Introductory Activities: Trees
Why is global warming harmful?
Greta Thunberg “Our House is on Fire!”
The effect of human activities has been to bring about a huge increase in the amount of the greenhouse gases, including carbon dioxide, in the atmosphere. As a consequence, more of the sun’s incoming heat is being trapped in the atmosphere. This is resulting in a, never before seen, rise in average global temperatures.
What are Greenhouse Gases?
A greenhouse gas is one that traps heat in the atmosphere and prevents the earth from cooling to maintain a balance between incoming and outgoing energy. By retaining heat in the atmosphere, the gases cause global temperatures to rise. The main greenhouse gases are:
Water vapour – H2O – this is water in gas form, when it condenses it forms clouds, that also reflect heat back to the atmosphere and keep the earth cool.
Carbon dioxide – CO2 – this gets into the atmosphere from the respiration of animals, from decaying vegetable matter and from the burning of wood, charcoal and fossil fuels.
Methane – CH4 – this gas is released from swamps, from rice paddies, from animals, from natural gas and coal.
Ozone – O3 – this is found in the upper atmosphere and helps to block out harmful radiation from the sun.
Nitrous Oxide – N2O – this is released by bacteria in the soil and the oceans and also by motor vehicles.
Chlorofluorocarbons – these complex compounds of carbon, hydrogen, chlorine and fluorine. They are made in industrial processes and are used in refrigeration systems and in spray cans. They damage the protective ozone layer.
In the last 150 years, increases in carbon dioxide, methane, nitrous oxide and chlorofluorocarbons, and the decrease in the amount of ozone have caused the atmosphere to get warmer.
Why is global warming harmful?
A useful source is the North American Space Agency: https://climate.nasa.gov/effects/
Rising global temperatures arise when more heat energy is trapped in the atmosphere. In geological time there have always been fluctuations in global temperatures. What is worrying people now, is that the rise in global air temperatures is faster than has ever been observed before and many scientists believe that the effects could be catastrophic for the future of life on earth. Average global temperatures have risen by more than 1 degree C in past 100 years – 2 degrees in Europe. 16 of the 17 warmest year on record have occurred since 2001.
Here is a summary of the effects of global warming:
- Global warming means a big increase in the amount of energy in the atmosphere.
- As the ground gets warmer – heat rises in stronger convection currents.
- Rising air causes the formation of bigger clouds and more thunder cells.
- Wind speeds rise and the warm air causes more turbulence.
- Rainstorms become heavier.
- There is more flooding and landslides (especially in areas where trees have been removed).
- Weather patterns become more variable.
- There are more heatwaves and droughts. Away from the equator, summers are hotter.
- Equatorial areas are experiencing marked dry seasons.
- Deserts are growing in some regions.
- There are more extreme weather events. Hurricanes and tornadoes are becoming more powerful.
- Mountain glaciers and polar ice sheets are melting and having an adverse effect on polar bears and penguins.
- Sea level is rising 3mm a year and may rise a metre by 2100 – flooding many coastal towns and cities.
- Oceans are acidifying as they absorb CO2 – coral reefs are dying.
- Many birds, insects and other animals and plants are having their habitats reduced. Bird migration is changing.
- Large areas of forest are lost through wildfires.
- There are water shortages in large areas and dangers of growing conflict between countries over access to major rivers, such as the River Nile.
- Some species do well e.g. mosquitoes, ticks and crop and tree pests are extending their ranges.
- Crops fail due to drought or are damaged by heavy rains or plant pest and diseases.
Further information can be found here: Intergovernmental Panel on Climate Change (IPCC) Special Report “Global Warming of 1.5°C” https://www.ipcc.ch/sr15/
Greta Thunberg “Our House is on Fire!”
Reversing the build-up of greenhouse gases in the atmosphere will take a lot of effort by everyone in every country on planet Earth. The process of releasing them has gone on for many decades, and global temperatures are set to rise by more than the 2-degree ceiling agreed by world governments in the Paris accord. We cannot delay any longer! The young Swedish school, Greta Thunberg, born on 3 January 2003, felt so strongly about the issue that she organised a school climate strike in her country. This quickly spread around the world and Greta has become the leader of a global climate protest movement.
She has spoken at large demonstrations and meetings of world leaders, including the 2018 United Nations Climate Change Conference and the 2019 UN Climate Action Summit. In 2019 there were protests in major cities around the world with some bringing over a million people onto the streets in protest. Greta has worked hard to get the following message across to world leaders.
- Our house (The Earth) is on fire and nobody is taking action.
- Business and political leaders are ignoring the threat.
- Young people and future generations are being left to cope with problems caused by current and past generations.
- The industrial countries of the world have caused the carbon emissions and the global warming, but poorer countries will be the ones to suffer through damage to crops and food supplies.
Actions on global warming?
The world is waking up to the threat of climate change. These are some of the measures being taken:
- Action on the use of fossil fuels: Coal-burning power stations are being closed down, though many oil and gas burning power stations remain.
- Action on wood and charcoal burning: more and more farmers are growing trees to provide a sustainable source of firewood to avoid having to cut down native forests. More efficient wood-burning stoves are being used by schools and households.
- Forest protection: governments are placing protection orders on remaining woodlands and forests, making it illegal to destroy them.
- Forest renewal: many countries are undertaking major tree planting programmes to restore the forested areas so they can act as carbon sinks and nature reserves.
- Renewable energy: governments and companies are making greater use of renewable energy for power generation, including hydro-electric power, wind turbines, solar panels, and ground-source heat pumps.
- Cleaner transport: the use of petrol and diesel engines for cars and lorries will be banned throughout Europe and in other parts of the world by 2030. Vehicle manufacturers and consumers will have to switch to making and using vehicles powered by electricity or clean fuels such as hydrogen.
- Energy conservation: we can all help the planet by using less energy. In colder climates with long dark winters people are reducing heat loss from their homes by installing wall and roof insulation, triple glazing, switching to more efficient LED lights. There is also progress on making machines more energy efficient including vehicles, heating and refrigeration systems, computers and TVs. Using less water reduces the energy used in pumping water. Reusing and recycling materials can also save energy.
Governments, companies and households are beginning to act. Let us hope it is not too little, too late!