Reflections on a fortnight in Fukushima
Earth Watch posts have been in smaller supply than usual in recent days.
For a week, your humble correspondent was virtually living inside the Fukushima nuclear power station, attempting to make sense of what we knew and what we didn't know as the situation unfolded.
Now - almost two weeks after the devastating Magnitude 9.0 Tohoku earthquake and tsunami, and a few hours before heading on leave for a little while - it seems like an apt time to take stock.
Fukushima has raised protests elsewhere in the world - how serious is another matter
In the broadest of senses, the situation at the power station itself appears slowly to be coming under control. Electrical power is progressively being restored across the site - no small task - and as time goes by, the rate of radioactive decay and therefore the heat output in the cores will naturally get lower.
Temperatures and pressures within some of the reactor containment vessels are well above the intended operating levels. A bulletin from the Tokyo Electric Power Company (Tepco) on Thursday put the vessel temperature in number 1 reactor building at 390-400C (734F), against an operating value of 138C (280F).
So the reactors themselves are not completely in the clear.
Nevertheless, the longer time goes by without any significant new development, the smaller the chances of something serious occurring.
It's important to point out a couple of things here.
Firstly, nothing definitive can yet be said about the sequence of events at the plant, nor about the response of Tepco employees in the critical early hours.
And it is certainly too early to make a comprehensive assessment of the health impacts. With the Windscale reactor fire of 1957 - like Fukushima, rated Level Five on the International Nuclear and Radiological Event Scale (INES) - the health consequences were still being assessed four years ago, on its 50th anniversary.
Fukushima will not take half a century to analyse because the facility has a civilian rather than a military purpose, because monitoring and knowledge of nuclear processes are far higher now than in 1957, and because the Japanese population is not likely to stand for it.
Operators have had to struggle with devastation from the earthquake and tsunami across the region
But at the moment, information is being disinterred bit by bit - and a truly comprehensive picture will in all probability have to wait on the first official inquiry.
The second point is that despite the allegations of secrecy and poor flow of information levelled against Tepco in the early days of the crisis, those allegations do not currently stand up to scrutiny.
The company is now publishing bulletins several times a day, sending them to reporters, responding to questions promptly and seriously, and posting mounds of data such as radiation levels on its website.
Whether the company is taking this stance entirely voluntarily or whether it has been dragged kicking and screaming by the government - whose leader, Prime Minister Naoto Kan, was possibly our best source of information early on - is not entirely clear.
And it cannot be proven that all the data we receive is entirely accurate. Nevertheless, this has to go down as a huge change from the situation seen at every other serious nuclear accident (by which I mean INES Level Five and above) in history.
At the time of writing, there are some intriguing tidbits.
Perhaps the most tantalising is a report by Kyodo News, Japan's principal news agency, to the effect that neutron radiation was observed more than a kilometre from reactor buildings 1 and 2.
Neutrons are emitted during a nuclear chain reaction; so given the context, is Kyodo's report to be taken as indicating that a chain reaction took place after the reactors shut down?
If it is, does that relate to the company's warning last week that there was a possibility of "re-criticality" in a pool storing fuel rods?
The neutron flux outlined by Kyodo - 0.02 microsieverts per hour - is within levels that are observed naturally in some locations - which raises the question of why it became an issue in conversations between reporters and Tepco representatives in Tokyo.
As I said, a tantalising tidbit; and a demonstration that in this story, every piece of information comes swimming in a sea of questions.
Meanwhile, what we are seeing away from the Fukushima site, in terms of restrictions on drinking milk and water and eating vegetables, recalls measures in place after Windscale and Chernobyl.
The big difference is that monitoring by Japanese agencies appears to have been prompt, informed and proactive, with results quickly disseminated to the public.
Milk has had to be thrown away near the plant
Outside Japan, the big issue is what Fukushima means for nuclear power - and by implication, for plans to switch away from fossil fuels to restrain carbon emissions.
There are plenty of analyses around suggesting climate targets can be met through efficiency and renewables alone - Greenpeace's is one of them - but the political equation is more complex.
Imagine, for example, a decision at European level not to build any new nuclear power stations.
Nuclear is the basis of low-carbon electricity in France. Finland and the UK are among other countries committed to a partially nuclear future.
The question is not whether it is technically feasible to scrap those plans and replace the shortfall with wind turbines, solar panels and storage capacity - clearly, it could be done.
But would it be politically feasible? Given that we are past the era of state direction, will the private sector deliver on this scale?
On the other hand, utilities that are currently sounding pretty bullish about continuing with new nuclear build may look at things rather differently if public discontent manifests itself at building sites where new plants are scheduled.
On yet another hand, will Fukushima actually lead to serious public opposition? In Germany, it produced marches; but the UK public does not appear to have taken against the technology completely because of an accident on the other side of the world.
Perhaps a bigger practical issue than new build is how ancient plants should be regulated - what should be insisted on in terms of upgrading, given that safety practices have changed hugely in the 40-odd years since the Fukushima generation of commercial reactors came online.
How all this plays out cannot, I think, be predicted; and events will be fascinating to follow.
But at the present time, Fukushima can be used to bolster the arguments of either anti-nuclear or pro-nuclear factions.
One can - and is - saying, essentially, "you see - nuclear will never be safe - here's proof".
The counter is that if you exclude events in closed societies and those that took place in the 1950s, there have only been two nuclear accidents big enough to rate a Level Five or above - Three Mile Island and Fukushima.
No-one appears to have died in the first; and it is possible that the second will end with a similar statistic, given that workers unaccounted for at the plant may have come to grief in the tsunami rather than any nuclear cause.
Fukushima Daiichi was designed to withstand seismic ground movements of the scale that materialised during the Tohoku quake.
But it was not designed to withstand a 14m (46ft) tsunami - the latest estimate of the wave height that engulfed the plant two weeks ago.
So whatever governments and societies decide on the nuclear question, however they prioritise questions of energy security and climate change, it will have to be on the basis of relative risks; because nothing in this arena comes with certainties attached.