing emissions have been able to accomplish but also more pessimistic than the net-zero emissions targets that Canada and other countries worldwide pledged in the Paris Agreement in 2015.
RCP 2.6, the low emission scenario, assumes that greenhouse gas emissions will continue to increase until mid-century and then decline significantly. This scenario results in the lowest level of global warming and climate change.
*This is the scenario we used for the stories in this series.
About the Local News Data Hub analysis
The LNDH analysis for this series of stories compared climate change data for the period 1951-80 with data for the period 2051-80. We chose the first period because it was an era with little climate change and relatively stable climate. It is also considered a good baseline because there are more observations from this period than preindustrial periods. We compared it to 2051-80 because that is within the lifetime of many Canadians who are around today.
Thirty-year averages are used to ensure that what is being described reflects the overall climate and not the more variable experience of weather. To arrive at these numbers, the variable of interest, whether it be the number of days above 30 C or the maximum one-day precipitation value, is calculated for each of the 30 years in the period and then averaged. This calculation is done for each model in the ensemble so that the range can be calculated afterwards.
The 30 communities included in the LNDH dataset include a mix of larger and smaller centres in Canada’s different regions. We downloaded climate projections for the 10km x 6km grid cell that contains the geographic centre of each community as indicated by latlong.net.
The analysis focused on five variables.
- The number of frost days per year on average when the temperature fell/will fall below 0 C
- The number of days per year on average when the temperature fell/will fall below -15 C
- The number of days per year on average when the temperature fell/will fall below -25 C
- The number of days per year on average when the temperature surpassed/will surpass 30 C
- The average precipitation (measured in millimetres) on the wettest day of the year
Although the models do generate a range of values for historical periods, we decided, in consultation with ClimateData.ca scientists, to use the median annual average over the 1951-80 period in the stories because it reflects the conditions during that period.
To reflect the uncertainty associated with the projections for 2051-80, they are presented as a range.
Determining meaningful change
To understand if the changes between the two time periods were meaningful in terms of having local ecological and other consequences, we compared the projections and calculated the difference in the number of days for both the 10th and 90th percentile. We then sought expert advice from climate scientist Trevor Murdock.
“Whether a change is meaningful will depend on the historical value at that particular location,” Murdock told us. “A reduction of five frost days in a place that had 50 in the past is minimal. However, a reduction in a place that only had five to begin with could have major ecosystem impacts since that place is not going to reach below freezing at all anymore (on average), whereas it used to in the past.”
Murdock suggested we apply the following guidelines as a rough estimate of whether the changes in climate between the two 30-year periods were meaningful, adding that it is important for users to consider what a meaningful change would be in their own context/location.
Average number of frost days per year (temperatures below 0 C)
If most projections indicate that the average number of frost days for the 10th percentile in the period 2051-80 has decreased by at least 30 days, or is at least 20 per cent less than the average value in 1951-80, the difference is considered meaningful.
Average number of days per year with minimum temperature colder than -25 C
If most projections indicate that the average number of days colder than -25 C for the 10th percentile in the period 2051-80 has decreased by at least 10 days, and is at least 25 per cent less than the average value in 1951-80, the difference is considered meaningful.
Average number of days with minimum temperature colder than -15 C
If most projections indicate that the average number of days colder than -15 C for the 10th percentile in the period 2051-80 has decreased by at least 10 days, and is at least 25 per cent less than the average value in 1951-80, the difference is considered meaningful.
Average number of days with temperatures above 30 C
If most projections indicate that the average number of days warmer than 30 C for the 90th percentile in the period 2051-80 has increased by at least 10 days, and is at least 50% more than the average value in 1951-80, the difference is considered meaningful.
Maximum 1 day precipitation amount (millimetres)
If the difference between the average maximum precipitation per day for the 90th percentile in the period 2051-80 has increased by more than 15 per cent compared to the average value in 1951-80, the difference is considered meaningful.
Percentage change and meaningful change could not be calculated where the median (50th percentile) value was zero for the period 1951-80 because it is not possible to divide by zero.
Look up the projections for your city on this map
View/download the data for this project here