European dust input linked with Saharan desertification and human impact

Northumbria research unlocks secrets of the Sahara
Credit: Northumbria University

A peat bog in Romania provides a new insight into our knowledge of when the Sahara began to transform from grassland into the desert we know today, and the impact this had on dust deposition within Eastern Europe.

Using carbon dating and chemical analysis, researchers from Northumbria University, Newcastle have shown that significant changes in levels occurred in Romania around 6,100 years ago, despite the in Eastern Europe being relatively wet at this time, indicative of an extraregional source of such dust, most likely to be from the Sahara.

This discovery is valuable new evidence of the impact changes in the climate and vegetation of North Africa may have on dust in Europe and may allow climate modellers to better understand the movement of dust and the impact of desertification, both in the past and the future.

The research was led by Jack Longman, a Geography PhD student at Northumbria. His resulting paper, Periodic input of dust over the Eastern Carpathians during the Holocene linked with Saharan desertification and human impact, has now been published in the journal Climate of the Past and is one of just 29 'highlight' papers selected by the journal as being of particular scientific interest.

Jack said: "We know that as recently as 6,000 years ago, what is now the vast, dusty and uninhabited Saharan desert was covered in lush grassland. However, the end of this period has been subject to much discussion, both with regards to its timing and its impact on the environment.

"To investigate the impact such a large climatic and environmental shift had on Europe, we analysed the elemental makeup of a peat bog in the Eastern Carpathians, Romania. Such bogs form slowly over thousands of years, with each new layer being deposited on top of the previous, trapping the chemical, and organic signature of that precise time period within it.

"Using carbon dating, the age of the bog was determined, allowing us to look back at the conditions which occurred at the time each layer formed. A core of almost 10 metres of peat sediment was recovered, representing nearly 11,000 years of deposition."

Jack and his team analysed peat from different periods in time, looking specifically for higher levels of titanium, potassium and silicon – all chemical elements associated with higher levels of dust within the peat.

In addition, they also counted the numbers of various types of single-celled organisms called testate amoebae, whose population changes depending on the amount of water in the bog, giving an indication of how wet or dry the climate was during different periods.

Combining this information allowed the team to determine when dust from the Sahara began to land in Romania. As Jack explains: "Between 10,800 and 6,100 years ago, the number of testate amoeba present appears to be in sync with the amount of dust recorded, indicating that the dust is likely to be related to local droughts and soil erosion. However, for the past 6,100 years the number of testate amoebae present show the bog was constantly wet, despite numerous large dust deposits during this time.

"We also saw that over the last 6,100 years the dust has contained higher levels of titanium, which suggests a major shift from a local source to one which appears Saharan in origin. The amount of dust recorded in the bog also shifts around this time, with much more deposited in the last 6,100 years than previously."

Between approximately 14,000 B.C. and 4,000 B.C. the climate in the Sahara was warm and humid due to of incoming solar radiation which modified the location of the African monsoon – a period known as the African Humid Period.

Today, the Sahara is the largest hot desert in the world, covering an area of 9.2 million square kilometres. Dust from the area has been deposited as far as the Caribbean and the Amazon basin and can affect air temperatures, cause ocean cooling, and alter rainfall amounts.

Jack added: "Dust is one of the most important aerosols for both the climate and the biology of an environment, and so understanding the amount of dust produced, and the distance and direction it travels is vital to allow us to understand its effect better."


Explore further

Study of Saharan dust offers insights into past and possible impact on future climate change

More information: Jack Longman et al. Periodic input of dust over the Eastern Carpathians during the Holocene linked with Saharan desertification and human impact, Climate of the Past (2017). DOI: 10.5194/cp-13-897-2017
Journal information: Climate of the Past

Citation: European dust input linked with Saharan desertification and human impact (2017, July 19) retrieved 24 May 2019 from https://phys.org/news/2017-07-european-linked-saharan-desertification-human.html
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Jul 19, 2017
"Between approximately 14,000 B.C. and 4,000 B.C. the climate in the Sahara was warm and humid due to higher levels of incoming solar radiation which modified the location of the African monsoon – a period known as the African Humid Period."

How is that possible? 97% of all scientists agree that it has never been warmer than it is today and this is all due to increased Co2 levels. This is an emergency, someone contact the Ministry of Truth immediately.

Jul 19, 2017
Well it used to be warm and humid, now it is hot and dry.

"97% of all scientists agree that it has never been warmer than it is today"

Interesting, do you have a reference?

Jul 19, 2017
"Interesting, do you have a reference?" Yup, just call the IPCC. If they don't answer just call the fraudster in chief, Al Gore.

Jul 19, 2017
BTW the climate models do not include changes in solar radiation in their calculations. It has been agreed that the suns output is a constant. You see I remember all of the early claims unlike the climate community that denies them when convenient.

Jul 19, 2017
How is that possible? 97% of all scientists agree that it has never been warmer than it is today
"Interesting, do you have a reference?"
Yup, just call the IPCC
@mr idiot
no
they say it's the warmest in recorded history
but then again, comprehending the difference between the two statements requires literacy, which you've not been able to provide evidence of
someone contact the Ministry of Truth immediately
thank you for validating the following study: http://journals.p....0075637


Jul 19, 2017
"Between approximately 14,000 B.C. and 4,000 B.C. the climate in the Sahara was warm and humid due to higher levels of incoming solar radiation which modified the location of the African monsoon – a period known as the African Humid Period."

18K years ago NA had glaciers 1 mile thick. 14000 B.C. is only 2K years after that. Thus in 2K years there was a huge climate change yet today's change is "unprecedented" and can only be caused by AGW. What BS.

Jul 19, 2017
@mr idiot
yet today's change is "unprecedented" and can only be caused by AGW
and here we see yet another strawman based upon your faulty interpretation

so you repeat old arguments proven wrong

wow

1- it is definitely unprecedented in recorded history

2- rate of changed (you know, that topic that you completely refused to accept over the past few years while various people explained it using a monosyllabic vocabulary tiny enough so that an 8 year old can comprehend what it means? and i've tried to discuss with you in the past despite your literacy problem and refusal to accept facts?
like here: https://phys.org/...ing.html

yeah... that rate of change)

3- thank you for validating this study: http://journals.p....0075637

and for proving me correct about you not being able to accept proven facts

so the tactic is to just repeat old posts now like above?

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