Net Zero


Urgent and ambitious action needed to tackle this challenge

Jim Skea

Professor Jim Skea CBE was elected IPCC Chair for the Seventh Assessment cycle in July 2023. He was Co-Chair of IPCC Working Group III for the 6th Assessment Cycle. From 2009 to 2023, Jim Skea was Professor of Sustainable Energy at Imperial College London. His research interests are in energy, climate change and technological innovation. He was Research Director of the UK Energy Research Centre 2004-12 and Director of the Policy Studies Institute 1998-2004. He has operated at the interface between research, policy-making and business throughout his career.


  • Greater action is urgently needed now
  • We are not powerless, we have the means to effect change
  • Without a focus on equity, the required consensus will not be achieved
  • Equity – in terms of just transition – is relevant nationally as well as globally
  • Net zero is not just about a date but also about cumulative emissions on the journey

The global messages of the Intergovernmental Panel on Climate Change (IPCC) can be summarised under three headings: Urgency, Agency and Equity.


Climate change is already upon us, we can see that plainly. In terms of emissions at a global level, we have bent the upward trend, but they have yet to start a downward path – and certainly not the steep downward path that we need to achieve net zero. Yet unless we get to net zero, global temperatures will continue to rise because of the cumulative nature of emissions.

Should warming go beyond 1.5˚ C, new risks will emerge: permafrost degradation; water scarcity in dry land areas; more extreme weather events; and potential damage to the productivity of food systems. Sea level rise, which is almost inevitable, is an existential threat for small island states and low-lying coastal areas.


Without immediate ambitious action, there are threats to planetary health and human systems. Now, that can easily turn into a message of despair. However, the IPCC has been very clear that we should not let the evidence provoke a sense of paralysis or lack of agency. We do have tools available, and if we deploy them we can avoid the worst impacts.

The world has already started to make progress on renewable energy – wind, solar, etc – and China has some of the biggest investments in all of these. On another front, the biggest deployment of electric vehicles globally is in China.

One thing that is clear, though, is the concentration of success in China, North America and Europe. There is a need to spread that more widely geographically, especially to developing countries such as in Sub-Saharan Africa, where much more investment in infrastructure is needed in order to enable the rollout of renewable energy.

In terms of successes, significant progress is being made on land-based measures, especially reforestation but also avoided-deforestation.

Significant progress is also being made on governance. We have the policy tools available to move us forward. More than 50% of global emissions are already covered by climate laws, policies and institutions. About a fifth of global emissions are covered by some kind of carbon pricing.

The tools are available then and there is enough money in the world – even though that means trillions of dollars – to deal with the challenge of climate change. But it means starting to get private sector funding to supplement funds from the public sector. So we have the technologies, we have the knowhow, we have the money – we just need to put them all to use.

A word of caution, though. So far, we have only achieved the easy wins. It may be a major engineering challenge to design and construct a 1GW offshore wind farm, but the really difficult challenge is to implement measures that involve changes to people's lives. The future challenges around transport, housing and diet will all be much more difficult.


Why should we be concerned about equity? Well, perhaps because it is simply the right thing to do. There is also, though, a pragmatic reason. Unless the actions we take are perceived to be fair, they will not gain the consent necessary for the transition to occur.

China has made some of the biggest investments in renewable energy such as solar power. 

There are two dimensions to equity. One is the global perspective: equity between the global south and the global north. The last IPCC report set out the facts about the cumulative historical emissions of greenhouse gases and also the wide variation in per capita emissions in different parts of the world. Those who are most vulnerable to the effects of climate change are those who have contributed least to the problem.

That is why there are three interlocking goals within the Paris Agreement. There is the long-term temperature goal, but also goals on adaptation and finance. We cannot achieve where we want to go without taking account of the whole package.

The symbolism of commitments like the $100 billion from developed countries is incredibly important. Now, Loss & Damage will come up as an issue again at COP28.

There is another dimension to equity, which pertains to national and sub-national perspectives. There are obviously big economic opportunities associated with a low carbon agenda, but also risks for those in declining sectors and the communities that host these economic activities.

There are also impacts on consumers. A feature of low-carbon transition is that it is capital intensive. You need to put money up front in order to lower the long-term costs. Who is going to pay for this will be absolutely critical.

At both the national and sub-national levels, how ‘just transition’ plays out for employers, employees and also consumers is important. But a transition that is perceived as just is a prerequisite for consent and effective change.

Net zero

When discussing net zero, the first thing to note is that it is not solely a matter of the date when that occurs, but also the cumulative emissions incurred on the journey. The pathway matters. Delayed action means the world will be warmer than it otherwise would have been.

Secondly, the reserves of fossil fuels in the ground would exceed the carbon budgets for the long term temperature goal in the Paris agreement if they were all burned. Some 80% of coal, 50% of gas, and 20% of oil current reserves need to stay in the ground to limit warming to 2˚ C – a very stark number. Therefore, any addition we make to reserves just creates more acute problems for future policymakers, who may have to choose between the economic revenues that they get from burning the fuels, versus actually meeting the Paris targets.

In summary, we are in a difficult and dangerous place and action is needed urgently. But we are not helpless, we have the agency to pursue our goals. Finally, paying attention to equity is essential if we are going to build the consensus to effectively combat climate change.