Matty Jacobson
Over 700 million years ago, Earth experienced an extreme glaciation event where ice sheets extended from pole to pole for an incredulous 57 million years – nearly 60 times longer than the ice age ending 11,700 years ago. New research from Australian scientists finally explains why this happened and what specific geological forces caused it.
A Giant Snowball in Earth’s Ancient Past
Australian geologists have uncovered new details on an extreme ancient ice age dubbed “Snowball Earth.” Their models reveal that around 717 million years ago, nearly the entire planet became engulfed in glacial ice that persisted for over 50 million years. This fascinating work gives insight into Earth’s climate regulation in response to changes in volcanic activity and chemical rock weathering which can dramatically reduce atmospheric carbon dioxide over extended periods.
The research was led by University of Sydney scientist Dr. Adriana Dutkiewicz who described the findings as cracking a longstanding mystery about the causes and mechanisms behind this prolonged global freeze event. Her team’s climate models suggest that historically low volcanic CO2 emissions, combined with chemical weathering of volcanic rocks that absorbed CO2, crossed a critical threshold required for ice sheets to cover the globe for 57 million years – a scenario where nearly the entire planet became a giant snowball.
Imagine Earth Blanketed in Ice, Equator to Pole
This ancient glaciation event from 717 to 660 million years ago, termed the Sturtian ice age, astonishingly lasted over 50 million years- nearly 60 times longer than the Pleistocene ice age which ended 11,700 years ago after 2.6 million years. The extreme duration has perplexed geologists for decades.
“Imagine the Earth almost completely frozen over,” said Dr. Dutkiewicz when vividly describing the planet encased during Snowball Earth.”That’s just what happened about 700 million years ago; the planet was blanketed in ice from poles to equator and temperatures plunged well below freezing nearly everywhere for over 50 million years.” Understanding the specific causes and mechanisms behind this global freeze persisted over ten times longer than the age of dinosaurs has proven extremely challenging until now.
What Sparked This Prolonged Deep Freeze?
Leveraging advanced geological and climate modeling, the research team systematically probed the onset and longevity of the Sturtian glaciation from 717 to 660 million years ago. Their simulations revealed a clear culprit in triggering and sustaining this Snowball Earth for over 50 million years: historically low volcanic carbon dioxide emissions occurring in conjunction with massive silicate rock weathering in modern-day Canada.
Specifically, atmospheric CO2 levels are believed to have plunged dramatically due to reduced global volcanism over this extended period. When coupled with the weathering of ancient volcanic rocks near Hudson Bay, enough CO2 was absorbed to drop greenhouse gas concentrations below the critical threshold required for global glaciation to set in. While other smaller forces likely contributed, the steep decline in atmospheric carbon dioxide is the smoking gun behind this enduring cryospheric freeze.
Rock Weathering Accelerated The CO2 Decline
Dr. Dutkiewicz summarized these findings, stating”We now think we have cracked the mystery: historically low volcanic carbon dioxide emissions, aided by weathering of a large pile of volcanic rocks in what is now Canada; a process that absorbs atmospheric carbon dioxide. Geology ruled climate at this time. The result was that atmospheric CO2 fell to a level where glaciation kicks in — which we estimate to be below 200 parts per million, less than half today’s level.”
Indeed, atmospheric carbon dioxide levels are estimated to have plunged below 200 parts per million during the Sturtian glaciation – a drastic reduction from the over 400 ppm today. By connecting these geological forces to climate shifts using advanced EarthByte models, the team demonstrated how falling greenhouse gases could sustain global ice coverage for over 50 million years.
Why This Extreme Glaciation Matters
Beyond resolving a longstanding mystery in geology, research on the Sturtian “Snowball Earth” also emphasizes important lessons about connections between slow-moving geological forces and climate. Occurring before the Cambrian explosion of complex life forms, this global freezer event represents an important chapter in early Earth climate history.
The team notes that during this period nearly 700 million years ago, geological processes had an overriding influence in shaping global temperatures and climate conditions. Plunging volcanic CO2 emissions and chemical rock weathering absorbing atmospheric carbon dioxide combined to allow ice to coat nearly the entire planet continuously for over 50 million years.
Earth’s Temperature Regulation in Flux
Beyond ancient climate shifts, the research emphasizes Earth’s continually fluctuating climate regulation over hundreds of millions of years. As volcanic forces decreased CO2 output long ago entering the Sturtian ice age, so too could global volcanism decline in the distant future to levels that may spur another Snowball Earth scenario 250+ million years from now.
However, lead author Dr. Dutkiewicz stresses that the pace of geological climate change happens orders of magnitude slower than current warming. But theorized future configurations of continents, volcanic activity, and other forces may again alter planetary temperatures given enough time. So while a hot, Pangaea-like supercontinent could form in several hundred million years, reduced volcanic greenhouse gases could set the stage for another extreme glacial period.
Contrasting Ancient and Modern Climate Change
This collaborative research on ancient glaciation events also highlights the unprecedented rate of current human-driven climate change warming the planet. “Geological climate change happens extremely slowly,” said Dr. Dutkiewicz, noting conditions shifted gradually over millions of years entering past ice ages.
While volcanoes and rock weathering could dramatically alter climate given enough time, as evidenced by the Sturtian ice age, current carbon dioxide and methane emissions from fossil fuel burning and deforestation are warming the planet at a breakneck pace in comparison. This poses substantial threats for ecosystems to adapt to conditions comparable to those 700 million years ago.
Earth’s Delicate Climate Balance
This collaborative Australian research on the mechanisms behind the extreme Sturtian “Snowball” glaciation illustrates Earth’s delicate climate balance in the long term. Even small changes in atmospheric greenhouse gasses- on geologic timescales- can cross tipping points that dramatically flip planetary conditions between hot and cold extremes.
The research also emphasizes how substantial cumulative shifts in volcanism, rock weathering, and other geological forces can alter global temperatures, even if the pace seems gradual. It shows how falling CO2 emissions coupled with weathering can cool the planet, just as rising CO2 from extensive volcanism has warmed conditions historically, like during the age of dinosaurs.
A Cryosphere Spanning 50 Million Years
While perhaps difficult to envision, global ice coverage enduring for over 50 million years represents a testament to the influence of waning volcanic CO2 emissions coupled with chemical rock weathering sequentially absorbing atmospheric carbon.
Models suggest that plunging CO2 levels crossed a critical threshold required for glacial conditions to continuously persist worldwide for far longer than the entire existence of modern human civilization. Scientists estimate nearly the entire planet remained below freezing for over 10 times longer than since wooly mammoths went extinct.
Cracking a Climate Conundrum
In summary, this collaborative Australian research team leveraged climate models and geological field work to elucidate the onset and remarkable longevity of global glaciation over 700 million years ago – an extreme cryosphere persisting over 50 million years from the equator to the pole.
By connecting shifts in volcanism and chemical weathering to prolonged CO2 decline, the project solves a longstanding mystery about the how and why of this ancient climate event. It also highlights the delicate climate balance enabling ice ages and melting events over hundreds of millions of years, contemplating similarities and vast differences with the modern climate crisis.
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