Amandine Denis-Ryan, Head of System Change and Capability, has recalculated the global carbon budget, finding it has fallen by 30 per cent. Reductions in travel and economic activity led to decreases in global carbon emissions in 2020, but investments in fossil fuel to support economic recovery are driving an emissions rebound. What are the implications for the carbon task ahead?

The amount of greenhouse gases that can be emitted while keeping warming below a specific temperature goal is known as a ‘carbon budget’. The pace of global emission reductions determines how quickly we use up the remaining global budget, and when we might reach net zero. 

Last year, global carbon emissions fell by about 7 per cent, due to travel reductions and a slowdown in economic activity. If this volume of reductions was sustained year-on-year, the world would be on a trajectory towards net zero emissions by about 2033. This would likely keep global warming below 1.5 degrees Celsius, avoiding the worst consequences of climate change.

However, recent analysis by the International Energy Agency shows that global carbon emissions are forecast to rebound this year – by approximately 1.5 bn tonnes.

These findings were released as the concentration of atmospheric CO₂ was measured at more than 420 parts per million, for the first time in recorded history (a 50 per cent increase on pre-industrial levels). Recent measurements have also shown that the planet was warmer by 1.2 degrees, from January to October in 2020, than the pre industrial average.

We have examined how these recent trends impact the remaining global carbon budget, for 1.5 and 2 degrees. 

At the start of 2021, the remaining global carbon budget for 1.5 degrees was 296 GtCO2. This is 30 per cent lower than the global budget for 1.5 degrees at the start of 2018 as published by the IPCC in their ‘Special Report on Global Warming of 1.5ºC’, and 12 per cent lower than the global budget at the start of 2020 as published by ClimateWorks in Decarbonisation Futures. 

It represents just seven years of emissions at estimated 2021 emissions levels. To stay within this budget, global emissions would need to reach net zero in a straight line by 2034. It could be stretched to 2050, if very steep emissions reductions are achieved in the next few years.

The remaining global carbon budget for 2 degrees was 1,046 GtCO2 at the start of 2021. This is 11 per cent lower than in 2018 and 4 per cent lower than in 2020. It represents just 25 years of emissions at 2021 levels. To stay within this budget, global emissions would need to reach net zero in a straight line by 2070.

If investment continues to drive emissions upwards, the carbon budgets for 2 and 1.5 degrees will be consumed more rapidly.

These figures show how critical the next few years will be for climate outcomes. We have no time to lose, and in particular the window to limit warming to 1.5 degrees is closing fast. 

As the focus on net zero targets grows after the Leaders Summit in the US and ahead of COP 26 in Glasgow, it will be critical for governments, businesses and investors to raise their climate ambition in regards to the pace of emissions reductions. We need to see both a renewed commitment for net zero by 2050 or earlier, and strong emissions reduction this decade to have any chance of staying within the global 1.5 degree carbon budget. 

Our Decarbonisation Futures report, released last year shows that these more rapid pathways to decarbonisation are possible for Australia – if governments, businesses and individuals go ‘all-in’. Read more from Decarbonisation Futures.