I think Russia's icebreaker fleet would struggle to come to Antarctica. The Arktika
class are generally thought of as being impossible to transit the equator due to thermal reasons. Russia and the earlier Soviets, have never sent a nuclear breaker to Antarctica. Also the Russians have not had good experiences with Antarctica, it is a far away place to get stuck.
The nuclear cargo ship Sevmorput, failed in its mission to get to Antarctica during summer, in an attempt to deliver their new base. They will try again this year, perhaps.
The 32-year old nuclear-powered container ship "Sevmorput" has an unexplained breakdown causing restricted maneuverability. The ship has sailed zig-zag outside port in Angola for more than two weeks.
The Akademik Shokalskiy got stuck in ice in 2014, which was then attempted to be rescued by the Chinese ship Xuě Lóng,
which then itself became stuck and the passengers were rescued by the Australian ship Aurora Australis.
So Russian capabilities have been pretty spectacular failures. Unlike the Artic they are very, very far from friendly help.
The Chinese are more of a concern, having set up a rash of new bases. They have also been investing heavily in Antartic Krill ships. They now have oversized krill ships, that are not designed to sustainably fish Krill. While sigining up to deals with the EU, it is expected the Chinese will openly break those deals.
An eye-catching new fishing vessel is generating fanfare in China.
China has declared plans for an unprecedented expansion of fishing for Antarctic krill, the crustacean at the heart of the polar food web.
China presents a number of headaches.
Despite China’s increasing assertiveness in Antarctica, the Antarctic Treaty System is not failing and Australia should refrain from geostrategic panic
Climate change in Antarctica isn't a problem for just nearby and claimants. It will be a global problem. Its already happening, and has been happening for quite a while. I don't see it being a great place to source fresh water from. However, the global impact of the melting will be very significant.
IMO some of the biggest issues will be fishing. We are already seeing fish stocks collapse in many parts of the world, and the Chinese fishing fleet now operate globally, and threaten fishstocks in every ocean. Beyond that, as stocks collapse it puts pressure immediately on other fish stocks else where to make up shortfalls. Taking huge amounts of krill out of the food chain is likely to have significant upfood chain impacts.
China in particular refers to Antarctica as a "global resource", and one they intend to utilize for the benefit of China. There is no interest in ecological management or anything like that. They don't want to make a claim to Antarctica, and reserve a special piece, they see the entire continent as a resource for the taking, and first come first served.
Reviewing China’s activities and commitments under the 60-year-old Antarctic Treaty.