When you dive into the report to see this notion illustrated you find a chart explaining the point about 100 pages into the nearly 4000-page long document.

Throughout the report the authors use a series of illustrative scenarios showing the likely amount of warming we can expect depending on how much more carbon we pump into the atmosphere.

It shows that even given the warming locked in,it is still possible to keep the climate within the 1.5 degree target range,physically if not politically.

The report even says how it must be done.

First,carbon emissions must be brought to zero quickly,says Dr Canadell. If we hope to keep within the 1.5 degree range – the more aspirational target in the Paris Agreement – this must be done by 2050.

Secondly,what new emissions we still allow into the atmosphere must be done within a carefully measured carbon budget,one that will likely be allocated to each country by negotiation.

Thirdly,we must then begin the job of withdrawing billions of tonnes of that accumulated carbon dioxide from the atmosphere and burying it back underground where it came from.

Can it be done?

Emissions reductions

One person worth asking is engineer and physicist Saul Griffith,who lives in a rambling suburban home backing onto the rainforest of the Illawarra escarpment at Austinmer south of Sydney.

Before he fled a locked down Los Angeles to return to Australia,Griffith,a graduate of the University of Sydney and MIT,completed the most detailed inventory of how American households use power.

He and a team at one of the non-profit organisations he co-founded,Rewiring America,worked out how much power and gas American homes and small businesses used for transport,heating,cooling and lighting and household appliances.

They established how much carbon dioxide - and money - they would save if all these processes were electrified and supplied by a clean grid. They even calculated how many jobs in trades would be created as the nation went about replacing gas-hungry kitchens,hot-water systems and space heaters.

Over the years Griffith has led US government funded research projects for agencies including NASA,Defense Advanced Research Projects Agency (DARPA),Advanced Research Projects Agency–Energy (ARPA-e),the National Science Foundation and the US military’s Special Operations Command.

Rewiring America is today working with several US senators and the White House on elements of energy policy.

NSW Energy and Environment Minister Matt Kean says Griffith,who he uses as a “sounding board” on similar issues,is “basically a genius”.

So can Australia decarbonise at the speed the IPCC says is necessary?

“Oh yeah,” says Griffith. “We could shit it in.”

Griffith’s mantra for Australia is the same as it is for America - electrify everything. Indeed he is establishing a Rewiring Australia organisation to advocate for such policies.

By his calculations Australia can reduce emissions by more than 50 per cent by the end of the decade by replacing gas and coal-fired power with renewables and helping households,small business and light-manufacturing deploy solar and battery technology to replace internal combustion vehicles as well as gas-burning water and space heating appliances.

Most light manufacturing could now electrify with existing technology,Griffith says.

Given the speed at which this technology is improving,the immediate result of this would be cleaner air and cost savings as well as emissions reductions,he says.

“The government should be pursuing populist climate policy that helps all Australians not only have solar on their roofs but electric vehicles in their garages and electric appliances inside the house,” he argues. “The people who spend their lives watching where the technology is going know that in the next three years we’ll come to the crossover point where doing the right thing environmentally will be doing the right thing economically.”

A further benefit of a large electric vehicle fleet would be that the batteries in parked cars would serve as a vast and interconnected back-up to the grid.

As these policies were being pursued,says Griffith,Australia should be funding research into the harder problem of decarbonising heavy industry,particularly the production of steel and metals.

Griffith believes the government’s support of nascent hydrogen technology is misplaced. Using electricity to create hydrogen to serve as a fuel,he argues,is inherently inefficient.

In a decarbonising world Griffith would focus on massively ramping up our renewable energy capacity and developing green steel. He would abandon Australia’s high-volume but low-margin export of coal,iron ore and bauxite and instead become the world’s foundry – making the clean metals the rest of the world will need as it replaces its old fossil-dependent systems.

“Half of the price of steel is the energy price of manufacturing it,” he says. “We will make the cheapest electricity in the world,we use that to make steel here,it’s going to be much cheaper than steel made in Japan with our hydrogen that we have shipped over there.”

Green Australian steel and aluminium exports,says Griffith,would be the most efficient way to export renewable energy.

Griffith is the first to admit that such a project of mass,rapid electrification would not be easy. If all the equipment he refers to in his charts and arguments was replaced at the end of its natural life we would still be on a path to warming of 1.8 degrees. And the world does not yet have the manufacturing capacity for such a project even if it had the will.

Rapid electrification would take an effort similar to the strategy the allies adopted to revolutionise their economies as World War II broke out.

“Where and once upon a time it was bullets and airplanes and jeeps,it’s now batteries,and wind turbines and electric vehicles,” says Griffith.

The carbon budget

Should emissions begin to rapidly fall,those that are still allowed into the atmosphere in the short-term must be carefully managed within the framework of a carbon budget. The IPCC report lays the foundation for how much greenhouse gases humans can emit through burning fossil fuels,farming and other activities,and still hope to prevent catastrophic warming.

This so-called carbon budget is actually a range of probabilities about how much cumulative emissions we have left to curb warming to a given temperature. The third tranche of the Sixth Assessment Report will go into more details about the most effective ways to avoid blowing the budget but that is not due out until March,well after November’s global climate summit in Glasgow.

The IPCC calculates anthropogenic emissions for the 170 years since the Industrial Revolution kicked off as 2.39 trillion tonnes of CO2,give or take about one-tenth of that. (1 trillion tonnes has been burnt since the IPCC reports began in 1990.)

What’s left to burn before we tick past 1.5,2 degrees or more actually starts from January 2020,so we have already exhausted almost 20 months of that budget.

As Alan Pears,an RMIT researcher who has advised governments on energy and climate policy for decades,says what budget you aim for “depends on how confident you want to be,and the target you’re aiming at”.

For instance,he highlights a 50-50 per cent chance of keeping global emissions to 500 billion tonnes of C02 to keep warming to 1.5 degrees,the ambitious end of the Paris agreement. At current rates of about 42 billion tonnes,the world has about 12 years’ to go until we reach carbon neutrality (net-zero emissions) with whatever pollution going up required to be captured in some form.

But as Pears notes,“if you hopped on an airplane and had only a 50 per cent chance of getting off alive,would you catch that plane?” At an 83 per cent chance of keeping to 1.5 degrees,the allowable budget shrinks to 300 billion tonnes of CO2,or a bit more than seven years’ worth of current-level emissions. (Non-CO2 greenhouse gases,such as methane,are excluded.)

What should Australia’s fair share of any carbon budget be? As Australia is a beneficiary of past unconstrained fossil fuel and land-clearing,one could argue the case that Australians have had our go already even if we were blissfully ignorant of the consequences until about 1990.

Pears says two other approaches would be to estimate what the budget would look like if we maintained our roughly 1.3 per cent share of global emissions in any reduction,or,more fairly calculated emissions based on our population of 25 million in a global tally of almost 8 billion.

If we were the most risk-adverse,taking the 83 per cent probability of hitting our temperature targets,then Australia has about 3.9 billion tonnes of CO2 left to burn,or about a decade’s worth,if we kept our current share. A fairer per capita share,though,leaves just 940 million tonnes in the kitty,or about two years’ worth of burning,Pears says.

And if we were willing to punt on merely a 17 per cent,or about one-sixth,chance of success? On that per capita gauge,Australia will still only be able to pollute for six years at existing rates before hitting net-zero if the 1.5-degree warming was our ceiling.

Negative emissions tech

With emissions rapidly declining in accordance with a carbon budget the report says,the best chance of stabilising the climate at or just over 1.5 degrees after mid-Century and hopefully see it begin to cool,demands we deploy technology that removes carbon dioxide from the sky.

So-called negative emissions technologies are like a break-glass-in-case-of-emergency last chance that crept into IPCC modelling as scientists worked on their last climate assessment,published in 2014. It wasn’t that anyone was drawn to the option,just that they could find no other way to keep the worst impacts of climate change out of their models.

The primary technology referred to in the report is known as Bioenergy with Carbon Capture and Storage (BECCS).

Yet to be proven at scale,BECCS envisages that plant matter is burnt for fuel and the resultant emissions captured and stored. This way the carbon absorbed by plants can be captured and sequestered.

It is far from an ideal solution. For it to work massive amounts of the world’s surface area - more than twice the size of Australia according to some models - would have to be turned over to growing plant matter destined for incinerators linked to carbon capture machines. Other technology being considered is known as direct air capture – machines designed solely to suck carbon dioxide out of the sky. Research published inNature Communications in 2019 found it possible that by 2100 a quarter of all energy generated may be dedicated to industrial-scale efforts like this.

Australian environmentalist Tim Flannery - who remains a climate optimist by sheer force of will - has written about negative emissions in his booksAtmosphere of Hope and The Climate Cure.

He sees possibilities in harnessing the properties of kelp,some species of which absorb carbon dioxide as it grows from oceans before sinking to the deep ocean floor.

Other possible drawdown technologies include grinding up and distributing silicate rocks,to which carbon dioxide from the atmosphere binds. This effort,Flannery notes,would be energy intensive in its own right.

Pinching a phrase from Al Gore,Flannery says that there is no single “silver bullet” solution to drawdown,rather there is “silver buckshot”. Many solutions will need to be harnessed and deployed. The scale at which this range of technologies will need to be deployed is “mind-blowing”.

The gap that negative carbon technologies will need to fill for us is around 10 billion tonnes of carbon dioxide per year until the end of the century if we are to stabilise and cool.

If it can be done,he says,we still don’t know what the world will look like.

“No one has ever run the[global warming] experiment in reverse.”

We know enough to try it though,he says. We know that if we get it right the world will be cooler. We know that the skies over cities will be clear. We know that the acid build-up caused by carbon dioxide in the seas could rapidly reverse,easing stress on species of crustaceans and corals.

Going over the figures and the extraordinary co-operative efforts and economic costs they suggest this week Flannery conceded that there is a “kind of madness” to the conversation.

“We know at the moment it costs about $250 a tonne to remove it,” he says.

“In a saner world it would cost more to dump the stuff in the atmosphere than suck it out.”