If all the carbon stored in fossil fuels was once in the atmosphere, should the planet then have been too warm to sustain life?
In: Planetary Science
Earth was way too hot at one point to sustain life yes. Even the time of the dinosaurs was much warmer than we are currently. We’re still coming out of an ice age after all.
The world used to be hotter and more humid, that’s why prehistoric animals are so big. Also, it took thousands of years for biomass to turn into fossil fuels and we’ve been burning through it way faster than that, so we’re releasing energy much much more quickly than it was sequestered.
Specific to your question the atmospheric Carbon Dioxide levels were much much higher around 500 million years ago. During this era temperatures likely average between 2 and 46 degrees C which is a moderately warmer than now.
Yet there’s evidence that temperatures could have soared as high as 80C consistently in some areas.
The Sun was also dimmer in this time and so the Earth received less energy overall so Earth relied more on green houses gases than now.
During this era there was no life on land, life was only in the oceans. The oceans were more moderate in temperature and provided important protection against radiation as there was no Ozone layer.
During the Jurassic (200 to 145 million years ago) the Earth was 5-10C hotter than now and more humid. Life flourished but the planet was very different to what we know now.
You have to keep in mind that the carbon in fossil fuels wasn’t removed from the atmosphere all at once, it was captured by plants over millions of years.
During this time oxygen created by algae built up in the atmosphere and reacted with methane destroying it and reducing the greenhouse gases rapidly. This resulted in Snowball Earth where the Earth was frozen over entirely for millions of years.
CO2 and Oxygen eventually reached a new equilibrium which melted the ice and allowed for the Cambrian explosion, the first major evolution of plant and animal life as we know it today.
We are burning millions of years worth of natural carbon capture in the span of a few decades. That’s why it’s having such a drastic effect.
Life can adapt to higher temperatures. It’s trivial. The problem is that naturally occurring temperature increases happen over hundreds if not thousands of years, not remotely at the speed it’s increasing now.
Life on Earth can adapt to many many things, but not at the speed things are currently changing thanks to humankind
It was once in the atmosphere, **but not all at once**. The carbon that forms coal and petroleum were pulled from the atmosphere over millions of years, but are being put back in time measured in centuries.
Analogy is saving money for 50 years, then using it all in an orgry of spending in one day. Yes you once had all that money, but not at the same time. The effects of that short term spending could be very high,
To echo some responses here.. yes, at one point in early formation the earth was entirely too hot to support almost any kind of life. However certain thermophile organisms would have possibly lived well. They exist to this day.. living in hot springs and ocean vent environments. When the dinosaurs reigned the earth would have looked far different than it does today.. very humid, very hot and covered by dense tropical forests. This is (arguably) why we have such an abundance of fossil fuels today.
Most of the coal we burn was captured over millions of years during the carboniferous. That’s were it gets its name. The carbon bearing period. Oil formed a bit later afaik. And the earth was up to 10C hotter at multiple points in its history. Life can be sustained at higher temperature but changing temperature quickly will cause mass extinctions and new adaptations. What can’t be sustained at these temperatures, however, is the civilisation we have built.
The life on the planet at thay time was simply adapted to the high temperatures.
At first, there was no oxygen in the atmosphere until the first autotrophs evolved (photosynthesizers)
They ate up so much carbon from the atmosphere and produced oxygen. That causes the first ice age (often called snowball Earth) and oxygen was toxic to most life at the time, resulting in the first mass extinction.
Only those who survived the mass extinction would go on to evolve into all life we have seen after that point, on this much cooler Earth. Eventually, it would evolve to use oxygen to its benefit, and the first aerobic life forms were born leading into the Cambrian Period. Oxygen would be so useful that life made huge leaps and bounds during this time. There’s a reason it’s called the Cambrian Explosion.
The first armor (shells) would evolve along side the first weapons (jaws) and it’s not until here thay we have a good fossil record of life
Oxygen levels would remain pretty high until the end of the Mesozoic Era, but most of the carbon in fossil fuels was tucked away during the Carboniferous Period
Volcanoes add extra CO2 over long time periods, carbon being stored in fossil fuels is one way the amount of atmospheric CO2 was moderated.
Also life on the whole will survive extra CO2, but many species would go extinct due to their habitat changing and because all of our important staple crops like temperate climates not tropical ones human society would face big difficulties in a hotter planet.
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