The aim is to forge a legally binding global climate treaty in Poland to cut carbon emissions. But it's easier said than done

What is happening in Warsaw?

It is COP19 of the UN Framework Convention on Climate Change – or, in other words, the latest round of the ongoing United Nations talks aimed at forging a new global agreement on climate change. The talks began on 11 November but the real business – the "high-level segment" in which government ministers take part – opens on Tuesday with a short session and gala dinner for the assembled dignitaries, then the ministers get down to talks on Wednesday with the aim of finishing up on Friday evening.

Haven't we had this before? What has changed?

The UN talks have been going on since 1992, with annual conferences producing a few highs and lows along the way, but so far no comprehensive legally binding agreement. In 1997, the Kyoto protocol was signed, binding rich nations to cut their emissions by about 5% by 2012. But the US never ratified the treaty, so its impact was limited. In 2009, the Copenhagen summit ended in scenes of chaos, but it did produce commitments from all of the world's major economies, developed and developing, to cut or curb their greenhouse gas emissions – a historic first. However, those commitments only run to 2020, and are far less than the cuts scientists say are needed. In September, the Intergovernmental Panel on Climate Change produced its most comprehensive review yet of the science of climate change, warning that the world is running out of its "carbon budget" – the amount of greenhouse gas we can pour into the atmosphere before warming the world by more than 2C, which scientists have identified as a crucial threshold beyond which many of the effects of climate change could become catastrophic and irreversible.

What is expected to come out of this year's talks?

The current goal of the negotiations is to forge an agreement, to be signed in Paris in 2015 and to come into force by 2020, that would involve substantial reductions in greenhouse gas emissions from all the major economies, as well as commitments from poorer countries. But this meeting is just a staging point on the road to that goal – there is as yet no draft text for an agreement, no consensus on what a new deal should involve, or what legal form it should take.

That doesn't sound very interesting.

In terms of the business of this COP, much of it will be "housekeeping" – clearing the decks on various technicalities so that work can begin soon after on the draft text. But the Warsaw meeting has already provided more drama than was bargained for.

How so?

It began just two days after the most powerful typhoon ever to make landfall devastated the Philippines, with the loss of thousands of lives. Yeb Sano, leading the country's delegation, made an opening statement at the start of the discussions in which he broke down and connected the devastation wrought by typhoon Haiyan to climate change. His words had an effect on David Cameron, who also linked extreme weather to climate change.

Then, Japan came under attack for announcing that instead of aiming for a 25% reduction in greenhouse gas emissions by 2020, it would increase its emissions by 3%, saying this was necessary after the Fukushima disaster. But many onlookers feared that it would lead to further backsliding – there are doubts over what Australia's new climate-sceptic government will do about its existing agreements, and over the commitment of Canada and Russia to the talks.

What have the Polish hosts done about this?

Mostly, attract their own controversy – by giving a two-day platform at the talks to the global coal industry and highlighting the role of coal in energy generation. Coal is the most carbon-intensive fossil fuel, but it supplies most of Poland's energy, and the government takes a hard line within Europe, resisting calls for more action on emissions.

What about developing countries?

They want clearer commitments on the provision of much-needed finance to help them move to a low-carbon economy: $100bn by 2020 is the aim. Some of this will come from public funds in rich nations, but that pot is likely to be meagre, so ways have to be found to raise money from the private sector. At present, it is not clear how that will happen, or what will count towards the $100bn (£62bn).

Some developing countries also want to resurrect the issue of "loss and damage", which some interpret as compensation to poor countries from the rich for the effects of climate change, such as an increase in the number or intensity of typhoons and hurricanes. Rich countries are determined that this will not happen. The rich nations also want major developing economies such as China and India to take on more of a role in curbing emissions.

Will these disagreements jeopardise the outcome?

This meeting is still likely to end with a feel-good statement that some form of progress has been made towards the 2015 goal, but the danger is that between now and that crucial date any further upsets, backsliding, failure to agree finance or deepening rifts between rich and poor could derail the whole process. That would leave the world without an agreement on tackling climate change, which would send a poor signal to investors and let countries that don't want to cut their emissions off the hook for years to come. Against a background of still-rising emissions, that is likely to take us well beyond our carbon budget.