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WonderPermafrost carbon fact

Yedoma is ancient frozen ground in Siberia, Alaska and Canada's Yukon, packed with ice and with plant and animal remains tens of thousands of years old. When it thaws, microbes can finally break that old carbon down, releasing carbon dioxide and methane.

Yedoma

ClimateNatureScience

The story behind the card

Yedoma formed during the Pleistocene, the ice-age epoch that ended about 11,700 years ago. Fine silt, carried by wind and water, piled up on cold plains that were never covered by glaciers, burying grasses and roots before they could rot, while huge wedges of ice grew in the ground. Ice now makes up 50 to 90 per cent of its volume, and the deposits, often tens of metres thick, cover more than a million square kilometres. Estimates of the carbon they hold range from about 210 to 500 billion tonnes, many times what burning fossil fuels releases each year. Because the ground is so icy, it slumps into pits and ponds, called thermokarst, as it thaws, exposing still more. Some of the carbon escapes as methane, a far more powerful greenhouse gas than carbon dioxide.

Türkçe oku
Yedoma, Sibirya'da, Alaska'da ve Kanada'nın Yukon bölgesinde bulunan çok eski donmuş topraktır; bol buz ve on binlerce yıllık bitki ve hayvan kalıntıları içerir. Çözüldüğünde mikroplar bu eski karbonu sonunda ayrıştırabilir ve havaya karbondioksit ile metan salınır.

Yedoma, yaklaşık 11.700 yıl önce sona eren buzul çağı dönemi Pleistosen'de oluştu. Rüzgârın ve suyun taşıdığı ince silt, hiçbir zaman buzulla kaplanmamış soğuk ovalarda birikti; otları ve kökleri çürümeye fırsat bulamadan gömdü. Bu sırada toprağın içinde dev buz kamaları büyüdü. Bugün yedomanın hacminin yüzde 50 ila 90'ı buzdur. Çoğu yerde onlarca metre kalınlıktaki bu katmanlar bir milyon kilometrekareden geniş bir alana yayılır. İçerdikleri karbonun 210 ila 500 milyar ton arasında olduğu tahmin ediliyor; bu, fosil yakıtların bir yılda saldığı karbonun kat kat fazlasıdır. Toprak bu kadar buzlu olduğu için çözüldükçe çöker, çukurlar ve gölcükler oluşur. Termokarst denen bu çöküntüler, altta kalan katmanları da açığa çıkarır. Karbonun bir kısmı, karbondioksitten çok daha güçlü bir sera gazı olan metan olarak havaya karışır.

Sources and further reading

Background reading: Yedoma
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