Variations in atmospheric oxygen levels shaped Earth's climate through the ages

June 11, 2015, University of Michigan
Schematic of the influence of oxygen concentrations on global climate. Credit: Chris Poulsen, University of Michigan

Variations in the amount of oxygen in Earth's atmosphere significantly altered global climate throughout the planet's history. Efforts to reconstruct past climates must include this previously overlooked factor, a new University of Michigan-led study concludes.

Oxygen currently comprises about 21 percent of Earth's atmosphere by volume but has varied between 10 percent and 35 percent over the past 541 million years.

In periods when declined, the resulting drop in led to increased surface evaporation, which in turn led to precipitation increases and warmer temperatures, according to University of Michigan paleoclimatologist Christopher Poulsen.

"The connection between oxygen levels and climate has never been considered. It turns out that it's an important factor over geological timescales," said Poulsen, a professor in the Department of Earth and Environmental Sciences. While not as critical to climate as levels of heat-trapping gas, oxygen plays a key role, he said.

"Oxygen concentration can help explain features in the paleoclimate record not accounted for by variations in carbon dioxide levels, and it must considered if we are to fully understand past climates," Poulsen said. "However, variations in oxygen levels are not an important factor in present-day climate change."

The study is scheduled for online publication in the journal Science on June 11.

Throughout Earth's history, oxygen levels repeatedly rose and fell. Removing thins the atmosphere, increasing the likelihood that incoming sunlight will make it to the surface without getting scattered away.

More sunlight means more evaporation from the surface, which leads to higher humidity levels and increased precipitation. As humidity levels rise, temperatures also increase because water vapor is a potent heat-trapping "greenhouse" gas.

Adding oxygen molecules has the opposite effect: a thicker atmosphere, more scattering of , reduced surface evaporation, and less heat trapped by water vapor.

In their Science paper, Poulsen and two colleagues quantify the effect of changing oxygen levels on climate using an atmospheric model to account for changes in atmospheric density, mass and molecular weights.

The team's computer simulations focused on the mid-Cretaceous, a period characterized by high atmospheric carbon dioxide levels and the warmest conditions of the last 100 million years. Specifically, they focused on Cenomanian Age, from 100.5 million years ago to 93.9 million years ago.

They developed a series of simulations in which oxygen levels varied from a low of 5 percent to a high of 35 percent. They found that decreased oxygen levels led to substantial increases in global precipitation rates and temperature.

Changing oxygen concentrations could help explain features of the paleoclimate record not accounted for by variations in carbon dioxide levels, such as warm polar temperatures and unexpectedly high precipitation rates in some periods, the researchers conclude.

Though previously unappreciated for its influence on climate, changing have long been recognized for shaping the course of life on Earth. Billions of years ago, for example, photosynthesizing cyanobacteria in the oceans released massive amounts of oxygen that eventually made it possible for animals to colonize the land.

Explore further: Boreal peatlands not a global warming time bomb

More information: Long-term climate forcing by atmospheric oxygen concentrations, www.sciencemag.org/lookup/doi/ … 1126/science.1260670

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15 comments

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wasp171
2.4 / 5 (11) Jun 11, 2015
Another item alarmists have overseen...just one more amongst heaps.
Captain Stumpy
3.5 / 5 (11) Jun 11, 2015
Another item alarmists have overseen...just one more amongst heaps.
@wasp
not really
this is what is called GOOD SCIENCE

it also doesn't apply very much to today as our O2 levels are not fluctuating

from the study
Unlike greenhouse gases, O2 is inactive in the infrared band, contributes weakly to the radiative forcing of the atmosphere, and is not considered an important factor in climate forcing.
so, perhaps next time you should read the study first before jumping to conclusions?

especially as you are simply repeating political/religious/conspiracy rhetoric and not substantiating your conjecture with evidence...

thanks
denglish
2.3 / 5 (9) Jun 11, 2015
Oxygen levels are always fluctuating...as is everything else...including the climate.

We know that living things in prehistoric eras were able to become massive due to the high oxygen levels.

http://en.wikiped...tion.png

The scale of the graph is large, but shows a down trend, so:

Throughout Earth's history, oxygen levels repeatedly rose and fell. Removing oxygen molecules thins the atmosphere, increasing the likelihood that incoming sunlight will make it to the surface without getting scattered away.

More sunlight means more evaporation from the surface, which leads to higher humidity levels and increased precipitation. As humidity levels rise, temperatures also increase because water vapor is a potent heat-trapping "greenhouse" gas.


Looks like it may be time to terrorize, tax, and cripple Oxygen too!

It will be interesting to see how/if the alarmists manipulate this.
Steve 200mph Cruiz
3.8 / 5 (10) Jun 11, 2015
Denglish,
If you want to look smart, you have to know how to read, Poulsen said. "However, variations in oxygen levels are not an important factor in present-day climate change."

Captain Stumpy
3.9 / 5 (7) Jun 12, 2015
Oxygen levels are always fluctuating...as is everything else...including the climate
@d
then show me the measurements for the last century
i am willing to bet that the historical O2 levels are constant, for the most part, for the last 150-250 years AT LEAST

we KNOW about the historical fluctuations... how is this relevant to YOUR argument?
i would ask for some scientific content, but i doubt you would comply as dedicated as you are to trolling with political arguments

If you want to look smart, you have to know how to read
@Steve 200mph Cruiz
Yeah, well... reading, comprehension and actually fact checking the content of his posts are not his strong points...
In fact, i am not sure he knows HOW ...

he is mad about the possible choices that will affect him, so he will deny the science till his last breath - except in astrophysics

Somehow he thinks the physics there is different than here. LOL
Steve 200mph Cruiz
5 / 5 (5) Jun 12, 2015
They're all just nuts. A normal person would read this and go, "oh, interesting, I have a greater appreciation of how the density of the atmosphere effects it's insulating properties" or whatever and go on with their day.
These guys just see the word "atmosphere" and think, "stupid blind liberals are trying to destroy the economy".
You would have to hook them up to the machine in a Clockwork Orange to actually get them to read it.
richard_f_cronin
1 / 5 (4) Jun 12, 2015
Well, we do know that when we looked closely at Chlorine, we discovered "ozone depletion". The 1978 Montreal Protocol is an unaudited, self-reporting charade. Everybody meets their CFC "targets" --- while Russia, China, India and Brazil all produce the original Freons and sell thru Third World nations. The re-packaged Freons flow back to the West in ever greater quantities thru the "recycle / re-use" program. Freon 11 and 12 are still the most widely used refrigerants globally. The market has robust growth. Now UN and the Protocol signatories pat themselves on the back and gleefully proclaim they have "stabilized" the ozone hole. Oh, wait !! It'll never close up. The ozone hole waxes and wanes naturally as exposure to UV-B radiation ceases during the polar winter. The UV-B makes ozone from diatomic oxygen. Ozone is the product of UV-B, not the protector from UV-B.

Now onto the thorough exam of Carbon and Oxygen. We're sure to find something to justify more grant funding.
denglish
1 / 5 (4) Jun 12, 2015
Denglish,
If you want to look smart, you have to know how to read, Poulsen said. "However, variations in oxygen levels are not an important factor in present-day climate change."


Looks have nothing to do with it.

I'm smart enough to know that AGW is a reason for bureaucrats to pursue agendas and get rich. That's enough for me.
Steve 200mph Cruiz
5 / 5 (6) Jun 12, 2015
Denglish,

What if I want them to be rich? What if I want to stop giving my money to oil companies when ever possible and give it to someone else, isn't that how the free market works?
Even if you think denying people have an impact on the climate is a reasonable claim, what if I'm still mad about Deep Water Horizons? What if I'm mad about the coal towns being polluted? What if I'm mad about all the money they spend on politicians that fundamentally disagree with me? What if I don't think oil and coal are good long term investments?

There are plenty of reasons to change up the system besides climate change.
denglish
1.8 / 5 (5) Jun 12, 2015
What if I want them to be rich? What if I want to stop giving my money to oil companies when ever possible and give it to someone else, isn't that how the free market works?

No.

Even if you think denying people have an impact on the climate is a reasonable claim, what if I'm still mad about Deep Water Horizons?

Perhaps you should develop safety systems. Systems tend to work better than hatred.

What if I'm mad about the coal towns being polluted?

Perhaps you should develop viable alternatives. Viable being the key term.

What if I'm mad about all the money they spend on politicians that fundamentally disagree with me?

Vote

What if I don't think oil and coal are good long term investments?

Find another one.

There are plenty of reasons to change up the system besides climate change.

Absolutely. However, there are not enough reasons to allow AGW bureaucrats to create chaos.
Captain Stumpy
4.2 / 5 (5) Jun 12, 2015
I'm smart enough to know that AGW is a reason for bureaucrats to pursue agendas and get rich. That's enough for me
@d
so is NON-smoking in federal & (most) state buildings... does this mean you are going to take up smoking and trying to enter FED buildings all lit up?

in fact, "bureaucrats" & politicians also got on the bandwagon about leaded gas - another get-rich agenda... right along with CFC's!

you should start poking holes in all your A/C systems to vent your R-coolant and put lead back in your gas to show us all how dedicated you are!

best yet -
you should forget all about those carcinogen warnings and go right back to licking asbestos!
because we all know that those were just about getting rich!

[sarc/satire/hyperbole]

just because YOU don't believe the science doesn't mean it aint true, troll-boy
Captain Stumpy
4.2 / 5 (5) Jun 12, 2015
Systems tend to work better than hatred
@d
you should take your own advice
in fact, you should go back to school and study physics and get to understand the "systems" and physics we DO know and stop ranting and spreading your hate

How many people are you willing to kill for your personal beliefs
@jyro
1- WTF? is this relevant?
2- if you DON'T fix the problem and it continues to worsen faster than we can adjust, adapt or deal with?

quit sticking your head in the sand

Mike_Massen
4.2 / 5 (5) Jun 12, 2015
jyro FAILs in meaningful position stating
How many people are you willing to kill for your personal beliefs
Eh ?
Only a psychopath would go down that path, you seem acquainted with such approach, why ?
Why do you manufacture a strawman type approach showing up your feeble approach to argue ?

jyro claims
The lack of coal or oil for heating backup and electricity will cause deaths in Northern as well as Southern climates when the grid goes down
Who says there's going to be a lack, making things up isn't your most intelligent endeavour ?

jyro says
Wind and solar are not viable alternatives without a energy storage system
Well doh !
AND depends on consistency, not touted as replacement its an added component - pfft !

jyro says
Unintended consequences kill people when their lives depend on warmth or cooling in the long cold winters and hot summers. Get alternatives in place first, then cut out the polluter fuels
Where is it suggested otherwise - doh ?
Mike_Massen
3.7 / 5 (6) Jun 12, 2015
jyro claims with immensely low intelligence
Earth's climate has continuously changed for 4 BILLION years. We exist in a brief span when the climate is good for man. Enjoy what time we are allowed on Earth. No power or force can keep the climate on Earth from changing. It's a total waste of time to even try
Psychopathic & pathetic jyro

FACT is from human sourced fuels & high combustion we ARE adding immense heat therefore, doh, by reducing that burden we can ameliorate climate change, its application of the classic bilateral logic re burning vs not burning as evidence shows rise in CO2 for last ~150yrs is from human activities - doh !

So it makes sense to reduce the consumption OR ameliorate the waste products ie CO2, this is where engineering comes in based upon foundations of Physics

So the obvious & logical imperative is to educate and NOT rely upon uneducated opinion barking negative sentiments from the sidelines

Community college for you jyro
Mike_Massen
3.7 / 5 (3) Jun 13, 2015
Ren82 asked
Earth's climate has continuously changed for 4 BILLION years. We exist in a brief span when the climate is good for man..


What are the grounds for such foolhardy claims?
its called Geological EVIDENCE !

Tell us Ren82 just HOW your claimed god communicates with ALL of us equally ?

Tell us Ren82 how you can reconcile your god acts like a Devil punishing EVERYONE ?

Is your god Ren82 a great example for parents to follow ?

ie Punish all children for ever because of entrapment ie Its written the god KNEW the future so created Satan to lie to Eve !

Are these the actions of a "loving god" Ren82 ?

Explain the source of your feeble intellect & immense emotional attachment to an old book that shows clearly your god can ONLY punish and is egotistically focused on itself ?

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