The chance to stop the Earth heating up by more than 1.5C above pre industrial levels could be lost within just six years, according to a new study.
The ‘carbon budget’ is the maximum amount of CO2 we can emit that would allow the planet to remain within the 1.5C temperature limit.
Scientists estimate that humanity can only emit around 250 more gigatonnes of carbon dioxide before there is a 50 per cent chance of the earth getting hotter than 1.5C.
At current rates this will be emitted by 2029.
Currently humanity is emitting around 40 gigatonnes of CO2 a year, so by 2029 too much will be produced.
Scientists say humanity will use up its remaining budget for carbon emissions by 2029 if current rates continue. They estimate that we can only emit around 250 more gigatonnes of carbon dioxide before there is a 50 per cent chance of the earth getting hotter than 1.5C
The carbon budget is how much CO2 can be emitted if there is to be a 50 per cent chance of keeping global warming below 1.5C
Current estimates from the IPCC, the United Nations body that is the world’s foremost authority on climate science,, has the Earth on track for nearly 3C of warming by 2100 with global emissions still increasing in 2023.
Scientists have said 3C would be catastrophic for humans and other forms of life on Earth, with some warning that breaching even the 1.5C limit could set off tipping points such as melting polar glaciers which could cause the planet to heat up independent of human emissions.
The Earth has already warmed by 1.1C since pre-industrial levels.
Dr Robin Lamboll, of Imperial College London’s Centre for Environmental Policy and lead author of the study, said: ‘Our finding confirms what we already know – we’re not doing nearly enough to keep warming below 1.5C.
‘The remaining budget is now so small that minor changes in our understanding of the world can result in large proportional changes to the budget. However, estimates point to less than a decade of emissions at current levels.
‘The lack of progress on emissions reduction means that we can be ever more certain that the window for keeping warming to safe levels is rapidly closing.’
Scientists see a global temperature increase of 1.5C as a tipping point for the climate which could cause the polar ice caps to melt, raising temperatures further even without human action
There has been a lot of uncertainty in judging how much the world can emit before breaching the target as there are numerous gases that cause warming as well as indirect effects of other pollutants such as the cooling aerosols.
The study authors said they used a new dataset and an improved climate model to give a more accurate estimate of the remaining budget.
Although 2023 is likely to have a global average temperature of above 1.5C and be the hottest year on record, this does not mean the Paris goal is dead as meteorologists measure the average figure taken over many years in order to account for a natural variability in temperature.
Many countries have targets in place to become net zero by around the middle of this century, meaning the amount of emissions put into the atmosphere equals those removed either by nature or technology.
Restored forests, wetlands and oceans may begin to draw more carbon from the atmosphere than is being emitted, cooling the Earth’s temperature, though the precise effect remains largely an educated guess.
Several factors contribute to determining the remaining carbon budget, including the target temperature, heating not caused by CO2 and an amount or warming expected after net zero
Dr Lamboll said: ‘At this stage, our best guess is that the opposing warming and cooling will approximately cancel each other out after we reach net zero.
‘However, it’s only when we cut emissions and get closer to net zero that we will be able to see what the longer-term heating and cooling adjustments will look like.
‘Every fraction of a degree of warming will make life harder for people and ecosystems. This study is yet another warning from the scientific community. Now it is up to governments to act.’
Professor Niklas Höhne, director and CEO, New Climate Institute, Cologne said: ‘The current study shows one thing above all: it will be very, very tight for the 1.5-degree limit. It is almost irrelevant whether the budget is used up in six years – as this study suggests – or in ten years, as previously thought, if emissions remain the same. It’s extremely tight either way. And that’s not a new finding.
‘But that in no way means we should give up, quite the opposite. It shows that every ton of carbon dioxide saved is all the more important because the budget is so extremely tight.
And even if the multi-year average temperature increase exceeds 1.5 degrees, it’s good to have saved as many emissions as possible beforehand, because every ton saved leads to less global temperature increase and therefore less damage.’
