What is the Global Carbon Budget (GCB)?
Since 2006, the Global Carbon Budget has summed up all anthropogenic emissions of carbon dioxide (CO2) to the atmosphere, and all the carbon removed from the atmosphere by land and ocean, to account for the rise in atmospheric CO2, as this drives climate warming. It brings together many independent sources of data, including systematic observations and state-of-the-art model ensembles, to provide a robust, independent scientific assessment of CO2 sources and sinks each year and their associated uncertainties. It tracks changes over time in CO2 emissions from burning and other uses of fossil fuels and from land use change. It also assesses how the Earth’s carbon sinks on the land and oceans are changing in response to human activities and climate change. These data are integrated at global, regional, and national levels, providing a benchmark against which UNFCCC negotiations can take place. The Paris Agreement goal of limiting global warming well below 2°C sets the budget for the additional CO2 that can be added to the atmosphere for this temperature target. The remaining carbon budget diminishes each year, and has direct ramifications for UNFCCC negotiators working to achieve the Paris Agreement goals. The GCB is the most comprehensive carbon budget assessment available, and contributes to assessments or reports by the IPCC and the World Meteorological Organization.
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What are the latest results of the GCB?
The GCB is updated annually; results for 2024:
The 2024 Global Carbon Budget projects fossil carbon dioxide (CO2) emissions of 37.4 billion tonnes, up 0.8% from 2023.
Despite the urgent need to cut emissions to slow climate change there is still “no sign” that the world has reached a peak in fossil CO2 emissions.
With projected emissions from land-use change (such as deforestation) of 4.2 billion tonnes, total CO2 emissions are projected to be 41.6 billion tonnes in 2024, up from 40.6 billion tonnes last year.
Over the last 10 years, fossil CO2 emissions have risen while land-use change CO2 emissions have declined on average – leaving total emissions roughly level over that period.
This year, both fossil and land-use change CO2 emissions are set to rise, with drought conditions exacerbating emissions from deforestation and forest degradation fires during the El Niño climate event of 2023-2024.
With over 40 billion tonnes released each year at present, the level of CO2 in the atmosphere continues to rise – driving increasingly dangerous global warming.
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What is the remaining carbon budget?
The remaining carbon budget is the amount of carbon dioxide that can still be emitted while keeping global warming within a certain temperature limit, such as 1.5°C above pre-industrial levels. The budget for 1.5°C is rapidly diminishing as human emissions from fossil fuels and land-use change continue to far outpace the rate at which carbon is removed from the atmosphere.
How long until we pass 1.5°C of global warming?
While many temperature records have been broken in recent years , the GCB study focuses on the remaining carbon budget before 1.5°C is consistently breached over multiple years. At the current rate of emissions, the team estimates a one-in-two chance that global warming will consistently pass 1.5°C in six years. All such projections have a degree of uncertainty, but it’s clear that the remaining carbon budget – and therefore, the time left to keep to the 1.5°C limit – is running out fast. Six years are clearly insufficient to decarbonize the world’s energy system, and therefore it is now inevitable that the 1.5°C target of the Paris agreement will be breached. In addition to reaching net zero emissions, large efforts to remove atmospheric CO2 could bring the global mean temperature back down to 1.5°C later in the century.
So far, there is little evidence of the credible policies required to cut global emissions enough to prevent the world from staying with the temperature targets of the Paris Agreement. However, trends in emissions in some regions are beginning to decline, showing climate policies can be effective. The New NDCs or national climate plans, due next year, are a vital opportunity to accelerate global action.