Featured Research

from universities, journals, and other organizations

Strong regional climatic fluctuations in the tropics

Date:
December 3, 2009
Source:
Helmholtz Association of German Research Centres
Summary:
Climatic fluctuations close to the equator show a different pattern to climate change in the Arctic and Antarctic. In the tropics, distinct 11,500-year fluctuations between wet and dry periods can be clearly identified which do not occur in temperature reconstructions of polar ice cores.

Climatic fluctuations close to the equator show a different pattern to climate change in the Arctic and Antarctic. In the tropics distinct 11500 year fluctuations between wet and dry periods can be clearly identified which do not occur in temperature reconstructions of polar ice cores. The investigations of the climate of the last 25000 years in tropical Africa show that dry phases prevailed during lower solar radiation in March and September, which caused the following rain period to be less intensive.

Related Articles


This emphasizes the significance of hydrological variations in regional climate change, as was formulated by a European consortium of earth scientists under the direction of Professor Dirk Verschuren (University of Gent, Belgium) in the latest issue of the journal Nature (Vol. 462, 7273).

Seasonally recurring rain periods are the decisive feature of the tropical climate, and are of existential importance for the life of the people there. In order to determine the reasons for the fluctuations in the intensities of the rain periods, the European research team examined the climate of equatorial East Africa on long-time scales. "To date there has been hardly any data on climate change in the tropics. Variations in the temperature do not a play a major role in comparison to hydrological changes," explains Achim Brauer from the GFZ German Research Centre for Geosciences: His working group, together with his European colleagues, analyses the deposits in the Challa-Lake, a crater lake at the eastern foot of the Kilimandscharo.

The GFZ scientists retrieved, for the first time in this region, annually laminated sediment cores from the lake bottom, down to depths of 21 meters. "With this, the sediment core covers the last 25000 years" explains Achim Brauer. "Detailed microscopic and geochemical investigations of the individual sediment layers deliver climatic information on a very exact time scale." This world-wide first long profile of such lake deposits in the tropics is further supplemented with modern high-resolution geophysical data.

The results show that the changes from wet to dry phases vary on the same temporal sample as fluctuations in the solar radiation, which are caused by cyclic changes in the Earth's orbit around the sun. In particular the rotating of the Earth's axis at a rhythm of 23000 years becomes obvious, which consequently leads to an alternating maximum solar radiation every 11500 years in the southern tropics and in northern tropics. These radiation maxima in turn steer the position and the intensity of the inner-tropical convergence zone(ITCZ), the rain-rich cloud belt close to the equator. The ITCZ is strongest there, where the radiation is intense and evaporation is high.

It can, thus, be proven that Earth's orbit around the sun and associated regional fluctuations of solar radiation, even if these are relatively weak, have a large influence on the climate at the equator. The question as to whether these tropical climatic fluctuations have influenced the global climatic history still remains open.

This research work was supported within the framework of the ESF-EuroCORES Programme "EuroCLIMATE," with national funding through the DFG, FWO Flandern, NWO and NERI.


Story Source:

The above story is based on materials provided by Helmholtz Association of German Research Centres. Note: Materials may be edited for content and length.


Cite This Page:

Helmholtz Association of German Research Centres. "Strong regional climatic fluctuations in the tropics." ScienceDaily. ScienceDaily, 3 December 2009. <www.sciencedaily.com/releases/2009/12/091202153808.htm>.
Helmholtz Association of German Research Centres. (2009, December 3). Strong regional climatic fluctuations in the tropics. ScienceDaily. Retrieved October 24, 2014 from www.sciencedaily.com/releases/2009/12/091202153808.htm
Helmholtz Association of German Research Centres. "Strong regional climatic fluctuations in the tropics." ScienceDaily. www.sciencedaily.com/releases/2009/12/091202153808.htm (accessed October 24, 2014).

Share This



More Earth & Climate News

Friday, October 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Raw: Tornado Rips Roofs in Washington State

Raw: Tornado Rips Roofs in Washington State

AP (Oct. 24, 2014) A rare tornado ripped roofs off buildings, uprooted trees and shattered windows Thursday afternoon in the southwest Washington city of Longview, but there were no reports of injuries. (Oct. 24) Video provided by AP
Powered by NewsLook.com
Dances With Wolves in China's Wild West

Dances With Wolves in China's Wild West

AFP (Oct. 23, 2014) One man is on a mission to boost the population of wolves in China's violence-wracked far west. The animal - symbol of the Uighur minority there - is under threat with a massive human resettlement program in the region. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
E.U. Leaders Agree To 40% CO2 Emissions Cut By 2030

E.U. Leaders Agree To 40% CO2 Emissions Cut By 2030

Newsy (Oct. 23, 2014) The latest E.U. emissions deal calls for a 40 percent greenhouse gas cut, which leaders say sets Europe up to lead in climate negotiations next year. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins