Fact Check: Ancient Warm Periods Don’t Disprove Modern Climate Change

A Facebook post, uploaded in September, shows a Washington Post headline and graph, suggesting that since Earth’s past temperatures had been higher very frequently, the concept of global warming is a hoax.

The post discusses a study on Earth’s climate over the past 485 million years.

Click here to view the link.

The Facebook post also shows a graph illustrating that earth is currently cooler compared to many points during ancient times and claims this as evidence that global warming is a hoax. The post has been shared over 70 times in one month.

Fact Check:

The claim is False. The study indeed mentioned earth was warmer during various points over the last 485 million years. However, it does not imply modern climate change is a hoax. Instead, the research highlights that the current rate of warming is alarmingly rapid and largely driven by human activity.

The paper, published in Science, provides a comprehensive analysis of temperature trends over the last 485 million years, blending fossil evidence with climate models. According to Emily Judd, the study's lead author and paleoclimate researcher at the Smithsonian Natural History Museum, the data reveals that while earth has indeed been warmer, today’s rapid temperature increase is concerning.

“I’ve seen quite a bit of misinformation crop up surrounding our paper, particularly the claim that we − humans − have nothing to worry about,” Judd told USA TODAY. “I cannot stress enough how reductive and problematic this viewpoint is.”

The study highlights that throughout history, significant warming events were often tied to high carbon dioxide levels. Judd emphasizes that “when CO2 and temperatures change rapidly, as is happening today due to [human emissions], evolution can’t keep pace with the environmental change.” This inability to adapt quickly has, in the past, led to catastrophic events like the end-Permian extinction, when nearly 90% of species were wiped out.

Human-Caused Climate Change

NASA data show that Earth’s average temperature has increased by about 2.45 degrees Fahrenheit since the late 1800s, primarily because of fossil fuel combustion, deforestation, and other human activities. This warming has been well-documented by independent climate organizations, as evidenced by the 2021 Intergovernmental Panel on Climate Change (IPCC) report, which draws from nearly 13,000 peer-reviewed studies.

Real-World Impacts

The consequences of today’s warming trend are vast: melting ice sheets, rising sea levels, disappearing Arctic ice, and extreme weather patterns that are becoming more frequent and severe. These changes are already having a tangible impact on human populations around the world.

While it is true that Earth's climate has experienced natural fluctuations over millions of years, the current, rapid warming trend is unprecedented and is overwhelmingly driven by human activities. Misrepresenting scientific findings to argue that global warming is a hoax undermines efforts to address the real and pressing challenges posed by climate change. The overwhelming consensus among climate scientists remains clear: modern global warming is real, dangerous, and demands immediate action.