What is net zero and how can it be achieved?

The term net zero refers to the target of reducing the greenhouse gas emissions that cause global warming to zero by balancing the amount released into the atmosphere from sources with the amount removed and stored by carbon sinks. This is also described as ‘carbon neutrality’ and sometimes ‘climate neutrality’.

Getting to net zero requires significant abatement of greenhouse gas emissions across all sectors of the economy. For example, switching from fossil fuels to renewables including wind and solar power to generate electricity is significantly reducing carbon dioxide emissions in many countries. To make deeper cuts in emissions, large-scale investment and innovation are needed to provide technologically-viable and economically-competitive alternatives to fossil-fuel-intensive technologies in sectors like heating and transport and to reduce emissions of greenhouse gases other than carbon dioxide (such as methane) from sectors like agriculture. 

Abating emissions from some sectors – such as cement, aviation and shipping – is currently difficult and expensive and it is unlikely they will be reduced to zero in the timescale needed to meet the Paris Agreement temperature targets. Therefore, there will be ‘residual’ emissions and the equivalent amount of these will need to be removed from the atmosphere as ‘negative emissions’. This can be done by offsetting from sectors such as land use and power, which have the potential to deploy greenhouse gas removal technologies, in order to achieve net-zero across an economy. 

Removing greenhouse gases can be achieved through natural solutions such as planting trees and land management changes to increase the amount of carbon sequestered into soil. Negative emissions technologies such as Direct Air Capture (DAC) and Bioenergy with Carbon Capture and Storage (BECCS) will also need to play a role. However, these technologies are as yet unproven at scale, can be expensive and energy-intensive, and have their own unwanted negative impacts.

Governments may also use international offsets to meet their own individual net zero targets. Offsets are used especially if it is difficult for the country to reduce some of its own territorial emissions, for example if, like Norway, it has a large oil and gas industry. Buying offsets allows a country to invest in an emissions reduction project outside its borders but is sometimes criticised for ‘moving the problem elsewhere’ and in some countries there is poor governance of offsets. 

Because of the limits to negative emissions technologies and the criticisms of offsetting, climate scientists stress the need to focus on abating domestic emissions as the primary way to bring emissions to net zero and thus avoid dangerous climate change.

The need for net zero in meeting the Paris Agreement targets

The Paris Agreement itself does not include the term ‘net-zero’. However, governments are increasingly recognising the need for net-zero targets to be included in their Nationally Determined Contributions (NDCs) and some are starting to legislate for net-zero targets (see below). The Intergovernmental Panel on Climate Change (IPCC) found in 2018 that to limit global warming to 1.5°C, the goal of the Paris Agreement, “Global net human-caused emissions of carbon dioxide would need to fall by about 45 per cent from 2010 levels by 2030, reaching ‘net zero’ around 2050.” Any remaining emissions, says the IPCC, “would need to be balanced by removing CO2 from the air”. Progress is not on track at present. The United Nations Environment Programme’s Emissions Gap Report published in December 2020 estimates that if every country meets it current emissions reduction commitments, the world will be on a path to warm by more than 3˚C this century. 

Who has made net zero commitments?

In 2019 the United Kingdom became the first major economy to legislate for net-zero, changing the long-term target in the Climate Change Act of 2008 to net-zero by 2050. The Government was following guidance from the UK’s independent advisory body, the Climate Change Committee, which stressed that a net-zero target was essential for the UK to meet its commitments to the Paris Agreement goals. 

The Energy and Climate Intelligence Unit’s ‘Net Zero Tracker’ shows that as of January 2021, five other countries had passed net-zero legislation: Sweden, France, Denmark, New Zealand and Hungary, all with a 2050 target date except Sweden (2045). Other countries have updated their NDCs, proposed legislation or expressed their intent to reach net zero. Notably, President Xi Jinping announced in September 2020 that China, the world’s biggest emitter, would strive to be carbon-neutral by 2060; China achieving this cut is crucial for meeting the global target. The European Union set out its bloc-wide net zero target for 2050 in its European Green Deal published in December 2019. 

It is not just countries that are making net zero commitments. In September 2020 the United Nations Framework Convention on Climate Change (UNFCCC) reported that the number of net zero commitments from local governments and businesses had roughly doubled in less than a year, mainly from actors taking part in the UN Race to Zero campaign. It is hoped that actions by businesses, cities, regions and investors will both directly contribute to meeting the Paris goals and influence governments to commit more to reducing emissions.

This Explainer was written by Georgina Kyriacou with Josh Burke.

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