Silent Chornobyl: Dry Aral Sea has made Central Asia dustier, with impacts on global climate, says study

Silent Chornobyl: Dry Aral Sea has made Central Asia dustier, with impacts on global climate, says study

Subject: Geography

Section: Mapping

Context:

• The Aral Sea, once the world’s fourth-largest lake, has dramatically shrunk since the 1960s due to Soviet irrigation projects, leading to severe environmental impacts.

Study findings on the Aral Sea:

• A recent study by the Leibniz Institute for Tropospheric Research and Freie Universität Berlin reveals that the desertification of the Aral Sea has increased dust emissions in Central Asia by 7% over the last three decades.
• The findings were released at the Second Central Asian Dust Conference (CADUC-2), held in Nukus, Uzbekistan, on the site of the former Aral Sea.
• From 1985 to 2015, annual dust emissions nearly doubled, rising from 14 million to 27 million tonnes. 
• This increase in dust is not only more hazardous than typical dust but also likely influences global climate, though further research is needed to confirm these effects.
• The study also highlighted that much of this dust activity is missed by traditional satellite observations due to its occurrence under cloudy conditions.
• This rising dust level poses health risks to local populations and contributes to air quality degradation in the capitals of Tajikistan and Turkmenistan.
• Moreover, the dust can accelerate glacier melt, worsening the water crisis in the region.

A Soviet legacy:

• The Aral Sea, once replenished by the Amu Darya and Syr Darya rivers from the mountain ranges of High Asia, suffered a drastic reduction in water input due to extensive irrigation practices for agriculture implemented during the Soviet era.
• This led to the drying up of large areas of the lake, reducing it to a fraction of its original size and transforming the majority of it into what is now known as the Aralkum Desert.
• Covering an area of 60,000 square kilometres, the Aralkum, though smaller than its neighbouring natural deserts, the Karakum and Kyzylkum, has become one of the most significant human-made dust sources in the world.
• The dust from the Aralkum is particularly hazardous as it contains residues of fertilizers and pesticides from its past agricultural use.

Climate impact:

• Researchers from TROPOS and FU Berlin have studied the climatic impacts of dust from the Aralkum Desert using the COSMO-MUSCAT atmospheric dust model. This model helps simulate dust emissions, atmospheric concentrations, and the radiative effects of dust particles.
• They found that dust from the Aralkum affects agricultural areas along the Syr Darya and reaches cities over 800 kilometres away, including Ashgabat and Dushanbe.
• The dust influences the local climate by cooling the surface during the day by dimming sunlight and warming it at night by re-emitting ground heat radiation. This dual effect—cooling or warming—depends on various factors such as dust amount, time of day, season, surface albedo, and dust’s mineralogical and optical properties.
• The recent increase in dust emissions from the Aral Sea/Aralkum region has affected radiative cooling and heating, generally leading to slight overall cooling at about -0.05 ±0.51 watts per square meter annually.
  Moreover, this dust is thought to alter weather patterns by increasing ground-level air pressure, intensifying the Siberian high during winter and weakening the Central Asian warm low during summer.
• The shrinking of other lakes like Urmia in Iran and Hamoun on the Iran-Afghanistan border, also turning into significant dust sources, highlights the broader regional and possibly global implications of such environmental changes.

Aral Sea:

• The Aral Sea was an endorheic lake lying between Kazakhstan to its north and Uzbekistan to its south which began shrinking in the 1960s and largely dried up by the 2010s.
• It was in the Aktobe and Kyzylorda regions of Kazakhstan and the Karakalpakstan autonomous region of Uzbekistan.
• The name roughly translates from Mongolic and Turkic languages to “Sea of Islands”, a reference to the large number of islands (over 1,100) that once dotted its waters.
• The Aral Sea drainage basin encompasses Uzbekistan and parts of Afghanistan, Iran, Kazakhstan, Kyrgyzstan, Tajikistan, and Turkmenistan.

Source: DTE