Planet Earth’s annual sequence of seasons is a defining characteristic. Weather and climate manifestations are intricately related to conditions generated by our seasons. As we travel north or south from equatorial regions, seasonal variety becomes an all-important factor in describing earth’s weather and climate. Mid-latitudes between 30º and 60º have well defined periods of gradual spring warming or progressive autumn cooling. Sandwiched between these intervals are more or less consistent warm summer or cold winter conditions for several months. Much of our world’s population is embedded in mid-latitude seasonal variety.
High latitude regions and equatorial regions have less seasonal variety. In the Arctic and Antarctic seasonal variety exists, but cold frozen conditions predominate all year. Weather at low latitudes is generally warm continually. In contrast, seasonal changes in mid-latitudes are more spectacular and fascinating. Temperatures alternate above and below freezing. Mid-latitude weather idiomatically packs a lot of wallop related to the presence of seasons.
What would Earth without seasons be like? We know that the current 23.4º tilt of the earth’s axis with respect to the plane of our planet’s orbit is the cause of seasons. If the axis were not tilted at all there would be no seasons. A greater tilt would result in more extreme seasons; with a smaller tilt seasonal effects would be less extreme. Planet Earth without seasons would be unable to support the seven billion population of Earth. Conclusions of scientists are based on observations of currently operating weather and climate systems.
Without seasons every latitude would experience only one set of weather conditions all year long. Those who currently abide permanently in warm climates such as southern Florida may relish their lifestyle with little need for an overcoat and plentiful opportunities for outdoor bathing all year long. The benefits of mid-latitude seasons with alternating seasonal periods separating cold and warm, however, should not be overlooked by residents of year-round warm regions such as southern Florida. Even low latitude locations have a modicum of seasonal variation in their weather conditions on our planet. This variation diminishes as we approach the equator. For example, the average daily high temperature fluctuates by over 50 degrees F from warmest to coldest months at typical mid-latitudes. We cite our personal experience living in northwest Illinois. In southern Florida the typical average daily high temperature varies only about 20 degrees F from warmest to coldest months. Statisticians have supplied weather “junkies” with an almost unlimited set of detailed information on variable conditions at multiple locations to describe effects of the healthy grip of Earth’s seasons. We resolve to counsel our southern Florida relatives to appreciate the cold winter regions to their north. We invite them to pay a mid-summer visit to mid-latitude agricultural states such as Illinois and Iowa to observe the extensive fields of lush cornfields, prolific soybean plots, and numerous other crops thriving in alternating seasons of summer heat and winter cold.
Research into the outcome of loss of seasonal variations in Earth’s climate, especially in mid-latitude regions, yields interesting results. Mainly, food production would be significantly reduced. Many of the world’s essential food crops such as wheat, corn, potatoes, oats, and barley, grow far better where cool or cold winters persist. Humanity learned to innovate agriculturally at the close of the Ice Age. This occurred roughly 10,000 BC, the beginning of the Neolithic period—“Antiquity’s Agricultural Revolution.” Man learned to domesticate plants, working within warm/cold seasonal cycles which intensified as the Ice Age waned. It was an exciting time in the history of humanity.
In a world without seasons, ecological anthropologist Don Atwood claims, “Humans would probably never have advanced past a stage of living in small, scattered settlements, scrounging for survival and often dying of horrific insect-born diseases.” Remove Earth’s seasons and Atwood asserts humanity world suffer in a sorry state. It is certain that our Earth’s population would not have burgeoned from one billion to over seven billion in the past 200 years.
The catastrophic effects of removing Earth’s seasons is hypothetical. We will never be able to test the hypothesis. Earth’s axis tilt is not about to change significantly. Astronomer/climatologist Milutin Milankovitch (1879-1958) has proposed that three earth motions change and affect climate over long periods of time. Axial tilt is one feature which changes slightly—from 22.1º to 24.5º—over a period of 41,000 years. The other two features are eccentricity (elongation of orbit) and axial precession (a “wobble” of the axis similar to the wobble of a toy top). Both of the latter conditions vary over long time periods. These factors affect long term climatic conditions, but axis tilt has the greatest effect on seasons year to year. Currently the tilt of our planet’s axis is very slowly decreasing within the above range of change without significantly affecting conditions on earth.
We briefly address a few other environmental conditions inherent in a hypothetical “Earth without seasons.” The habits of animals and plants would change. There would likely be altered reproductive habits, no hibernation, changed adaptive responses, and minimal migration of animals or insects. Living things would change in their ability to cope with a non-changing environment. Tree rings would not exist. There would be no deciduous plants. Mid-latitude weather would differ considerably. Changing seasons produce mixing of moving air masses on a seasonal basis. Seasonal hurricanes, thunderstorms, and snowstorms may not form. Instead of blessings, these changes may result in less precipitation, perhaps even droughts. Some scientists propose that thick ice caps would form at the north and south poles, lowering sea level around the world. These scenarios are not all testable but inspire thoughtful speculation.
Why do we have axial tilt and why do we have seasons? A sound theory is that the Earth’s Moon was formed by a giant impactor, a protoplanet which collided with Earth early in the history of the Solar System. The impact of the smaller protoplanet imparted a tilt to Earth’s axis. Debris from the monstrous collision later became the Moon. Currently our companion Moon stabilizes the axial tilt of the Earth. Without the Moon, chaotic forces would disrupt Earth’s consistent axial tilt to the detriment of Earth’s population.
The timeless God of Creation created all things In the Beginning. Hundreds of physical constants and laws of nature, present from the initial creation, have fashioned our universe according to His divine plan for this created sphere. The presence of Earth’s seasons is the result of a transformational miracle. We delay detailed discussion of this type of miracle for another post. Scripture records dozens of environmental events and conditions on Earth such as rain, snow, thunder, wind, cold, and heat. These events are intricately connected with the presence of seasons which characterize our planet. Hundreds of beneficial yet awesome seasonal events have the unmistakeable handiwork of God’s intelligent agency.