What is net zero and how are the UK and other countries doing?

In order to help meet international climate targets, the world needs to cut carbon dioxide emissions to "net zero" by 2050, the UN says.

This will involve major changes for governments, businesses and individuals.

Net zero means no longer adding to the total amount of greenhouse gases in the atmosphere.

This main way to do this is to cut greenhouse gas emissions in the first place. But not all emissions can be eliminated completely, so those that remain need to actively removed.

Greenhouse gases include carbon dioxide (CO2) and methane. CO2 is released when oil, gas and coal are burned in homes, factories and to power transport. Methane is produced through farming and landfill, as well as other sources.

These gases increase global temperatures by trapping extra energy in the Earth's atmosphere.

Meanwhile, rapid deforestation across the world means there are fewer trees to absorb CO2.

Under the 2015 Paris climate agreement, nearly 200 countries agreed to try to limit global temperature rises to 1.5C by 2100.

To achieve this, CO2 emissions need to fall by nearly half by 2030 and reach net zero by 2050, according to the UN's climate body, the IPCC. But despite these international commitments, emissions remain at record highs.

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Natural ways of removing CO2 include planting trees and restoring peatlands.

There are also novel, human-designed methods - at very early stages - designed to take CO2 directly out of the air.

Carbon capture is a related technology, where CO2 produced in power stations or other industrial processes is captured before it is released into the atmosphere, and stored underground.

While these technologies could be important in future, they are expensive, and can currently only cancel out a very small fraction of greenhouse gas emissions which are still being produced.

They are not a substitute for making drastic cuts to fossil fuel use, the International Energy Agency warns.

To help achieve its 2050 target, UK governments have made a series of pledges, which include:

• achieving so-called 'clean' electricity by 2030, by rapidly increasing wind and solar generation
• ending the sale of new fully petrol and diesel cars by 2030
• installing 600,000 electric heat pumps a year by 2028
• investing in technology to capture and store CO2

The UK's greenhouse gas emissions in 2023 were around 50% of 1990 levels. This figure only includes emissions generated within the UK, in line with UN reporting standards.

Under the Paris climate agreement, the UK needs to reduce its emissions by 68% by 2030 compared with 1990 levels - a key step towards achieving net zero by 2050.

In July 2024, the UK's independent climate advisers, the Climate Change Committee (CCC), warned that only a third of emissions cuts needed to meet this goal were backed up by credible policies.

At the COP29 climate summit in Azerbaijan, Prime Minister Sir Keir Starmer announced a new target to cut the UK's annual emissions by 81% versus 1990 levels by 2035.

Piers Forster, interim chair of the CCC, welcomed the announcement, which he said would "support jobs and investment".

However, he warned that UK also needed to demonstrate greater progress regarding electric vehicles, heat pumps and tree planting.

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About 145 countries have - or are considering - net zero targets, covering about 90% of global emissions. However, not all have set a 2050 deadline.

China - currently the biggest producer of CO2 worldwide - is aiming for "carbon neutrality" by 2060. Its plans to cut emissions are not fully developed, but its electric vehicle sales and renewable energy sector have been growing rapidly.

The US has historically been the biggest carbon emitter, and still emits more than China per head. It has pledged to reach net zero by 2050. In August 2022, it announced a major green investment package called the Inflation Reduction Act, which aims to boost renewables and other clean technologies.

The EU, the third biggest emitter of CO2, also has a 2050 net zero target. In March 2023, it announced its own green investment package, called the Net Zero Industry Act.

Russia and India are also significant emitters. They have pledged to reach net zero by 2060 and 2070 respectively, but have published few policies to back this up.

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There is controversy about how some countries and companies might reach net zero.

For instance, a country might record lower emissions if it imports energy-intensive goods from overseas, rather than producing the goods itself.

But in reality, it may not have reduced the total amount of greenhouse gases going into the atmosphere.

There are also schemes that enable countries or companies to reach net zero by paying others to reduce theirs instead - for example giving funds to plant trees.

But these can be controversial, with concerns about how effective these schemes really are.

Some climate scientists also fear that a focus on net zero targets in 2050 or beyond can underplay the need for rapid emissions cuts now, with the world far off track to meet its climate goals.

While the most significant changes need to come from government, individuals can also play their part to help reach net zero.

This could include:

• taking fewer flights
• reducing energy use
• improving home insulation and energy efficiency
• switching to electric vehicles
• replacing gas central heating with electric systems such as heat pumps
• eating less red meat

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