Specifically, she recalls the summer of 2019-20.

During what became known as Black Summer, Canberrans choked through the world's most polluted air, sweltered through temperatures as high as 44 degrees and watched anxiously as bushfires marched to the doorstep of the ACT's outer suburbs.

Across the country, blazes burnt through 24 million hectares of land, destroyed more than 3000 homes, killed 33 people and killed or displaced nearly 3 billion animals.

Dr Lewis, the ACT Commissioner for Sustainability and the Environment, points out that the Black Summer happened when the planet was about 1 degree warmer than pre-industrial levels.

Add another half a degree of warming and Dr Lewis predicts dangerous heatwaves would run for longer, be more ferocious, occur out of season and across a wider area of Australia.

And for the consequences of warming substantially beyond that?

"That is a future I either don't want to, or can't, imagine," Dr Lewis says.

After a fortnight of talks in Glasgow, almost 200 countries - including Australia - have agreed to a new pact designed to avert the type of future which Dr Lewis doesn't want to countenance.

The aim at the outset of the COP26 summit was to keep "alive" the hope of limiting global average temperature rise to 1.5 degrees above pre-industrial levels, amid warnings from the United Nations that countries had put the planet on a "catastrophic pathway" to 2.7 degrees of heating by the end of the century.

Does that goal remain alive?

Yes, according to the summit's UK president, Alok Sharma. But the pulse is "weak".

Fijian President Frank Bainimarama said Glasgow had left the target "battered, bruised, but alive".

The so-called Glasgow Climate Pact reaffirmed the Paris Agreement goals of holding global warming to "well below" 2 degrees, and to pursue efforts to limit temperature rise to 1.5 degrees.

The text stated that "rapid, deep and sustained cuts" to global greenhouse gas emissions would be required to limit warming to 1.5 degrees, noting that the consequences of climate change would be much lower at that level than at 2 degrees.

Australian National University professor and ACT Climate Change Council chair Mark Howden says "significant progress" was made at the conference, with most countries now appearing to grasp the urgency which the science has long demanded.

"This has injected a very strong, increased ambition to the whole process which simply wasn't quite apparent before," he says.

"And that reflects the science. The science is very clear that we have to have very rapid cuts to greenhouse gas emissions.

"It's a big step forward. But there's still a significant part of the journey to go."

The pact included a landmark commitment to "phase down" the use of unabated coal power and "inefficient" subsidies for fossil fuels, as part of an acceleration in the global shift to clean energy.

While a last-minute intervention from India and China forced what was initially a pledge to "phase out" coal to be watered down, the mere mention of the future of the fossil fuel in a global climate pact was an historic first.

The 10-page pact also "requests" countries return next year with more ambitious 2030 emissions targets, aligned with the Paris goals.

This section, and the one on coal, have immediate implications for Australia and the Morrison government.

Despite many countries pledging new, more ambitious climate targets either before or during the Glasgow summit, global warming still remains on track to breach the 1.5-degree threshold - and not just by a small margin.

Among the most optimistic modelling, published by the International Energy Agency during COP26, is a prediction that warming could be held to 1.8 degrees if all countries delivered on their promises in full and on time.

A separate analysis from internationally respected not-for-profit Climate Analytics put the figure at 2.4 degrees, amid warmings about the "totally inadequate" emissions cuts planned for this decade.

The firm's chief executive, Bill Hare, has repeatedly sounded the alarm about the so-called "emissions gap" - the difference between where greenhouse gas levels are projected to be under countries' official climate commitments, and where the science says they need to be in 2030 in order to meet the Paris temperature targets.

Mr Hare says that gap wasn't closed at the Glasgow summit. But the request to have countries come back next year with higher 2030 goals does provide an "urgent process" to rectify it.

If they don't, the consequences could be "catastrophic" - particularly for low-lying countries, including in the Pacific.

"If countries do not step up substantially in the next year or two - by taking action like phasing out coal, addressing the role of gas - then the future picture is really bleak," Mr Hare says.

"We would be locking in warming of well over 2 degrees, and as high as 2.7 degrees, which would be really catastrophic for many countries."

So what must happen in the next decade to keep 1.5 alive not just in rhetoric, but in reality?

Professor Howden says global greenhouse gas emissions must be slashed by 45 to 50 per cent by 2030 for the world to remain on track to meet the Paris goals.

To put that into context, UN analysis published on the eve of the summit showed that greenhouse gas emissions were set to increase 16 per cent by 2030 under the targets - or nationally determined contributions - which countries had put forward at that point.

"The change requires massive policy changes across the economy," Professor Howden says.

"It will require massive policy intervention. It is just not feasible that market responses and technology responses will actually deliver that sort of emissions reduction."

The Morrison government resisted domestic and international pressure to take a higher 2030 emissions-reduction target to the Glasgow summit, choosing instead to unveil a new "projection" showing greenhouse gas levels would fall by 35 per cent.

Now it is already preparing to snub the freshly signed climate pact and ignore requests to arrive at next year's COP conference with a new, Paris-aligned 2030 target.

Prime Minister Scott Morrison and Energy Minister Angus Taylor were on Monday relying on the specifics of the pact to excuse their position.

Mr Morrison pointed out that the pact only "requests" countries update their targets next year, while Mr Taylor noted that "different national circumstances" could be taken into account.

Australia was "unique" among developed countries, Mr Taylor said, because its economy relied on "energy-intensive commodities and agricultural commodities".

Unless something changes, and if the Coalition is re-elected, the target of cutting emissions to 26 to 28 per cent below 2005 levels - which was set when Tony Abbott was prime minister - looks set to remain Australia's official 2030 target for some time.

"I've been very clear about what our target is, and that we will meet and beat it," Mr Morrison said on Monday.

"We are going to achieve a 35 per cent reduction in emissions by 2030. That's what we're going to achieve and that's what actually matters."

Labor is yet to say what short-term target it will take to the next election, and whether it will be a target for 2030 or 2035.

The Morrison government's interpretation of the coal "phase down" clause also differs from that of other countries.

UK Prime Minister Boris Johnson said the summit had sounded the "death knell for coal power".

Asked on Monday if he agreed with that assessment, Mr Morrison said: "No."

"I don't believe it did," he said.

"And for all of those who are working in that industry in Australia, they'll continue to be working in that industry for decades to come, because there will be a transition that will occur over a long period of time."

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Nationals leader Barnaby Joyce said Australia would keep exporting coal because other countries wanted to buy it.

He also mocked Alok Sharma's emotional response after the final Glasgow pact was watered down, questioning why the UK was pushing other countries to phase out coal while it was protecting its oil exports.

Professor Howden says countries such as Australia which refused to raise their targets would increasingly be seen as "freeloaders", a position which would put them at risk of having carbon border tariffs slapped on their exports.

"In terms of the government, for me the key message [after COP26] is that there is less and less wiggle room for positions and policies which don't match those of our peer countries," he says.

Dr Lewis says the Black Summer showed Canberra wasn't prepared for a warmer planet.

But she is optimistic that if the Paris goal can be met - and that remains a big "if" - then Canberra and Canberrans will be able to adapt.

She says that requires thinking about everything from the types of trees being planted, to the ventilation in our schools, to the capacity of our hospitals to manage patients amid extended heatwaves.

"I have a lot of hope that there is a lot of positive change associated with that," she says.

"But this is really about recognising that we need to limit warming, and that is the priority and the responsibility of governments."

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