Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Where climate is made in a greenhouse world

02.06.2006


New scientific results for the Late Cretaceous greenhouse indicate radically different climatic mechanisms operating about 75-90 million years ago compared to the ones that control today’s climate. The study, published on 29 May 2006 in “Palaeogeography, Palaeoclimatology, Palaeoecology” as part of a special issue on “Causes and Consequence of Marine Organic Carbon Burial Through Time” by Sascha Floegel from the IFM-GEOMAR in Kiel/Germany and Thomas Wagner from the University of Newcastle upon Tyne/UK aims to identify the main ‘climate kitchen’ in a world with about 5-9°C warmer global temperatures than today.



The researchers focus their interest on the causal relationships and feedbacks between the tropics and higher latitudes. Using marine geological records and data from global paleoclimate simulations they identify a previously unrecognized link between higher latitude climate dynamics and tropical African climate, the latter leading to exceptionally high burial of organic carbon in the deep tropical Atlantic. Marine geological record show that enhanced burial of organic carbon in the deep sea was confined to short time envelops of about 5 thousand years that reoccurred over millions of years at a regular pattern (see Beckmann and co-workers, published 8 September 2005 in Nature 437).

Climate modelling is one key technique to identify and understand the larger-scale mechanisms that result in geological evidence. By varying one of Earth’s orbital parameters, the precession of the equinoxes, the modelling setup used in this study provides new insights to the dynamics of global climate during past greenhouse conditions. Accordingly, changes in the amount of energy approaching the top of the atmosphere, called “insolation”, finally triggered cyclic variations of the tropical water cycle in tropical Africa. Periods of enhanced precipitation and freshwater runoff then resulted in massive burial of organic carbon at the sea floor suggesting that processes in the atmosphere drive changes in the ocean. The remaining, fundamental question on the source area(s) where cyclic fluctuations in tropical water cycling and marine carbon burial were triggered was addressed using global climate simulation.


Applying four different orbital configurations of one complete precession cycle the model identifies cross-latitudinal variations of atmospheric pressure systems, fluctuations in the magnitude and direction of surface winds, and associated precipitation and runoff patterns. Previously unrecognized, the model identifies the strongest variations in atmospheric pressure above the South Atlantic at mid-southern latitudes between 25–55°S. Establishment of an atmospheric teleconnection between this area and tropical Africa, however, is limited to one specific orbital configuration, which lasted for about 5 thousand years and caused strongest climate contrasts in a seasonal cycle.

These new results challenge current notions on role of the tropics as main driver of Cretaceous climate. They rather support the conclusion that tropical climate in a greenhouse world is ultimately triggered by climate change at mid-southern latitudes, with precipitation and river discharge being the transport mechanisms.

Today the tropics control a big fraction of Earth’s climate. The new findings reported here suggest that the mid-latitudes will have a much stronger impact on low latitude climate system at predicted future levels of atmospheric CO2. This conclusion has severe consequences for the future low latitude water cycle and associated nutrient and carbon fluxes to coastal areas. The latter fluxes from the continent strongly influence surface ocean productivity, O2 consumption in the water column and thus marine ecosystems, and many other processes affecting the global carbon balance. The broader implications support substantial interaction between the water cycle and atmospheric circulation on regional and hemispheric scales during times of global warmth. As evident from this study we probably still do not realise all the relevant processes that drive future global warming. Knowing them, however, is critical to get prepared and mitigate the effects for society and ecosystems.

Professor Thomas Wagner | alfa
Further information:
http://www.ncl.ac.uk

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

nachricht Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.

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: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Machine-learning predicted a superhard and high-energy-density tungsten nitride

18.07.2018 | Materials Sciences

NYSCF researchers develop novel bioengineering technique for personalized bone grafts

18.07.2018 | Life Sciences

Why might reading make myopic?

18.07.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>