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The Next Economy
What’s Your Organization’s Carbon Budget?

The reduction in total carbon emissions due to COVID-19 just about equals the annual reduction we need to put in place over the next decade. That’s quite a challenge — and it will require us to examine every aspect of our organizations’ operations.

In our previous articles on carbon and the built environment, we covered these topics:

As individuals, governments, organizations and corporations begin to track the amount of greenhous gas (GHG) emissions for which they are responsible, the question frequently arises: “Now that I know our carbon footprint (annual CO2e emissions) what should I do about it?”

At Cuningham Group, we advise our clients to develop a carbon budget specific to their operations. The carbon budget of any entity can be mapped against a number of different scenarios for the global carbon budget. The result is a roadmap for GHG-emissions reduction that can be followed and implemented by that entity.

History of CO2e emissions

Scientists are able to estimate the total amount of GHG emitted into the atmosphere since the beginning of the Industrial Revolution. Through 2011, that amount stood at 1,890 gigatons CO2e (CO2 equivalent — representing all greenhouse gases and estimating their global warming impact as it they were CO2). In 2019, human activities resulted in another 40 gigatons of CO2e. That means that, in just one year, humans accounted for 2.1 percent of all the GHG ever put into the atmosphere. It is clear to the scientific community that the rate of 40 gigatons annually cannot continue without devastating consequences for climate and life on our planet.

Definition of a carbon budget

The Carbon Tracker Initiative defines a carbon budget as “the cumulative amount of carbon dioxide (CO2) emissions permitted over a period of time to keep within a certain temperature threshold.” Using climate models, climate scientists can estimate the probability of not overshooting the accepted 1.5° C target for maximum average global temperature increase, with different amounts of total GHG remaining emissions. Per the Architecture 2030 Challenge, the most current and commonly accepted values for this are:

  • 600 gigatons = 33% chance (of staying at or below 1.5 degrees C)

  • 500 gigatons = 50% chance

  • 340 gigatons = 67% chance

The GHG amounts above are the totals from all human-related sources, until such time as net emissions stop. Many governments have established timelines for the complete elimination of net emissions by certain dates, such as 2030, 2040 or 2050. But do these timelines get us there fast enough?

The roadmap

A strictly linear reduction of GHG emissions from now until 2050 will result in another 600 gigatons of CO2e being released into the atmosphere. That would be an annual reduction of 3.3 percent, or 1.33 gigatons less per year. As seen above, that results in only a 33 percent probability of limiting temperature rise to 1.5° C. A more ambitious linear reduction that reaches net zero in 2040 still results in total remaining emissions of 400 gigatons GHG. That would be a yearly reduction of 5 percent, or 2.0 gigatons less per year. Even this more ambitious plan doesn’t lead to a strong probability of avoiding 1.5° C increase. For this reason, the Architecture 2030 organization has proposed a global carbon budget of 340 gigatons allocated per the chart below.

This plan proposes a more aggressive reduction between now and 2030, followed by a slightly less rapid reduction leading to net zero emissions by 2040. This plan leads to a 67 percent probability of limiting temperature increase to 1.5 degrees C average. The 65 percent reduction in emission over the next ten years requires a commitment to 6.5 percent annual reduction.

Whatever your organizations carbon footprint and annual GHG emissions are now, we recommend you consider a reduction plan similar to the chart above. That requires a 6.5 percent annual reduction starting this year, to be followed by a more gradual 3.5 percent reduction until 2040. If your organization can achieve net zero GHG emissions sooner, all the better!

Impact of COVID-19

Our clients often ask: “Hasn’t COVID-19 already resulted in a drastic reduction in GHG emissions? Do we need to do much more than that?” The answer is complex. Although most organizations have substantially reduced GHG emissions due to transportation, the building sector has generally not reduced emissions. Nearly empty buildings are still running most of their heating, cooling and ventilating systems. The World Meteorological Organization estimates the global reduction in GHG emissions for all of 2020 will be only 4.2 to 7.5 percent.

In other words, the reduction in total carbon emissions due to the COVID-19 pandemic just about equals the annual reduction we need to put in place over the next decade. That’s quite a challenge — and it will require us to examine every aspect of our organizations’ operations.

Note: This article concludes Cuningham Group’s four-part series on Carbon and the Built Environment. Please contact us at to find out more.