2013年6月17日星期一

Global cooling as significant as global warming, study of marine ecosystems during Cretaceous period shows

Global cooling as significant as global warming, study of marine ecosystems during Cretaceous period shows

The international study involving experts from the universities of Newcastle, UK, Cologne, Frankfurt and GEOMAR-Kiel, confirms the link between global cooling and a crash in the marine ecosystem during the mid-Cretaceous greenhouse period.

It also quantifies for the first time the amplitude and duration of the temperature change. Analysing the geochemistry and micropaleontology of a marine sediment core taken from the North Atlantic Ocean, the team show that a global temperature drop of up to 5oC resulted in a major shift in the global carbon cycle over a period of 2.5 million years.

Occurring during a time of high tectonic activity that drove the breaking up of the super-continent Pangaea, the research explains how the opening and widening of new ocean basins around Africa, South America and Europe created additional space where large amounts of atmospheric CO2 was fixed by photosynthetic organisms like marine algae. The dead organisms were then buried in the sediments on the sea bed, producing organic, carbon rich shale in these new basins, locking away the carbon that was previously in the atmosphere.

The result of this massive carbon fixing mechanism was a drop in the levels of atmospheric CO2, reducing the greenhouse effect and lowering global temperature.

This period of global cooling came to an end after about 2 million years following the onset of a period of intense local volcanic activity in the Indian Ocean. Producing huge volumes of volcanic gas, carbon that had been removed from the atmosphere when it was locked away in the shale was replaced with CO2 from Earth's interior, re-instating a greenhouse effect which led to warmer climate and an end to the "cold snap."

The research team highlight in this study how global climate is intrinsically linked to processes taking place in Earth's interior at million year time scales. These processes can modify ecospace for marine life, driving evolution.

Current research efforts tend to concentrate on global warming and the impact that a rise of a few degrees might have on past and present day ecosystems. This study shows that if global temperatures swing the other way by a similar amount, the result can be just as severe, at least for marine life.

However, the research team emphasise that the observed changes of the Earth system in the Cretaceous happened over millions of years, rather than decades or centennial, which cannot easily be related to our rapidly changing modern climate conditions.

"As always it's a question of fine balance and scale," explains Thomas Wagner, Professor of Earth Systems Science at Newcastle University, and one of the leaders of this study.

"All earth system processes are operating all the time and at different temporal and spatial scales; but when something upsets the balance -- be it a large scale but long term natural phenomenon or a short and massive change to global greenhouse gases due to anthropogenic activity -- there are multiple, potential knock-on effects on the whole system.

"The trick is to identify and quantify the initial drivers and consequences, which remains an ongoing challenge in climate research."


Welcome to SUV System Ltd!

SUV System Ltd is ISO 90012008 Certified electronics distributor with 10 years of experiences.

We have built up long term business relationship with about many companies which are stockers and authorized agents. we have a steady and reliable supply to meet customer's demands to the greatest extent .Confidently, we are able to lower your cost and support your business with our years of professional service.

SUV System Ltd is Electronic Components Distributor Supplies,Find Quality Electronic Components Supplies Products IC(Integrated Circuits),Connectors,Capacitor,Resistors,Diodes,Transistors,LED at Suvsystem.com. Sourcing Other Energy, Environment, Excess Inventory Products from Manufacturers and Suppliers at Suvsystem.com

Electronic Components distributor:http://www.suvsystem.com

Connectors Distributor:http://www.suvsystem.com/l/Connectors-1.html

IC Distributor:http://www.suvsystem.com/l/IC(Integrated-Circuits)-1.html

LED Distributor:http://www.suvsystem.com/l/LED-1.html

Capacitor Distributor:http://www.suvsystem.com/l/Capacitor-1.html

Transistor Distributor:http://www.suvsystem.com/l/Transistors-1.html

Resistor Distributor:http://www.suvsystem.com/l/Resistors-1.html

Diode Distributor:http://www.suvsystem.com/l/Diodes-1.html

SUV System Ltd insists on the managing faith ofsincereness,speciality,foresight, win-win,so we build up stable-relationship customers located all over the world, including the States, Europe, Argentina, UAE, Malaysia, Australia,and India etc

we are focus on the following fields,and hope we can help you.


C1206C185K3PAL C1206C185K3PACTU C1206C185J8RAC7800 C1206C185J8RAC C1206C184M5UACTU C1206C184M5UAC7800 C1206C184M5UAC C1206C184M5RACTU C1206C184M5RAC7800 C1206C184M5RAC C1206C184M4RACTU C1206C184K5RALTU C1206C184K5RAL7800 C1206C184K5RAL7025 C1206C184K5RAL C1206C184K5RACTU C1206C184K5RACTM C1206C184K5RAC C1206C184K4RAC7800 C1206C184K4RAC C1206C200JBRACTU C1206C200JBRAC C1206C200JBGACTU C1206C200J5GACTU C1206C200J5GACTM C1206C200J5GAC C1206C200J3GAC C1206C200J2GACTU C1206C200J2GAC C1206C200J1GACTU C1206C200J1GAC7800 C1206C200GCGAC C1206C200GBGACTU C1206C200G5GALTU C1206C200G5GACTU C1206C200G5GACTM C1206C200G5GAC C1206C200G2GACTU C1206C200G2GAC C1206C200G1GACTU
http://www.suvsystem.com/a/2862.aspx