Earth's carbon budget for 1.5°C will be exhausted by 2029, says IPCC

Humanity is burning through its available carbon budget quicker than originally thought, scientists say.

Without urgent and concerted global efforts to reduce atmospheric CO2 emissions that cause climate change, we could breach the 1.5°C limit by 2029 instead of the mid-2030s, The Guardian reports.

Globally, 2023 saw extreme heat and unprecedented temperatures, including the world's hottest-ever month recorded in July. Mean-average annual temperatures for the year are expected to be close to 1.5°C above pre-industrial levels.

While this could be a one-off extreme year, scientists are concerned that soon the volume of CO2 in the atmosphere will keep temperatures at dangerous levels for longer.

UN advisory body the Intergovernmental Panel on Climate Change, had forecast that the world could afford to emit another 500 billion tonnes of CO2 and have a 50% chance of keeping below the 1.5°C target. This budget assumed annual carbon dioxide emissions of around 40 tonnes.

However, new research into the impact of a global ban on aerosols, which worked to cool the atmosphere by reflecting sunlight back into space, has led scientists to recalculate the remaining carbon budget.

The latest estimate leaves 250 billion tonnes, which brings forward the 1.5°C deadline to 2029 - just six years from now, The Guardian says.

Increasing global atmospheric CO2 concentrations over time.

Image: Our World in Data

Global average atmospheric concentrations of CO2 continue to increase over time, from around 336 parts per million (PPM) in 1979 to around 419 PPM in 2023, as the image above shows.

As there is a lag between atmospheric conditions and resulting temperature increases, even if temperatures are stabilized the atmosphere will continue to heat for several years.