July 2014 Philadelphia Chapter of Pax Christi U.S.A.

Climate Change: Threat to Survival

Climate change is a present reality and at the same time like the elephant in the room that everyone pretends not to see. We listen to weather forecasts every day and never hear any mention of it. We read about unusual weather—severe floods, hurricanes, droughts, tsunamis—without its being linked to climate change.

There have been numerous times of climate change in Earth’s 4.5-billion-year history, from ice ages to rapid heating, but never in so short a time span as we are now experiencing. It is a matter of undeniable fact that global temperatures are rising. While there are a number of natural causes implicated, climate scientists are almost unanimous in believing that rising carbon dioxide levels related to increased use of fossil fuels play an important part and the only part that we have any hope of controlling.

Carbon dioxide in the near atmosphere acts like the glass in a greenhouse, trapping heat near the surface. While it is not the only greenhouse gas, it is the one now in greatest concentration and therefore of greatest concern. In addition to the burning of fossil fuels, all respiration releases carbon dioxide, from animals, from microbes and even from plants at night. Carbon dioxide is also released in chemical reactions and physical changes in the non- living world, including forest fires and various industrial processes. The accelerating rise in carbon dioxide in the atmosphere is another undeniable fact.

How and when will we be affected? What makes prediction difficult is that while average temperatures are global, weather effects are local. Some areas, for example, will become cooler, even while others are becoming warmer. In general, however, weather will become more extreme, with colder winters and hotter summers and more floods and droughts. Deserts and arable lands will both move toward the poles, while ice caps melt. Sea levels will rise, both because water expands when warmed and also because melting ice will increase their volume. The lowest-lying lands will be under water, reducing habitable land in the face of rising population.

If that were all, the problem would be simpler and more tractable. But our planet has numerous feedback mechanisms, physical and chemical processes which help maintain stability. For example, if the carbon dioxide concentration in the atmosphere should decrease, the oceans would release some dissolved carbon dioxide; if its concentration should increase, it would dissolve more. This kind of process, called negative feedback, brings a system back into balance.

If the imbalance becomes too great, however, negative feedback is replaced by positive feedback, a kind of vicious cycle moving the system ever farther from balance. For example, at warmer temperatures the solubility of carbon dioxide in water decreases, so the oceans release carbon dioxide into the atmosphere and so raising the temperature further. For many processes, negative feedback operates within a relatively narrow range. Beyond that range, the system flips into positive feedback, and one has a runaway explosion.

As an example of positive feedback there is the matter of melting ice. Ice reflects sunlight, so a certain amount escapes without heating the atmosphere. As the ice cover recedes, more sunlight strikes water or land where it is mostly absorbed and reradiated, thus raising the temperature and thereby melting more ice, around the cycle again and again. This process, of course, is not related to carbon dioxide and not under human control. At what point it will come in strongly is not clear.

Another example is release of methane from permafrost, the permanently frozen soil in subarctic regions. Methane is a much more destructive greenhouse gas than carbon dioxide. It is not usually taken into consideration because there is not much of it in the atmosphere. As warmer temperatures melt the permafrost, releasing methane into the atmosphere, however, the greenhouse effect causes more warming, which in its turn melts more permafrost, and on it goes.

An important natural absorber of carbon dioxide is photosynthesis in green plants and algae, which converts carbon dioxide and water into oxygen and plant tissue. In a beautiful symbiotic relationship between plants and animals, each provides what the other needs. As a result the concentration of carbon dioxide in the atmosphere rises in the winter when deciduous trees lose their leaves and then decreases when the trees resume photosynthesis in the spring.

Deforestation, then, is equivalent to adding an additional source of carbon dioxide. While all green plants carry out photosynthesis, trees do it the most, and trees in rain forests most of all. So cutting timber is equivalent to burning fossil fuels, particularly if replacement trees are not planted at the same time. As warmer conditions advance toward the poles, we can expect to see forests replaced by grassland. Here we have another example of positive feedback as loss of trees leads to more carbon dioxide which leads to fewer trees and around again and again.

The atmosphere is actually a complex and finely balanced system with many such mechanisms, undoubtedly some not yet understood or even identified. What we can be sure of is that the atmosphere has evolved over its four-billion-year history into conditions favorable and perhaps essential for life. Any rapid alterations will almost certainly endanger life, even technologically advanced human life. For a time, the privileged may be able to move to higher ground, apply new technologies and adjust their lifestyles. The rest of humanity will be subject to massive genocide, a crime for which no individuals will feel at fault. There will also be mass extinction of species, effectively destroying our life support system.

Is it too late to do anything about the looming crisis? It is not too late. What must be done is clear. There are only two choices. We can continue to burn fossil fuels as we are doing, and even more to meet increased demand from rising populations aspiring to more energy-intensive lifestyles. At the point of crisis we will need to resort to sequestration of carbon dioxide from the atmosphere using technology not yet developed but certain to be costly and possibly ineffective. Failing, perhaps we will all perish.

The other choice is to stop using fossil fuels now. It is certain that this choice will be effective. The technology is here and has been for many decades. What is lacking is the will to do it in the face of the opposition of powerful special interests.

How can we help? Be informed. Be aware that peacemaking has to include concern for the Earth ecosystem.

Make changes in your lifestyle. Let your example preach without words. Pray. Love.

Dom Roberti, PhD