Navigation Links
Microfossils unravel climate history of tropical Africa

Scientists from the NIOZ Royal Netherlands Institute for Sea Research obtained for the first time a detailed temperature record for tropical central Africa over the past 25,000 years. They did this in cooperation with a German colleague from the University of Bremen, The scientists developed an entirely new method to reconstruct the history of land temperatures based on the molecular fossils of soil bacteria. They applied the method to a marine sediment core taken in the outflow of the Congo River. This core contained eroded land material and microfossils from marine algae. The results show that the land environment of tropical Africa was cooled more than the adjacent Atlantic Ocean during the last ice-age. This large temperature difference between land and ocean surface resulted in drier conditions compared to the current situation, which favours the growth of a lush rainforest. These findings provide further insight in natural variations in climate and the possible consequences of a warming earth on precipitation in central Africa. The results will be published in this week's issue of 'Science'.

One of the techniques currently used to estimate past sea surface temperatures, is based on organic molecules from algae growing in the surface layer of the Ocean. These organisms adapt the molecular composition of their cell membranes to ambient temperature to maintain constant physiological properties. When such molecules sink to the sea floor and are buried in sediments where oxygen does not penetrate, they can be preserved for thousands of years. The ratios between the different molecules from the algal cell membrane can be used to approximate the past temperature of the sea surface. These techniques are therefore called 'proxies'.

New method to measure soil temperatures

Reconstructing continental temperature history is more difficult than for the oceans, because soils on the continent do not form a continuous archive but are often e roded. The researchers developed an entirely new proxy for the annual mean air temperature on land, based on molecules from the cell membrane of soil inhabiting bacteria. They analysed eroded soil material in a sediment core in the outflow area of the river Congo in the South Atlantic Ocean at a depth of almost 1000m. Since the Congo River drains a large part of tropical central Africa, the land derived material gives an integrated signal for a very large area.

Cool tropical Africa

The new proxy was used in this sediment core to obtain both a continental and a sea surface temperature record. A comparison of both records shows that ocean surface and land temperatures behaved differently during the past 25,000 years. During the last ice age, temperatures over tropical Africa were 21°C, about 4°C lower than today, whereas the tropical Atlantic Ocean was only about 2.5°C colder. By comparing this temperature difference with existing records of continental rainfall variability, lead author Johan Weijers and his colleagues concluded that the land-sea temperature difference has by far the largest influence on continental rainfall. This can be explained by the strong relationship of air pressure to temperature. When the temperature of the sea surface is higher than that of the continent, stronger offshore winds reduce the flow of moist sea air onto the African continent. This occurred during the last ice age and, as a consequence, the land climate in tropical Africa was drier than it is in today's world, where it favours the growth of a lush rainforest. These results provide further insight into the natural variation of climate and the possible consequences of a warming earth on precipitation in central Africa.


'"/>

Source:Netherlands Organization for Scientific Research


Related biology news :

1. PET/MRI scans may help unravel mechanisms of prenatal drug damage
2. A puzzle piece found in unraveling the wiring of the brain
3. Scientists journey to southern Africa to unravel the secret world of elephant communication
4. ORNL, UC Berkeley unravel real-world clues to Earths mysteries
5. UT Southwestern researchers unravel control of growing blood vessels
6. University of Arizona plant scientists to unravel maize genome
7. UW scientists unravel critical genetic puzzle for flu virus replication
8. Researchers unravel DNA tangles and enzyme seamstresses
9. UGA scientists unravel molecular inch-worm structure of walking-pneumonia bacterium
10. UCLA researchers unravel a mystery about DNA
11. Computer scientists unravel language of surgery
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:2/8/2017)... Feb. 7, 2017  Aware, Inc. (NASDAQ: AWRE ... reported financial results for its quarter and year ended December ... of 2016 was $3.9 million compared to $6.9 million in ... quarter of 2016 was $0.6 million compared to $2.6 million ... fourth quarter of 2016 was $0.5 million, or $0.02 per ...
(Date:2/7/2017)... , Feb. 7, 2017   MedNet Solutions , ... entire spectrum of clinical research, is pleased to announce ... , its innovative, highly flexible and award winning eClinical ... customers. iMedNet is a proven Software-as-a-Service (SaaS) ... Data Capture (EDC), but also delivers an entire suite ...
(Date:2/3/2017)... , Feb. 3, 2017  Texas Biomedical Research Institute ... Larry Schlesinger as the Institute,s new President ... Biomed effective May 31, 2017. He is currently the Chair ... of the Center for Microbial Interface Biology at Ohio State ... as the new President and CEO of Texas Biomed," said ...
Breaking Biology News(10 mins):
(Date:2/24/2017)... ... February 24, 2017 , ... A study recently ... in an ambulatory surgery center (ASC) with satisfactory clinical and patient-reported outcomes, when ... studies. , Jake Lubinski, president of AxioMed, commented on the recent publication, ...
(Date:2/24/2017)... Feb. 24, 2017  Aethlon Medical, Inc. (Nasdaq: ... by its Chairman and CEO, Jim Joyce . ... Security Conference last Saturday, Bill Gates warned ... more people than nuclear weapons. Mr. Gates expressed his ... intelligence agencies, that scientific terrorists have access to the ...
(Date:2/24/2017)... (PRWEB) , ... February 24, 2017 , ... FireflySci, Inc ... Founded in late 2014, FireflySci had the goal of bringing their powerful cuvette ... continues to shape the path that FireflySci is going on as they add yet ...
(Date:2/23/2017)... NEW YORK , Feb. 23, 2017 /PRNewswire/ ... leading digital health company, and Digital Noema ... and remote patient monitoring, announce they are partnering ... DN Telehealth maximizes collaboration compatibility for ... consultations beyond a physical clinical setting to include ...
Breaking Biology Technology: