Second to water vapor (H2O), Carbon dioxide (CO2) is one of more abundant greenhouse gases (or GHGs) in the atmosphere and is “generated” by human activity. Other GHGs include water vapor, methane, nitrous oxide, among others, but paleoclimate records have shown the close feedback between atmospheric CO2 concentrations and temperature (Figure A-2). The quick bottle experiment shown in the previous page with Bill Nye demonstrates this principle.
Rises in average global temperatures have received much notice over the last 50 years it has affected climate patterns globally, which in turn has affected habitat regions, migratory patterns, and natural resources. What was once termed Global Warming; Climate Change incorporates all of the changing climate patterns both globally and locally, whether they are warmer vs. cooler or wetter vs. drier.
The Carbon Cycle
A brief explanation of the carbon cycle demonstrates the natural cycles and processes of carbon and how human activity has impacted the movement of this compound. (Fig A-3) Carbon is the building block of all organic materials, cycling through air, water, and land as living things grow and decay. The movement of carbon through time depends on its solubility as a source or how firmly locked it is into a sink. Trees and vegetation in forest that lives through decades or centuries of growth build a carbon sink. In contrast, grasses in a prairie that grow and die each year store much less carbon at the surface, but rather sequester carbon into the soil. Wetland bogs capture plant biomass as a sink, decaying slowly in extreme cold or when completely saturated with water for long time periods. The ocean is the largest carbon sink on the planet as organic sediments from flora and fauna sink to the deepest depths. Fossil fuels were once locked into ground forever but are now being added back into the active cycle by human activity.
Since the beginning of the Industrial Revolution in the late 1700s, innovations in technology improved economic production a well as the quality of life for many people, enabling an increase in the growth of the world’s population. Yet, this population boom created ever more demands on the Earth’s resources including energy, food, and water. Fossil fuel energy resources were readily available and easy to extract because of new technologies and has been the world’s major source of energy ever since.
However, fossil fuels are carbon and methane sinks that have been sequestered over hundreds of billions of years through slow geologic time. Human extraction has tapped, consumed, and released most of the more accessible fossil fuel sources in a matter of a few short centuries. Today’s new technologies have increased the ability for the extraction of fossil fuels once considered impossible access, with very little incentives to stop the continuing habit. (Fig. A-4)
Carbon emission trends closely follow the rise in all atmospheric GHG concentrations (Fig. A-5), indicating that anthropogenic sources of GHGs are strongly linked with increases in the average global rise in temperatures that have been recorded.