What Are The Natural Causes Of Climate Change?
- Sami Hoeldtke
- 6 hours ago
- 4 min read
There is agreement among the scientific community that humans are causing climate change, but the public's opinions are a bit more reserved. Some confusion lies in whether or not natural processes contribute to the levels of climate change and global warming currently being observed. There is no denying that human activity plays a major role in the increase in greenhouse gases in the atmosphere, but why are the natural causes of climate change never a part of the conversation? Keep reading to learn more about the various natural causes of climate change and how they differ from humanity's impact.
What is "Natural Climate Change"?
Humanity is at the center of conversations surrounding climate change, and for good reason. We are seeing unprecedented rises in temperatures and extreme weather events that are directly linked to our impact on the environment. However, humans have not always been the cause of climate change across Earth's long history. Natural climate change refers to just that; climate change at the hands of natural environmental processes or occurrences unrelated to humanity's impact. These natural processes are not to blame for the recent warming that has been observed, though they can have major effects on the global climate and living conditions. Read on to learn more about 4 natural causes of climate change, and why they are irrelevant to what we are experiencing right now.
Natural Causes Of Climate Change:
Milankovich Cycles:
The Earth's precise distance from the sun is part of what allows for life on this planet. If its positioning changes, that will result in changes in climate as the amount of solar radiation received by the Earth would vary. Scientist Milutin Milankovitch hypothesized these effects, which are split into three types:
Eccentricity: The measure of how circular its orbit is is called eccentricity. The Earth's orbit is not perfectly circular, but is close. It can be acted upon by the gravitational pull from other planets, Jupiter and Saturn, which pulls Earth's path to be more elliptical. This occurs in cycles lasting about 100,000 years.
Precession: Axial precession is the phenomenon that Earth does not spin perfectly straight on its axis, but wobbles more like a spinning top instead. This is caused by tidal forces and gravitational pulls from the Earth and the moon, making Earth bulge slightly at the equator. This effect operates in cycles as well, lasting just under 26,000 years.
Obliquity: Earth is tilted on its axis as it travels around the sun, which is what gives Earth its seasons. The hemisphere tilted towards the sun experiences summer, while the hemisphere tilted away experiences winter. The greater the tilt of Earth, the more extreme the seasons. This also happens in cycles, occurring over the span of 41,000 years.
Volcanism:
Volcanic activity has helped shape the landscape and topography of the Earth as we know it, and their erruptions can also shape the climate. Erruptions release a combination of greenhouse gases in addition to aerosols. These aerosol particles become suspended in the atmosphere and actually have a cooling effect on the climate as they spread through the atmosphere and decrease the amount of energy absorbed from the sun. The climate is affected by cooling, not the standard warming effect we often associate with climate change.
Solar Cycles:
Similar to everything else in the natural world, the sun also operates in cycles. As such, the sun experiences times of high and low solar activity. In years of high activity, there is an increase in sunspots and solar flares, which increase the energy given off and, therefore, received by Earth, which leads to warmer temperatures. The sun's cycles last on average 10-12 years. The cycles are much shorter than the observed steady rise in temperatures over the last ~200 years, making them an improbable cause for a steady warming climate.
Plate Tectonics:
The movement of plate tectonics over millions of years is what has given us Earth's current landscape and placement of the continents. Although their movement does not have much impact on the climate experienced by Earth, the location of land in relation to the poles and equator does impact its specific climate. Land closer to the equator is warmer than land closer to the poles. Because this process occurs over millions of years, it is not responsible for the current rate of climate change.
What Causes Climate Change? Humans, or Natural Processes?
Various natural processes contribute to climate change over the course of millions of years, with some cycles as short as 12 years. These natural sources and their cycles are not contributing factors to the exponential rate of warming that Earth has been experiencing since the mid 19th century. These natural cycles operate at drastically different scales.
In the past 800,000 years that humans have been able to track carbon levels in the atmosphere through different proxies such as ice cores, the carbon levels have never been as high as they currently are. It has been proven over that same timeline that every warmer period is marked by higher concentrations of carbon in the atmosphere, the hottest on record prior to now having been 300ppm. We are currently exceeding 400ppm. The sharp increase matches up with the timeline of the industrial revolution, when western societies became more dependent on processes like combustion that release carbon.
Conclusion
While natural environmental processes do contribute to a changing climate, the scales and time periods over which they operate make it highly unlikely they have impact over the past 200 years of warming and increasing atmospheric carbon levels.
To learn more about what causes modern climate change and global warming, check out our previous Climate Change 101 post.
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