We have covered the United Nations Framework Convention on Climate Change (UNFCCC) Paris Agreement of 2016 and the Intergovernmental Panel on Climate Change (IPCC) ‘Special Report on Global Warming of 1.5°C’ (SR15) of last October in a number of IFRF’s blogposts over the last few years.  However, the terminology regarding mitigating climate change has changed radically over this time:  Talk of “transition to low-carbon”, “X% reduction in CO₂ emissions by year Y”, “carbon budgets” and even “decarbonisation” has largely been superseded by talk of “net-zero emissions” –  it’s a term on everyone’s lips, from governments, city mayors and CEOs of global companies to Extinction Rebellion and school children!

Through various updates in our Monday Night Mail e-newsletter and Combustion Industry News blogs, we have tried to keep you posted about the rapid pace of developments in so-called ‘net-zero’ legislation, strategies, policies and targets for different regions, countries, cities and companies.  But what does it all mean?  What emissions?  Are these targets comparable?  What are the technology and other options?  Can it all be achieved more quickly?  In this blogpost, we aim to ‘lift the lid’ on some of these questions.

Firstly, for the sake of this blog let’s assume that we are all broadly on the same page when it comes to what the latest research is saying about human-caused (anthropogenic) greenhouse gas (GHG) emissions, their impacts on global warming, and what this is likely to mean in terms of climate change and associated impacts.  The ‘bottom line’ is that in order to avoid the worst climate impacts, global GHG emissions will not only need to be halved in the next decade, but they will then have to reach carbon neutrality (i.e. net-zero carbon emissions) by around the middle of this century.

So, what does ‘net-zero emissions’ mean?

We are not talking about ‘gross-zero’ targets, which would reduce emissions from all sources uniformly to zero, but about ‘net-zero’ targets –  more realistic because they allow for some residual emissions.  We will achieve net-zero emissions when any residual anthropogenic GHG emissions are balanced out by removing GHGs from the atmosphere – a process generally referred to as ‘carbon dioxide removal’ (CDR).  To achieve such a balance, it will be vital to reduce anthropogenic GHG emissions to as close to zero as possible, with any residual emissions counterbalanced with an equivalent amount of CDR (e.g. through reforestation or ‘negative-emission’ technologies such as bioenergy with carbon capture and storage (BECCS), direct air capture (DAC) and storage, etc.).

It is important, here, to make the distinction between net-zero CO₂ and net-zero GHG (i.e. including methane, nitrous oxide, hydrofluorocarbons, etc.) emissions, as some of the non-CO₂ emissions are generally considered somewhat more difficult to address.

Did the Paris Agreement foresee the need for net-zero emissions?

Put simply, yes.  Although the ‘headline’ (temperature) goal of the Paris Agreement is to limit average global warming to well below 2°C – and ideally below 1.5°C – compared to pre-industrial levels, the Agreement also has a long-term goal of achieving “a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of this century, on the basis of equity, and in the context of sustainable development and efforts to eradicate poverty.”  This balancing of emissions and removals is akin to reaching net-zero GHG emissions.

How do we achieve net-zero emissions?

It is clear that achieving net-zero will need policy, technology and behaviour to change across the board.  Analysis of pathways that would limit average global warming to 1.5°C above pre-industrial levels generally see renewable energy sources supplying 70-85% of global electricity supply, huge improvements in the efficiency of energy use across all sectors, fuel-switching measures in transportation, improving the efficiency of food production, changing dietary choices, halting deforestation and restoring degraded land, and reducing food loss and waste.  The good news is that most of the technologies needed to effect such changes are already available and are becoming increasingly cost-competitive with incumbent, higher-carbon alternatives.  However, additional investment and development will be needed in CDR and the associated technology solutions.

The World Resources Institute has summarised nicely 10 key solutions needed to reduce GHG emissions as follows:

1. Phase-out coal plants
2. Invest in clean energy and efficiency
3. Retrofit buildings
4. Decarbonise cement, steel and plastics
5. Shift to electric vehicles
6. Increase public transport
7. Decarbonise aviation and shipping
8. Halt deforestation and restore degraded lands
9. Reduce food loss and waste
10. Eat more plants and less meat.

When does the world need to achieve net-zero emissions by?

As stated above, the Paris Agreement commits those countries that ratify it to achieving net-zero GHG emissions “in the second half of this century”.

The latest scientific research on mitigation pathways, presented as part of the IPCC’s SR15, suggests that in order to meet the Paris Agreement’s temperature goals, the world will need to reach net-zero emissions on the following timelines:

• In scenarios that limit warming to 1.5°C: CO₂ reaches net-zero on average by 2050 (in scenarios with low or no ‘overshoot’) to 2052 (in scenarios that have high overshoot, in which temperature rise surpasses 1.5°C for some time before being brought down); total GHG emissions reach net-zero between 2063 and 2068.
• In 2°C scenarios: CO₂ reaches net-zero on average by 2070 (in scenarios with a greater than 66% likelihood of limiting warming to 2°C) to 2085 (50-66% likelihood); total GHG emissions reach net-zero by the end of the century.

SR15 analysis also indicates that if the world reaches net-zero CO₂ emissions one decade earlier, i.e. by 2040, the chances of limiting warming to 1.5°C are considerably higher.  The sooner  emissions peak and the lower they are at that point, the more realistic it is that the world achieves net-zero in time to avert the worst impacts of climate change.  We would also need to rely less on CDR in the second half of the century.

As a result of this realisation and its urgency, UN Secretary-General António Guterres wrote to every head of state in July, demanding that they set out plans to achieve “carbon neutrality by 2050” in advance of the UN Summit in New York in September, at which they were due to present concrete proposals to accelerate the pace of decarbonisation.  Although the Summit was regarded as somewhat disappointing (see our CIN blog of 30^th September), 77 nations did pledge to reach net-zero emissions by 2050, albeit excluding the USA and China.

Do all countries need to achieve net-zero at the same time? 

The answer is no, the above timelines are global averages.  As different countries’ economies and stages of development vary widely, and they have different ‘starting points’ and physical resources or technologies available, there is no ‘one-size-fits-all’ timeline for all countries.  That said, there is a physical limit to the total emissions inventory that the atmosphere can support while limiting the average global temperature increase in line with the Paris Agreement (see IFRF blog on ‘The trillionth tonne and why we can’t release it’ of November 2017’:  As a consequence, it is vital that major emitters such as the USA, China and the EU reach net-zero GHG emissions by 2050 or else it will be hard to make the maths work regardless of what other countries may do.  Also, given their dominant effect in determining global emission trajectories, it would be ideal if such major emitters reach net-zero much earlier.

What progress has been made in setting net-zero targets? 

There is an accelerating momentum towards net-zero targets around the world.  As of today, 16 countries have adopted net-zero GHG (unless otherwise indicated) targets:  two (Bhutan and Suriname) are already negative emission economies; four have targets enshrined in law (Norway, Sweden, the UK and France); two are in the process of developing legislation (Chile and New Zealand); and eight have targets set within policy documents (Uruguay (CO₂ only), Finland, Iceland (CO₂ only but also references measures covering other GHGs), Denmark, Portugal, Costa Rica, Fiji (as for Iceland) and the Marshall Islands).  In addition, Germany, Spain, the Netherlands and Ireland – as well as the EU as a bloc – are currently discussing targets.  As can be seen from the Energy & Climate Intelligence Unit (a UK not-for-profit organisation) ‘Net-Zero Scorecard’ for 2019, while the majority of these countries have 2050 as the date by which net-zero will be achieved, Norway and Uruguay are targeting 2030, Finland 2035, Iceland 2040 and Sweden 2045.

Furthermore, Canada, Colombia, Ethiopia, Luxembourg and Mexico – along with many of the countries listed above – are members of the Carbon Neutrality Coalition (CNC), members of which have committed to taking concrete and ambitious actions “in-line with the agreed long-term temperature increase limit… well ahead of 2020”.  From the CNC ‘Declaration’ and ‘Plan of Action’, it isn’t entirely clear whether net-zero in this context refers to CO₂ (as per the Coalition’s name) or GHGs (as the website broadly implies).

As well as individual countries, a number of ‘states’ have committed to net-zero GHG targets:  the US states of California, Hawaii and New York; the Australian states of New South Wales, Victoria, Queensland and Tasmania, plus the Australian Capital Territory; Scotland (UK); and Catalonia (Spain).  Of these, California, Hawaii, ACT and Scotland have targets for net-zero emissions by 2045, with the others targeting 2050.  To date targets are enshrined in legislation in California, Hawaii, Victoria and Catalonia, with legislation pending in New York State and Scotland.

Moreover, at least 21 cities have already set net-zero GHG targets of 2050 or before (New York City, Los Angeles, London, Washington DC, San Francisco, Seattle, Sydney, Boston, Paris, Stockholm, Barcelona, Copenhagen, Austin, Melbourne, Helsinki, Manchester, Oslo, Nottingham, Adelaide, Bristol and Heidelberg).  Some of these targets have very challenging timelines – particularly Adelaide and Copenhagen at 2025, Nottingham at 2028, Bristol and Oslo at 2030, Helsinki at 2035, Manchester at 2038 and Stockholm at 2040.  Around 90 other cities have committed to set net-zero targets to be reached by 2050 before the end of 2020 as part of the C40 ‘Deadline2020’ initiative, led by city mayors.

Lastly, at least 34 companies with annual revenues in excess of $1 billion have committed to net-zero GHG targets by 2050.  The list includes Google, Microsoft, Siemens, Bank of America, Bosch, ENI, ArcelorMittal, Sony, Unilever, etc.).  Some of these companies claim to have met the target already (Google, Microsoft, Avis and Lyft), while others are anticipating being net-zero GHG emitters as soon as 2020 (Bank of America, Bosch, Philips and Evian).

A wider initiative, the Climate Ambition Alliance, launched at the UN Climate Action Summit in September, has secured commitments from 102 cities, 10 regions, 93 businesses and 12 investors to reach net-zero CO2 by 2050.  While there is considerable duplication between this alliance and the net-zero GHG initiatives listed previously, the developing momentum is impressive.

While there are new countries, ‘states’, cities and companies announcing net-zero CO₂ or GHG targets every month, the proportion of global emissions covered by some form of net-zero target remains relatively low at around 5%.

Can we accelerate the timescales to net-zero?

The long-term goal of the UNFCCC’s Paris Agreement, coupled with the analysis behind the IPCC’s SR15, point towards the need to achieve global average net-zero CO₂ emission by around 2050, and global average net-zero GHG emissions by around a decade later, if average global temperature rises are to be limited to 1.5°C.  The targets adopted or likely to be adopted by the countries, states, cities and companies above appear to match this imperative.  However, as stated above, only around 5% of global GHG emissions are ‘covered’ in these commitments, and the USA and China have not committed to net-zero.  Also, despite the best of intentions, some of these commitments will not be realised, some of the targets not attained.

Given this, and given the benefits of attaining net-zero earlier (i.e. in terms of increasing considerably the chances of limiting warming to 1.5°C and having to rely less on the more difficult/expensive CDR options later), what scope is there to foreshorten the timelines of the net-zero targets?  Certainly, this is the challenge promoted by the Extinction Rebellion movement, amongst others, which point to the need to declare a ‘climate emergency’ and achieve net-zero GHG emissions by 2025…

Achieving net-zero emissions is a complex challenge with technical, economic, social, ethical and geopolitical dimensions.  As stated above, for individual countries, states, cities and companies it also depends on what their starting point is, and what resources and technologies they have available.

Personally, I think that some targets could be tightened somewhat (although others appear to me to be very challenging already).  Also, as national policies mature in the face of increasing climate change impacts, technology options develop further (and their technology- and market-readiness increases) and our own individual (and hence societal) behaviours shift, there is likely to be scope for more ambitious targets.  For the UK – which I know best – my view is that the current legally-binding net-zero GHG emissions by 2050 target could be tightened – perhaps brought forward to 2045 or even nearer to 2040 . What about Extinction Rebellion’s 2025 date?  I think that such a short timeline is unrealistic:  Some of the technologies to deliver net-zero GHG emissions don’t yet exist, some of those that do can’t physically be built in time, and it takes decades for planted trees to grow.  Let alone the economics…!

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