Twentieth-century wealth was built with ever-expanding quantities of fossil fuels. Their widespread exploitation and availability was critical to growing economies, to increasing international travel and to emerging globalisation.

And yet a majority of humankind has come to realise the quicker the world stops their use in the 21st century, the sooner economies get on a path to long-term sustainability and have some chance of avoiding climate disaster.

For doubters, look at the latest financial turmoil within oil giants such as Exxon and BP as they are forced to face up to that new reality. Clobbered by Covid-19, they are facing a storm as activist shareholders demand they focus more on renewable fuels and pivot away from their fossil-fuel legacy. The world looks on, horrified as more details emerge about their irresponsible behaviour when they knew the consequences of their role in overheating Planet Earth.

There is widespread acceptance of the need for accelerated action, especially in the coming decade, to have any chance of achieving “net-zero” carbon emissions by 2050 – when any remaining human-caused greenhouse gases must be balanced out by removal from the atmosphere.

For too long countries did not face up to their obligations. Some let climate denialism cloud the picture while continuing to rely on cheap oil and gas, but much has changed in a matter of months.

US president Joe Biden has committed the US to net-zero, intends to decarbonise the US electricity grid by 2035, end subsidies for fossil fuels and spend $2 trillion on “green” measures. Factor in the European Green Deal, and “green finance” is set to become the dominant global investment arm. Not so long ago, we wondered whether clean energy could survive without lavish government support. Now the question is how far it can spread and how cheap will it go.

Financial pain

How to get to carbon neutrality is the crucial issue and choosing the exact route is full of hard choices that will initially be inconvenient, if not financially painful. Technologist, business leader and philanthropist Bill Gates seeks to set out a strategic path for each of the key influencers/actors in driving decarbonisation – consumers, employees, employers and politicians.

Each player’s role is laid out in accessible language, yet it necessitates a complex, well-timed interaction of forces, where a “green premium” is applied at every turn. This is his mechanism to determine the cost for each sector of switching to a green alternative, such as changing from oil/gas boilers to heat pumps in warming homes. Degree of difficulty becomes immediately obvious; the extent to which the premium is lowered the key indicator of progress.

Environmentalist Bill McKibben has described where we are right now: “The elements are now in place for truly rapid action, but success will require going far faster than economics alone can push us, and far faster than politicians will find comfortable . . . our best chance to take the actions that will end the trajectory of rising emissions comes this decade.”

Having spent a decade investigating causes and effects of climate change, Gates is starting out from this juncture. His strategy amounts to an unprecedented orchestration of climate actions by each of those elements pushing for change and abandoning carbon pollutants.

This has to be facilitated by governments underwriting risk and funding research, and markets buying in, to achieve clean energy. Achieving carbon-free electricity first can help decarbonise lots of other activities, like how we get around and how we make things.

Climate puritans

He acknowledges the technology gaps in getting to net-zero, while some attempts to address this by capturing carbon or inventing new fuels will fail. Without innovation, using more renewables won’t be enough to get us all the way to zero.

Gates risks antagonising climate puritans advocating sharp decarbonisation and degrowth, as he contends this provides insufficient time for recasting energy-intensive lifestyles.

He is upfront in admitting he is “an imperfect messenger” who owns big houses, flies in private planes and launched Breakthrough Energy to commercialise clean energy and climate-related technologies including “just too promising to ignore” possibilities from using nuclear energy.

Half-hearted and slowly adopted actions won’t work – “a 50 per cent drop in emissions wouldn’t stop the rise in temperatures, it would only slow things down, somewhat postponing but not preventing a climate catastrophe”.

He acknowledges where alternatives are not yet in place, though his optimism suggests it’s all doable. So natural gas will be required for a while though its use has to end. His assessment of potential “breakthrough technologies” is brilliantly outlined, as are implications of success at scale. If we get a breakthrough in cheap hydrogen, we might not need to worry as much about getting a magic battery.

Carbon capture and storage is the only effective way in the short term to prevent heavy industries and some production processes from continuing to pour emissions into the atmosphere. He is betting on unproven “direct air capture” sucking carbon dioxide out of the atmosphere; “it would allow us to capture carbon dioxide no matter when or where it was produced”.

His grand plan is reinforced by frank commentary: “virtually all zero-carbon solutions are more expensive that their fossil-fuel counterparts”. As the world’s population grows and get richer, new ways have to be found to produce cement, steel and fertiliser with radically less carbon, including “low emission meat”.

Early chapters include well-crafted explainers on climate disruption, the case for net-zero, energy dynamics and the scale of what’s needed. It culminates in “what each of us can do”, a pragmatic guide without heaping guilt on individuals. It ranks among the best climate action handbooks on where we need to get to, informed by sound science and strategic thinking, while accepting many unknowns.

Earth damage

The eminent theoretical physicist Lawrence Krauss applies fundamental physics to show how human activity has damaged the Earth up to this point. Charting the Earth's natural cycles over billions of years, he unthreads the factors contributing to a radically altered atmosphere arising within the blip of the past 200 years.

The first half of his book is a forensic account of the physical forces involved, and how understanding of their interaction emerged. The chief antagonist is “radiative forcing”; the additional radiation due to excess CO2 in the atmosphere that is radiated back down towards Earth, causing warming.

Krauss admits this requires the knowledge of a physics undergraduate but “what we know and why” summaries are helpful and enable the non-specialist reader to ask reasonably: how did we let it get to this?

He justifies the detail because science needs to be explained comprehensively and humanity must know. “Climate change, evolution and the Big Bang are all empirical facts, not speculation, and the relevant data validate fundamental theoretical expectations.”

More alarming aspects arise when applying that knowledge to “climate modelling”. Even if carbon production stops soon, elevated temperatures are likely until 3,000, it indicates, unless new technology to remove carbon is found, “or geoengineering that manipulates the atmosphere on a global scale to otherwise remove the radiative forcing that already exists”. While modelling may be speculative, a likely sea-level change of several metres in a few centuries “is not implausible”.

Drastic effects

The climate modeller’s lot is challenging in attempting to predict with accuracy “feedback loops” that may amplify or diminish “climate forcings”. He explains: “When this happens, predictive capabilities are rapidly lost. So goes the famous example of chaos, where a butterfly flaps its wings in Kansas, ultimately causing a tornado to rip through Nebraska.”

Likewise in trying to anticipate tipping points, when large climatic changes may trigger drastic effects that once set in motion are likely to be irrevocable. What’s happening in the Arctic, notably the rapidly melting Greenland ice sheet, and in the Antarctic, are viewed through this prism.

Kraus admits he is talking of a future that might be. But any of these effects could have a short-term impact more devastating than “the slow and steady rise in global temperature might otherwise suggest”.

These distinct risks could be small or, in combination, cause devastation. The critical question is whether it’s enough to convince politicians and the public “we need to act globally now”. That is if it is not already too late.

Citing the likely fate of the Mekong river delta in this scenario, he is not optimistic, “but neither do I see us travelling down an inexorable road to oblivion”. The future is charging at us like a freight train, on tracks we have built. There is time to divert it “or perhaps build a bridge so it safely bypasses us”.

Like Gates, he believes technological ingenuity combined with rational action, tempered by empathy and support for the most vulnerable, might just do it.

Kevin O’Sullivan is Environment and Science Editor