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Carbon jargon: What net zero really means and how we can achieve it


Ryan Borrett


January 2022

Just like the world we live in, words are always evolving, flowing and changing shape. The transient nature of language becomes particularly heightened when attached to topics in the global spotlight: news articles, research papers, social media, political policy, memes, advertisements and entertainment all stretch and pull words away from their roots, which can often be hard to trace.

The buzzwords, slogans and jargon attached to the climate and biodiversity crises are no exception – indeed they are notoriously slippery and prone to malleability. As scientific research on climate change is discussed, debated, and shared along new avenues, its language can easily be stripped of its original intent, and, often, its meaning. A prime example of this is a term we hear every day in relation to climate action: net zero.

What is net zero?

The focal point of climate policy in recent years, net zero has featured strongly in headlines in 2020 and 2021 as climate ambitions became formalised and its narrative was adopted by more countries and organisations than ever.

Essentially, net zero means that what goes out must come back in. In a net zero world, if a tonne of carbon dioxide is emitted into the atmosphere from human-generated sources like fossil fuels and land-use change, a tonne of carbon dioxide must be deliberately removed from the atmosphere. The flow of carbon from human-generated sources, like fossil fuels and land use change, must balance on aggregate with carbon being drawn down into carbon sinks.

But what’s a carbon sink? These are natural carbon sponges that absorb more carbon than they release, typically carbon reservoirs like forests, soil and oceans. The carbon they store becomes part of the nutrient cycle within these ecosystems. They can still emit carbon, but they take up much more.

Current flows of carbon from human sources far exceed its removal into the planet’s carbon sinks.

Some confusion over the idea of net zero comes from the similar term absolute zero. In a net zero world, emissions are still being generated, but they’re balanced out by offsets or mechanisms that settle the carbon budget. Absolute zero refers to no emissions being generated at all. Currently, this is unrealistic – any activity that produces emissions would have to be scrapped, which simply isn’t feasible in this day and age. In some modern processes, emissions are unavoidable, so offsets will continue to have a key role to play as we transition to reducing emissions across different sectors.

Reaching net zero

To limit a rise in global average temperatures, a defined budget of CO2 and other greenhouse gas emissions that can be allowed into the atmosphere must be set; meeting the Paris Agreement goal of only a 1.5°C rise by 2100 limits the world to an emissions budget of 400 – 800 GtCO2. To avoid overspending this budget, greenhouse gas emissions must rapidly reach a maximum peak before 2030, and then drop to net zero by around 2050.

The lifetime and legacy of CO2 and other greenhouse gases means the balance of removals and emissions for net zero must continue over many decades. Emitting now and removing later is not an acceptable solution; all the time greenhouse gases are in the atmosphere, they are contributing to rising global temperatures, pushing our climates to a tipping point that could cause irreversible damage.

A recent paper from the journal Nature outlined seven attributes essential to achieving credible net-zero:

  • Front-loaded emission reductions
  • Comprehensive emission reductions
  • Cautious use of carbon dioxide removal
  • Effective regulation of carbon offsets
  • Equitable transition to net zero
  • Socio-ecological sustainability
  • New economic opportunities

For net zero to be realised on a global scale, there needs to be better governance, accountability and reporting mechanisms. After all, pledges can easily appear empty if they lack detailed plans and long-term social integrity. There are broad shifts needed across industries, technologies, and the way we live that frequently dip into the muddy waters of economics, politics, and social dynamics. We will be covering some of these strategies and transitions in upcoming featured pieces.

Net zero verifications and certifications

The concept of net zero, however, is susceptible to alternative interpretations and blurred definitions from different sources.

The Science Based Targets initiative (SBTi) for organisations defines its version of net zero only as emission reductions that align with a 1.5°C trajectory – even though net zero as a concept isn’t tied to a specific temperature target. As 1.5°C will likely slip from reach (based on the weakness of current global commitments), net zero will still be applied as a concept to a 2.0°C or 2.5°C target.

SBTi also sets out that net zero claims must cover all Scope 1, 2, and 3 emissions, and that eligible offsets must be carbon removals, as opposed to carbon avoidance (a definition of net zero based on The British Standards Institution’s PAS 2060 verification).

Australia, meanwhile, has its own verification for net zero – Climate Active’s Carbon Neutral Standard. This is achieved in three steps that link to each other, and can apply to organisations, products, services, events, buildings, or precincts:

  1. Calculating a carbon footprint by measuring the amount of greenhouse gas emissions currently being produced.
  2. Reducing emissions where possible.
  3. Remaining emissions that can’t be avoided are offset by purchasing carbon credits.

Find out more about measuring your carbon footprint here.

What about carbon neutral and climate neutral?

Net zero, when applied to an entity or organisation, is not the same thing as carbon neutrality.

To be carbon neutral, an organisation or entity must prevent any increases in emissions and use offsets to balance current emissions. To be net zero, an organisation must first reduce its emissions as much as possible, then use offsets to balance out any remaining emissions.

Because people like to simplify things, we have grown to see carbon as the major factor in climate change; this use of carbon as a single, easy-to-measure unit of impact on global warming in turn leads to an inference that carbon neutrality only refers to carbon dioxide, and that climate neutrality refers to all greenhouse gases. But in reality, this is not the case. Offset credits are measured in CO2-equivalent (CO2-e) units, but can still account for other greenhouse gases other than just CO2. These other greenhouse gases, such as nitrous oxide and hydrofluorocarbons, have different levels of impact of climate. In general, these are shorter-lived than CO2, and so global warming resulting from their levels is better determined by present-day emission rate (plus a small correction) rather than cumulative emissions.


The meaning of net zero and how to get it right, Nature, 2021.

Towards net zero: Practical policies to offset carbon emissions, Grattan Institute, 2021.

Carbon neutral certification, Carbon Trust, 2021.

Additional icons sourced from Flaticon.

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