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Climate Change: “Just the facts, Ma’am”

Prepared for

Immanuel Adult Forum

Series on Climate Change November 20, 27, December 4, 2011

Editor: Richard Anderson, PhD

climate change: ‘Just the facts, ma’am’

The Science of Global Warmingpolar bear climate change

Climate change has become a deeply controversial subject. What should be a scientific discussion has become a political argument. This essay will attempt to avoid the issues of the overheated discussion and deal instead only with scientific facts. It will not discuss who got us into this mess, nor how we may possibly get out of it. Those are topics for another essay, perhaps.

What are the facts about climate change, as understood by the great majority of scientists in the field? (There are always a few dissenters, just as there are some people who still contend that the earth is flat.)

1. Climate is affected by a great variety of events and forces. Climate (or weather, for a narrower, more focused view) is exceedingly complex. Climate is strongly influenced by cyclical trends, many of which are not fully understood by scientists. These cycles include glaciation and withdrawal of ice fields, alterations in ocean currents, and shifts in land-based air streams. A second major influence is the temperature of the atmosphere, at which we will take a closer look later in this essay. The third force affecting climate takes the form of cataclysmic events, most notably, earthquakes, volcanos, tsunamis, and collision with other parts of the solar system or meteors.

It is, therefore, almost impossible to say that today’s weather or even this decade’s climate is directly due to one particular cause. (Volcanos, earthquakes, and meteors are fairly obvious, so they can usually be ruled out.) Nevertheless, the signs of rising global temperature are evident in almost every part of the planet, and the expected outcome of this temperature rise is being noted in many ways.

2. There is a direct relationship between the global average temperature and the amount of carbon dioxide in the atmosphere. CO2 is the second most abundant of the so-called ‘greenhouse gases’, which raise atmospheric temperature by absorbing solar energy. Thanks to the studies of paleoclimatologists, it is now possible to determine the composition of the atmosphere and global temperatures for several key periods in the history of the planet.

3. CO2 levels have been rising dramatically in the past century. For 1750, before the industrial era, the amount of CO2 in the atmosphere was estimated at 280 ppm (parts per million). By 2010, this has risen to 388 ppm and has been increasing at the rate of almost 2 ppm a year. Recent history shows this dangerous trend: in 1900, the level was less than 300 ppm; in 1988, it was 350.

4. The combustion of fossil fuels is a major factor in the rise of CO2 levels. It is not clear that the consumption of oil and coal are the largest single factor in this change, but it is certainly in the top three. For the past 60 years, it has been the leading cause of the accelerated buildup of greenhouse gases. Another major contributing factor is the deforestation and clearing of land, resulting in fires and decomposition of plants. Currently the five major sources of CO2 level increase are China, the United States, India, Brazil, and Indonesia.

5. A rise in global average temperature directly affects the melting of polar ice caps and glaciers, and in turn, the level of oceans. The problem here is: how much? Even international conferences of scientists cannot agree on the impact of global warming on the Greenland and Antarctic ice sheets, though climatologists are becoming alarmed at what they have seen in the past 5 years. Likewise, the effect that glacial melting will have on the volume and temperature of the oceans evokes heated debate among oceanographers: estimates of ocean rise with 3° (Celsius) increase in temperature range from 18 inches to 16 feet. Clearly, if the latter turns out to be correct, the entire Eastern Seaboard of the United States is in big trouble.

6. Increases in average global temperature will have profound effects on weather patterns. Here the work of climate modeling is generally more helpful than paleoclimatology. Almost of the models done to date predict drastic changes in the planet’s weather, from severe droughts to deadly monsoons. Most models point to some form of banding, in which deserts and temperate zones spread across entire continents. The predictions from these studies are for greater extremes of rain, snow, and flooding, and the likelihood of Category 6 tropical storms. As always, the devil is in the detail, and scientists are not agreed on what level of CO2 concentration will bring these effects.

7. Nature has ‘feedback’ mechanisms. This is scary stuff, but there is enough evidence in the planet’s history to take it seriously. ‘Feedback’ sounds like a term from white-collar crime or politics, but to biophysicists it means that Earth has ways of accelerating natural processes or launching new mechanisms when prodded by cataclysm or other stress.

The most common of these feedbacks is seen in the Arctic, where the melting ice replaces light surfaces with dark, thus increasing the absorption of solar energy. Similar processes are at work in the ocean and in subarctic tundra, rich in CO2 and methane. The scariest of all are methane deposits deep in the ocean, which if released, can lead to major degradation of the atmosphere. Some oceanographers believe that warming of the oceans by 5° or 6° could trigger such a scenario. It appears that just such a methane release occurred at the end of the Permian period, about 250 million years ago, and resulted in the extinction of 80% of all life forms.

Scientists are, for the most part, not predicting catastrophes on this order, but the fact remains that trigger events for biophysical feedback are not well understood, and Nature may have some unpleasant surprises unless global warming is stopped.

HELPFUL LINKS FOR YOU:

August 28, 1993 Evangelical Lutheran Church in America Social Statement on the Care of Creation

May 24, 2015, Pope Francis ENCYCLICAL LETTER ON CARE FOR OUR COMMON HOME

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