Carbon Dioxide and Climate Change
If the amount of CO2 in the atmosphere were to double, the average temperature on Earth would increase by about one degree Celsius or 1.8 degrees Fahrenheit. But the climate system is complex, and the initial warming is followed by further effects called feedbacks. These can amplify the warming or suppress it.
CO2 is a greenhouse gas
Carbon dioxide (CO2) is the most important greenhouse gas in the atmosphere and accounts for 66% of the warming effect on climate. It is emitted by the burning of fossil fuels, industrial processes, and wildfires. In the last 200 years, carbon dioxide levels have increased significantly, reaching a new record high of 413.2 parts per million (ppm) in 2020. Although the increase was smaller than the year before, it was still greater than the average growth rate over the past decade. While emissions of fossil fuels declined by 5.6% in 2020, monitoring stations have shown that they continued to rise in 2021.
Carbon dioxide in the atmosphere has increased over the last few decades, far above historical levels. Most of this CO2 is from burning fossil fuels used in automobiles, trucks, and planes which emit CO2, as do many electric power plants as opposed to green energy tech. Additionally, humans release CO2 into the atmosphere by clearing forests, which contain large amounts of carbon.
The amount of carbon dioxide in the atmosphere has increased dramatically over the past century, mostly because of human activity. Today’s atmospheric levels of CO2 are many times higher than those of the last ice age 20,000 years ago. Hence, the presence of CO2 in the atmosphere has significant implications for our climate.
It absorbs heat
Carbon dioxide is a major greenhouse gas that is released into the atmosphere as a result of human activities. This substance is very effective at trapping heat in the atmosphere, and most climate experts believe that increased CO2 concentrations are linked to increased global temperatures. Watch this NOVA/FRONTLINE segment to learn more about the role carbon dioxide plays in climate change.
Carbon dioxide absorbs infrared radiation. When there is an abundance of it in the atmosphere, it traps this infrared radiation and prevents it from reaching space. This trapping of infrared radiation causes the earth’s surface air to warm. And hotter air holds more water vapour, which is a greenhouse gas.
It affects vegetation
As CO2 levels rise in the atmosphere, plants are less able to absorb water. To compensate for the decreased water use, plants have a system known as stomata that allows CO2 to enter their cells and moisture to leave. Consequently, plants need less water to photosynthesise. As a result, they partially close these stomata, which decreases the amount of water that plants lose by 5 to 20 percent.
In addition to changing water availability, the increased levels of CO2 will also make plants more susceptible to harmful pathogens and invasive species. Furthermore, plants are also impacted by climate change in terms of temperature and nutrients. Rising temperatures are detrimental to local plants, making them more susceptible to disease and pests.
The amount of CO2 in the atmosphere has increased significantly due to human activities. Today, the atmosphere has about 150 ppm more CO2 than it was in 1750. This is much higher than the CO2 levels present 20,000 years ago, when the last ice age ended. It’s also important to consider that the concentration of CO2 in the atmosphere varies in the seasons. For example, the amount of CO2 in the air during the summer months is higher than the amount of CO2 in the air during the winter.
Although the effects of CO2 on vegetation are unclear, there is evidence that increased CO2 concentrations affect plant growth. In fact, doubling atmospheric CO2 concentrations results in a 30% increase in plant growth. In addition, doubling the amount of CO2 causes a 37% decrease in the stomatal conductance, which reduces evapotranspiration and increases leaf temperature. Therefore, the positive effects of CO2 are offset by the negative effects of CO2 on plant growth.
Prof Dianne Jolley in an environmental chemist and toxicologist leading a dynamic research group which is investigating the assessment and prediction of toxicity. Her research includes establishing field-based tools to assess the risk of contaminants in aquatic and agricultural systems; investigating the biological impacts of contaminants and using the outcomes to critically inform the science that underpins the water and sediment quality guidelines; and probing the mechanisms of contaminant toxicity and biomarkers to diagnose this toxicity. Dianne Jolley’s research spans the tropics, temperate and polar regions in both freshwater/terrestrial and coastal marine systems. Dianne Jolley has well-established collaborations with government, financial institutions and industry, including CSIRO Land and Water and the Australian Antarctic Division.
Dianne Jolley