How Did The Petm Stimulate Biological Change For Terrestrial Plants And Animals?

Global Warming and Paleoclimate

Earth in the Eocene.

It has been said that the by informs the present, so as World's present climate changes at a seemingly unprecedented rate, the paleoclimate record becomes an important analog for examining the potential impacts of present global warming on life on Earth.

As humankind continues to add CO₂ and other greenhouse gases to the temper, we are contributing to the possibility of tipping the climate to one that is dramatically different from anything our species has ever experienced. Many ask: What changes volition this new climate state trigger, and how volition the Earth systems respond?

According to the records in the bounding main sediment cores, our best example of a relatively precipitous increment in global CO₂ concentrations (and subsequent temperature increase) occurred 56 millions years ago, during the Paleocene-Eocene Thermal Maximum (PETM). The relatively rapid—x,000 year—increase in World's temperature significantly altered life on Earth, and in the sea. The new climate land lasted roughly 150,000 years. This time period, known as the Eocene Optimum, lasted from 52 million years ago to 50 1000000 years ago.

Abrupt Changes for Life on Earth

Temperature reconstruction of the past 65 one thousand thousand years.

Even so, for many of World's species, the Eocene Optimum was anything but optimal! During this period of time, both the land and deep ocean temperatures rose between half-dozen and ix degrees Celsius. The PETM warming was triggered past a rapid release of greenhouse gases into the atmosphere, most likely from biological sources. The CO_ii concentration at this fourth dimension is estimated to have been as high equally 2000 parts per million. Some scientists hypothesize that CH₄ (methane) may take come from methane hydrates and been speedily converted to CO₂ in the bounding main and atmosphere.

The impacts of the PETM were not express to changes in Earth'southward atmosphere and surface temperature. Considering Earth's systems are coupled, the sea acts every bit a buffer to the atmosphere, absorbing CO_two that is released from natural and anthropogenic (man-fabricated) sources. CO₂ increases in the atmosphere crusade acidification, or a decrease in the pH, of the sea. During the PETM the ocean "soured." As this acidification occurred, ocean animals with calcified shells were more often than not unable to adapt to the rapid change. As a result, xxx-50% of the benthic foraminifera became extinct. Not simply did living animals disappear in the acidic bounding main, calcareous microfossils were also dissolved. Previously difficult, carbonate-rich sediments were transformed into dirt ooze.

Some Species Flourish in the New Climate

Nano Fossil: Morozovella velascoensis

Not all of the impacts of this upshot were catastrophic; some animals and plants flourished in the new environment. In the sea, planktonic foraminifera diversified and dinoflagellates bloomed. Many terrestrial organisms migrated to higher latitudes (moved N or South), while others responded to the warmer, wetter climate by adapting and evolving. In fact, fossil records show that this catamenia produced the showtime ancestors of the hoofed mammals, relatives of the modern twenty-four hour period horse. Fortunately, because this event took identify during an ice-free period, body of water level rise was minimal. The changing sea levels were limited to the impacts of the sea h2o'due south thermal expansion.

Still "optimum" the Early Eocene was for life in general, it was beyond the ideal thermal range for humankind. If nosotros compare the PETM to the projected warming for 2100 of five to 6 degrees Celsius, we come across changes that are comparable to the dramatic temperature change that concluded the last Water ice Age. Given our current climate weather, besides every bit the human population density and distribution, a change of this magnitude would exist catastrophic to the human species and would, one time once again, rearrange the landscape and living species on Earth.

This chapter focuses on the Paleocene-Eocene Thermal Maximum (PETM), which occurred approximately 56 1000000 years ago (MA). In this affiliate, yous volition be examining ocean core records for changes in planktonic foraminifera. These planktonic species continuously fall to the ocean flooring, and are preserved equally fossils in the accumulating sediment. Naturally, the more fossils preserved in the record, the better the resolution of information. College resolution data makes it easier to identify rapid species changes associated with irresolute bounding main temperature.

The Integrated Ocean Drilling Project (IODP) has thousands of marine sediment core data, which can be accessed using Virtual Ocean. Users of this chapter volition use graphing tools inside Virtual Sea to create an age-depth plot (ADP). They then will create species diversity curves to search for abrupt changes associated with Paleocene-Eocene Thermal Maximum (PETM).

Source: https://serc.carleton.edu/eet/deep_sea_sediments/case_study.html

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