New Insights Into Prehistoric Global Warming

Although an ancient global-warming episode -known as the Paleocene-Eocene Thermal Maximum (PETM)- remains incompletely explained, a geo-biology team at Cal Tech believes it might provide insights into possible global warming in the future. During the PETM, 55-million years ago, the Earth warmed by more than 9 degrees Fahrenheit after huge amounts of carbon entered the atmosphere over a period of just a few thousand years.

The Paleocene–Eocene Thermal Maximum lasted around 20,000 years, and was superimposed on the Eocene -a 6-million-year period of more gradual global warming,

During the Eocene around 1,500 to 2,000 gigatons of carbon were released into the ocean/atmosphere system over the course of 1,000 years. This rate of carbon addition -which peaked during the PETM- almost equals the rate at which carbon is being released into the atmosphere today through human activity.

The team of scientists  from Caltech and McGill University, discovered microscopic, magnetic fossils resembling spears and spindles, unlike anything previously seen, among sediment layers deposited during an ancient global-warming event along the Atlantic coastal plain of the United States.

"Imagine our surprise to discover not only a fossil bloom of bacteria that make iron-oxide magnets within their cells, but also an entirely unknown set of organisms that grew magnetic crystals to giant sizes," said Caltech's Timothy Raub, who collected the samples from an International Ocean Drilling Program drill-core storehouse at Rutgers University in New Jersey. The research team believes these fossils may be telling a story of radical environmental transformation

Perhaps in response to the environmental stress of the PETM, many land mammals in North America became dwarfed. Almost half of the common sea bottom-dwelling microorganisms known as foraminifera became extinct in newly warmer waters that were incapable of carrying the levels of dissolved oxygen for which they were adapted.

A typical "giant" spearhead-shaped crystal is only about four microns long, which means that hundreds would fit on the period at the end of this sentence. However, the crystals found recently are eight times larger than the previous world record for the largest bacterial iron-oxide crystal.

According to Dirk Schumann, a geologist and electron microscopist at McGill University and lead author of the study, "It was easy to focus on the thousands of other bacterial fossils, but these single, unusual crystals kept appearing in the background. It soon became evident that they were everywhere."

In addition to their unusually large sizes, the magnetic crystals occur in a surprising array of shapes. For example, the spearhead-like crystals have a six-sided "stalk" at one end, a bulbous middle, and a sharp, tapered tip at the other end. Once reaching a certain size, spearhead crystals grow longer but not wider, a directed growth pattern that is characteristic of most higher biological organisms.

The spearhead magnetic crystals compose a minor fraction of all of the iron-oxide crystals in the PETM clay layer. Most of the crystals have smaller sizes and special shapes, which indicate that they are fossils of magnetotactic bacteria. This group of microorganisms, long studied at Caltech by study coauthor Joseph Kirschvink, the Nico and Marilyn Van Wingen Professor of Geobiology, use magnets to orient themselves within Earth's magnetic field, and proliferate in oxygen-poor water.

Spearheads are not, however, the rarest fossil type in the deposit. That honor belongs to a spherical cluster of spearheads informally dubbed the "Magnetic Death Star" by the researchers. The Magnetic Death Star may have preserved the crystals as they occurred in their original biological structure.

The researchers could not find a similar-shaped organism anywhere in the paleontological annals. They hypothesize that it may have been a single-celled eukaryote that evolved for the first time during the PETM and was outcompeted once the strange climate conditions of that time diminished. Alternatively, it may still exist today in a currently undiscovered location.

"The continental shelf of the mid-Atlantic states during the PETM must have been very iron-rich, much like the Amazon shelf today," notes study coauthor Robert Kopp of Princeton University, who first started working on the project while a graduate student at Caltech. "These fossils may be telling a story of radical environmental transformation: imagine a river like the Amazon flowing at least occasionally where the Potomac is today."

The Caltech work was supported by the NASA Exobiology program.

Posted by Casey Kazan from materials provided by California Institute of Technology.

Source: : http://mr.caltech.edu/press_releases/13195

The Paleocene–Eocene Thermal Maximum lasted around 20,000 years, and was superimposed on the Eocene -a 6-million-year period of more gradual global warming,

During the Eocene around 1,500 to 2,000 gigatons of carbon were released into the ocean/atmosphere system over the course of 1,000 years. This rate of carbon addition -which peaked during the PETM- almost equals the rate at which carbon is being released into the atmosphere today through human activity.

The team of scientists  from Caltech and McGill University, discovered microscopic, magnetic fossils resembling spears and spindles, unlike anything previously seen, among sediment layers deposited during an ancient global-warming event along the Atlantic coastal plain of the United States.

"Imagine our surprise to discover not only a fossil bloom of bacteria that make iron-oxide magnets within their cells, but also an entirely unknown set of organisms that grew magnetic crystals to giant sizes," said Caltech's Timothy Raub, who collected the samples from an International Ocean Drilling Program drill-core storehouse at Rutgers University in New Jersey. The research team believes these fossils may be telling a story of radical environmental transformation

Perhaps in response to the environmental stress of the PETM, many land mammals in North America became dwarfed. Almost half of the common sea bottom-dwelling microorganisms known as foraminifera became extinct in newly warmer waters that were incapable of carrying the levels of dissolved oxygen for which they were adapted.

A typical "giant" spearhead-shaped crystal is only about four microns long, which means that hundreds would fit on the period at the end of this sentence. However, the crystals found recently are eight times larger than the previous world record for the largest bacterial iron-oxide crystal.

According to Dirk Schumann, a geologist and electron microscopist at McGill University and lead author of the study, "It was easy to focus on the thousands of other bacterial fossils, but these single, unusual crystals kept appearing in the background. It soon became evident that they were everywhere."

In addition to their unusually large sizes, the magnetic crystals occur in a surprising array of shapes. For example, the spearhead-like crystals have a six-sided "stalk" at one end, a bulbous middle, and a sharp, tapered tip at the other end. Once reaching a certain size, spearhead crystals grow longer but not wider, a directed growth pattern that is characteristic of most higher biological organisms.

The spearhead magnetic crystals compose a minor fraction of all of the iron-oxide crystals in the PETM clay layer. Most of the crystals have smaller sizes and special shapes, which indicate that they are fossils of magnetotactic bacteria. This group of microorganisms, long studied at Caltech by study coauthor Joseph Kirschvink, the Nico and Marilyn Van Wingen Professor of Geobiology, use magnets to orient themselves within Earth's magnetic field, and proliferate in oxygen-poor water.

Spearheads are not, however, the rarest fossil type in the deposit. That honor belongs to a spherical cluster of spearheads informally dubbed the "Magnetic Death Star" by the researchers. The Magnetic Death Star may have preserved the crystals as they occurred in their original biological structure.

The researchers could not find a similar-shaped organism anywhere in the paleontological annals. They hypothesize that it may have been a single-celled eukaryote that evolved for the first time during the PETM and was outcompeted once the strange climate conditions of that time diminished. Alternatively, it may still exist today in a currently undiscovered location.

"The continental shelf of the mid-Atlantic states during the PETM must have been very iron-rich, much like the Amazon shelf today," notes study coauthor Robert Kopp of Princeton University, who first started working on the project while a graduate student at Caltech. "These fossils may be telling a story of radical environmental transformation: imagine a river like the Amazon flowing at least occasionally where the Potomac is today."

The Caltech work was supported by the NASA Exobiology program.

Posted by Casey Kazan from materials provided by California Institute of Technology.

Source: : http://mr.caltech.edu/press_releases/13195

Comments

[Mark]

Very clever find. Using my scant knowledge of geology, can we assume that the erosion of the Appalachian Mtns and/or the piedmont region caused the influx of iron oxide into the Middle Atlantic states ocean region? That part of the US has soils that are permanently stained red. I was under the impression that this indicates the presence of large amounts of iron oxide. It seems to me that this was the raw material for the evolution of this microorganism.

[LEAH]

In view of the extensive research into past warming periods e.g. PETM, and having clear proof that Earth has been through several warming and cooling cycles, e.g. 12,000 year warm, and 90,000 year cooling period (which fits the Milankovitch cycle), isn't it time that mankind admit to itself that we are not the cause. We have added an unknown number of degrees to the maximum temperature that would have been otherwise reached at the conclusion of this particular warm period, by the burning of fossil fuels and de-forrestation, to mention but 2 of man's activities. Earth is at the conclusion of the present 12,000 year warm period (since the end of the the last cool period), with scientists quoting that we have pushed the onset of appreciable cooling, 800 years into the future, giving mankind time to prepare, change lifestyle or relocate, in order to accomodate and survive what is an unavoidable long period of colder conditions.
The polution we cause should and must stop, but we may have inadvertantly also bought time to further research and understand the life cycles of our home, Earth.
Wellbeing for all life, always,
Leah

[Mark]

In a closed system, there is no possible way to burn the amount of carbon products we daily burn and not change the chemical composition of the Earth's atmosphere.

The simple fact that WE are the burners and that DAILY we burn nearly 24 million (with an M) barrels of oil is enough to cause catastrophic changes to our global atmospheric system. No amount of denying it is going to change that fact.

The migration that Leah talks about (casually, I will add) will be into mass graves. I suspect those graves won't be dug either. By the time the mass die-offs occur we will have gone past Peak Oil.

BTW, 'scientists' have quoted no such thing. No reputable ones, that is.

[anon]

Life gets bigger in warm periods, because photosynthesis, at least in the olde school version, works by a combination of sunlight and carbon dioxide. More of both equals more plants equals larger herbivores equals larger carnivores. Like dinasaurs and megalodons and all those other unsustainable species.