The Earth has always experienced natural cycles of warming and cooling. From ice ages to interglacial periods, our planet’s climate has never been static^[1]. This undeniable truth is often seized upon by those who seek to downplay the severity of contemporary climate change, claiming that today’s rapid temperature increases are simply part of these ongoing natural fluctuations. However, this argument overlooks a crucial distinction: the timescale and speed of the changes we are witnessing today compared to natural cycles.

One of the most prominent natural drivers of long-term climate shifts are the Milankovitch Cycles^[2]. These cycles describe the collective effects of changes in the Earth’s movements on its climate over thousands of years. They are named after Serbian geophysicist Milutin Milanković, who quantified their influence on the amount of solar radiation reaching different parts of the Earth.

There are three primary Milankovitch Cycles^[3]:

• Eccentricity: Changes in the shape of Earth’s orbit around the Sun, varying from nearly circular to more elliptical over a cycle of approximately 100,000 years.
• Obliquity (Axial Tilt): Variations in the tilt of Earth’s axis relative to its orbit, ranging from 22.1 to 24.5 degrees over a period of about 41,000 years. This tilt is responsible for the seasons.
• Precession: The wobble of Earth’s axis, similar to a spinning top, which affects the timing of the seasons relative to Earth’s position in its orbit. This cycle occurs over roughly 23,000 years.

The critical distinction: Time scales and speed

Herein lies the fundamental difference between natural cycles and the climate change we are experiencing today. Milankovitch cycles operate on timescales of tens of thousands to hundreds of thousands of years. The warming and cooling associated with these cycles unfold gradually, allowing natural systems to adapt over vast spans of time^[4].

In stark contrast, the warming observed since the Industrial Revolution – roughly the last 150 years – has been extraordinarily rapid. Scientific data, including temperature records, ice core analyses, and tree rings, consistently show a steep and unprecedented increase in global average temperatures over a mere few centuries, not millennia.

Consider the speed: the Earth has warmed by approximately 1.2 degrees Celsius (2.2 degrees Fahrenheit) since pre-industrial times. To put this into perspective, the transition out of the last ice age, a natural warming event of far greater magnitude, occurred over thousands of years. The current rate of warming is at least ten times faster than the average rate of warming after an ice age^[5].

The role of CO2 emissions

This rapid warming cannot be explained by Milankovitch cycles or any other known natural phenomenon operating on such short timescales. The overwhelming scientific consensus points to the dramatic increase in atmospheric concentrations of greenhouse gases, particularly carbon dioxide (CO2), as the primary driver. These gases, released in massive quantities through human activities like burning fossil fuels, deforestation, and industrial processes, trap heat in the Earth’s atmosphere, leading to a warming effect^[6].

Ice core data, which provides a historical record of atmospheric composition, clearly shows that CO2 levels remained relatively stable for hundreds of thousands of years, fluctuating within a predictable range corresponding to natural cycles. However, since the Industrial Revolution, CO2 concentrations have skyrocketed to levels not seen in at least 800,000 years, and the rate of increase is unprecedented in geological history^[7]. This dramatic rise in CO2 directly correlates with the rapid increase in global temperatures.

Conclusion

While acknowledging Earth’s natural climate variability is important, attributing current rapid warming solely to these cycles is a misleading oversimplification. Milankovitch cycles are indeed powerful drivers of long-term climate shifts, operating over immense periods of time. However, they cannot account for the speed and magnitude of the warming we are witnessing today. The scientific evidence overwhelmingly demonstrates that the current accelerated warming is primarily driven by human-induced greenhouse gas emissions, a phenomenon distinctly separate from the Earth’s ancient, slow-moving natural rhythms.

Understanding this distinction is vital for accurately assessing the challenges posed by climate change and for developing effective solutions.

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^[1] https://climate.mit.edu/ask-mit/todays-climate-change-similar-natural-warming-between-ice-ages

^[2]https://science.nasa.gov/science-research/earth-science/milankovitch-orbital-cycles-and-their-role-in-earths-climate/

^[3]https://science.nasa.gov/science-research/earth-science/milankovitch-orbital-cycles-and-their-role-in-earths-climate/

^[4] https://climateandnature.org.nz/climate-change-is-just-a-cycle/

^[5] https://science.nasa.gov/climate-change/evidence/

^[6]https://www.researchgate.net/publication/358498680_Global_Warming_and_Climate_Change_Fossil_fuels_and_anthropogenic_activities_have_warmed_the_Earth%27s_atmosphere_oceans_and_land

^[7]https://theconversation.com/the-three-minute-story-of-800-000-years-of-climate-change-with-a-sting-in-the-tail-73368