Cooling and Warming Periods in Earth’s History
Over the course of billions of years, the Earth has undergone drastic changes in climate. Excessive heat and the unbearable cold have played a huge part in the Earth’s current condition. The question is, however, how did these fluctuations work, and is our current crisis a natural ecological phenomenon or a man-made greenhouse gas disaster?
Icehouse and Greenhouse Climates
Throughout the Earth’s history, there have been warming and cooling periods. During warming periods, called greenhouse climates, there is a surplus of life, water, and greenhouse gases, like methane and carbon dioxide. The entire planet is very warm, which causes almost all of the ice sheets to melt off the northern and southern poles. This climate also makes the equator uninhabitable.
The most recent warming period, roughly 55 million years ago, reached a thermal maximum and marked a cooling period, known as icehouse climates. During icehouse climates, the climate is rich in oxygen and lower in carbon dioxide, which allows for the Earth to cool, essentially an ice age.
Icehouse climates, which last anywhere from 30 million to 215 million years, based on previous cooling periods, are often confused with interglacial periods, intervals of warmer climate between two cooling periods which last anywhere from 80,000–100,00 years.
Scientists have come up with multiple theories explaining the warming and cooling periods in the past. One of the theories behind cooling and warming periods is the increased intensity of the sun over time. When the Earth was young, the sun was dimmer and less intense. The climate was also cooler. Over the course of billions of years, the sun got much warmer, causing a rise in greenhouse gases and warming up our planet.
The second theory that provides insight into our weather is the Earth’s distance from the sun. The distance of Earth to the sun varies and can cause a solar radiation difference of anywhere to 6 to 30 percent.
One of the last theories revolving around warming periods is the evolution of life. Humans began using more oxygen and emitting more carbon dioxide which created an imbalance and led to warmer weather. Once plants started to use that carbon dioxide, the climate began to cool again. Human impact has become much more prevalent since fossil fuels have been utilized as primary sources of energy.
The Impact of Fossil Fuels on Earth
As previously mentioned, fossil fuels have been used much more by humans to achieve basic functions. We use fossil fuels to cook, get electricity, travel, etc. On average, humans release 43 billion tons of carbon dioxide each year. The rising amounts of emissions have led to our planet heating up, which leads to long-term effects like melting glaciers and extinct animals. Some people argue that climate change as we know it is simply a natural phenomenon, possibly an interglacial period, while most believe that the crisis is man-made and a result of human carbon emissions. The claim that climate change is natural has been used by various politicians and speakers in protest of legislation that reshapes the world’s infrastructure and energy but has little scientific traction, as most scientists support the notion that humans caused (or, at least, contributed, to the climate crisis).