Energy, Climate, Environment

When Things Go Awry and Upset the Natural Balance

Greenhouse Gases and Global Warming

The Earth is constantly changing. There are natural cycles, as described above, that balance and regulate earth and its atmosphere keeping it in perfect balance ¹⁴. Since the onset of the Industrial Revolution human activities have caused changes to these natural cycles resulting from an increase in the amount of greenhouse gases in the atmosphere. The greenhouse gases that are worth discussing in this unit are carbon dioxide CO ₂, methane CH ₄, water vapor H ₂O, and Chlorofluorocarbons CFCs. An increased amount of ant of these greenhouse gases accelerates the greenhouse effect.

Global warming, described as an increase in heat energy trapped by CO ₂ in the atmosphere, enhances the water cycle. The evaporation of water from the surface back into the atmosphere is accelerated. Condensation of water vapor in the atmosphere is increased and precipitation, in the form of rain, sleet, hail, or snow, back to the surface is intensified. The increase in greenhouse gases in the atmosphere, CO ₂ in particular, causes the atmosphere to be warmer resulting in a higher capacity to hold water causing an enhanced greenhouse effect. In areas that are near a water source, a warmer atmosphere holds more water characterized by more clouds and an increase in precipitation. More precipitation results in higher amounts of ground water causing a rise in sea level due to increased runoff. If there is no increase in runoff, the ground becomes more saturated resulting in increased flood conditions. The increased availability of water vapor in the atmosphere also leads to a significant increase in the energy available to drive storms and associated weather fronts, affecting rainfall rates, precipitation amounts, storm intensity, and related runoff. ¹⁵

In areas that are not near water sources, intensified evapotranspiration causes the soil and vegetation to dry out resulting in fewer clouds and less precipitation. The result is drought conditions, shallower rivers and lakes, and a decreased amount of ground water. These results of flooding and drought conditions can significantly impact the decline of food crops and world food supply.

As part of the biosphere, humans participate in the natural carbon cycle. However, by extracting fossil fuels from the ground and burning fossil fuels such as coal, oil, and natural gas for energy to power cars and factories, humans are adding CO ₂ to the atmosphere faster than carbon is released through natural processes. The pace at which the natural carbon cycle works is in sync with the natural processes through which carbon is released. The carbon cycle is ill equipped to handle the unnatural human induced releases of carbon into the atmosphere. Therefore, the concentration of carbon dioxide in the atmosphere has been disrupted and is consequently out of balance. The carbon cycle is additionally overloaded when trees are cut down because they can no longer take carbon dioxide out of the atmosphere. When the wood is burned, organic carbon becomes carbon dioxide and is released into the atmosphere. When the concentration of CO ₂ is upset the carbon cycle, which is a closed system, works to return to its natural state but the natural processes involved work so slowly that they cannot keep up with the rapid pace that CO ₂ is being released into the atmosphere. The additional carbon dioxide released into the atmosphere, overloading the carbon cycle, has contributed to global warming. ¹⁶

Evidence of Global Warming and Climate Change

The greenhouse gas of particular focus, when discussing global warming and climate change, is CO ₂ because it is the greenhouse gas whose concentration in the atmosphere is influenced most by human activities. Measurements from tree rings, ice core boreholes, and retreating glaciers provide sufficient evidence that the surface temperature of the Earth in the last few decades of the 20th century was higher than any comparable period for the past 400 years. The global average surface temperature has risen by approximately 1.5 degree Fahrenheit since 1900 and is projected to rise another 2 to 11.5ºF by 2100. ¹⁷

Scientists have been engaged in studying our past climate in order to confirm that carbon dioxide in the atmosphere is indeed an important factor in controlling global climate. One way they have accomplished this is from drilling ice cores in both Antarctica and Greenland. Ice cores help tell the historical story of the atmosphere in the following way. When snow falls to the ground it is light and fluffy containing a lot of air, some of which becomes trapped as the snow slowly compacts to ice. Scientists extract these air bubbles and measure the percentage of greenhouse gases that are present. These measurements represent the percentage of greenhouse gases that were in the atmosphere at the particular time of the dated ice core. By drilling over two miles down into Greenland's and Antarctica's ice sheets, scientists have been able to determine the amount of greenhouse gases that were present in the atmosphere over the last half a million years. In addition, they were able to estimate what the temperature was when the ice was formed. This information gave rise to the discovery that carbon dioxide (CO ₂) and methane (CH ₄) co-varied with temperatures over the last 400,000 years. ¹⁸

Information gathered from the study of the ice cores in addition to the study of the concentration of carbon dioxide in the atmosphere at the top of Mauna Loa Mountain in Hawaii helped establish carbon dioxide as a greenhouse gas that has a direct impact on global climate and therefore climate change. We need to distinguish between weather and climate to understand the phenomenon of climate change.

Weather is the day-by-day occurrences of the atmosphere near the earth's surface. Meteorologists and/or forecasters predict weather conditions each day, which may include a mix of events like temperature, humidity, cloudiness, precipitation, or the onset of a storm. Basically weather is the state of the atmosphere at a particular location at a given point in time, it is what you experience.

Climate is the long-term average temperature and/or weather conditions of a particular region over a period of time. It is the average weather in a place over many years. While the weather can change in just a few hours, climate takes hundreds, thousands, even millions of years to change when the natural cycles are working under normal, balanced conditions. It is the type of weather conditions one expects to experience in a particular region during a certain time of year. In other words, because of its climate, someone would expect it to be very cold and snowy in Buffalo, New York in the winter months of January and February. Climate can also determine the type of plant and animal life one would expect to find native to a particular area. Temperature and precipitation are the two primary factors that climatologists rely on to determine climate.

Climate Change refers to changes in the long-term trends in the average climate like changes in average temperatures. It is natural or human induced change in the average global temperature of the atmosphere near the Earth's surface. This is the condition that climatologists are most worried about because it poses significant dangers around the world, potentially causing disasters like flooding, drought, and disease. Observations undeniably illustrate that warming of the climate exists. ¹⁹ The cryosphere was once considered a passive responder to the climate but is now believed to be an active player in climate change. ^{2 0} The amount of sea ice in the Arctic has decreased severely over the last 50 years as the ice melts. Our glaciers are melting in response to warming.