The UN climate talks in Qatar, which ended last month, were as inconsequential as you might imagine when the host nation chairing the event has the highest per capita carbon emissions in the world.

In other words, not a lot happened — except for one thing. For the first time, nations agreed that “developing nations that are particularly vulnerable to the adverse effects of climate change” might have a right to redress from major polluting nations for any resulting “loss and damage.” The conference then directed its staff to begin research on how to ensure that redress.

The U.S. delegation in particular worked hard to make certain there was no mention of compensation or litigation. Nonetheless, the action taken in Qatar suggests nations now concede that damaging impacts of climate change are inescapable. Given that those nations are already under an obligation in international law to prevent dangerous climate change, it brings closer the day when nations may seek redress in the courts for damages caused by climate change. And it may make more likely the prospect of citizens successfully bringing major polluters to court and making them responsible for their contributions to climate change.

The fact that negotiators are even discussing how to respond to “loss and damage” from climate change shows how badly climate diplomacy has failed since nations, including the U.S. under George H.W. Bush, signed up to the UN Framework Convention on Climate Change (UNFCCC) at the original Earth Summit in Rio de Janeiro in 1992. Under that convention, nations promised to ensure the “stabilization of greenhouse gas concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.”

If countries can sue each other, why not private actions against corporate polluters?

But greenhouse gas concentrations have continued to rise since, because the promised mitigation of emissions has not happened. After 17 years — with the pitifully weak Kyoto Protocol of 1997 the only sign of progress — negotiators at the much-anticipated climate conference in Copenhagen in 2009 admitted that mitigation was failing. So the Copenhagen Accord added another element. Besides mitigation, governments pledged to set aside money for an “adaptation fund” to help poorer nations adjust to what now looked like inevitable climate change.

Today, three years later, the prospect of a new global treaty to mitigate emissions seems as far away as ever, and the adaptation fund is largely empty. So, in Qatar, they added a third leg by launching studies into how to respond to the growing threat of “loss and damage.” What they are, in effect, telling the world is that neither mitigation nor adaptation will work.

The steps taken in Qatar are just words for now. But they could matter a great deal as droughts intensify, floods spread, heat waves kill, seas rise, and islands disappear. Since the big nations are palpably failing to meet their legal obligation to prevent dangerous climate change, it cannot be long before some small nation decides to invoke the disputes procedure laid out in article 14 of the UNFCCC. This procedure allows countries to take those nations failing in their duties under the convention to the UN’s International Court of Justice.

At that point, the legal floodgates may open. For if countries can sue each other, why not private actions against fossil fuel companies and other corporate polluters?

The few attempts so far by citizens to take climate change to court, mostly in the U.S., have been unsuccessful. Courts have dismissed their actions on the grounds that climate change is a political rather than a legal issue. But the longer the politicians delay, the less viable the courts’ position becomes. Judges may feel forced to fill the void.

One court case brought echoes of the class actions against tobacco and asbestos companies.

The first such legal excursion was in 2005, when victims of Hurricane Katrina filed a suit against a group of oil companies, claiming that by emitting gases that contributed to the warmer Gulf of Mexico that helped intensify Katrina before it made landfall. The case was dismissed in 2007, partly because judges said the harm could not be traced to individual defendants.

Then in 2008, an Inupiat Eskimo community living on a barrier reef off the west coast of Alaska brought an action against Exxon Mobil and 23 other large oil, coal and electricity utility companies. The community said its village of Kivalina was being eroded by the sea. It blamed rising sea levels and melting coastal sea ice that left it exposed to storms and tidal surges, and it sought $400 million to pay for the relocation of the village further inland in Alaska.

Attorney Matt Pawa of the Pawa Law Group in Boston, which brought the case, argued that the energy companies were liable not just because they emitted millions of tons of greenhouse gases, but also because some have engaged in a conspiracy to misinform the public about the dangers of those emissions. This latter point brought echoes of the famous class actions against tobacco and asbestos companies that hung, in part, on their denial of the science proving the risks from their products.

In September this year, the Kivalina case suffered a setback when federal appeal judges ruled that the issue was for politicians in Congress and not the courts. Pawa says his clients have not given up and may try to take the case to the U.S. Supreme Court for review.

Meanwhile, on the international stage, a group of small island nations, headed by Palau in the western Pacific, has asked the UN General Assembly to seek an advisory opinion from the International Court of Justice on the legal responsibilities of nations whose corporations cause international harm through contributing to climate change. The action is not being taken under UNFCCC, but it opens up the door to that possibility in future.

Yale law professor Douglas Kysar, who is helping bring the case, says the island nations, all of which could disappear as sea levels rise, want “to show that the issue is a matter of law and justice, rather than merely politics.” That probably explains why, at the last meeting of the General Assembly this fall, the U.S. government exerted what Kysar calls “significant diplomatic pressure to stop the resolution reaching the floor for a vote.” Those efforts ultimately proved successful.

Courts cannot stay away from climate change much longer if politicians continue to fail in their responsibilities.

But Palau and its fellow small island nations intend to push the resolution again at future General Assemblies, according to Kysar. “We are seeking nothing more than that the rule of law be introduced into the climate issue,” he says. Kysar believes the courts can no longer shy away from climate change. “Part of the reason why climate change treaty negotiations have cycled through the same set of arguments for the last 20 years,” he says, “is that we don’t have a clear baseline understanding of state responsibility.”

The new diplomatic language about “loss and damage” adopted in Qatar signifies that there has been a potential breach of the UNFCCC agreement. And that breach can only intensify the demand for the responsibilities of nations to be defined in law.

Not everyone is convinced that the new agenda of “loss and damage” will help civil litigators. Pawa believes that if there ever were intergovernmental action on compensation for climate victims, it might reduce the chance of success for private actions against fossil fuel companies. “If they set up a mechanism for compensation internationally, that would make private litigation more difficult, at least in the U.S., because our courts might defer to that process,” he told me.

But that still looks like a long way off. One way or another, lawyers spoken to for this article agree, the courts cannot stay away from climate change much longer if politicians continue to fail in their responsibilities. And it may take court rulings to force politicians to act.

Once the law gets involved, however, there has to be proof linking polluters to damaging weather. That requires good attribution science. In many cases, in order for actions to succeed, it will not be enough to show that polluters cause climate change. Scientists will have to show that individual extreme weather events are attributable to anthropogenic climate change.

The scientist most active in this area has been British climate modeler Myles Allen. He and colleagues at the University of Oxford have shown that both the European heat wave of 2003, which killed an estimated 35,000 people, and devastating floods that hit England in 2000 were made at least twice as likely by climate change. Allen says there is also convincing evidence from others that background global warming turned a heat wave in western Russia in 2010 into an extreme event, in which record temperatures triggered massive forest and peat-bog fires that blanketed Moscow in smog. In past cases involving environmental and health disasters, says Allen, a doubling of risk has been enough to trigger civil liability.

British barrister Richard Lord of Brick Court Chambers in London, editor of Climate Change Liability, believes that attribution research such as that undertaken by Allen and his colleagues makes litigation against climate polluters more likely to succeed in the future, especially if political negotiations continue to falter and climate impacts worsen.

Allen makes another point about knowledge, culpability and liability. Before 1990, he notes, no corporation or government could be held accountable for the impacts of their emissions of greenhouse gases. We simply did not know enough about their impacts on climate. But that year the Intergovernmental Panel on Climate Change published its first assessment of climate change, providing clear evidence. It was enough to persuade diplomats at the UN to begin drawing up the UN Framework Convention on Climate Change, and for governments to sign it two years later in Rio de Janeiro. From that moment on, claims of ignorance have been harder to justify.

That means culpability is growing with time. Within a decade, approaching two-thirds of the greenhouse gases in the atmosphere will have been emitted since 1990. And courts may say that culpability means liability. The argument that emitters should take some legal responsibility for the consequences of their emissions will harden. This will be especially true for those companies still in denial about the climate. They will look ever more like the tobacco corporations denying, against all the evidence, that their products are cancer sticks.