Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Disappearance of Coral Reefs, Drastically Altered Marine Food Web on the Horizon

06.08.2013
If current climate trends follow historical precedent, ocean ecosystems will be in state of flux for next 10,000 years, according to Scripps Oceanography researchers

If history’s closest analog is any indication, the look of the oceans will change drastically in the future as the coming greenhouse world alters marine food webs and gives certain species advantages over others.


Coral Gardens: A school of surgeonfish cruise coral reefs near Palmyra Atoll.

Scripps Institution of Oceanography, UC San Diego, paleobiologist Richard Norris and colleagues show that the ancient greenhouse world had few large reefs, a poorly oxygenated ocean, tropical surface waters like a hot tub, and food webs that did not sustain the abundance of large sharks, whales, seabirds, and seals of the modern ocean. Aspects of this greenhouse ocean could reappear in the future if greenhouse gases continue to rise at current accelerating rates.

The researchers base their projections on what is known about the “greenhouse world” of 50 million years ago when levels of greenhouse gases in the atmosphere were much higher than those that have been present during human history. Their review article appears in an Aug. 2 special edition of the journal Science titled “Natural Systems in Changing Climates.”

For the past million years, atmospheric CO2 concentrations have never exceeded 280 parts per million, but industrialization, forest clearing, agriculture, and other human activities have rapidly increased concentrations of CO2 and other gases known to create a “greenhouse” effect that traps heat in the atmosphere. For several days in May 2013, CO2 levels exceeded 400 parts per million for the first time in human history and that milestone could be left well behind in the next decades. At its current pace, Earth could recreate the CO2 content of the atmosphere in the greenhouse world in just 80 years.

In the greenhouse world, fossils indicate that CO2 concentrations reached 800-1,000 parts per million. Tropical ocean temperatures reached 35º C (95º F), and the polar oceans reached 12°C (53°F)—similar to current ocean temperatures offshore San Francisco. There were no polar ice sheets. Scientists have identified a “reef gap” between 42 and 57 million years ago in which complex coral reefs largely disappeared and the seabed was dominated by piles of pebble-like single-celled organisms called foraminifera.

“The ‘rainforests-of-the-sea’ reefs were replaced by the ‘gravel parking lots’ of the greenhouse world,” said Norris.

Changing marine life characteristics: Comparison of present, past, and future ocean ecosystemstates. Click on image for larger view. Image courtesy of Science

The greenhouse world was also marked by differences in the ocean food web with large parts of the tropical and subtropical ocean ecosystems supported by minute picoplankton instead of the larger diatoms typically found in highly productive ecosystems today. Indeed, large marine animals—sharks, tunas, whales, seals, even seabirds—mostly became abundant when algae became large enough to support top predators in the cold oceans of recent geologic times.

“The tiny algae of the greenhouse world were just too small to support big animals,” said Norris. “It’s like trying to keep lions happy on mice instead of antelope; lions can’t get by on only tiny snacks.”

Within the greenhouse world, there were rapid warming events that resemble our projected future. One well-studied event is known as the Paleocene-Eocene Thermal Maximum (PETM) 56 million years ago, which serves as a guide to predicting what may happen under current climate trends.

That event lasted about 200,000 years and warmed the earth by 5-9° C (9-16° F) with massive migrations of animals and plants and shifts in climate zones. Notably, despite the disruption to Earth’s ecosystems, the extinction of species was remarkably light, other than a mass extinction in the rapidly warming deep ocean.

“In many respects the PETM warmed the world more than we project for future climate change, so it should come as some comfort that extinctions were mostly limited to the deep sea,” said Norris. “Unfortunately, the PETM also shows that ecological disruption can last tens of thousands of years.”

Indeed, Norris added that continuing the fossil fuel economy even for decades magnifies the period of climate instability. An abrupt halt to fossil fuel use at current levels would limit the period of future climate instability to less than 1,000 years before climate largely returns to pre-industrial norms. But, if fossil fuel use stays on its current trajectory until the end of this century, then the climate effects begin to resemble those of the PETM, with major ecological changes lasting for 20,000 years or more and a recognizable human “fingerprint” on Earth’s climate lasting for 100,000 years.

Co-authors of the review are Sandra Kirtland-Turner of Scripps Oceanography, Pincelli Hull of Yale University, and Andy Ridgwell of the University of Bristol in the United Kingdom.

Robert Monroe | EurekAlert!
Further information:
http://www.ucsd.edu

More articles from Ecology, The Environment and Conservation:

nachricht Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen

nachricht A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: The pyrenoid is a carbon-fixing liquid droplet

Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.

A warming planet

Im Focus: Highly precise wiring in the Cerebral Cortex

Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.

The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...

Im Focus: Tiny lasers from a gallery of whispers

New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...

Im Focus: Ultrafast snapshots of relaxing electrons in solids

Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!

When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...

Im Focus: Quantum Sensors Decipher Magnetic Ordering in a New Semiconducting Material

For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.

Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

“Lasers in Composites Symposium” in Aachen – from Science to Application

19.09.2017 | Event News

I-ESA 2018 – Call for Papers

12.09.2017 | Event News

EMBO at Basel Life, a new conference on current and emerging life science research

06.09.2017 | Event News

 
Latest News

Rainbow colors reveal cell history: Uncovering β-cell heterogeneity

22.09.2017 | Life Sciences

Penn first in world to treat patient with new radiation technology

22.09.2017 | Medical Engineering

Calculating quietness

22.09.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>