• Whenever it rains in our city, chemicals such as oils, gasoline, salts, and litter from our roads and sidewalks eventually get washed into streams, wetlands, rivers, and oceans. The fewer trees, grasses, and shrubs there are to absorb these chemicals, the faster they will enter our community waterways. This can pollute aquatic life and have a negative impact on the health of our entire ecosystem.
• Our trees act as mini-reservoirs, controlling and slowing water and chemicals from reaching our waterways. Here are some ways they do this:
  • Holding rain on their leaves, branches, and bark
  • Filtering and storing rainwater in their roots
  • Slowing soil erosion by catching raindrops before they fall on the soil

• Trees help us save money on our energy bills by changing the temperature of our buildings (houses, schools, recreation centres, libraries, etc.) in three important ways:
  • They provide shade so less heat is absorbed and stored by buildings
  • They store and release moisture in their leaves to cool the air
  • They block wind to reduce the amount of heat lost from our buildings
• Trees that are placed in the right areas around a building can help you save even more energy in your buildings. In the summer, trees that are planted on the east and west walls will keep your building cooler. In the winter, the sun shining on the south side of your building can warm it up naturally so you won’t need to use your furnace as much. On the other hand, a tree planted in the wrong space could cause a small increase in your energy bill. if it is not placed in a good area. For example, if your south wall is shaded by big evergreen trees, your winter heating costs could be a little more expensive.
• Here are some important things to keep in mind when you are choosing where to plant your trees:
  • A building that is not heated or air conditioned will have no energy savings.
  • A tree that is too small or too far away from a building will have no energy savings.
  • A tree might still have energy savings even if it seems far away from a building because of wind breaks.

Air pollution is bad for our health. It can cause problems including asthma, coughing, headaches, and even heart disease and cancer. More than 150 million people live in places where the air is not healthy, and they often breathe in too much dust and bad particles in the air. This includes ozone, a gas that protects us from the sun’s UV radiation when it is in the atmosphere but at ground level, ozone can cause a number of respiratory problems, particularly in children and people who do not have a strong immune system.

The good news is that trees can help! Urban forests, or groups of trees in cities, can make the air cleaner by:

• Taking in harmful gases like ground-level ozone, carbon monoxide, and sulfur dioxide through their leaves
• Catching tiny particles like dust and smoke before they get into the air
• Making the oxygen we breathe
• Cooling the air down, which helps reduce the amount of ground-level ozone
• Reducing pollution from power plants because we don’t need to use as much energy

At the same time, some trees release certain gases that might create more ground-level ozone, so not all trees are perfect for cleaning the air. But with all the different benefits that trees give us, there is no doubt that they do more good than harm and we should try our best to protect them.

Most car owners drive about 19,312 kilometers each year, and this creates around 4,990 kilograms of carbon dioxide (CO2), a gas that harms our planet. Trees can help by lowering the amount of CO2 in our air in two ways:

• They "trap" CO2 in their roots, trunks, stems, and leaves while they grow. Even after trees are cut down and turned into wood products, they can still hold onto that carbon to stop it from going into our air.
• Trees around buildings can help keep us cool so that we don’t need to use our air conditioning and heating as much. This means less CO2 is made by power plants.

• The overall dollar savings given by each tree is calculated by converting each of the benefits you learned about into its own dollar amount and adding them all together. To learn more about how each benefit is converted into a dollar amount, please visit itreetools.org.

At the end of the day, fighting climate change needs people everywhere to help, but small things like planting trees, driving less, or using conference calls instead of flying can all make a big difference in keeping our carbon "footprints" small.