Carbon budget explained

In 2015, nearly every nation committed to keep the world’s temperatures by 2030 well below 2°C above pre-industrial and to pursue efforts to reduce temperatures even further to 1.5°C, by signing the Paris Climate Change Agreement.

As low-carbon policies and innovations develop, businesses, investors and policymakers are increasingly using carbon budgets as a crucial component for analyzing the potential positive effects of a future that carbon is inhibited. Similarly, individuals also play a key role in raising awareness about the importance of the carbon budget and the paths to a no-carbon world.

What’s a Carbon Budget?

The concept of a Carbon Budget which connects a potential warming rate with the total CO2 level. It is described as the amount of carbon dioxide emissions we can emit while still likely restricting global temperature rises to 2°C above pre-industrial levels and limiting to 1.5°C.

In this way, the carbon dioxide that can be emitted globally in order to remain under a certain warming limit is finite.

The International Panel on Climate Change (IPCC) report highlights what we will face if the temperature rises. Extreme events on our planet such as more storms, forest fires, hurricanes, biodiversity loss, water scarcity and increasingly extreme droughts.

Where do we stand now?

The global mean temperature in 2020 is estimated to have been 1.27°C.

According to the latest IPCC Special Report on the 1.5 degrees, it estimated anthropogenic global warming is currently increasing at 0.2°C per decade and to reverse global warming, we can absorb no more than 420 gigatonnes (Gt) of CO2 implying a 66% chance if we want the planet to remain below the 1.5°C level. 

The carbon budget and the probability of success. The budget (vertical axis) is related to the risk of failure (overshooting the 2°C horizontal axes) along the blue curve. Emissions to date are indicated by the grey box, leaving the available budget as the distance between the blue curve and grey box. As a chance of not exceeding the target increases from 33% (green) to 50% (orange) to 66% (red), the budget decreases. At 90% chance of not exceeding the target (black), no carbon budget remains. 

Source: Spratt, David and Dunlop, Ian, “Dangerous Warming: Myth, reality and risk management”, and Raupach (2013, unpublished), based on Raupach, M.R., I.N. Harman and J.G. Canadell (2011) “Global climate goals for temperature, concentrations, emissions and cumulative emissions”

However, as approximately 42 Gt of CO2 is emitted annually worldwide, an equivalent of 1332 tonnes per second. So, if the emissions continuously exceed 40 Gt per year, this budget is projected to be used in less than 10 years. This means that we have less than 10 years left to rapidly reduce the carbon emissions to potentially sustain the Earth for our most beloved people and at the same time mitigating the extreme disasters that might possibly occur to our planet.

What do we need to do to stay within budget and keep the temperature below 1.5°C?

The IPCC has projected that global carbon dioxide needs to fall rapidly to about 20–30 Gt per year, and then drop sharply to zero Gtn per year to stay on the budget.

Yet the world shifts in the other direction. By 2030, emissions are expected to grow at a level of 49.4 Gigatonnes. This indicates that by 2030, the 1.5 degrees carbon budget could be used on our trajectory over the next few years, which will have catastrophic effects on the planet.

The only way to remain within the carbon budget is to reduce carbon emissions to zero as quickly as possible.

Is carbon offsetting a solution to stay within the budget?

Offsetting is a key factor to keep the carbon budget, but if undertaken in isolation, it is not the solution. On the other hand, offsets also allow businesses and individuals to invest and support communities and protect the biodiversity that is more vulnerable to the impact of rising temperatures. At No Carbon, we believe that only measuring and defining strategies of carbon emissions can lead to a zero-carbon world to sustain the planet for future generations. That’s how we deal with this issue with a broad-based solution, encouraging individuals and businesses to recognize and endorse their plan to gradually decrease emissions to zero.


Berkeley Earth. Global Temperature Report for 2020. Posted on January 14, 2021, by Robert Rohde.

Global carbon budget bucket 2020. Youtube website. Concept by Rob Jackson, Stanford University, with input from Alistair Scrutton, Future Earth. Animation by Jerker Lokrantz/Azote.

Friedlingstein, P., O’Sullivan, M., Jones, M. W., Andrew, R. M., Hauck, J., Olsen, A., … & Zaehle, S. (2020). Global carbon budget 2020. Earth System Science Data12(4), 3269-3340.

Mercator Research Institute on Global Commons and Climate Change. “That’s how fast the carbon clock is ticking”, 2020.

IPCC, 2014c: Summary for policymakers. In: Field CB, Barros VR, Dokken DJ, Mach KJ, Mastrandrea MD, Bilir TE, Chatterjee M, Ebi KL, Estrada YO, Genova RC, Girma B, Kissel ES, Levy AN, MacCracken S, Mastrandrea PR, White LL (eds) Climate change 2014: impacts, adaptation, and vulnerability. Part A: global and sectoral aspects. Contribution of Working Group II to the Fifth Assessment Report of the
Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, pp 1–32

IPCC, 2018: Summary for Policymakers. In: Global Warming of 1.5°C. An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate poverty [Masson-Delmotte, V., P. Zhai, H.-O. Pörtner, D. Roberts, J. Skea, P.R. Shukla, A. Pirani, W. Moufouma-Okia, C. Péan, R. Pidcock, S. Connors, J.B.R. Matthews, Y. Chen, X. Zhou, M.I. Gomis, E. Lonnoy, T. Maycock, M. Tignor, and T. Waterfield (eds.)]. World Meteorological Organization, Geneva, Switzerland, 32 pp.

World Resources Institute. Infographic on Carbon Budget.

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