20 October 2020 Project Update: Poster Presentation by Arushi Nath, a Grade 6 Student on Mapping Tree Density of School Parks and Local Parks in Toronto, Canada at Google Earth “Geo for Good” Summit.


Full poster can be accessed at: https://docs.google.com/presentation/d/e/2PACX-1vRaRJbEc3jnG8iP5dN6ZOH4mHhhmZuGbEPd_SY-xEgcyKR-1jnutWohpD4MGLmDK2Z6N-b00mD8zbB7/pub?start=false&loop=false&delayms=3000&slide=id.g9dd41497f3_0_0

It is not easy being a young person. There is school, school friends, studies, sports, and social media to catch up with. And in what spare time there is left, there is the task of showing adults the way – on how to leave a world that is peaceful and beautiful which their generation and subsequent generations can enjoy.

And the task is not easy. Youths have the most marginal voices, minimal resources, and freedom. And yet they are getting more organized, taking direct action and leading protests globally on issues that affect them and where adults have failed them.

Global Youth Movements

Since last year, we have seen two powerful youth movements on issues that directly affect them. On 24 March 2018, young people all across the United States rallied together for March for Our Lives in Washington DC to support legislation to end gun violence after the school shooting in Parkland, Florida. The turnout was estimated to be between 1.2 and 2 million people making it one of the largest protests in American history.

This year, youths led by 16-year-old Greta Thunberg have set into motion a global protest campaign: the School Strike for Climate Action. Coordinating under Fridays for Future over 1.5 million schoolchildren have taken part in strikes. Children have walked out of schools in thousands of cities in China to Canada to show that they understand climate change, how it will affect them and other species, and how everyday adults, corporations, and governments are failing them.

They are showing they are unhappy over the business as usual scenario they are seeing instead of immediate, concrete steps that should be taking place globally to tackle the climate change issue.

Canadian Youths for Climate Action

Youths in Canada too, are in the environmental forefront. They are showing the same leadership shown by youths in other countries. We are seeing homegrown youth movements, direct action, and awareness about the environment and climate change in all corners of the country: A Mari Usque Ad Mare.

Artash and Arushi participating in Climate Change March Toronto on 27 September 2019.

We are seeing young people protesting against pollution in lakes and waterways, on cutting down of forests, and mining activities on pristine land.

Autumn Peltier, a teenage activist from Wiikwemkoong First Nation on Manitoulin Island has been fighting to protect water in Canada’s Indigenous communities for years. Stella Bowles, a teenager from Nova Scotia who protested against sending raw sewage directly into the local waterway and lead to the clean up of the LaHave River. And there are thousands of other youths who are using activism and collaboration through social media to bring about change on the environmental issue they are working on.

Space Technologies for Climate Action: Using Satellite Imagery, GIS and Carbon Emissions data

There is a role for everyone and all skills are needed to tackle climate change. We need science, media, economics, arts, and music to come up with solutions for a cleaner and greener world. From green technologies to space technologies, science has a big role to play in climate change monitoring and action.

We have been using space technologies, including data from Orbiting Carbon Observatory-2 (OCO), satellite imagery from NASA and Google Maps to monitor tree cover and carbon absorption in Toronto.

Measuring Tree Densities in School Playgrounds (Satellites, In situ measurement + Crowdsourcing)

As school playgrounds are small and their tree densities are less than 20% they usually do not figure out in city green cover maps. But it is important to measure and monitor school tree densities as it is the children who use them the most during school hours and even outside of them. Trees in cities and urban areas provide climate, biodiversity and health-related benefits.


As the challenge asked the teams to use (1) satellite data, (2) in situ measurements, and (3) crowdsourcing, I came up with a way to measure tree densities for 15 French-board schools in Toronto combining all three methods.

1. I used vegetation data from the NASA Satellite Data (LandSat 8) and i-Tree Canopy Tool provided free of charge by USDA Forest Service to measure the tree canopy area within the school boundary.


2. I ranked the schools according to their tree densities and the climate benefits provided by the trees and mapped them on a crowdsourcing platform. Students can then check tree densities of their schools and also submit pictures of trees they are planting to make their schools greener.

I ranked Tree Densities in Playgrounds of different schools

“Fix the Six” Space-Climate Project

Our “Fix the Six” project is aimed at reducing climate emissions in Toronto by advocating planting of more trees on street sides and in schools and creating more parks and green spaces within the city. 

We found out that over more 2.2 Million Trees are missing in Toronto – taken away from our neighborhood parks and streets. The missing trees would have removed an extra 10,000 tonnes of carbon from air each year – equivalent to carbon emissions of 7000 cars and provide a direct economic value of $3.9 million (Figure 1).

“Fix the Six” project was conceived by us during the 24 hours #Climathon Toronto (Climate Hackathon) organized by Climate-KIC on October 28-29, 2016. We won the First Prize as well as the Climate Hero Award for this project.

Figure 1: Direct economic value of 2.2 million missing trees

Using Google Maps, Geographical Information Software (GIS) and I-Tree application, we calculated the tree cover of 7 Toronto parks and 4 Toronto streets and took carbon emission readings at major downtown intersections (Figure 2).

Over 6400 sample points were taken while carrying out the GIS survey of the Toronto Parks and Streets taken in our sample – giving an error margin of +/- 2%.

Based on the tree cover we calculated their carbon sequestration rate – the rate at which trees absorb carbon from the atmosphere. Excessive carbon emissions are one of the reasons behind global warming and climate change.

Figure 2: Tree Survey of Toronto Parks and Streets for missing trees

Among the 7 parks (High Park, Rouge Park, Dufferin Grove, Trinity Bellwoods Park, Stanley Park,  High Park and the Pierre Elliot School playground) High Park had the highest carbon sequestration rate of 3.1 tonnes per acre while the Pierre Elliot Trudeau school playground had the lowest carbon sequestration rate of 1.32 tonnes per acre. (Figure 3)

Among the 4 Toronto streets – King, Queen, College and Eglinton (sampled between Yonge Street and Bathurst street) we found out College street is the “king” of carbon sequestration. College Street had carbon sequestration rate of 1.34 tonnes per acre which was almost double of 0.7 tonnes per acre for Eglinton street (Figure 4). 

If High Park and College Street can achieve higher carbon sequestration rates because of their higher tree canopy areas, so can other parks and streets. If all other Toronto Parks and Streets were to maintain tree canopy densities similar to High Park and College Street then we would have at least 2.2 million more trees in Toronto! 

We are missing these trees.

These trees would have filled our neighborhood parks, streets, school playgrounds, and open spaces – making Toronto greener and our air cleaner while playing an important role in checking climate change. Trees also reduce noise pollution, make cities more livable for children and adults alike, and provide habitat for our shrinking urban biodiversity including bees, butterflies and smaller animals.

Two Key Findings

1. Small Parks are More Efficient Carbon Sinks

Parks located in downtown and densely populated neighborhoods may be smaller but they offer higher carbon sequestration per unit area. For instance, carbon sequestration rate of Queens Park (2.12), Dufferin Grove (2.7)  and High Park (3.7) are higher than the Rouge Park (2.03) which is many times bigger.

Figure 3: Small parks play powerful role in carbon sequestration in cities

We need big parks and conservation areas such as Rouge Park which act as the green lung of Toronto and remove a massive amount of carbon and pollutants from our atmosphere. But smaller parks are equally important. Due to their higher tree densities, they are more efficient in carbon sequestration and improve their immediate environment by removing particulate matter (pollutants) from automobile emissions, providing temperature control and checking rainwater runoff. Tree intensification should also be carried out on School playgrounds, especially on the boundaries to offer more shade and healthier environment.

The city’s climate policy has to put greater emphasis on smaller parks – and more so in view of the construction boom, we are seeing. Planting space which is razed for building, streets, and condos is no longer available for tree planting.

2. Transform Streets to STrees (Street + Trees)

The carbon sequestration rates of Toronto Parks are higher than in Toronto Streets. However, the higher end of carbon sequestration rates of Toronto streets (for instance of College Street) can match with the lower end values of those of Toronto parks (Figure 5). It makes both trees and parks as useful spaces for implementing carbon reduction initiatives.

Figure 4: We need to have minimum tree density for each of the Toronto Streets to sequester air pollution

All streets in Toronto should have minimum Tree canopy cover standards. And these standards should be met by planting native trees which are efficient in carbon sequestration. We are fortunate in that aspect –  Sugar Maple (Acer saccharum) which is native to Canada tops the list of trees adept at gobbling carbon from the atmosphere. We need more tree-lined streets (STrees) in Toronto!

Figure 5: Higher end of carbon sequestration rates of Toronto streets can match with the lower end values of those of Toronto parks.

Tree planting and tree protection are one of those activities which can provide immediate benefits to downtown population in terms of providing better air quality, reduce noise pollution, better habitat for urban biodiversity, and make cities more livable for children and adults alike. At present, few people are aware of the role of trees in trapping particulate matter and absorbing carbon – playing an important role in checking climate change.

We plan to continue work on this project to cover more area of Toronto and even expand this eco-centric and inter-generational approach to other cities in Canada and globally.

In conclusion

The voices of youth, their anger, and concern are powerful indicators of the health of a society. If you turn away from them, they will only get louder and if you do nothing, they will get stronger. We would be better off have the support of youths, their enthusiasm, energy and their organizing power on our side to get serious on tackling climate change.

To tackle climate change, adults will have to change themselves and make way for voices and actions by youths. This means supporting them, appreciating them and joining forces with them.

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