Net Zero vs Absolute Zero

The majority of official climate targets, put in place via the Paris Agreement and during various climate conferences, are based upon the concept of ‘net zero.’ Many countries across the world have pledged to achieve net zero anytime between 2035 and 2060. However, net zero is not the only model on which we can base our reduction of emissions. The concept of ‘absolute zero’ has also been introduced, asking the question: which should we follow to effectively prevent further global warming?

As news recently emerged that the world has surpassed 1.5 degrees of global warming consistently over a whole year[1], more may be required than net zero. In this article, the Institute will explore the advantages and disadvantages of both concepts.

What do these concepts mean?

Net zero and absolute zero can be attributed to countries as per climate targets, but also smaller entities such as companies and organisations.

Net Zero

Under net zero, an entity will ensure that they are not increasing the levels of greenhouse gases in the atmosphere through two courses of action. The first is to reduce emissions, for example by using renewable sources of energy over fossil fuels.

The second is to use processes to balance out any remaining emissions, such as using carbon capture, usage and storage (CCUS) or purchasing carbon credits.

Through this method, the levels of greenhouse gases in the atmosphere will not increase and existing levels will be slowly reduced through natural means, such as absorption via forests.

Net zero is sometimes also described as carbon neutral, however this only applies to emissions of carbon dioxide and not other greenhouse gases, such as methane or hydrofluorocarbons.
Companies that claim to be carbon neutral include: Sky Media, Google and Quorn.

Absolute Zero

Absolute zero goes further than net zero. Under this scenario, no emissions are created by a country or organisation at all and as a result there is no need to balance or remove remaining emissions. This applies to the entire value chain of a company or country; i.e. it must take into account any emissions produced by suppliers or consumers as well.

As such, this is much more difficult to achieve in general and potentially impossible for some sectors.

Absolute zero can also be described as carbon negative, but again this only applies to carbon dioxide emissions. To be described as carbon negative, a company must remove more carbon from the atmosphere than they create.
Microsoft have announced that they plan to be carbon negative by 2030.

Why should we aim for net zero?

In short, we cannot solve the climate crisis without trying to work towards net zero. The IPCC has made it clear that reaching net zero is non-negotiable if we want to prevent further global warming. Simply reducing emissions will not be enough.

Climate related disasters, such as floods and wildfires, are already impacting people across the world and there is no telling what further warming may cause. The presence of high levels of greenhouse gases in the atmosphere also has a direct impact on our health with early deaths due to air pollution currently at 7 million per year globally.[2] The World Health Organisation (WHO) highlights that the populations of South-East Asia and Western Pacific Regions are disproportionately affected by this issue; however WHO reports have also shown that as much as 99% of the global population live in areas where air quality does not meet healthy guidelines, showing the vast scale of the issue.[3]

Net zero is a useful concept, in that it provides a specific target to work towards and a goal post against which we can measure progress and the effectiveness of projects. For many countries, net zero targets have been signed into law which further increases the effectiveness of this. Working towards a shared target also allows for collaboration and idea sharing between entities to help us reach the goal faster.
You can read more about the benefits of global collaboration on climate issues here.

What are the barriers to net zero?

Achieving net zero is not a simple task; many small organisations and developing countries do not have the means to put the required infrastructure in place. As with most aspects of the climate crisis, funding is a major issue that stands in the way of success. For a country to become net zero, every aspect of society must be decarbonised; from transport, to housing and agriculture. Decarbonising each of these sectors requires a huge amount of money and mobilisation.

Critics argue that the carbon offsetting projects required under net zero provide an excuse to avoid reducing emissions further. For example, oil and gas companies can publicly invest in carbon offsetting or other methods yet still plan to increase the levels of fossil fuels they produce. Carbon offsetting focuses on the fact that we can remove what we emit, rather than the idea that we should take all possible actions towards not emitting in the first place.

Net zero

Although the concept of carbon capture has been around for over a century, CCUS technologies are still relatively new and require further work and research for them to reach their full effectiveness. Furthermore, these technologies generally focus on removing specifically carbon dioxide from the atmosphere; this does not account for other harmful greenhouse gases, such as methane, which continues to be emitted but cannot be recaptured in the same way.
You can read more about CCUS here.

Under net zero, the levels of greenhouse gases in the atmosphere will not increase. However, considering that we are already experiencing dangerously high levels now, this only serves to stop the situation worsening, it may not improve the situation. As mentioned, remaining gases in the atmosphere can be reduced via natural processes, but this may take a long time.

Should we be pushing for absolute zero instead?

If net zero aims to maintain the balance in terms of emissions, should we not be aiming higher? To actively remove greenhouse gases from the atmosphere and return to past levels?

Absolute zero does not rely on breakthroughs in carbon capture technologies as mentioned above and ensures that the main focus is placed on reducing our emissions rather than negating them.

By choosing to aim for absolute zero we can therefore reduce the levels of greenhouse gases in the atmosphere at a faster rate and begin to heal the damage that has already been caused by rising temperatures.

What are the barriers to absolute zero?

Absolute zero would require a world in which we use no fossil fuels and derive all of our energy needs from renewable generated electricity. Likewise, all transport would need to be electrified. In a world generally motivated by convenience, this would be a drastic change and likely unpopular to begin with, as people adapt to these significant changes.

For certain sectors, such as aviation, agriculture and shipping it is extremely unlikely that all emissions can be negated. In these cases, carbon offsetting is the only course of action, unless we learn to live without these until technology is developed that can make them emission free. However, with our reliance on these sectors, for food imports and exports, it is unlikely that society could effectively make this change. Another such example is the use of cement; at this time, the process to create cement cannot adhere to absolute zero. However, it would be very difficult for society to progress without cement for infrastructure, including the realisation of renewable energy projects.

As with net zero, absolute zero relies heavily, and perhaps even more so, on funding and technology.

There are no official targets put in place by law to achieve absolute zero, therefore this falls upon individual organisations to assess if it is possible. The collaborative aspect mentioned in relation to net zero is therefore also lacking.

What can we take away from all of this?

In an ideal world, each country and company worldwide would be aiming to achieve absolute zero within the next couple of decades. However, we have seen how this is not realistic due to barriers including funding, shortfalls of technology and a human reliance on certain sectors. It is still not obvious how countries will reach their net zero targets, never mind surpassing this to reach absolute zero.

This does not mean that we should disregard absolute zero, but embrace it where we can.
For those that are able to reach net zero, absolute zero then provides another goal to work towards to ensure that they do not become complacent or back track on their progress. Commentators have argued that those entities that can achieve absolute zero should do so in order to carry the shortfall of those who cannot.

It is unlikely that we will reach absolute zero worldwide using current technology, however a mixture of absolute zero and net zero may be the answer to halting the climate crisis in its tracks.

Be part of the fight against climate change by enrolling on the REI’s accredited Net Zero Consultant Expert Certificate. Combining our Global Energy Transition, Hydrogen Energy and Electric Vehicles courses, this pathway will help you delve further into how we can reach our climate goals.

You can also learn more about carbon accounting and CCUS in the accredited Carbon Finance Consultant Expert Certificate. Providing access to 3 accredited courses and 80 hours of continuous professional development hours, this is a great starting point for those looking to start or grow a career in the carbon sector.