OUR SMALL HOMEBy Clarence “Clare” Maday, PhD Emeritus Professor of Mechanical and Aerospace Engineering North Carolina State University
Earth is our home. It’s all we got! 8,000 miles diameter----25,000 miles all around.
Compare: 93,000,000 miles Earth to the Sun whose diameter is 865,000 miles. Still pretty small compared to a light-year - 5,880,000,000,000 miles – yep, that’s TRILLION.
Range of a Boeing 777-200LR is about 11,000 miles. The 777 can fly nonstop NY to Singapore, Bangkok or Auckland. Nonstop almost half-way around the world!
So Earth isn’t all that big. And it carries about 7,700,000,000 people! Yep, that’s almost 8 billion people. Everything on Earth is confined to Earth. Can’t throw anything away, only move it around, except for the few things we send to the moon, Mars or beyond. We are part of one not-so-large system. Intuitively, we should we take care of it. Have we taken care of it? Some preliminaries first.
In recent years, especially 2018, storm activity has increased significantly. Flooding is the most common disaster in the United States. It will get worse. A recent estimate by the Administration is the surface of the oceans will rise about 7” by 2100.Current plans are to ignore the rise. Witness the Carolinas, the Northeast, Pennsylvania, the Midwest, the Plains, and the Southwest. Also, note the unprecedented tornado activity in Pennsylvania and Wisconsin. Climate change is reality. It is not a hoax. It is not junk science. The science behind climate change is the same science that put man on the moon and brought him back, gives us pharmaceuticals, MRIs, CT Scans, and air conditioners, to cite a few. So what is the cause? Global Warming is the most likely reason.
In a recent news item on the web, an older gentleman (not from Sunnyside) was asked what he thought should be done. His reply, “Nothing, why should I worry? I’ll be dead by then.” Maybe so, but his great grandchildren will suffer the consequences. (Like “What, Me worry?” from Alfred E. Neuman.)
What follows is taken from parts of the NASA website, https://climate.nasa.gov/causes/. Verbatim quotes, some edited, will be italicized. I recommend all sections of the site.
A Blanket around the Earth
Not enough greenhouse effect: The planet Mars has a very thin atmosphere, nearly all carbon dioxide. Because of the low atmospheric pressure, and with little to no methane or water vapor to reinforce the weak greenhouse effect, Mars has a largely frozen surface that shows no evidence of life.
Too much greenhouse effect: The atmosphere of Venus, like Mars, is nearly all carbon dioxide. But Venus has about 154,000 times as much carbon dioxide in its atmosphere as Earth (and about 19,000 times as much as Mars does), producing a runaway greenhouse effect and a surface temperature hot enough to melt lead.
We Live in a Greenhouse
Life on Earth depends on energy coming from the sun. About half the light reaching Earth’s atmosphere passes through the air and clouds to the surface, where it is absorbed and then radiated upward in the form of infrared heat. About 90 percent of this heat is then absorbed by the greenhouse gases and radiated back toward the surface, which is warmed to a life-supporting average of 59 degrees Fahrenheit.
How do we know that changes in the sun aren’t to blame for current global warming trends? Since 1978, a series of satellite instruments have measured the energy output of the sun directly. The satellite data show a very slight drop in solar irradiance (which is a measure of the amount of energy the sun gives off) over this time period. So the sun doesn’t appear to be responsible for the warming trend observed over the past several decades.
Longer-term estimates of solar irradiance have been made using sunspot records and other so-called “proxy indicators,” such as the amount of carbon in tree rings. The most recent analyses of these proxies indicate that solar irradiance changes cannot plausibly account for more than 10 percent of the 20th century’s warming.
Most climate scientists agree the main cause of the current global warming trend is human expansion of the “greenhouse effect” — warming that results when the atmosphere traps heat radiating from Earth toward space.
Certain gases in the atmosphere block heat from escaping. Gases that contribute to the greenhouse effect include: • Water vapor. The most abundant greenhouse gas. Water vapor increases as the Earth’s atmosphere warms, and so does the possibility of clouds and precipitation. • Carbon dioxide (CO2). A minor but very important component of the atmosphere, carbon dioxide is released through natural processes such as respiration and volcano eruptions and through human activities such as deforestation, land use changes, and burning fossil fuels. Humans have increased atmospheric CO2 concentration by more than a third since the Industrial Revolution began. • Methane (CH4). A hydrocarbon gas produced both through natural sources and human activities, including the decomposition of wastes in landfills, agriculture, and especially rice cultivation, as well as ruminant digestion and manure management associated with domestic livestock. • Nitrous oxide (N2O). A powerful greenhouse gas produced by soil cultivation practices, especially the use of commercial and organic fertilizers, fossil fuel combustion (aircraft and automotive vehicles especially), nitric acid production, and biomass burning. (Remember smog?) • Chlorofluorocarbons (CFCs). Synthetic compounds entirely of industrial origin used in a number of applications such as refrigerators and air conditioning systems, but now largely regulated in production and release to the atmosphere by international agreement for their ability to contribute to destruction of the ozone layer. They are also greenhouse gases. Air conditioning example is Freon12 (CCl2F2).
On Earth, human activities are changing the natural greenhouse. Over the last century the burning of fossil fuels like coal and oil has increased the concentration of atmospheric carbon dioxide (CO2). This happens because the coal or oil burning process combines carbon with oxygen in the air to make CO2. To a lesser extent, the clearing of land for agriculture, industry, and other human activities has increased concentrations of greenhouse gases.
The industrial activities that our modern civilization depends upon have raised atmospheric carbon dioxide levels from 280 parts per million to 400 parts per million in the last 150 years. We conclude there's a better than 95 percent probability that human-produced greenhouse gases such as carbon dioxide, methane, nitrous oxide and CFCs have caused much of the observed increase in Earth's temperatures over the past 50 years.