Daily Earth Science Repost

Hot earth is normal

Multiple times in its geologic history planet earth has experienced extended periods of glaciation. During these cold periods, vast amounts of the earth’s available water have been locked away in glaciers and ice sheets. These glacial periods each lasted from 30 million years to over 100 million years. During the Cryogenian (720 million years ago), the earth went into a deep freeze and ice extended over the oceans from the poles to the equator.  Today, we are in a glacial period that began 34 million years ago. But despite these glacial periods, a hot earth is normal, not a cold earth. 

Glacial periods need to be distinguished from the term “ice ages.” Saying that the last ice age ended about 12,000 years ago is a reference to a period when glaciers and ice sheets covered much larger portions of the globe. When ice sheets retreat to where we see them today, the terminology we use is ‘interglacial period’. In reality, however, we are still in a long-term glacial period. Until all the ice has melted and sea levels have risen another 70 meters (230 feet), we won’t be out of that glacial period.

Hotter times

In total, the earth has spent about 670 million years out of its 4.5 billion year history in glacial periods. Thust glacial periods account for 15% of the earth’s existence.  The corollary is that the normal state of the earth is an ice-free planet with large inland seas and vast areas of the continental coasts underwater. Houston, Miami, New Orleans, Charleston New York, Boston, and Washington DC are all sites for scuba diving in a post-glacial world.

History, over a geologic timeframe, provides a perspective that is not in sync with our normal view of global warming.  Warming today moves the earth closer to its normal state. This perspective, however, overlooks the existential threat that a truly ice-free world poses. 

We look at global warming as an undesirable change from the status quo, not a return to the norm. Approximately a third of the world’s population lives within 100 meters of sea level. If not managed properly, human migration due to coastal displacement will cause social disintegration. Many countries will be wiped out and their populations will need to be integrated elsewhere.

There is no question that the planet earth can survive rapid global warming. The real question is can the species Homo sapiens survive such a disruption to its social and cultural structure?


Embrace a Hot Earth (Source: ArcheanWeb) –  https://archeanweb.com/2020/01/12/embrace-a-hot-earth/


Hypsographic demography: The distribution of human population by altitude – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC24316/

Article Photo: Photographer – Brocken Inaglory – This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.

William House
William is an earth scientist and writer with an interest in providing the science "backstory" for breaking environmental, earth science, and climate change news.