Natural factors
Natural factors such as changes in the Earth's orbit, solar output, volcanic activity and ocean currents account for some of the changes our climate is currently experiencing. However, Environment Canada and the Intergovernmental Panel on Climate Change attribute much of the warming in the past 50 to 100 years to human activity. It is this human enhancement (anthropogenic) of the greenhouse effect that has the potential to warm the Earth to dangerous levels.
The Greenhouse Effect
Like the glass in a greenhouse, the gases in the Earth's atmosphere allow the sun's ultraviolet energy to pass through. This energy is absorbed by vegetation and soil on the Earth's surface and then converted to heat. Particular gases in the atmosphere act like the glass of a greenhouse by trapping the energy that the Earth would normally radiate back to space as infrared light.
FACT: Burning carbon-based fuels is responsible for more than just global warming. The carbon that falls back down from the atmosphere into the ocean makes the water more acidic. Higher acidity damages anything with a shell, from the tiny organisms that are essential to the food chain all the way up to the more familiar creatures such as shellfish and coral.
These greenhouse gases (GHGs) absorb heat and radiate some of it back to the Earth's surface, causing surface temperatures to be higher than they would otherwise be. The largest GHG contributor to the natural greenhouse effect is water vapour; however, other gases released by human activities play a growing role preventing the heat from escaping. These include carbon dioxide, methane and nitrous oxide.
The average state of the Earth is naturally regulated through mechanisms such as its orbit around the sun and the greenhouse gas effect. In fact, the natural phenomenon known as the greenhouse gas effect is what makes the Earth habitable. Without the atmosphere to capture heat escaping from the Earth's surface, our planet would not be warm enough to support life.
Picture the atmosphere as a giant blanket surrounding the Earth. As we burn large quantities of fossil fuels that release carbon into the air, we increase the thickness of that blanket. Thickening this blanket in the atmosphere traps heat close to the Earth and causes dramatic shifts in global temperature. The amount of heat-trapping gases released into the atmosphere has dramatically increased since the wide scale switch to fossil fuel powered industries and changes in land use practices that took place during the Industrial Revolution (approximately 150 years ago). By converting huge swaths of land to agricultural and urban uses, cutting down trees and burning large amounts of coal, oil and natural gas, human activities have dramatically altered the composition of the global atmosphere. Essentially, it is this increase in human generated heat-trapping gases that is the cause of current global concern.
To really understand climate change, there are three important numbers to remember: 275, 390 and 350. Greenhouse gases in the atmosphere are measured by parts per million (ppm), which expresses the number of carbon dioxide molecules contained within a million molecules of atmosphere. The average amount of carbon dioxide in the atmosphere prior to the Industrial Revolution is 275 ppm - a good level to have as it retains enough heat in the atmosphere to support life on Earth.
The current amount of carbon dioxide in our atmosphere is 390 ppm - a number that is rising by approximately two ppm per year with current emission levels. The third and most important number is 350, how many parts per million most leading scientists agree is the safe upper limit for carbon dioxide. This means that it is the maximum amount of carbon that we can have in the atmosphere and maintain life as we know it on Earth. Since we are already well past this level, it is the number that we need to get back to as soon as possible to avoid disastrous changes in our climate.
The Earth's atmosphere can safely handle around 700 billion tonnes of carbon which corresponds to 350 ppm, and we have already put 800 billion tonnes into it. The majority of the world's scientists agree that this carbon overload is causing drastic, and in some cases irreversible changes in global weather patterns.
Canada is the world's eighth largest contributor (see: Our Fair Share, Table 1) of global warming gases. Alberta is the largest single contributor of Canada's global warming gases. Both Canada and Alberta, therefore, have an enormous responsibility to act on climate change and dramatically reduce our emissions of heat-trapping gases. By changing our reliance on fossil fuels, we can create a clean energy future fuelled by innovation, local job growth and environmental stewardship.
Carbon dioxide (CO2) is an important greenhouse gas, which is released through natural processes (e.g., plant respiration and volcano eruptions) and human activities (e.g., burning fossil fuels and deforestation). The chart on the left shows the historical levels of CO2 in the Earth's atmosphere. The chart on the right shows the levels of CO2 in recent years (corrected for average seasonal cycles).
From: NASA, data last updated 11.11.09
Climate change happens when we overload the atmosphere with carbon. Basically, we are putting too much carbon where it doesn't belong and this is causing disastrous consequences on a global scale.
FACT: Canadian landfill sites release over 1.2 million tonnes of methane into the atmosphere each year. Methane is a potent greenhouse gas that has a global warming effect that is 25 times than that of carbon dioxide. This means that the methane released by the things we throw out is the equivalent of the total emissions from more than six million cars or over 40 per cent of all Canadian passenger vehicles.
On average, each Canadian produces 16.8 tonnes of carbon dioxide per year, over four times the global average. Amongst the G8 (Canada, France, Germany, Italy, Japan, Russia, United Kingdom and United States), Canada ranks seventh worst in terms of overall emissions. The United States emits 20 tonnes of CO2 per person into the atmosphere each year, compared to 10 tonnes for the European Union (EU) countries, five tonnes in China, two in India and less than one in some parts of Africa. While the world's richest 20 per cent that are responsible for the majority of global emissions, the associated climatic disasters will be mostly borne by the world's poorest 80 per cent.
The Intergovernmental Panel on Climate Change (IPCC), the world's leading climate science body, has demonstrated that in order to avoid exceeding the 2°C limit, industrialized countries such as Canada and the United States need to reduce their combined emissions of greenhouse gases by 25 to 40 per cent relative to 1990 levels by 2020. A reduction of this scale represents a fair and equitable contribution to the necessary global cuts in carbon emissions.
Climate change is like termites consuming the foundation of our house.
If we
ignore the problem we will face serious structural damage. Patch-work
and
temporary fixes will only leave the house in worse shape for future
generations. We currently have an opportunity to solve this problem of
climate
change by creating change at the foundation. By solving this common
problem, we
can reclaim
our position as global scientific, technological and
industrial
leaders.
In this guide:
