World poised to hit 1.5 degrees a year earlier than expected: projections

While massive investments into clean energy technology continue across the globe, carbon dioxide emissions continue to rise to record levels, according to an annual accounting of human-made greenhouse gases relative to temperature targets.

Each year, the independent scientific consortium known as the Global Carbon Project (GCP) calculates how much greenhouse gas can be produced through human activity to keep below specific global warming trajectories. It says there’s now a 50:50 chance the world will exhaust the remaining carbon budget to keep warming below 1.5°C by 2031.

That’s a year earlier than last year’s projections.

Annual carbon dioxide emissions have gone up every year since the GCP started compiling the Global Carbon Budget in 2006, except during the COVID-19 pandemic and global financial crisis.

A thermal power station in front of solar energy panels
Coal is still the biggest source of carbon emissions, even as renewables enter global markets. Credit: owngarden via Getty Images

This year is no different. Projections indicate 36.8 billion tonnes of CO2 will be produced by year’s end, with increased emissions from each of the main pollution sources coal, oil and methane gas. Increases are largely driven by developing economic powerhouses China and India, with continued slow declines from the USA and Europe.

That’s a 1.1% increase on 2022 levels, though an uncertainty range from 0.0-2.1% means this year may mark an annual emissions peak.

Even if that’s the case, the trajectory for the planet it still grim.

The Paris Climate Agreement, signed in 2015, aspires to keep global average temperatures at no more than 1.5°C above pre-industrial levels. But the amount of carbon dioxide pumped into the atmosphere this year, combined with refinements into the behaviour of the planet’s carbon cycle, has brought the anticipated date that figure will be reached forward by a year.

Global Carbon Budget Projected timelines

 2022 GCB2023 GCB
1.5*~2032 (9 years)~2031 (7)
1.7*~2041 (18)~2039 (15)
1.9*~2053 (30)~ 2052 (28)
*50% chance of reaching temperature above pre-industrial levels, based on current emissions.

Among other estimates, carbon dioxide is expected to reach an atmospheric concentration of about 419.3 parts per million this year – about 51% greater than pre-industrial levels.

Why does a carbon budget matter?

Carbon budgeting is a valuable tool for policymakers and the public to understand efforts to cut greenhouse gas emissions, most of which are carbon-based (carbon dioxide and methane) and released from the burning of coal, oil and gas.

Each year, the Global Carbon Project assesses the world’s carbon emission sources, and sinks,  to calculate how much carbon is left in the budget to keep global average temperatures below particular thresholds – typically 1.5, 1.7 and 1.9°C above pre-industrial levels.

A graph showing annual increase in global carbon dioxide emissions
Annual Global Fossil Carbon Dioxide Emissions. Credit: Global Carbon Project.

Once that carbon allowance is exhausted, no more can be produced – in net terms – if the planet is to remain under one of these temperature thresholds.

While there are many potent greenhouse gases, carbon dioxide is a particularly important marker as it potentially lasts thousands of years in the atmosphere.

“The remaining carbon budget is giving you a reality check,” says Dr Pep Canadell, the chief research scientist of the CSIRO and executive director of the Global Carbon Project.

That reality check is effectively a map to the future that governments, working together, can alter course for a faster or slower decline in greenhouse gas emissions.

At the same time, Canadell highlights the uncertain road ahead for carbon reduction.

“Overall, it’s a strong, pessimistic view in the sense that even if we were to actually pick next year [as an emissions peak], it won’t be a ‘peak and decline’ as these emissions [reduction] scenarios that we’re talking about are really asking for.

“We need to really go many notches up [with] how aggressive we go into this climate policy development and implementation, tracking and verification of what’s been done.”

Graph showing increases over time in carbon emissions from coal, oil, gas and other sources.
Credit: Global Carbon Project

Tracking toward 1.5°C

Carbon concentrated in the atmosphere is highly potent – capable of trapping heat from the Earth’s surface and reflecting it back.

Alongside carbon budgeting is the concept of ‘net zero’ – an important marker indicating a point where every carbon molecule produced by human activity is removed from the atmosphere through other means. At net zero, global temperatures should begin to stabilise, and the budget helps plot a trajectory towards this target, but achieving that requires an orderly scale-down on polluting activity.

But based on current activity, the world would need to decrease its carbon dioxide output by an average of 1.5 gigatonnes every year up until 2050. That’s a figure close to the reductions seen in 2020, when much of the world locked down due to COVID-19.

Even with 26 developed economies continuing to decrease their emissions while growing their economies, and large nations like China continue to scale back their annual growth (though it is still increasing), it’s likely net zero will be reached at 1.7 or 2 degrees of warming, from which point substantial carbon removal would be required to bring temperatures back below 1.5°C.

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