Mother Jones thinks the deal is a game changer, so does Joe Romm at Climate Progress. Climate scientists what agree with some cautions, including the big one that it’s not nearly enough.

In the broad, China has agreed to peak emissions by 2030, the US will reduce emissions by 26 to 28% by 2025, relative to 2005.

Yet China will still be getting 80% of its power from fossil fuels in 2030.

They said China would never do a deal of significance, and the US could not make significant reductions politically while China did nothing. That’s why the deal is a game changer.

Now Republicans are saying that China is doing nothing for 16 years. That’s not true. China will install 800-1,000 gigawatts of nuclear, wind, solar and other zero emission generation capacity by 2030.

Joe Hockey implied that Obama will not deliver, because of an unfriendly Congress. Obama said on Sunday specifically that he is not relying on Congress for anything – he’ll do it without their help. Republicans are freaking out and will no doubt destroy the deal if they reclaim the presidency.

Given the unhelpfulness of Congress Obama’s plan is surprisingly ambitious, roughly doubling the pace of reductions:

The overall impact is portrayed by this graph from Climate Interactive:

That would see emissions in 2100 roughly the same as they are now. According to the recent IPCC Synthesis Report most of the stabilisation scenarios you’d want to follow see zero emissions some time before 2100. You can get a rough idea of what’s required from this graph by Prof Hans Joachim Schellnhuber:

That is for a 67% chance of not exceeding 2°C.

With emissions trading that would be modified thus:

I would assume that China is a Group 2 country in this scenario.

At a rough guess, then, I suspect that China and the US are doing no more than half what they really should, if we assume that 2°C is OK, which I don’t.

Mother Jones lists some of the detailed items covered in the agreement:

• Expanding funding for clean energy technology research at the US-China Clean Energy Research Center, a think tank Obama created in 2009 with Xi’s predecessor Hu Jintao.

• Launching a large-scale pilot project in China to study carbon capture and sequestration.

• A push to further limit the use of hydroflourocarbons, a potent greenhouse gas found in refrigerants.

• A federal framework for cities in both countries to share experiences and best practices for low-carbon economic growth and adaptation to the impacts of climate change at the municipal level.

• A call to boost trade in “green” goods, including energy efficiency technology and resilient infrastructure, kicked off by a tour of China next spring by Commerce Secretary Penny Pritzker and Energy Secretary Ernest Moniz.

All good stuff. One valid criticism is that the agreement neglects the issue of adaptation, necessary because under the implied scenario warming will continue.

Our government has chosen to be a follower rather than a leader. It is now time to follow. But in doing so they should take a look at Prof Schellnhuber’s graphs to understand their true responsibility – and why buying carbon credits offshore is not such a bad idea.

To take the politics out of the issue they could even flick it to The Climate Change Authority. That’s what it was set up for.