Scientists say that greenhouse gas emissions from its thaw could eventually match or even exceed the European Union's industrial emissions due to the sheer volume of decaying organic matter.
A source close to the regional administration said at least two people had died.
A photo essay captures the stories of six Torah scrolls from around the world - Yemen, Siberia, France, Germany - which all ended up in Israel.
Tomsk is symbolic for many Russian Jews for its Cantonist community, which has become an icon of the determination of many Jews in Russia to adhere to their faith and culture.
The menorah was made by Seva Mayorov, a local non-Jewish artist whose work also features regularly at the annual Tomsk Ice Park exhibition.
Navalny, a fierce critic of President Vladimir Putin, had started feeling ill when returning to Moscow from Tomsk in Siberia by plane on Wednesday morning.
Part of its skull, several ribs and foreleg bones, some with soft tissue still attached to them, were retrieved from Russia's remote Yamal peninsula above the Arctic circle on July 23
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The menorah is expected to stand outside the synagogue in Tomsk until it warms up around Pesach.