This means the world's two largest economies, and two largest emitters, are no longer holding climate talks between them and the fourth largest emitter, Russia, is a diplomatic pariah.
Speaking to the Herald ahead of his trip, Shaw said the breakdown in the US-China relationship would make things difficult.
"Obviously when China and the US get together that's the signal the rest of the world really needs to crack on with things," Shaw said.
"The situation is pretty toxic - they are definitely drifting apart," he said.
Shaw said that last year's COP, held in Glasgow, Scotland, showed what could happen when the US and China co-operated.
"The US and China came out with their Glasgow agreement they had clearly been working on that for months and so they took the opportunity to make a big splash in the early days of Glasgow," Shaw said.
This made it easy for other countries to work towards agreement.
As a small country, New Zealand is affected by the breakdown in that relationship but can do very little to stop it.
Shaw said that what tends to happen at COPs is that negotiations take place topic-by-topic in different rooms throughout the conference centre. The "views" of China and the US and their "proxies" will be shared and New Zealand will work to "bridge" the two views.
"We'll have a team that is working on loss and damage for example. China will have a view that they'll put into the room and the US will have a view that they'll put into the room and all of the proxies for China and the US will also adopt positions
"What we try and do is to bridge build. We don't try and do shuttle diplomacy between China and the US. While we hold our own positions on things - we seek progress. We try to be helpful by being constructive and trying to seek language that works for everyone rather than adopt a hard position," Shaw said.
Aside from the bleak outlook, this year's COP is about details and implementation. This is not a big landmark conference like Paris in 2015, which produced the eponymous climate agreement, or last year's Glasgow COP, which ironed out details in the Paris agreement and saw many countries up their emissions pledges.
Egypt, the COP president and host country, is keen to have this COP forge ahead on loss and damage from climate change, energy, highlighting the impact of climate change on Africa and implementing existing climate commitments, rather than just upping existing targets.
"The way the Egyptian presidency is framing this is, 'let's stop making grand commitments to big numbers and let's do something with the numbers we have already committed to," Shaw said.
Shaw said Egypt was keen to work out some kind of agreement on how the international community dealt with losses and damage for climate change, although he believed any deal would be difficult this year.
"Anything that sounds like compensation for historical emissions will be extremely fiercely resisted by [large countries with large historic emissions]," Shaw said.
New Zealand will also use the conference to push countries away from subsidising fossil fuels, a long-standing climate goal of the Government's, and to "amplify" the Pacific Countries' priorities.
"It's really important that we don't speak for other countries, but take every opportunity we can to amplify their priorities," Shaw said.
Pacific Countries are emphatic that warming cannot exceed 1.5C above pre-industrial levels. Unfortunately, the most recent UN report suggested the window to hit that target is narrowing and that in we are much more likely to land in the realm of 2.1 to 2.9C.
Shaw said the window on hitting a less severe level of warming was continuously closing - but that was not a reason for pessimism.
"That's not a give up message, that's a get cracking message," he said.
