Climatologists are able to explain why rain falls, clouds form, the patterns of atmospheric circulation, the movement of the ocean currents, and much more. Nonetheless, the transference and acceptance of this knowledge to the majority of society has taken centuries. Even though empirical evidence indicates that global warming has affected and will continue to affect our society, economy, and environment negatively, skeptics have hindered efforts to reduce the human-induced greenhouse gases that facilitate global warming.
Naturally-induced Global Warming
An examination of the geographic and temporal distribution of proxy indicators such as organisms, atmospheric composition signature, and sediments in Earth’s geological record indicates that changes in the global climate have occurred naturally for centuries as the result of climate carbon dioxide (CO2) emitted into the atmosphere by volcanic activity. On top of that, ocean currents facilitate the release of CO2 into the atmosphere thereby compounding the greenhouse effect that causes global warming.
In addition, naturally occurring methane (CH4) and nitrous oxide gas (N2O) also contribute to the greenhouse effect. Sources of CH4 emissions include decaying organic material that is void of oxygen in wetlands, gas hydrates from permafrost, termite mounds, oceans, freshwater bodies, non-wetland soils, and wildfires. Sources of naturally occurring N2O are biologically produced by microbial action in soil and water. As a consequence of the conglomeration of various greenhouse gases, significant global warming in the past has transformed the polar climate of the Canadian High Arctic into a mid-latitude climate zone where boreal forests were able to flourish.
Human-induced Global Warming
In contrast to the past, recent studies of ice core data, ancient pollen, coral reefs, and sediments indicate that CO2 emissions have risen from around 300 ppm prior to the beginning of the industrial revolution around 1750 to 389 ppm in 2011 due to human activities. Consequently, the last century had the highest average global temperatures within the last 120,000 years.* The primary source of human-induced CO2 emissions involves the combustion of various non-sustainable fuels. According to the International Energy Agency, 43% of the CO2 emissions from fuel combustion were produced from coal, 37% from oil and 20% from gas.
Another major source of CO2 emissions is from deforestation, which accounts for 20% of the human-induced greenhouse gases.
In the 1990s, 1.5 billion metric tons of carbon (GtC) was released into the atmosphere by tropical deforestation. Current projections indicate that an additional 87 to 130 GtC will be added by 2100. Deforestation also precipitates a reduction in Earth’s carbon sink capacity due to a decrease of carbon “fixed” into plant cells during the process of respiration. Conversely, absorption of high concentrations of CO2 emissions by the ocean causes seawater acidification that reduces its carbon sink capacity and that harms marine species that build structures out of calcium carbonate. The ocean absorbs approximately 50% of the CO2 in the atmosphere. In correlation with increases in atmospheric CO2 emissions, acidification of the ocean has risen by 30% between approximately 1750 and 2008.
Exacerbating the problem, humanity currently wastes approximately 1.3 billion tons of food per year during the process of food production, transport, and waste disposal. This is a travesty that equates to about 135 tons of additional greenhouse emissions into the atmosphere, or about 1.5% of the total human-induced greenhouse gases. Furthermore, human-induced CH4 emissions have increased by 17% since 1750 and are increasing at a faster rate than CO2. Approximately 70% of the excess CH4 comes from bacterial action in the intestinal tracts of domesticated livestock, agricultural activity, and controlled vegetation burns. Currently, human-induced CH4 emissions account for 19% of the total greenhouse effect.
As a consequence of the increasing amount of human-induced greenhouse gases produced between 1880 and 1980, the observed global surface air temperature has risen more than 0.7°C at an average rate of 0.20° C per decade. If CO2 concentrations in the atmosphere continue to climb and reach 450 ppm, the Earth’s temperature will increase by 2° C. As a result of global warming, the additional heat energy added to the atmospheric system will generate stronger gradients between regions of high and low pressure. In turn, the stronger pressure gradients will cause prolonged droughts that will foster the desertification of the Southwest. Global warming will also increase the concentration of water vapor in the atmosphere that can serve to facilitate the amplification of hurricanes and severe flooding in other regions.
Thus, unless we want to feel the wrath of nature and spend billions of tax dollars in reaction to impacts caused by global warming, I suggest we take action to reduce human-induced greenhouse gases. When greenhouse gases are emitted–from anywhere–into the atmosphere they spread everywhere and have a half-life on the order of one whole century.
How big is your carbon footprint?
(* Italics added by editor for emphasis)