With the big Copenhagen climate summit looming in a few months, negotiators have just made public an early, 200-page draft of the global treaty that will, in theory, replace the Kyoto Protocol. But that's only if an endless yarn of differences can get untangled. The current draft is very, very far from official, and still has plenty of sections couched in square brackets—which signals issues still up for squabbling. The bracketmania is a little unnerving to look at. Here, for instance, is one section on the responsibilities of wealthy countries:

[In reflection of] [Because of] their historical responsibility for the accumulation of greenhouse gas emissions in the atmosphere, [developed country Parties [and other Parties included in Annex I of the Convention] [must] [should] [show leadership] [in the global effort to build a low-carbon economy that ensures continued growth and sustainable development and strengthens capacity to adapt to the impacts of climate change] [shall take the lead in combating climate change] [and the adverse effects thereof] [in] [by] [in particular on taking corresponding measures in] [mitigation] [in taking on ambitious economy-wide quantified emission limitation and reduction] commitments [immediately implementing ambitious and legally binding emissions reductions] [through deep reductions in their emissions.] [or actions.]

You get the picture. Not only is it unclear whether rich countries need to make cuts "immediately," but it's not even agreed whether these nations "must" or merely "should" show leadership. (It's not clear to me what the practical differences would be here, anyway.) And what about developing countries? Yeah, this carries us deep into brackets-within-brackets territory:

[All Parties should aim to undertake a similar level of effort to others at a similar level of development and with similar national circumstances.] [Developing countries] [Those Parties] whose national circumstances reflect greater [responsibilities] [responsibility] and [capabilities] [capability] [must contribute to the effort] [should make a greater contribution to the global effort] to address climate change, including for limitations of emissions and enhancement of removals of greenhouse gas emissions and in assisting the most vulnerable Parties and populations to adapt to climate change.]]

What the fine distinction between "capability" and "capabilities" is, I can't say. Anyway, if wading through sub-brackets isn't your idea of a fun afternoon, then the Guardian has a handy summary of the major points of contention.

P.S. Also of note: On page 14 there's a raging dispute about what goals the world, as whole, should adopt. Should we try to limit overall warming to 2°C above pre-industrial levels? Or is 1.5°C safer? And, once we're agreed on that, do we aim to limit carbon concentrations in the atmosphere so that there's a "low risk" of that happening or a less-than-50-percent chance—since we don't know, precisely, what amount of carbon will lead to what exact amount of temperature increase (especially when you factor in potential feedbacks like methane bubbling out of the tundra). Do we try to hover below 450 parts per million of CO2 in the air, or embrace the more recent idea of 350 ppm, which would require going back from current levels. You guessed it, square brackets and sub-brackets for all of this. Pass the aspirin.