The former Environment Minister Noel Dempsey once related a story to me about how politicians respond to climate change - and it's instructive.

Dempsey had been in Japan in 1997 as part of an EU delegation negotiating the Kyoto Protocol.

This was the first inter-governmental treaty aiming to reduce greenhouse gas emissions.

At the time I was RTÉ's Environment Correspondent and I was writing a book, 'Ireland’s Burning’ on the challenges posed by climate change.

The Minister told me he brought the proposal to Cabinet that Ireland would keep emissions within 13% above 1990 levels - and secured resounding support for the plan.

However, when he later returned to Cabinet with a breakdown of what each department had to do to achieve the goal, Minister after Minister found reasons to push-back on the plan.

The Kyoto Protocol was succeeded by the Paris Agreement in 2015 - and there remains a gap between what climate science is demanding and the political response.

In many ways, climate campaigner Greta Thunberg was right when she tweeted today that the latest IPCC report "contains no surprises" but only "confirms what we already know."

In essence, the IPCC's latest report concludes that climate change is happening more quickly than predicted, and with a greater intensity than expected.

But that's not to say the report is any less stark and worrying.

That concern is best illustrated by the language used by the UN Secretary General, Antonio Guterres, today when he warned: "the alarm bells are deafening."

He added: "The evidence is irrefutable: greenhouse gas emissions from fossil fuel burning and deforestation are choking our planet and putting billions of people at immediate risk."

In the 41-page summary for policymakers, released today, one statistic looms large - the 1.5 degree Celsius threshold.

The UN says that limiting temperature rises to 1.5 degrees above pre-industrial levels is vital, as otherwise it could have catastrophic consequences for the planet.

To date, the temperature has already increased by 1.2 degrees Celsius, and the trajectory is going upwards.

Today's IPCC report warned that global temperatures could surpass 1.5 degrees by 2040 even if significant emissions reductions took place.

That's less than 20 years from now - and a decade earlier than had previously been projected.

To me, this report has one killer line: "Unless there are immediate, rapid and large-scale reductions in greenhouse gas emissions - limiting warming to close to 1.5 degrees Celsius, or even 2 degrees Celsius, will be beyond reach."

Basically, the IPCC is issuing a dire warning that we are on the cusp of widespread, destructive, and irretrievable climate change.

How will politicians respond?

Well, we will get some indication of that in November when the annual UN Climate Change conference takes place in Glasgow.

In advance of these critical discussions, the UN Secretary General tried to put some heat under governments today.

Mr Guterres said: "Extreme weather and climate disasters are increasing in frequency and intensity. That's why this year's UN climate conference in Glasgow is so important."

Ireland's current Climate Action Minister, Eamon Ryan, says that Ireland will be able to "hold its head high" in Glasgow because the government passed its Climate Action Bill.

The legislation compels the country to cut emissions by 51% by the year 2030, and to be carbon neutral by the year 2050.

But Ireland's promises on reducing emissions don't cut too much ice, given our consistent failure to meet targets in the past.

And the Tánaiste, Leo Varadkar, told the European Parliament as much in 2019, when he accepted that Ireland was a "laggard" when it came to emissions reductions.

Emeritus Professor at Maynooth University, John Sweeney, put it more harshly a few years previously when he described Ireland as "delinquent" when it comes to meeting our targets.

Could it be that this time there will be significant and coordinated political action leading to substantial emissions reductions?

After all, as the IPCC put it: "Strong and sustained reductions in emissions of carbon dioxide and other greenhouse gases would limit climate change."

Maybe, just maybe, things will change after six comprehensive IPCC reports and nearly a quarter of a century of data since the drafting of the Kyoto Protocol.

If not - we do know what's going to happen.

In 2007, I reported from Paris on the IPCC's 4th Assessment Report.

One of its predictions went as follows: "In some projections, arctic late-summer sea ice disappears almost entirely by the latter part of the 21st century."

In today's 6th Assessment Report, the prediction goes as follows: "The Arctic is likely to be practically sea ice free in September at least once before 2050 - under the five illustrative scenarios considered in this report."

A couple of years ago, when reporting for RTÉ's Climate Week, I returned after more than a decade to western Greenland, where Arctic sea-ice had all but disappeared between October and March that year.

The rate of climate change is speeding-up, which means less time for our politicians to respond adequately - something they've found particularly difficult to do up to now.