About the Author
Dr. Tom Pypker is an associate professor in the Department of Natural Resource Sciences at Thompson Rivers University. He is an ecohydrologist whose research focuses on the effect management and climate change has on biological processes in ecosystems at scales ranging from the leaf to whole watersheds. He teaches courses in watershed management, soil science and climate change.
Fundamentals of Climate Change
by Dr. Tom Pypker
The earth’s atmosphere is critical to life on this planet. Most of us associate the atmosphere with the oxygen we need to breathe. However, the atmosphere does many critical things. One is to warm the planet. Without an atmosphere the planet would have an average surface temperature of only -18 degrees Celsius. Yes, our planet would be completely frozen.
Our planet is warmed by the atmosphere because the atmosphere acts a bit like a greenhouse. Like the glass of a greenhouse, the atmosphere allows most of the energy from the sun to reach the earth’s surface where most of it is absorbed. That absorbed energy cannot stay and must be lost, or the surface will continue to heat up. The earth eliminates that energy in different ways. Much of that energy is emitted in a form that is absorbed by greenhouse gases in the atmosphere.
Humans have altered the gases in the atmosphere, thereby changing how energy moves to and from the planet. Not all gases in our atmosphere are effective greenhouse gases. The main gases in our atmosphere that cause the greenhouse effect are water vapour, carbon dioxide (CO2), methane and nitrous oxide. Since the industrial revolution, humans have increased the concentrations of CO2, methane and nitrous oxide while also adding new synthetic greenhouse gases (e.g., chlorofluorcarbons (CFCs), hydroflurocarbons (HFCs), perflurocarbons (PFCs) and sulfur hexafluoride (SF6)).
The main way humans have increased greenhouse gas concentrations is from burning fossil fuels. Fossil fuel burning involves the combustion of stored fuels such as coal, natural gas and oil. Burning of fossil fuels adds greenhouse gases like CO2 back into the atmosphere faster than it can be removed by the ocean or by terrestrial plants. Changes in land management disrupts the balance between CO2 removed from the atmosphere by plants and the return of CO2 back to the atmosphere via respiration and decomposition.
A key component to the addition and removal of greenhouse gases from the atmosphere is through biological processes. Plants remove CO2 from the atmosphere during photosynthesis. Hence, most of plant growth is from the air NOT from the soil. Photosynthesis reduces the amount of CO2 in the air. Therefore, concentrations of CO2 in the atmosphere will change slightly throughout the year. During our summer, the concentration of CO2 declines and it goes up during our winter.
The oceans absorb CO2 from the atmosphere through photosynthesis and by dissolving CO2 into the water. If not for the oceans, the atmosphere’s temperature and greenhouse gas concentrations would be substantially higher. The movement of energy and CO2 into the ocean is complex as the ocean is deep and it can absorb large amounts of energy and CO2. The oceans are suffering because when dissolved in water, CO2 forms carbonic acid. This reduces the pH of the water making it less alkaline (i.e., more acidic). The greater acidity affects biological processes. One group that suffers are shelled organisms as higher acidity makes it harder to maintain shells made of calcium carbonate.
Humans have disrupted the cycling of greenhouse gases through their land management. When we remove forests or drain wetlands, we alter how much CO2 is being removed by photosynthesis and how much is being lost by decomposition/respiration. For example, when a wetland is drained, the carbon stored in dead plant material like peat can decompose. Prior to drainage, the water prevented sufficient oxygen from reaching the peat, thereby slowing decomposition. However, once drained, there is more oxygen reaching the peat, and decomposition will increase. This will change how much CO2 is lost by decomposition/respiration versus how much is stored by photosynthesis. The same phenomenon can be seen during forest clearing. Anything that suppresses photosynthesis and/or increases respiration/decomposition results in more CO2 ending up in the atmosphere. Land alteration represents about 20% of the increase in greenhouse gases.
CO2 is not the only gas that affects climate change, in fact, CO2 is one of the least powerful greenhouse gases. For example, excessive use of fertilizer results in the production of nitrous oxide. This gas is a much more powerful greenhouse gas (300 times greater than CO2). As a society, we need to recognize that our choices on the land can either increase or decrease greenhouse gas emissions to the atmosphere.
Even if we stopped producing excessive greenhouse gases now, the planet’s temperature is expected to rise 1 or 2 degrees. With changes in our lifestyle, we can limit the increase in the global temperature to about 2 degrees Celsius. Without intervention, we will likely increase the global temperature by 4 to 6 degrees. This change in the earth’s temperature will cause dramatic increases in wildfire, droughts, heat waves, loss of glaciers and rapid sea level rise. It is predicted that the cost of not changing will ultimately be greater than the cost of adapting now.
To prevent catastrophic changes to our climate, we must act now to reduce the amount of greenhouse gases going into the atmosphere. This requires a shift from a dependence on fossil fuels to other forms of energy and better land management practices. Two examples are shifting toward electric vehicles that are recharged by non-fossil fuels and supporting agricultural practices, such as regenerative agriculture, that pulls CO2 out of the atmosphere. This change will require individuals to alter their lifestyle and for governments to intervene to support climate friendly technologies. We already have many of the tools needed to reduce our climate footprint while also improving quality of life. The question is whether we will choose to make the change.