When we credit God with creating all things or with designing our intricate climate system, we express a sense of worship or devotion. Our general understanding of the power of the Creator or our tacit appreciation of our many global systems, however, are insufficiently weak unless we work to understand the realities of our climate system more fully.
Research on historical climatological data for our recent posts on weather and climate has revealed unfamiliar facts concerning North America ’s climate events of the past thousand years. Our tendency to generalize about weather and climate or to pass judgments based on events in recent years or recent decades based on our personal memory is unwise. It is also imprudent to generalize concerning future weather and climate based on observations from the past several decades. Notwithstanding great strides in short and long-term weather forecasting, the science of climate prediction is still imprecise in many significant respects. Knowledge of climate swings even in the past thousand years affirms this truth.
The earth has evolved through many cycles of warm and cold or wet and dry conditions. Weather proxy records such as tree rings, ice cores, and sediments reveal ancient temperature and precipitation fluctuations predating instrumental records. The historical advance and retreat of desert conditions is a clear indicator of diminished rainfall. There is evidence that extreme and extended droughts occur at a rate of two to three per thousand years. Prior to the 17th century, before the settlement of the Great Plains by Europeans, megadroughts afflicted huge areas of the continent and sometimes extended as far as the east coast. There are tens of thousands of square miles of the Great Plains where active sand dunes were moving across the landscape in the past thousand years.
Superimposed on megadroughts are more frequent droughts of lesser severity and time scope such as the one on the Great Plains around 1860 before heavy settlement occurred. Prior to that, in 1810, the explorer Zebulon Pike wrote about desert conditions in parts of Colorado and Kansas: “These vast plains of the western hemisphere may in time be equally celebrated with the sandy deserts of Africa; for I saw in my route, in various places, tracts of many leagues where the wind had thrown up the sand, in all the fanciful forms of the ocean’s rolling wave, and on which not a speck of vegetable matter existed.” We may ask if the horrendous drought and heat of the 1930s rivaled any of these events. The answer is no. But desert dunes could have formed within a few years had drought conditions continued.
Temperature variations triggering such dry or wet conditions do not seem extreme by our standards. Long term average temperature swings as small as 1-2˚C could bring about long term events such as the Medieval Warm Period (950-1250 AD) or the Little Ice Age (1550-1850 AD) which followed. Perhaps our “to visit” list should include a visit to the Nebraska Sand Hills or abandoned Pueblo culture ruins, remnants of megadroughts between 800-1600 AD when desert conditions profoundly molded landscapes and altered the lifestyles of native residents of the time. Evidence visible today provides a flashback.
Climate changes such as long term megadroughts lasting more than two decades or shorter droughts of lesser duration would result in significant economic and social upheavals within our greatly expanded population of the last two centuries. Technology has enabled man to keep pace with the growing health and nutritional needs of Earth’s expanding population. But who would dispute that our societies tread a fine line of balance between prosperity and disaster caused by extended climate shifts?
Geoscientists who have knowledge of the many complex natural causes of climate variation are also aware that we bear responsibility to monitor effects of human-induced climate change. Scientists are becoming more knowledgeable about periodic natural oceanic and atmospheric oscillations and more aware of their impact on expanding global population. The disputes between climate deniers and climate alarmists originate with disagreements in interpretation of climate data and differences of opinion in what remedies are applicable. Our past blog posts have highlighted these differences. We should prudently explore middle ground to address these problems.
In the past 150 years earth’s climate has warmed somewhat, in keeping with the established pattern of climate swings for thousands of years of earth history. Our current levels of population could not have been sustained had we experienced megadroughts since the so-called Little Ice Age concluded in 1850. Even shorter droughts such as the 1930s, 1950s, 1988, and 2012 events were minor compared with true megadroughts were they to occur today.
By God’s grace, extended megadroughts have not devastated the United States 1:28 ). Given the uptick in knowledge of our earth’s climate system, past and present, humanity must observe the counsel to “Handle with Care.”
