Yes, it's still about the climate, very much so. But there are also compelling reasons of national and global security to reduce the world's dependence on fossil fuels, oil in particular.
The first thing to be said about the terrorist attacks on Paris yesterday is that they are a dreadful crime that deserves only the most fervent condemnation.
The attackers showed a total contempt for human life and chose soft, civilian targets where their victims were unable to put up any defence against military grade weaponry.
But we must also ask: Why Paris? And why now?
Yes, France has been especially active in its air strikes against ISIS in Syria. And yes, there there is a huge reservoir of discontent among the socially excluded youth of the banlieue, the concrete jungle of impoverished outer suburbs that surround Paris and other big cities - where ISIS can perhaps find willing recruits to its ranks.
But is that all? In just a few weeks time, the COP21 climate conference will take place, in Paris, the biggest such event since COP15 in Copenhagen six years ago. The event offers the world a desperately needed opportunity to reduce its carbon emissions and limit global warming to 2C.
And that's surely something the attackers, or at least their (presumably) ISIS commanders, must know all about.
Could the attacks and COP21 possibly be related?
To answer that question we should first ask, what do the attacks mean for COP21?
For a start, the negotiations taking place at the conference centre at Le Bourget will surely be even more isolated from Paris itself, and civil society, than they were already going to be. Le Bourget is home to one of Paris's main international airports - perfect for VIPs to fly in and out without ever leaving the airport and conference complex.
Undoubtedly France already had a high level of security planned for Le Bourget. But now, whatever those plans are, they will be redoubled. Expect a ring of steel and concrete to go up.
Expect it to be far harder for accredited journalists, campaigners, activists, even businessmen to gain access to the conference, with stringent searches, long queues, and arbitrary refusals to people who may have travelled thousands of miles to be there.
Expect leaders, politicians, negotiators present at the conference to remain more firmly ensconced in their secure surroundings at Le Bourget - instead of travelling into central Paris to enjoy the city's many charms.
And as for civil society ...
It's estimated that ten thousand or more climate activists from around the world may be planning to stay in Paris for the duration of the conference, both to demand a strong and effective agreement, and to develop their own agenda, alliances and plans for climate action.
There is certain to be a far larger and more repressive security presence around them than previously planned - not just at Le Bourget but in central Paris where most of the events, conferences and demonstrations are due to take place.
Police surely fear the presence of terrorists taking shelter among the climate activists - and in many a policeman's world view, there may be no huge difference between murderous terrorists and (generally) peaceful demonstrators anyway. Both are likely to be seen as the 'enemy'.
Meanwhile the activists could reasonably fear terrorism themselves. What yesterday's attacks tell us is that any target will do. Climate campaigners have no reason to feel any safer than anyone else. And a demonstration of tens of thousands densely packed on the streets of Paris would offer a highly vulnerable target.
So the effect of the attacks on COP21 is likely to be a chilling one. Faced with a combination of terrorist threat, and likely heavy-handed policing, their numbers - and their political impact - are likely to fall.
Eyes off the climate ball?
Another outcome that will surely be felt at the highest levels in the conference itself is a loss of focus on the climate, and a refocussing among world leaders present in Paris on terrorism and security.
Yes, negotiators will still be arguing over square brackets in texts as they always do. But the potential of important 'big picture' climate deals cemented between presidents and prime ministers now look less likely than before - for the simple reason that world leaders are likely to take the opportunity of COP21 to talk about more immediately pressing security matters.
So with world leaders distracted from questions of climate, the prospects of serious inter-governmental agreement on the key issues at stake in the talks - from climate finance to the legal status of any agreement reached - have just receded.
Of course, this may all be accidental. Maybe Paris was just hit because of French attacks on ISIS. And maybe the now more likely failure of COP21 to achieve its aims is mere collateral damage in the increasingly savage 'great game' of global power politics.
ISIS Inc defending its corporate interests?
But it may not be. As the FT put it last week in an article titled 'Isis Inc: how oil fuels the jihadi terrorists', "Oil is the black gold that funds Isis' black flag - it fuels its war machine, provides electricity and gives the fanatical jihadis critical leverage against their neighbours ...
"Estimates by local traders and engineers put crude production in Isis-held territory at about 34,000-40,000 bpd. The oil is sold at the wellhead for between $20 and $45 a barrel, earning the militants an average of $1.5m a day ...
"While al-Qaeda, the global terrorist network, depended on donations from wealthy foreign sponsors, Isis has derived its financial strength from its status as monopoly producer of an essential commodity consumed in vast quantities throughout the area it controls. Even without being able to export, it can thrive because it has a huge captive market in Syria and Iraq."
But ISIS's ambitions surely don't stop there. Its aim is to consolidate its hold of the regions it already occupies, extend its empire to new regions and countries, and establish a Caliphate whose power and income will largely derive from oil. So the last thing it needs is a global climate agreement that will, over time, limit global consumption of fossil fuels.
Oil prices are low at around $50 per barrel. The IEA estimates that OPEC states have lost half a trillion dollars a year in revenues since the oil price fell from over $100 a barrel in 2011-2014 to current levels. And this is causing deep tensions among OPEC members - due to meet on 4th December in Vienna to thrash out solutions.
The main problem is that Saudi Arabia is over-producing oil in order to suppress investment in and production of high cost oil in the the US, Canada, UK and other countries - and so capture the lion's share of an oil market it thinks will keep on growing for decades to come.
Thus OPEC scenarios foresee oil demand increasing from 111 to 132 million barrels per day (mb/d) by 2040. However the International Energy Agency thinks that even modest carbon constraints will see demand for oil slump to around 100 mb/d by 2040 - and considerably lower with tough climate policies.
And that is surely an outcome that not just ISIS but all major oil exporters fear and wish to avoid.
Was it or wasn't it?
So, assuming - as seems probable at this stage - that the Paris outrage was carried out by or for ISIS, was it in any way motivated by a desire to scupper a strong climate agreement at COP21? And so maintain high demand for oil long into the future, together with a high oil price?
Let's just say that it could have been a factor, one of several, in the choice of target and of their timing. And of course ISIS was not necessarily acting entirely on its own. While not alleging direct collusion between ISIS and other oil producing nations and companies, it's not hard to see a coincidence of interests.
So if that is the case, or even if might be the case, there's an important message in it for us all. The effort to shrink the importance of fossil fuels in the global energy landscape - and oil in particular - just took on a whole new dimension.
Yes, it's still about the climate, very much so. But there are also immediate and compelling reasons of national and global security to reduce the world's demand for oil even faster than the IEA's projections.
And an important part of achieving that is to reach a strong agreement in Paris next month, sending a clear message to energy corporations and investors that oil and other fossil fuels are no longer a smart investment - and instead to put their resources into the clean, green, renewable energy technologies of the future.
So as well as standing with France in at this time of horror, we must also take a powerful resolve - and communicate it it ceaselessly to our leaders - for a strong, effective climate agreement: the Paris Treaty.
Oliver Tickell edits The Ecologist.