100 Million years ago

The sky is alive with flight

 

 

 

 

About 15-35 million years ago a long period of climate stability sees carbon dioxide levels at or higher than the present.  Temperatures hover at about 5 degrees above current levels and seas rise to 50 meters. An evolutionary explosion fills the sky with flying creatures that feed on flowering plants in a new ecosystem based on animal pollination.  (more)

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Approximate location of current oil fields relative to their continental plates. 

100 M years ago map full screen.jpg
 
(adapted from Ron Blakey, DeepTimeMaps.com and Peace Research Institute Oslo, Petroleum Dataset, (prio.org)

Measures 

 
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Population

7.8 billion in 2021

CO2 concentration

415 parts per million in 2021

Average Temperature

15° C in 2021

Sea Level 

in hundreds of meters from datum in 1900

Asteroid strike; K-T Extinction of 3/4 of species

Increase in Antarctic ice

Temp. High 27-30°C

Sea level high 120-140 meters

Ice

Millions of years

Hundreds of millions of years

Over 100 million years large cycles of warming and cooling supercharged by volcanic activity add massive amounts of carbon dioxide to the atmosphere, driving temperatures extremely high.  Seas rise to a peak of 100± meters higher than the present, with temperate conditions at the poles. The coevolution of plants and animals accelerates the diversification of life on the planet.  Plants develop flowers to attract and reward specific animals, particularly those with wings, who deliver their pollen to the right mate.  Animals respond by evolving a body form and habit that fit the flower and do the job in exchange for nourishing nectar.  Plants blossom into a sky of flying Cupids.  About 80 million years ago, some plants find an advantage in making larger seeds, wrapped in tasty fruits, which animals eat and plant in their dung in new locations.  A new food source that is richer than leaves or grasses feeds a new evolutionary spiral. 

 

This generative pulse of life is hardly dampened when an asteroid hits the Earth 66 million years ago, wiping out 75 percent of species.  Non-avian dinosaurs are lost but the avian group, birds, particularly aquatic birds, survive to diversify into about 10,000 species worldwide. Mammals emerge out of nocturnal habits into the light of day to find open ecological niches, sparking rapid evolution in sync with the recovery of plants.

9 million years later, global temperatures rise about 6-8°C driven by increased release of carbon dioxide over 20,000 years. This rate is about 1/10th that of current carbon release and recent temperature rise.  Warming and acidification of the oceans cause extinctions in deep water, but land animals and plants simply move north and evolve as necessary. Grazing mammals with hooves (both one-toed and two-toed) and primates appear across Europe, Asia, and North America, following vegetation over the land bridge. They survived because the pace of change allowed their habitat to move with them.

 

At the scale of hundreds of millions of years, the movement of tectonic plates comes into view.  Pangea is only the most recent of supercontinents. It formed from the pieces of Laurasia and Gondwana about 336 million years ago. Gondwana, in turn, assembled about 600 million years ago from pieces of Rodinia.  At this time scale, oceans open and close, while the landmass of continents float high on Earth’s underlying mantle and remain dry. Sea levels can be extremely high, not from ice-melt, but water displaced on to land when mid-ocean ridges rise.

 

Through these long years, the Earth slowly absorbs carbon dioxide out of the atmosphere, building deep organic deposits on land.  Under the seas even older deposits are pressed by the weight of the water into coal and oil.

 

References

Text: Ollerton, J. and E. Coulthard (2009). "Evolution of Animal Pollination." Science 326: 808-809.

Image: Composite of Adobe Stock images, pterosaur images from American Museum of Natural History.

Map: Blakey, R. "Global Paleogeography and Tectonics in Deep Time Series." 2019 https://deeptimemaps.com

WorldMap. (2015). "Oil & Gas Map."   Retrieved 22 September 2018, 2018, from http://worldmap.harvard.edu/maps/6718.

Scotese. (2001). "3D Cretaceus World (100 mya Albian)."   Retrieved 20 September 2018, 2018, from http://www.scotese.com/pg100anim1.htm.

Prio. (2007). "Petroleum Dataset v. 1.2."   Retrieved 22 Sept 2018, 2018, from https://www.prio.org/Data/Geographical-and-Resource-Datasets/Petroleum-Dataset/Petroleum-Dataset-v-12/.

CO2: Tierney, Jessica et. al "Past climates inform our future" Science 370 (680) https://doi.org/10.1126/science.aay3701

Foster, G.L; Royer, D.L.; Lunt, D.J, "Future climate forcing potentially without precedent in the last 420 million years" Nature Communications 8 (1) 14845 https://doi.org/10.1038/ncomms14845

Temperature: Tierney, Jessica et. al "Past climates inform our future" Science 370 (680) https://doi.org/10.1126/science.aay3701

Sea Level: James Hansen, M. S., Gary Russell, Pushker Kharecha (2013). "Climate sensitivity, sea level and atmospheric carbon dioxide." Philosophical Transactions of the Royal Society A: Mathematical, Physical, and Engineering Sciences 371(20120294). https://doi.org/10.1098/rsta.2012.0294

Sea Level: Miller, K. G., M. A. Kominz, J. V. Browning, J. D. Wright, G. S. Mountain, M. E. Katz, P. J. Sugarman, B. S. Cramer, N. Christie-Blick and S. F. Peka (2005). "The Phanerozoic Record of Global Sea-Level Change." Science 310(5752): 1293-1298.https://doi.org/10.1126/science.1116412