By 2030, Earth’s Climate Could Look Like It Did 3 Million Years Ago

Those who do not learn history are doomed to repeat it.” It’s an aphorism frequently cited for its relevance to social change—but it may apply to science just as well.

In a study published Monday in the Proceedings of the National Academy of Sciences (PNAS), scientists report that a planet-wide cooling trend that began nearly 50 million years ago is reversing due to climate change. 


According to the researchers, if current emission trends continue, then by 2030, Earth’s climate may resemble the mid-Pliocene epoch, which lasted from 3.3 million to three million years ago. During that period, there were no large ice sheets in the Northern Hemisphere and sea levels were about 60 feet higher than present. The epoch also marked the dawn of hominid evolution.

What’s more, the researchers found that—again, if current emission trends continue—Earth’s climate could plunge further into the past. By 2150, the planet could look something like the Eocene epoch, which began just after dinosaurs went extinct and was characterized by high carbon dioxide levels, gigantic volcanic eruptions, and the advent of the ancestors of modern mammals.

In short, if our planet’s history were a movie, we’re currently pressing the “rewind” button.

The study’s lead author, Kevin Burke, worked with paleoecologist Dr. John Williams of the University of Wisconsin-Madison to assess the climatic characteristics of several geologic time periods, including the Early Eocene (beginning 56 million years ago), the mid-Pliocene (beginning 3.3 million years ago), the Last Interglacial (beginning 130,000 years ago), the mid-Holocene (beginning 7,000 years ago), the pre-industrial era (beginning in 1750), and the early 20th century.

Using several climate scenarios put forth by the IPCC Fifth Assessment (the fifth in a series of reports from the United Nations and the World Meteorological Organization designed to assess scientific information on climate change)—including one known as “Representative Concentration Pathway 8.5” (RCP8.5), which paints a picture of a future sans climate mitigation attempts (what climate scientists call the “business-as-usual” scenario), and RCP4.5, which depicts a future in which we’ve moderately reduced emissions—Burke and Williams compared years-from-now conditions across every inch of the planet to the past.

I think one of the real challenges of 21st century climate change is that it’s very hard for us to imagine what the world looks like when it’s 2 degrees warmer or 4 degrees warmer, or it’s outside of anything we’ve seen in our history,” Williams said. 

Having this data is therefore helpful—we can better visualize what our home will be like decades and even a century from now. From these past climate conditions, we can start to draw comparisons and analogies to help conceptualize the climates we can expect in the coming decades.

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