The Arctic Hasn't Been This Warm For 3 Million Years and That Means Big Changes For The Planet

The Arctic Hasn't Been This Warm For 3 Million Years and That Means Big Changes For The Planet
Ice floe drifting in Svalbard, Norway.
Sven-Erik Arndt/Arterra/Universal Images Group via Getty Images

Every year, sea ice cover in the Arctic Ocean shrinks to a low point in mid-September. This year it measures just 1.44 million square miles (3.74 million square kilometers) – the second-lowest value in the 42 years since satellites began taking measurements. The ice today covers only 50% of the area it covered 40 years ago in late summer.

This year’s minimum ice extent is the lowest in the 42-year-old satellite record except for 2012This year’s minimum ice extent is the lowest in the 42-year-old satellite record except for 2012, reinforcing a long-term downward trend in Arctic ice cover. Each of the past four decades averages successively less summer sea ice. NSIDC

As the Intergovernmental Panel on Climate Change has shown, carbon dioxide levels in the atmosphere are higher than at any time in human history. The last time that atmospheric CO2 concentrations reached today’s level – about 412 parts per million – was 3 million years ago, during the Pliocene Epoch.

As geoscientists who study the evolution of Earth’s climate and how it creates conditions for life, we see evolving conditions in the Arctic as an indicator of how climate change could transform the planet. If global greenhouse gas emissions continue to rise, they could return the Earth to Pliocene conditions, with higher sea levels, shifted weather patterns and altered conditions in both the natural world and human societies.

The Pliocene Arctic

We are part of a team of scientists who analyzed sediment cores from Lake El’gygytgyn in northeast Russia in 2013 to understand the Arctic’s climate under higher atmospheric carbon dioxide levels. Fossil pollen preserved in these cores shows that the Pliocene Arctic was very different from its current state.

Today the Arctic is a treeless plain with only sparse tundra vegetation, such as grasses, sedges and a few flowering plants. In contrast, the Russian sediment cores contained pollen from trees such as larch, spruce, fir and hemlock. This shows that boreal forests, which today end hundreds of miles farther south and west in Russia and at the Arctic Circle in Alaska, once reached all the way to the Arctic Ocean across much of Arctic Russia and North America.

Because the Arctic was much warmer in the Pliocene, the Greenland Ice Sheet did not exist. Small glaciers along Greenland’s mountainous eastern coast were among the few places with year-round ice in the Arctic. The Pliocene Earth had ice only at one end – in Antarctica – and that ice was less extensive and more susceptible to melting.

Because the oceans were warmer and there were no large ice sheets in the Northern Hemisphere, sea levels were 30 to 50 feet (9 to 15 meters) higher around the globe than they are today. Coastlines were far inland from their current locations. The areas that are now California’s Central Valley, the Florida Peninsula and the Gulf Coast all were underwater. So was the land where major coastal cities like New York, Miami, Los Angeles, Houston and Seattle stand.

Warmer winters across what is now the western U.S. reduced snowpack, which these days supplies much of the region’s water. Today’s Midwest and Great Plains were so much warmer and dryer that it would have been impossible to grow corn or wheat there.

Why was there so much CO2 in the Pliocene?

How did CO2 concentrations during the Pliocene reach levels similar to today’s? Humans would not appear on Earth for at least another million years, and our use of fossil fuels is even more recent. The answer is that some natural processes that have occurred on Earth throughout its history release CO2 to the atmosphere, while others consume it. The main system that keeps these dynamics in balance and controls Earth’s climate is a natural global thermostat, regulated by rocks that chemically react with CO2 and pull it out of the atmosphere.

The strength of the Greenhouse Effect relies on atmospheric CO2 levels. The Greenhouse Effect leads to increases in surface temperatures and, in some places, rainfall. Together these accelerate silicate rock weathering. Faster weathering in turn removes more CO2 from the atmosphere (yellow arrow). The strength of the Greenhouse Effect relies on atmospheric CO2 levels. Gretashum/Wikipedia

In soils, certain rocks continually break down into new materials in reactions that consume CO2. These reactions tend to speed up when temperatures and rainfall are higher – exactly the climate conditions that occur when atmospheric greenhouse gas concentrations rise.

But this thermostat has a built-in control. When CO2 and temperatures increase and rock weathering accelerates, it pulls more CO2 from the atmosphere. If CO2 begins to fall, temperatures cool and rock weathering slows globally, pulling out less CO2.

Rock weathering reactions also can work faster where soil contains lots of newly exposed mineral surfaces. Examples include areas with high erosion or periods when Earth’s tectonic processes pushed land upward, creating major mountain chains with steep slopes.

The rock weathering thermostat operates at a geologically slow pace. For example, at the end of the Age of Dinosaurs about 65 million years ago, scientists estimate that atmospheric CO2 levels were between 2,000 and 4,000 parts per million. It took over 50 million years to reduce them naturally to around 400 parts per million in the Pliocene.

Because natural changes in CO2 levels happened very slowly, cyclic shifts in Earth’s climate system were also very slow. Ecosystems had millions of years to adapt, adjust and slowly respond to changing climates.


Summer heat waves are altering northern Siberia, thawing permafrost and creating conditions for large-scale wildfires.

A Pliocene-like future?

Today human activities are overwhelming the natural processes that pull CO2 out of the atmosphere. At the dawn of the Industrial Era in 1750, atmospheric CO2 stood at about 280 parts per million. It has taken humans only 200 years to completely reverse the trajectory begun 50 million years ago and return the planet to CO2 levels not experienced for millions of years.

Most of that shift has happened since World War II. Yearly increases of 2-3 parts per million now are common. And in response, the Earth is warming at a fast pace. Since roughly 1880 the planet has warmed by 1 degree Celsius (2 degrees Fahrenheit) – many times faster than any warming episode in the past 65 million years of Earth’s history.

In the Arctic, losses of reflective snow and ice cover have amplified this warming to +5 C (9 F). As a result, summertime Arctic sea ice coverage is trending lower and lower. Scientists project that the Arctic will be completely ice-free in summer within the next two decades.

This isn’t the only evidence of drastic Arctic warming. Scientists have recorded extreme summer melt rates across the Greenland Ice Sheet. In early August, Canada’s last remaining ice shelf, in the territory of Nunavut, collapsed into the sea. Parts of Arctic Siberia and Svalbard, a group of Norwegian islands in the Arctic Ocean, reached record-shattering high temperatures this summer.

Coastal cities, agricultural breadbasket regions and water supplies for many communities all will be radically different if this planet returns to a Pliocene CO2 world. This future is not inevitable – but avoiding it will require big steps now to decrease fossil fuel use and turn down Earth’s thermostat.The Conversation

About the Authors

Julie Brigham-Grette, Professor of Geosciences, University of Massachusetts Amherst and Steve Petsch, Associate Professor of Geosciences, University of Massachusetts Amherst

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Related Books

Life After Carbon: The Next Global Transformation of Cities

by Peter Plastrik , John Cleveland
1610918495The future of our cities is not what it used to be. The modern-city model that took hold globally in the twentieth century has outlived its usefulness. It cannot solve the problems it helped to create—especially global warming. Fortunately, a new model for urban development is emerging in cities to aggressively tackle the realities of climate change. It transforms the way cities design and use physical space, generate economic wealth, consume and dispose of resources, exploit and sustain the natural ecosystems, and prepare for the future. Available On Amazon

The Sixth Extinction: An Unnatural History

by Elizabeth Kolbert
1250062187Over the last half-billion years, there have been Five mass extinctions, when the diversity of life on earth suddenly and dramatically contracted. Scientists around the world are currently monitoring the sixth extinction, predicted to be the most devastating extinction event since the asteroid impact that wiped out the dinosaurs. This time around, the cataclysm is us. In prose that is at once frank, entertaining, and deeply informed, New Yorker writer Elizabeth Kolbert tells us why and how human beings have altered life on the planet in a way no species has before. Interweaving research in half a dozen disciplines, descriptions of the fascinating species that have already been lost, and the history of extinction as a concept, Kolbert provides a moving and comprehensive account of the disappearances occurring before our very eyes. She shows that the sixth extinction is likely to be mankind's most lasting legacy, compelling us to rethink the fundamental question of what it means to be human. Available On Amazon

Climate Wars: The Fight for Survival as the World Overheats

by Gwynne Dyer
1851687181Waves of climate refugees. Dozens of failed states. All-out war. From one of the world’s great geopolitical analysts comes a terrifying glimpse of the strategic realities of the near future, when climate change drives the world’s powers towards the cut-throat politics of survival. Prescient and unflinching, Climate Wars will be one of the most important books of the coming years. Read it and find out what we’re heading for. Available On Amazon

From The Publisher:
Purchases on Amazon go to defray the cost of bringing you InnerSelf.comelf.com, MightyNatural.com, and ClimateImpactNews.com at no cost and without advertisers that track your browsing habits. Even if you click on a link but don't buy these selected products, anything else you buy in that same visit on Amazon pays us a small commission. There is no additional cost to you, so please contribute to the effort. You can also use this link to use to Amazon at any time so you can help support our efforts.

 

enafarzh-CNzh-TWdanltlfifrdeiwhihuiditjakomsnofaplptruesswsvthtrukurvi

follow InnerSelf on

facebook icontwitter iconyoutube iconinstagram iconpintrest iconrss icon

 Get The Latest By Email

Weekly Magazine Daily Inspiration

LATEST VIDEOS

can we cool the planet 7 22
Can We Cool The Planet?
by Robert Jennings, InnerSelf.com
Climate change has emerged as one of the most pressing challenges of our time. Over the past century, human activities…
i5w7rk3a
The Devastating Impact of 3C Global Warming
by Robert Jennings, InnerSelf.com
Global warming is a pressing issue that poses severe threats to our planet and all its inhabitants. In recent years,…
The Great Climate Migration Has Begun
The Great Climate Migration Has Begun
by Super User
The climate crisis is forcing thousands around the world to flee as their homes become increasingly uninhabitable.
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
The Last Ice Age Tells Us Why We Need To Care About A 2℃ Change In Temperature
by Alan N Williams, et al
The latest report from the Intergovernmental Panel on Climate Change (IPCC) states that without a substantial decrease…
The Caspian Sea Is Set To Fall By 9 Metres Or More This Century
The Caspian Sea Is Set To Fall By 9 Metres Or More This Century
by Frank Wesselingh and Matteo Lattuada
Imagine you are on the coast, looking out to sea. In front of you lies 100 metres of barren sand that looks like a…
Five Climate Disbeliefs: A Crash Course In Climate Misinformation
The Five Climate Disbeliefs: A Crash Course In Climate Misinformation
by John Cook
This video is a crash course in climate misinformation, summarizing the key arguments used to cast doubt on the reality…
The Arctic Hasn't Been This Warm For 3 Million Years and That Means Big Changes For The Planet
The Arctic Hasn't Been This Warm For 3 Million Years and That Means Big Changes For The Planet
by Julie Brigham-Grette and Steve Petsch
Every year, sea ice cover in the Arctic Ocean shrinks to a low point in mid-September. This year it measures just 1.44…
What Is A Hurricane Storm Surge and Why Is It So Dangerous?
What Is A Hurricane Storm Surge and Why Is It So Dangerous?
by Anthony C. Didlake Jr
As Hurricane Sally headed for the northern Gulf Coast on Tuesday, September 15, 2020, forecasters warned of a…

LATEST ARTICLES

global boiling is here 7 29
U.N. Warns: The Era of Global Boiling Has Arrived
by Robert Jennings, InnerSelf.com
The world faces an unprecedented climate crisis as temperatures soar and heat records are shattered across the globe.
amoc map 7 26
The Unseen Tipping Point: Understanding the Potential Impact of an AMOC Shutdown
by Robert Jennings, InnerSelf.com
The Unseen Tipping Point: Understanding the Potential Impact of an AMOC Shutdown Have you ever heard of the Atlantic…
can we cool the planet 7 22
Can We Cool The Planet?
by Robert Jennings, InnerSelf.com
Climate change has emerged as one of the most pressing challenges of our time. Over the past century, human activities…
global hungry 7 22
The Rising Tide of Global Hunger: Pandemic, Climate & Conflict Fuel Food Insecurity
by Robert Jennings, InnerSelf.com
In recent years, the world has witnessed a distressing surge in global hunger, painting a bleak picture of food…
keeping cool 7 20
Beat the Heat: Your Guide to Staying Safe in Extreme Temperatures
by Robert Jennings, InnerSelf.com
As the temperatures rise during the summer months, it's important to be aware of the risks associated with extreme heat.
i5w7rk3a
The Devastating Impact of 3C Global Warming
by Robert Jennings, InnerSelf.com
Global warming is a pressing issue that poses severe threats to our planet and all its inhabitants. In recent years,…
how hot is too hot 7 19
How Hot is Too Hot? The Risks of Extreme Heat on the Human Body
by W. Larry Kenney, Penn State et al
The answer goes beyond the temperature you see on the thermometer. It’s also about humidity. Our research is designed…
european heatwave 7 18
European Heatwave: What’s Causing It And Is Climate Change To Blame?
by Emma Hill and Ben Vivian, Coventry University
Europe is currently in the midst of a heatwave. Italy, in particular, is expected to face blistering heat, with…

Tropical cyclones are among the most destructive weather systems on Earth, and the Southwest Pacific region is very exposed and vulnerable to these extreme events.

COLUMBIA - When Sherry Miller moved to Columbia from New Jersey, the heavy pollen in the air here triggered her asthma and sent her to the emergency room three times in a matter of months. In the...

Plastic trash—widespread throughout the world’s oceans—intensifies disease for coral and so puts reefs in peril, a new study suggests.

  Brace yourselves, allergy sufferers – new research shows pollen season is going to get a lot longer and more intense with climate change.

To help curb climate change, President Biden has set a goal of lowering U.S. greenhouse gas emissions 50%-52% below 2005 levels by 2030. Meeting this target will require rapidly converting as many...

The tropical water at the equator is renowned for having the richest diversity of marine life on Earth, with vibrant coral reefs and large aggregations of tunas, sea turtles, manta rays and whale...


 Get The Latest By Email

Weekly Magazine Daily Inspiration

New Attitudes - New Possibilities

InnerSelf.comClimateImpactNews.com | InnerPower.net
MightyNatural.com | WholisticPolitics.com | InnerSelf Market
Copyright ©1985 - 2021 InnerSelf Publications. All Rights Reserved.