The Global Carbon Budget in 2021

Humans have raised carbon dioxide (CO2) levels in the Earth’s atmosphere to the highest point in at least the past 800,000 years.¹ This has increased global temperatures about 1°C above pre-industrial levels.² The carbon budget connects anthropogenic CO2 production with climate change. It represents the amount of carbon emissions permitted in a specific time to limit temperatures to a particular threshold.³ 

Over the last century, we have reached our current precarious situation by burning fossil fuels, such as coal, oil and natural gas. Combustion releases large quantities of carbon from these dirty fuels, which ends up in the atmosphere. CO2 and other greenhouse gases block heat escaping from the planet, hence the term the greenhouse effect.⁴  

Carbon budgets are, therefore, crucial to cap emissions and prevent further global warming.

What is the carbon budget?

The Intergovernmental Panel on Climate Change (IPCC), a body of the United Nations, has outlined the dangers of a planetary increase in temperature of 1.5°C.⁵ Scenarios include rising sea levels, heightened risk and intensity of droughts in some areas, and an increase in the frequency and/or amount of precipitation and floods in other regions.⁶ A carbon budget aligns to the direct link between carbon emissions and global warming. It aims to prevent climate change’s catastrophic repercussions by capping CO2 emissions before it is too late.

The carbon budget involves limiting global emissions to reduce the atmospheric concentration of carbon dioxide. It also includes offsetting emissions through carbon sinks and using carbon capture and storage technology.⁷

What is the global carbon budget?

The global carbon budget is a simple target for the world to adhere to in order to prevent climate change. It is the total remaining CO2 emissions that can be allowed whilst maintaining a likely chance of capping global warming to 1.5°C this century.⁸ Just 8 per cent of the carbon budget remains, and it will be exhausted in the coming decade if we do not reduce our emissions.⁹ This is according to models and estimates produced by the Global Carbon Budget report 2020.¹⁰ 

196 Parties worldwide have agreed to adhere to the global carbon budget by signing the Paris Agreement. Its objective is to limit global warming to well below 2°C – ideally to 1.5°C – as recommended by the IPCC. To realise this goal, the signatories aim to peak their greenhouse gas emissions as soon as possible and achieve a net-zero world by mid-century. These countries recognise the importance of the rapidly shrinking carbon budget to protect the planet.¹¹ 

How can we meet the global carbon budget?

Fossil fuel consumption and emissions reduction

To meet the global carbon budget and prevent global temperatures from exceeding 1.5°C, carbon emissions must be curtailed. This means reducing our dirty fuel consumption. In 2018, fossil fuels and industry contributed 89 per cent of global CO2 emissions.¹² Coal, natural gas and oil supplied 84 per cent of the world’s energy needs in 2019.¹³

Coal alone is responsible for over 0.3°C of the 1°C increase in global average temperatures, making it the largest source of global warming. Oil releases vast quantities of carbon when burned and accounts for about one-third of the world’s carbon emissions. Natural gas may be promoted as a cleaner source of energy than coal and oil. Nonetheless, a fifth of global CO2 emissions come from natural gas.¹⁴ 

Transitioning to renewable energy sources

A transition to renewable energy sources is crucial to meet the carbon budget. Clean energy solutions do not emit CO2 or other greenhouse gases.¹⁵ It will be impossible to avoid the worst effects of climate change without sourcing at least two-thirds of our energy from renewables by 2050.¹⁶ 

We are already moving in the right direction. The average growth rate in renewable sources was 3.1 per cent from 2000 to 2019. 13.5 per cent of the world’s total energy supply was produced by the sector in 2018, including hydro, solar PV, solar thermal, wind, geothermal and tidal. In 2018, renewables had an even larger global share of electricity production. At 25.2 per cent, they were ahead of gas, nuclear and oil.

We are making progress. But as long as we are still burning fossil fuels, we continue to eat up our remaining carbon budget.¹⁷

Carbon capture and storage (CCS)

Carbon capture and storage (CCS) is one potential solution to meeting energy needs whilst continuing to burn coal, oil and natural gas. CCS involves separating and capturing the carbon dioxide produced by industrial or power generation activities. Once captured, it can be transported and stored underground.¹⁸ By installing CCS technology, it would enable facilities to continue operating and burning fossil fuels without producing CO2 emissions. 

However, the capabilities of current CCS technologies should not be overstated. Currently, there are a mere 19 large-scale industrial and two large-scale CCS power facilities in operation in the world. Collectively, their annual carbon collection capacity is about 40 million tonnes of CO2. There are a further 20 projects under development. However, to capture enough carbon to stay on a 1.5°C rise climate trajectory, CCS facilities would need to increase by a factor of 35.¹⁹ 

Many CCS projects have been beset by problems. For example, Boundary Dam in Canada became the first generating station in the world to successfully use CCS technology on one of its full-scale units in 2014.²⁰ But, in 2015, issues with a cylinder meant that the capture portion only worked 40 per cent of the year.²¹ 

Similarly, FutureGen in the US was supposed to be the first commercial-scale power plant in the country with CCS.²² However, a decade of rising project costs and decreasing likelihood of meeting deadlines led the US government to pull funding, resulting in the projects’ abandonment.²³

Net negative emissions

To meet some of the more ambitious international climate goals, it is being posited that we may require global CO2 emissions to fall below zero in the second half of the century. This would achieve what is known among the climate change community as net negative emissions.²⁴

The global carbon budget in 2021

The science behind the global carbon budget is simple. We must stop producing greenhouse gas emissions, or global warming will exceed 1.5°C above pre-industrial levels. To do this, we need to stop relying on fossil fuels for our energy needs. Technologies that seem to permit their usage, such as CCS, are unreliable. Past examples show that we cannot depend upon them to remove sufficient carbon from industry or power plants. It would be better to spend funding for CCS by investing in clean energy solutions.

Renewable energies offer a dependable option that can meet our energy needs without jeopardising the planet. We need to bolster these industries, at the expense of dirty fuels, before we run out of time. 

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