Strikes, protests and demonstrations have brought the climate crisis into sharp public focus, prompting governments to announce net-zero carbon targets for 2050 or earlier. But how realistic are these aims?

School-strike protests, Extinction Rebellion demonstrations around the world and impassioned speeches at the UN have helped bring the climate crisis into sharp public focus, prompting many administrations to announce net-zero carbon targets for 2050 or earlier. But how realistic are these aims, and do we have the technical, financial and organisational resources to achieve them?

It could come to be called the Greta Thunberg effect: the sudden and widespread realisation, in the closing months of this year, that immediate and far-reaching action is essential if the escalating crisis in the world’s climate is to be slowed down and eventually halted.

For while millions have been risking arrest on city streets in Extinction Rebellion-style climate protests and politicians continue to make bold promises to halt carbon emissions by 2050 or earlier, it has taken a quiet 16 year-old schoolgirl’s impassioned address to September’s United Nations Climate Summit in New York to finally bring the message home to the mass audience.

“Entire ecosystems are collapsing,” Greta Thunberg angrily told the delegates, after having first harangued them for expecting young people to solve the crisis. “We are in the beginning of a mass extinction and all you can talk about is money and fairy tales of eternal economic growth. How dare you!” On the evidence of the months that have followed, Thunberg has hit the nail right on the head.

Climate change shot to the front and centre of mainstream news coverage, multinational companies rushed to sign up to the UN Global Compact to keep the global temperature rise below 1.5 degrees Celsius, and the Bank of England governor rounded on international capital markets for backing projects that will result in planetary heating of over four degrees. At the same time the International Energy Association (IEA) calculated that offshore wind power could meet all the world’s energy needs several times over.

Pretty soon hundreds of organisations, from local councils to steelmakers, automakers, supermarkets and national governments, were competing with each other to make ever grander promises of zero-carbon futures and environmental good behaviour. But are these bold statements real commitments or just hollow public relations greenwash to tick the boxes of corporate social responsibility? And most important of all, if these promises are to be fulfilled, how is the carbon circle going to be squared, if at all?

“there are very different policy frameworks in different parts of the world, it is my view that it is the policy agenda that will really drive things”

“There is no doubt,” says Tim Curtis, managing director of Ricardo Energy & Environment, “that there are enough natural resources to generate all the energy we need. But it is more complicated than that. Finance plays a big part, and so does government policy – these crucial factors impact on whether a technology can be developed, invested in, applied, and to what level. “There are very different policy frameworks in different parts of the world,” he continues, “and it is my view that it is the policy agenda that will really drive things. Whilst technology can always be better, cheaper and more efficient, it’s much more about the commitment from governments and international agencies that will make this happen.”

Decarbonisation: energy

The challenge facing this most pivotal of all sectors is aptly summed up by Dr Fatih Birol, executive director of the IEA (International Energy Agency), in his comments on the organisation’s latest energy report: “What comes through with crystal clarity in this year’s World Energy Outlook is there is no single or simple solution to transforming global energy systems. Many technologies and fuels have a part to play across all sectors of the economy.”

Even with today’s policies and the ambitious decarbonisation targets announced by some governments, sustainability will not be achieved on current trends, says the IEA. The momentum behind clean energy technologies is building but is currently not enough to offset the effects of an expanding global economy and growing population. In an earlier report, the IEA calculated that offshore wind power has the potential to meet the world’s aggregate energy demand several times over: the Agency now counts wind power as the third key shift in the energy market, after shale gas and solar power. 

In the broader picture almost all GHG-producing fossil fuels must be eliminated to achieve zero net carbon. ‘Green’ hydrogen from electrolysis is widely regarded as the dream fuel, but until the electricity grid has sufficient renewable capacity to generate that hydrogen cleanly, natural gas could be useful as an interim source of ‘blue’ hydrogen – as long as the process includes carbon capture and storage (CCS) to keep the CO2 out of the atmosphere.

“If we had to decarbonise all the natural gas in Europe and convert it to hydrogen, that would remove about 800 million tonnes of CO2 per year or about 19 percent of current GHG emissions in Europe,” says Nils Anders Røkke, chairman of the European Energy Research Alliance. “That’s quite substantial.”

What does net-zero mean?

Achieving net-zero carbon effectively means ceasing to add to the stock of greenhouse gases (GHGs) already in the atmosphere – so any activities that still emit GHGs will have to be balanced by processes that remove those gases from the air. Natural carbon sink systems such as plants, trees, some soils and the oceans will of course continue to absorb GHGs, but their capacity to do so is limited and probably reducing. And the industrial CO2 removal technology that will be needed to complement natural absorption mechanisms is in its infancy and is unproven at scale.

The scale of the challenge is vast. According to the Global Carbon Project some 55 gigatonnes (Gt) of CO2 and other GHGs are emitted each year by everything from farm animals and home fireplaces to power stations, blast furnaces and transport systems. To absorb this through natural processes would require an area 20 times the size of the Amazon rainforest, according to AP News. 

Much has been made about the cost of tackling the climate crisis. Yet, argues Curtis, we need to look much further ahead than the next four- or five-year political cycle. “Yes, of course there is a cost of acting and investing. But what is the cost of not acting? It is 12 years since Sir Nicholas Stern said ‘The evidence on the seriousness of the risks from inaction or delayed action is now overwhelming. We risk damages on a scale larger than the two world wars of the last century’. And the case now is even more compelling – we need to act now to mitigate the catastrophic potential impacts of climate change, and the huge future cost implications. It’s challenging for the political policy agenda, I know, but the investment today is critical for the benefits we will see in 50 or 100 years’ time.”

The 2015 Paris Agreement brought a measure of commitment between nations on jointly reducing GHG emissions, albeit with some major emitters jumping ship, and many others lagging on their agreed timescales; Europe is leading by example when it comes to putting pro-climate promises into law, giving some hope that other global players may follow, and technology advances across a scattering of industry sectors offer the hope of carbon-free or at least low-carbon alternatives for today’s industrial processes. 

But will all this be enough to deliver on the widely hyped zero-carbon targets for 2050 or even earlier? 

“Historically,” says Curtis, “climate change has not really been on the agenda at the board level of most corporates, and it has largely been ignored by the finance sector. However, things are changing, and the Environment, Social and Governance (ESG) agenda has gained traction over the last couple of years, and this is beginning to unlock climate-related investment.” Also, Curtis adds, “I think that a lot of the corporate response to date has been about compliance. With the increased awareness of the ESG Agenda, and the impact of the Taskforce on Financial-related Climate Disclosure (TCFD), we are seeing major corporates and asset managers becoming concerned at the risks and opportunities as a result of climate change.”

“the evidence on the seriousness of the risks from inaction or delayed action is now overwhelming. We risk damages on a scale larger than the two world wars of the last century” 

His colleague James Harries, principal consultant, environmental evidence and data for Ricardo Energy & Environment, concurs: “Lack of progress tends to be a failure of political leadership – set the right policy framework and the rest will follow. “But also,” Harries argues, “it is a failure of individuals. Many of us understand the problem but still don’t take action to cut back on flights, car journeys, meat consumption and other carbon-intensive activities. Some people talk about the need to educate people, but even for people that understand climate change, cognitive dissonance can be huge.” 

Decarbonisation: industry

GHG emissions from industry are dominated by the large, energy-intensive branches such as steelmaking, cement production, and the various forms of materials processing. Another significant and rapidly growing contributor is the ICT sector, whose server complexes are major energy consumers. Further complications are the substantial sunk costs in legacy plants and equipment worldwide, and the slow pace and high cost of renewal with updated technology. 

Switching from dirty fossil fuels such as coal is already having a beneficial effect on both GHG emissions and air quality, but a major challenge will be to ensure that rapidly expanding economies such as India, China and Nigeria come onboard with this switch, too. Hydrogen could become an important player in a clean industry future and can in most applications directly replace natural or coal-derived gas.

However, the cleanness of hydrogen would be directly contingent on the availability of sufficient renewable energy for electrolysis or, as an interim condition, effective CCS provision to decarbonise hydrogen production from natural gas.

The Gupta steel empire, for instance, has set itself the target of 2030 to become fully carbon neutral across its activities.

Stretching the definition of industry to include agriculture and land management, significant changes will be required to achieve carbon neutrality; one of the key enablers in any such transition will be a big shift in human diet, away from high-impact foods such as meat and dairy, and towards more plant-based foods. In parallel with the eventual imposition of a moratorium on deforestation, this could lead to major reductions in GHG emissions from the farming sector, along with a win-win improvement in air, soil and water quality.

Decarbonisation: transport

Transport is the sector where the moves towards sustainability are most clearly visible. The migration to electric power for private cars is just beginning, aided – for once – by a certain amount of clarity at the political level on the phase-out of combustion-engined vehicles. But although battery technologies are now well established, the battle is not yet won: most of the legislative developments have so far been confined to Europe, and satisfactory solutions for commercial vehicles are some way behind. 

In the rail and urban mobility subsectors it is safe to assume that electricity and hydrogen will become the predominant energy vectors, though the now-familiar adage that a battery vehicle is only as green as the electricity it runs on will once more come back into focus. 

Shipping and aviation continue to present a dilemma. Aviation is growing unsustainably but probably represents the best potential application for expensive synthetic liquid fuels, while the turnover in shipping fleets is very slow and changes will take a long time to bring benefits. Potential green fuels could include batteries for short-haul ferries and green hydrogen and ammonia for longer voyages. 

In addition, both sectors are still relatively unregulated and untaxed – a disincentive to the application of clean technologies.

Carbon capture and storage (CCS)

The idea of negative emissions technologies (NETs) appeals to those who want to reduce atmospheric CO2 concentrations but prefer to keep disruption to existing industries to a minimum. How much we will be able to rely on NETs depends on timeframes. The paradox is that the earlier a net zero target, the more you need NETs but the less you can rely on them. Taking a zero-carbon target of 2030, NETs are not likely to help as governments estimate CCS will come onstream during the 2030s. For 2050 it is easier to envisage a role for CCS – indeed, the CCC says it is a requirement not an option. Nevertheless, debate continues over how much CCS can do, and there is uncertainty around costs and feasibility. 

The role of authorities

Greta Thunberg’s appeal to the UN summit could be seen as an urgent wake-up call to those with their hands on the levers of power and influence; a call to governments, NGOs, finance houses and industry regulators to work together. And thankfully, in recent years a new kind of linkage has emerged: an intermediary function that can bridge the divide between developed and developing nations – many of which find themselves on the front line of climate crisis effects. 

These intermediaries, well connected with governments as well as in the spheres of technology and finance, can help prime the pumps for climate funding, establish targets and pathways, and play a co-ordinating role. And, as Curtis explains, Ricardo Energy & Environment is a leading player in these initiatives, initiatives that lie at the core of the calculations underpinning the 2015 Paris Agreement: “We’ve supported Nationally Determined Contributions (NDC) implementation in 17 countries including Bangladesh, Nigeria, Myanmar and Thailand – these are basically action plans to reduce their carbon emissions.”

Countries are encouraged to update their UN climate commitments in 2020, taking into account outcomes and developments in the intervening period. Though technologies have certainly moved on since 2015, the evolution in climate finance is just as significant, as Tim Curtis again explains: “With the Climate Finance Accelerator approach, Ricardo’s experts have been able to bring together international financial institutions, government aid funding, banks and the countries’ governments. We see that collaboration and a ‘blended finance’ approach as a very significant part of the future.”

Principal sectors to decarbonise

The unlocking of climate finance through these new international mechanisms has the potential to kick-start a wide range of programmes across an even broader spectrum of nations. Many vulnerable island states, for instance, are already leading the way on reducing their own emissions but at the same time urgently need to adapt to the effects of climate change, while for industrial nations a major priority is to help mitigate the amount of GHGs emitted. And it is with the latter that the sectoral approach comes into play, with technical and organisational developments offering significant reductions in emissions of all types. 

The most important sector in this context is without doubt that for generating electricity and producing heat. However, Ricardo consultancy and engineering teams are active in almost every field, and in our ‘hitlist’ panels we take a quick tour of some key sectors to outline the principal issues involved and the steps that will be required to achieve a controlled descent in GHG emissions towards a 2050 zero-carbon goal.

Co-benefits of decarbonisation

The recent air quality emergency in Delhi provides a graphic illustration of how climate change – and especially global heating – can exacerbate the effects of existing pollution in densely populated areas, sometimes with tragic consequences. Air that is drier and hotter, and which remains static, tends to trap local pollution, especially particulate matter.

November’s report from the Lancet Countdown, examining the impact of climate change on human health, sounds an even more alarming note but also advises that climate mitigation policies would have almost immediate beneficial effects on health. A lot of the actions to address air quality will be the same as the ones that are needed to address the climate emergency, adds Ricardo’s James Harries. These might include transport measures such as electric cars and vans, hydrogen fuel cells for HGVs. “So it will be important for local authorities, etc, to take a holistic approach and to consider and accurately measure the potential co-benefits of climate actions,” he notes.


Whatever the timing for the commitment, even if it is as late as 2050, reaching net-zero carbon is a formidable task and will entail massive disruption to our lifestyles, how we live, how we travel, and what we eat.

“Yet,” asserts Harries, “achieving net zero is definitely theoretically possible, and we can show that the technologies and other measures exist to deliver it. But the question is how fast we can realistically move, and at what cost.”

The UK Climate Change Committee (CCC) is also clear on what is feasible: “it is technically possible based on current consumer behaviours and known technologies” [for the UK] to achieve a net-zero target by 2050. Even so, Ricardo’s Tim Curtis adds an all-important rider: “Net zero may be more challenging in other countries, but that doesn’t alter the fact that we can achieve huge reductions, globally, from current technologies. The socio-economic conditions and political will are more significant barriers than the technology.”

Some governments and NGOs are aiming for 2040, 2030, or even 2025; many of these targets are likely to be unachievable. But does that matter? Ambition and communicating the sense of urgency are important motivators, and those going fastest will help shift the centre ground to spur others into action.

But while individuals and local groups may be ready for change, inertia at higher levels continues to stifle initiative. Just 13 of the world’s 132 largest energy producers have made any commitment to reduce their GHG emissions to zero, according to a study conducted by the London School of Economics’ Grantham Research Institute on Climate Change, and the CCC warns that the UK’s role as a genuine climate leader now rests on tangible action – summing up the stasis that seems to be paralysing so many administrations. 

Yet, says Curtis, the signs are increasingly encouraging. “The mood has changed dramatically in the past six months, and there has been a breakthrough in the investment community. In the private sector, climate is going mainstream, and fund managers are now asking us where do we start, and what do we do? I love those conversations, because I know we have a pool of extremely talented consultants as well as the ability to understand our clients’ needs and then articulate clear proposals for action.” 

Decarbonisation: other factors

Energy use by the residential sector is another candidate for efficiency improvements: some studies estimate that one-fifth of global energy demand goes into heating and refrigeration. Already, in North America, residential cooling absorbs as much energy as space heating, and the position will worsen as weather extremes become greater and more frequent.

Taking the UK as an example, Ricardo’s Tim Curtis notes that decarbonising domestic heat is a major challenge because of the country’s inefficient housing stock.