Yukio Hatoyama's golden carrot
Well okay, it's happened a bit earlier than forecast in these quarters, but Japan's incoming Prime Minister Yukio Hatoyama has announced what could prove a significant move in climate circles, pledging to cut his country's greenhouse gas emissions by 25% from 1990 levels by 2020.
This goes way beyond the 8% set by Taro Aso's outgoing Liberal Democratic Party government.
It's already being welcomed in campaigning circles. Greenpeace described it as "the first sign of climate leadership we have seen out of any developed country for quite some time," while WWF said it would "be a big force in moving one step forward the stalled talks between developed and developing countries".
One of the reasons why the talks leading up to December's Copenhagen summit are "stalled" is because in general, western nations are not promising emissions cuts by 2020 of anything like the 25-40% that developing countries are asking for.
There should be no doubt that Japan's new target is, in sporting terminology, a "big ask". Because Japan's emissions have risen since 1990, it amounts to a cut of about one-third from current levels.
There is, though, one big caveat: there has to be a global deal through the UN framework, with other developed countries making pledges of similar scale, and some kind of action also promised by at least some developing countries "in the process of achieving sustainable development and eliminating poverty under the principle of 'common but differentiated responsibilities'.''
So you could regard Mr Hatoyama's pledge as a "golden carrot" for UN negotiators. The incoming Democratic Party government hasn't said what will happen if there isn't a global deal, but you can be fairly sure Japan won't hold to the 25% figure as a unilateral pledge.
The carrot is similar to the one being dangled by the EU; a deal will bring a bigger cut (in the EU's case: 30% with a global deal; 20% without).
A slightly anoraky (but important) point is that Japan has also returned to the logic of measuring everything against a single baseline, 1990, rather than inventing new ones (as Australia has by choosing 2000, Mr Aso did by announcing his target relative to 2005, and US President Barack Obama did during his election campaign by continually referring to 2007).
Slightly more exciting than the concept of common baselines is the comparisons that are already being whispered with the US, which remains the single most important country in this whole process.
Developing countries view the current US carrot as anything but golden: too small, too poor in nutrients and stained through by the brown canker of "business as usual".
Like Japan, US emissions have risen since 1990. Until this Japanese election, leaders in Tokyo, like their counterparts in Washington, were insisting that this made a really steep cut in emissions by 2020 impossible.
Now Japan has broken that mould. Mr Hatoyama believes a major cut is feasible, and in a country that is already far more frugal with energy than the US.
Tokyo, therefore, has laid down a gauntlet to Washington. We shall see whether Washington responds.