GLOBAL WARMING
Climatic change and especially “climate warming” is a “hot’ topic nationally and worldwide. Sadly, there is much disinformation of what the term actually means and what level of threat climate change actually poses to human life. Though historic analogies are often misused as well, in these disinformation real scientific based earth history can provide critical information on past events.
PALEOZOIC ERA ENDS WITH MASSIVE EXTINCTIONS OF LIFE —THE GREAT DYING—
Earth history is long on years an almost unimaginable 4.5 billion of them! Life on Earth —divided into the Proterozoic Eon and Phanerozoic Eon (period of visible life) and the latter divided into the Paleozoic (ancient life) , Mesozoic (middle Life) Cenozoic (recent life) Eras.
Life on Earth appears only in profusion very “recently” at least in geological terms. A profusion of fossil evidence occurs abruptly at @ 500 million years ago. That is—visible life—life more complex than bacteria and algae do not arrive on the scene until the last chapter of a nine chapter book. The last one-ninth of history is rich with all kinds of multicellular life of almost all the phyla that exist today.
Then halfway through the ninth chapter—or 250 years later—a climatic disaster nearly wiped out all the evolutionary progress made over the last quarter of a billion years. This catastrophic disaster caused the extinction of 70% of all land species and about 90% of all known marine species. This collapse of life forms on both land and sea marked the dramatic, or catastrophic end of the flourishing life of the Paleozoic Era.
CAUSES?
What caused it? Why did it occur? How does it relate to modern times?
THE PALEOZOIC ERA
The Paleozoic Era began about @550 million years ago (mya) and came to an abrupt end about to 250 million years ago.
When the Paleozoic begins about 550 million years before the present time the earth’s atmosphere had become close to what we breathe today, with oxygen at about 20% and and nitrogen about 70%. Earth’s continents which have a pattern of coalescing into one super continent and then breaking apart about every 500 million years per cycle were at this time clustered together in the southern hemisphere, into a “super continent”. Almost all (North America, Africa, South America, Australia, India, Antarctica) were located in the Southern Hemisphere, below the 30th parallel. Thus, the in the early Paleozoic the climate of most were tropical or semitropical.
There was little glaciation in this period so global sea levels were high, and many shallow seas covered low lying parts of the continental masses. It is in these warm shallow seas that multicellular life flourished in an explosion of marine life forms. By the end of the Paleozoic Era (250 million years ago) almost all the animal phyla were represented. Plants flourished on land and by mid Paleozoic the growth of forests and burial of carbon rich decaying organic matter in swamps took carbon out of circulation and led to even higher levels of oxygen (@35%).
Marine animals such as trilobites, brachiopods, sea scorpions, crinoids (sea lilies), corals all flourished in the shallow well lighted oxygenated seas. Near the latter period of the Era primitive fish such as jawless fish and cartilaginous (sharks) fish all flourished. Due to exposure to solar radiation in shallow water many sea creatures evolved with protective shells or exoskeletons. On land later in the Paleozoic, plants such as ferns had appeared first, and were followed by tree-like vascular plants in the later part of the Era. Tree-like ferns expanded overland to form vast forests which also contributed to higher oxygen levels. CO2 sequestered in the coal seams formed in these times kept the planet relatively cooler.
Animal life on land was concentrated near bodies of water and swamps where large vertebrate tetrapods such as amphibians flourished, while late in the Era drier conditions led to the evolution of reptiles adapted to these new conditions. Arthropods and millipedes developed in these areas as well/ Some claim that higher oxygen concentrations encouraged the evolution of giant arthropods such as giant dragonflies and huge cockroaches which evolved to populate highlands and desert areas.
At 250 million years ago the climate changed abruptly! Large quantities of carbon dioxide a greenhouse gas were released over a period of about 2 million years. This caused massive changes in the post Paleozoic climate—often referred to as the Permian-Triassic Extinction.
Air temperatures rose sharply, sea water became warmer. Some estimates of equatorial sea surface temperatures indicate temperatures as high as 104 0 F (or 40 0 C). Then too, carbon dioxide is soluble in water and when dissolved causes acidification. Acid sea water may have interfered with the ability of marine animals to generate their protective exoskeletons and calcium/magnesium carbonate shells.
What caused this massive climate alteration?
SIBERIA FLOOD BASALTS OR QUIET LAVA FLOWS
Siberia Flood Basalts (a form of quiet non explosive volcanic eruption)
In the 1870s Alexander Czekanowski (1833-1876) a Polish botanist and natural historian discovered a vast area in Siberia covered in volcanic rock. The rock type was basalt—a dark heavy rock with mineral characteristics similar to the material deep below the earth crust.
In the late 19th century Poland was a dependent kingdom within the Empire of Russia. Czekanowski was an outspoken activist for Polish independence and was involved in the 1863 “January Uprising” for Polish independence. For his activism Czekanowski was arrested by Russian officials and exiled in far off, icy cold, Irkutsk, Siberia.
His imprisonment and exile in this isolated region of Siberia about 6,000 Km or 3,600 miles from St Petersburg. The vast distances from civilization ment that there was no need for formal confinement, and Czzekanowski had a modest levell of freedom to travel locally. While confined he continued his studies of geology as best he could, keeping records of natural history and geology observations he made during his travels.
Over decades of Czekanowski’s research resulted in the discovery of an unimagined vast area of of volcanic terrane in north-central Russia. The region had been flooded in the distant past by vast sheets of molten volcanic rock called basalt or “trap rock”. Czekanowski’s studies eventually delineated an area of about 3 million square miles of volcanic terrane or “flood basalts” (or and area of about equal to the size of the lower 48 states in the USA). Czekanowski reported that this area was once covered with hot (@ 10000 C or @ 20000 F) molten lava. By 1873 his trips to the vast unexplored areas of Siberia while in exile in Irkutsk resulted in the publication of regional geologic maps, as well as fossil and mineral collections that were instrumental in bringing to light this the geological significance of this previously unknown immense area of the Earth’s surface.
In the 19th and early 20th centuries Czekanowski’s publications met with interest in the fact of the magnitude of the process of volcanic material flooding from a localized “hot spot” in the earth crust and spreading widely. The formidable area of Siberian flood basalts were previously unknown from other areas in the world. While trap rock floods are known from India and the Columbia River plateau in USA are recorded, but are in no way comparable to those in Siberia.
In the late 20th century French geologist Vincent Courtilliot at the University of Paris (1980s and 90s) suggested that the Siberian floods basalts and Paleozoic end or “great dying” (in geology known as the Permian-Triassic extinctions) released enormous amounts of greenhouse gases which caused catastrophic climate change and widespread species extinctions.
Later studies by Professor Paul Renne a geochronologist Universityof California< Berkeley focused on the age of the trap rocks. Renne visited the site and used Argon (Ar-Ar) dating to refine the ages of the floods. Renne determined that based on hid dating methods the flows were about the same age as the great extinctions. In 1992 Renne concluded there was a “genetic relationship” between the floods and the great extinctions at the end of the Paleozoic Era.
Based on these studies the flood basalts, or fissure eruptions appear to have lasted about 2 million years. Geologists concluded further that the Siberian event may have been the largest volcanic eruption in the last 500 million years. They also concluded that the event was caused by a hot plume of basaltic mantle which melted its way through Siberian craton (the continental core area) and erupted through a fissure vent in the crust which continued active for about two million (2x 10^6) years.
Other studies have indicated that though basaltic lava flows, do not emit great amounts of carbon dioxide gas, they are very hot (1000oC) and active basalt lava flows would burn any organic matter encountered, such as forests, peat deposits, coal beds, and by oxidizing these carbon sources generate great quantities of CO2. Some studies indicate that the lava floods may have produced about 1.34 x 10^5 Giggatons of CO2 gas from the lava itself, as well as about 2.08 x 10^5 Gigatons of CO2 resulting from the lava igniting organic matter it encountered in the vast 3million square miles are it flowed over and oxidized these materials to CO2.
COMPARISONS
The total CO2: burned material (2.08x10^5 Gt) + Gas from lava rock ( 1.34x10^5 Gt)= 342,000 or total CO2 generated + 3.42 x10^5 Gigatons of CO2.
How does this actual exitential threat to ancient life as a result of the natural release of CO2 by fissure eruptions of basaltic lava compare to our present circumstance of anthropogenic release of CO2?
Below is a comparison of the levels of carbon released to the atmosphere in the end Paleozoic eruption of the Serbian traps to the amount of carbon dioxide being released by humans over the last 200 years or since the 18th century.
In comparison to the release of 3.4 x10^5 Gigatons of greenhouse gas as a result of the Siberian lava flows humans in the USA since the 1750s have released about 430 million metric tons of Carbon dioxide. In modern times we anre often warned that these level will cause catastrophic changes to our planet. Will they?
Siberian Traps and burning coal peat forests release: 3.4 x10^5 Gigatons of CO2 Siberian Traps over 2 million years
1 Gigaton = 10^9 tons
3.4x10^5 Gt = ? Tons of carbon gas?= 3.4x 10^14 tons of CO2 released by Flood Basalts
USA from 1750 to present release: 430 million tons of CO2 over two hundred years.
4.3 x 10^8 tons
End Paleozoic release of greenhouse gases vs recent human release of greenhouse gases:
Siberian Traps divided by Recent CO2 Release
(3.4 x10^14)/(4.3x10^8)=790,697.674 or about 800 thousand times (8x10^5 times greater)
7.9 x 10^5 times or about eight hundred thousand (800,000 times) greater!
Thus the Siberian release of greenhouse gases was almost a million times six orders of magnitude greater than recent greenhouse gases released by USA from 1750 to present.
But!
More recent figures of release of green house gases suggest that since the 18th century approximately 2,500 Gt (2.5x10^3) of carbon dioxide have been released into the atmosphere. And most of the accumulation has occurred since the 1990s.
Using those figures:
(3.4 x10^5)/ (2.5 x10^3)=136 times greater or only a bit more than two orders of magnitude greater!
This is a worrying result. Only two orders of magnitude of gas release to the atmosphere separate the worst climate disaster in Earth history and that of modern times.
The devil is in the details. How much carbon has been released? There are several estimates. We do have good estimates of the level of CO2 released by the Siberian flood basalts,
The numbers above suggest we have time, but change in our behavior is needed!
We have dumped a lot of CO2 into the atmosphere for puny humans to be comfortable and fat!
Two million years is a lot of lead time to get the human act on track…..Let’s hope humans are smart enough!
POST SCRIPT
What caused the great flood basalts fissure eruptions in Siberia? Most geologists theorized a hot spot or plume of magma rising up through the earth mantle melted through the crust and exited on the Siberian plain to spread over vast areas for 2 million years.
Others suggest that there may be a cause for this fissure eruption.
In the recent decades a great crator had been indicated under the Antarctic ice at the almost exact opposite point from the fissure eruptions in Siberia (the antipodal point). Some suggest this massive crator bigger than the Chixilub Crator in the Gulf of Mexico struck the Earth at 250 million years ago and the the shock disrupted the crust to cause the fissure!
A catastrophic change in climate caused by massive fissure in earth crust, in turn caused by a huge meteor impact on the opposite side of the Earth? .Fascinating material for further of our oh so alive and active Earth!
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