Climate change: What is 'net zero' and why does it matter?

A growing number of countries, cities and companies are aiming for 'net zero' emissions to meet climate goals, and the International Energy Agency has unveiled a plan to get there.

The International Energy Agency has released a long-awaited roadmap showing how the world's energy sector can slash its planet-heating emissions to net zero by 2050, which it says would give the best chance of limiting global warming to 1.5 degrees Celsius.

Under the 2015 Paris Agreement, more than 190 countries committed to keep global average temperature rise to “well below” 2C above preindustrial times, and ideally 1.5C, to avoid the worst impacts from more extreme weather and rising seas.

In its special report, the energy agency said reaching net-zero emissions by mid-century was possible.

But, it added, the pathway to get there was "narrow and requires immediate action across all countries to begin an unprecedented transformation of how energy is produced, transported and used worldwide".

The report's key insights include the following:

- Climate pledges by governments so far – even if fully met – are well short of what’s needed to bring global energy-related carbon dioxide emissions to net zero by 2050.

- Meeting that goal will require rapid and massive deployment of all available clean and efficient energy technologies, including a big jump in new solar and wind power, with almost 90% of electricity generation coming from renewable sources by 2050.

- There should be no investment in new projects to boost oil, gas and coal supplies, nor further funding for new coal plants that are not fitted with technology to reduce their emissions.

- Sales of new petrol and diesel passenger cars should be halted by 2035.

- Total annual energy investment should surge to $5 trillion by 2030 from $2 trillion today, which could create millions of clean energy jobs and push global GDP 4% higher by the end of the decade than it would reach based on current trends.

A growing number of governments and companies have now set net-zero emissions targets for the middle of the century - we take a closer look at the trend and its importance for the Earth's climate:

Why does 'net-zero' matter?

It may be the latest buzzword in the world of climate action but it's key to keeping us safe from harm, scientists say.

The U.N. climate science panel has said that man-made carbon dioxide emissions need to fall by about 45% by 2030, from 2010 levels, and reach "net zero" by mid-century to give the world a good chance of limiting warming to 1.5C and avoiding the worst impacts of climate change.

Under the 2015 Paris Agreement, nearly 200 countries said they would act to limit the rise in global average temperatures to "well below" 2 degrees Celsius above pre-industrial times and strive to keep it to a ceiling of 1.5C.

But the world has already heated up by about 1.2C and is currently on track for warming of about 3C this century as emissions continue to rise, despite a dip in 2020 due to the coronavirus pandemic.

Scientists say that would bring ever-worsening extreme weather and potentially catastrophic sea level rise, making some parts of the planet uninhabitable and fuelling hunger and migration.

That - and mounting public pressure - is why a growing number of countries, companies and others are promising to cut their planet-warming emissions to net zero by 2050 or before.

What is net zero?

Achieving net-zero emissions isn't the same as eliminating all emissions.

It means ensuring any human-produced carbon dioxide or other planet-warming gases that can't be done away with are removed from the atmosphere some other way.

This can be done naturally, such as by restoring forests that suck CO2 out of the air. Or it can be done using technology that can capture and store emissions from power plants and factories or directly pull CO2 from the atmosphere.

Planting more trees worldwide is a popular way to absorb and store more carbon, but technologies that do the same job are still expensive and have yet to be deployed on a large-scale.

Scientists say carbon "removals", in any form, cannot substitute for cutting planet-heating emissions as fast as possible.

Who has committed to net zero?

Analysis in late 2020 by Oxford-ECIU found that net-zero commitments globally covered at least 68% of the global economy, 56% of the global population - more than 4.2 billion people - and 61% of global greenhouse gas emissions.

But it said less than a fifth of net-zero targets meet key criteria, including a goal for decarbonisation before 2050; a law, policy or strategy that confirms that goal; annual reporting on progress; a published plan for meeting the goal; and interim targets.

A Net Zero Tracker by the UK-based Energy and Climate Intelligence Unit (ECIU) shows that two tiny developing countries, Suriname and Bhutan, have already achieved net-zero emissions, though measures such as restoring or planting forests and adopting renewable energy.

Seven countries, including Denmark, France, New Zealand, Britain and Spain, have enshrined their targets in law, and the European Union is expected to do so in the coming months.

A few others have proposed legislation on a net-zero goal, while about 20 more - including China, Norway, Costa Rica and the Marshall Islands - have put it in a policy document.

Some100 additional nations are considering putting in place net-zero targets, the ECIU says.

How do you set a net zero target?

The World Resources Institute (WRI) and the 2050 Pathways Platform - which work with governments and others on their climate commitments - say cutting emissions within national boundaries should be the first priority, with efforts to offset what remains only considered after that.

Right now, countries vary in whether their net-zero targets can include offsetting emissions internationally, such as by paying to protect forests in the Amazon.

To be credible, net-zero targets should cover all greenhouse gases, including methane, and all economic sectors, as well as international aviation and shipping, WRI says.

Those trying to achieve net-zero emissions should do so by 2050 or earlier, with the highest-emitting countries doing the most, fastest.

Plans also need to be reached in consultation with those they will affect and clearly communicated, WRI said.

When it comes to companies, net-zero targets vary widely in terms of which parts of supply chains - and sources of emissions - they cover, and are difficult to compare, says the Science Based Targets initiative (SBTi), which has released guidelines to help remedy that.

Is net zero an excuse to kick action down the road?

The "Race to Zero", launched on World Environment Day in June 2020, brings together businesses, cities and other organisations that aim by around mid-century to cut their planet-heating emissions to net zero - meaning they produce no more emissions than they can offset through measures such as planting trees.

With a growing focus on the robustness of net-zero commitments, Race to Zero members must all meet stringent criteria, including submitting a plan in line with climate science and setting interim targets to reduce emissions, it added.

U.N. climate chief Patricia Espinosa says companies, cities and others that join the "Race to Zero" campaign will be held to their promises, although it is unclear how that will be done.

Governments are due to submit stronger climate action plans before the postponed COP26 U.N. summit in Glasgow this November, after the coronavirus pandemic delayed that conference and many of the national plans.

Some climate activists have criticised 2050 net-zero goals for enabling countries to postpone emissions reductions until a vague later date.

The steps needed to get there must be incorporated into ambitious 2030 emissions reduction targets in national plans now and reflected in day-to-day decision-making, to avoid investments going into high-carbon technologies or infrastructure, according to WRI researcher Kelly Levin.

How can net-zero targets be translated into short-term practical tools? One way is by using carbon budgets, Levin said - in Britain, these place a cap on the total amount of greenhouse gases the country can emit over a five-year period.