Net Zero


The road to 2050

Paul Monks

Professor Paul Monks is the Chief Scientific Adviser (CSA) for the Department for Energy Security and Net Zero (DESNZ). As the CSA, he delivers independent and impartial scientific advice to Ministers and policy makers across the DESNZ portfolio. Paul also works closely with the Government Chief Scientific Adviser, other Departmental CSAs, and the Department’s Chief Economist, to strengthen the links within and across departments, encouraging effective engagement and knowledge sharing, and to support delivery of a robust evidence base to underpin DESNZ policy decisions.


  • Achieving net zero is a complex challenge requiring a systems approach
  • The UK was the first country to legislate for net zero
  • Achieving the necessary reductions in emissions requires a combination of social, technical and economic measures
  • Some sectors will be much harder to decarbonise than others
  • Research and innovation will be critical to delivering net zero by 2050.

According to HL Mencken, “For every complex problem, there's an answer that is clear, simple and wrong.” The challenge of net zero is a complex systems problem – and there are no simple answers.

The UK was the first country to legislate for net zero and is one of the few that still has mandatory legislative outcomes. In 2019, the Government increased the goal to 100% emissions reduction by 2050, compared to 1990 levels.

We work towards that goal through a series of carbon budgets set under the Climate Change Act. Carbon Budget 6 (CB6) has to be met by the mid-2030s. We are just beginning to think about CB7. The Climate Change Committee (CCC), as well as being the independent body that holds the Government to account, also links to the international process and the setting of Nationally Determined Contributions (NDCs).

Carbon Budget 6

CB6 set a goal of a 78% emissions reduction by 2037. The Government laid out the science and the policies to achieve that in the Net Zero Strategy that was published in 2021. The UK has a good track record globally with respect to decarbonisation: we have already achieved reductions of nearly 40% on 1990 levels. To meet the goal of net zero by 2050, though, we will require a greater rate of change.

The sector that has gone furthest in decarbonisation is power, with fuel supply second: other sectors such as transport and buildings have been much slower (Figure 1). And that gives a sense of where the challenges lie in the future. Electricity is a great story, renewables have grown strongly while the last coal station is about to be turned off – although we are still quite dependent on imported gas. Nuclear is an important part of the low carbon electricity mix.

Looking at the total amount of energy that we use, though, about 40% is used in transport, 40% in heating and only about 20% is accounted for by electricity. Much of the decarbonisation of the first two sectors will be through increased use of electricity. In fact, we will have to at least double electricity generation capacity by 2050. It will have to be low carbon and available 24 hours a day.

While technological change is required, success is also dependent on consumer behaviour change. This is a social problem as well as a technical one. Finance is also required. So this is a social, technical and economic problem. When we talk about this as a systems problem then, it is actually a system of systems problem in the UK and global context.

Green choices

Under Carbon Budget 6, 44% of the required emissions savings require the public to make green choices (Figure 2). So it is unlikely the target can be achieved by a purely technocratic approach to net zero: there will have to be a socio-technical-economic approach. As part of that we will need to work out what the correct mixture of production, storage and uses are to achieve a net zero society. That will include the different flows within the energy system, including hydrogen, synthetic hydrocarbon fuels, and the like, the different ways of storing that and the different ways of using energy, in a way that creates a balanced system. Many people do not yet understand the way the energy system – and much else – will change by 2050. It will involve a fundamental shift, from very carbon-intensive, centralised generation to a low carbon, more distributed system. The net zero world will be very different.

Research and innovation

The International Energy Agency said recently that, on the journey to the 2030 target, we already have 80% of the technologies that we need. Looking at the hardest to decarbonise sectors and looking forward to 2050, a great deal of research and innovation is still required. The IEA estimates that the technologies needed to deliver almost half of the CO2 reductions required are still in prototype phases.

Figure 1. Sectoral reduction in emissions (%)

If net zero transition is to be sustainable and resilient, progress must be measurable, so that we can see the distance travelled. Deliverability is primarily an engineering challenge. We have the technologies to decarbonise the power system by 2035, but we have to roll them out. Part of that is a matter of scalability but there are some key science challenges as well.

These include hydrogen as well as carbon capture, use and storage (CCUS), and negative emissions (which people rarely talk about). There is the challenge of sourcing critical minerals as we move away from fossil fuel feedstocks to electrification. Resource and energy efficiency is an enormous problem that is continually overlooked. There are significant issues around agricultural emissions – this will be a very tricky sector to decarbonise.

Net zero is not just a mitigation problem, there is adaptation to address as well. This includes achieving the behaviour changes and green choices needed.

The Government has published its UK Net Zero Research & Innovation Framework, which takes a systems approach. It recognises that much of the decarbonisation programme is underpinned by digital technologies. The crucial role of finance is also detailed. And let us not forget the role of skills in delivering a sustainable net zero future.

Net zero is so pervasive through everything we do that only a systems approach will work. Research and innovation will be critical to delivering the outcomes that we need.

Figure 2. People are concerned about climate change and will need to take action themselves