The location for this year's Camp for Climate Action - outside the Kingsnorth power station in Kent - was well chosen: it is here that E.ON wants to build the first new coal-fired plant in the UK in nearly 30 years. With coal the most global-warming-intensive fuel on the market, and six more coal plants in the pipeline if Kingsnorth gets the go-ahead, there is a clear line to be drawn in the sand.
But the Kent protesters are not the only ones banging the drum against coal. Dr James Hansen, head of the Nasa Goddard Institute for Space Studies and probably the best-known climato logist alive, has been travelling the globe trying to persuade politicians that the best way to rein in future climate change is by a rapid phase-out of coal-burning power stations. First stop was Germany, where Hansen met the environment minister, Sigmar Gabriel. Germany is planning more than 20 new plants, despite Chancellor Angela Merkel's much-vaunted determination to combat climate change. The meeting ended without success. "We agreed to disagree, as we were both trying to be cordial," Hansen reports.
Next stop was Britain, where Hansen received a letter from the environment minister Phil Woolas in response to his earlier petitioning of Gordon Brown to lead a moratorium on new coal plants. The letter - available on Hansen's website - is notable for its "self-deception" (in Hansen's words): the government pretends that new fossil-fuel plants can be built almost with impunity as long as they are "carbon-capture ready", allowing "economic retrofit of the technology when commercially available, by 2020 if possible". In essence, the government is putting all its environmental eggs in the basket of a technology that has not yet been invented. Self- deception indeed.
Then Hansen moved on to Japan, where carbon emissions are rising - almost entirely due, as in the UK, to a resurgence of coal burning in power generation. First, Hansen fired off a letter to the prime minister, Yasuo Fukuda, restating the urgency of the situation - that the "global climate is approaching critical tipping points" and that we are already in the zone of extreme danger even at current levels of atmospheric CO2. Then came the ask: Hansen begged Japan to use its platform at the G8 summit to demonstrate world leadership on the issue of a global phase-out of coal emissions between 2010 and 2030, with most of the world's remaining coal reserves allowed to remain in the ground. He was, as anyone who reads the papers will know, disappointed.
Hansen's message is unpalatable to governments because he states his points bluntly and with constant references to irrefutable scientific evidence. "A strategy based on 20 per cent, 50 per cent or 80 per cent CO2 emission reduction is doomed to failure," he asserts, because of the long atmospheric lifetime of carbon dioxide (a significant fraction hangs around for 1,000 years or more). It is the total carbon input to the atmosphere that counts, not the time taken to burn it. Yet emissions reduction is the only strategy talked about at the global level. A more realistic approach would be to adopt a "production cap" - as advocated by Oliver Tickell in his current book Kyoto2 - and mine only as much fossil fuel as the planet can withstand us burning. The long-term objective, over a century or so, is to reduce carbon levels to 350 parts per million at most (they are at 385ppm and rising fast), but that is something no leading politician is yet prepared to contemplate.
Hansen is a self-declared "agnostic" on nuclear power, a topic which recently landed the writer George Monbiot in hot water when he admitted in his Guardian environment column that he "no longer cared" if nuclear power was part of the answer. The article upset many in the environmental movement. I would take a stronger position myself: that increased use of nuclear (an outright competitor to coal as a deliverer of baseload power) is essential to combat climate change, but clearly there need to be some signi ficant technical advances in nuclear fission if it is to become acceptable to many in the west.
There is plenty of opportunity for improvement: one design of fast-breeder plant, the integral fast reactor - unfortunately mothballed by the Clinton administration for political reasons - could generate power by burning up nuclear waste, leaving only short-lived by-products unfit for nuclear bombs (and therefore weapons proliferation). The reactor design is also close to "fail-safe": it automatically shuts down if things begin to go wrong, because the safety mechanisms are inherent, and do not depend on human or mechanical intervention.
Such "fourth-generation" nuclear power is still a dream, but potentially a much more realistic one than carbon capture and storage. Deployed entirely in tandem with renewables, fourth-generation nuclear could offer a complete decarbonisation of the world's electricity supply - and on the sort of timetable that Dr Hansen and his fellow climatologists demand.