How much do forest fires contribute to CO2 emissions? - it can range from 5 % to almost 300 times that of all fossil fuels burned, depending on the area and population density

Worldwide, wildfires in 2021 released about 1.8 billion tons of CO2 into the atmosphere, compared to about 38 billion from fossil fuels and industry, according to Phys.org. That is less than 5 percent of total emissions. 

Cover photo: Aerial photo of the wildfires in the Northwest Territories in northern Canada summer of 2023. Photo: N.W.T. Fire

However, for a country or region with a small population compared to the forested area, the percentage which forest fires emit can be quite different. 

In the Canadian province of British Columbia - a province with only 5 million people and vast forests - forest wildfires in recent years have emitted more CO2 than all fossil fuel burned by the population and industry in the province.

In the remote Northwest Territories - with an even smaller ratio of population to area of forested land - the catastrophic forest fires in 2023 contributed almost 300 times as much CO2 as human activities in that same province, during a typical year. 

Dr. Werner Kurz,  a Senior Research Scientist with Natural Resources Canada, told the CBC in an interview in 2018 that already in 2017, forest fires in the province of BC  emitted between two and three times the amount of CO2 compared to all the fossil fuels burned in the province the same year. 

Dr Kurz also leads the team that develops Canada's forest greenhouse gas inventories and the Forest Carbon Management Project of the Pacific Institute for Climate Solutions (PICS). 

Here are the numbers: In 2017 about 1.2 million hectares of forest burned in British Columbia.  Compared to the average annual area burned in the province between 1990 and 2015, each of the last two years burned 15 times more than the average area. Forest fires like these release carbon dioxide and other greenhouse gasses, such as methane, into the atmosphere.

The estimate is that the direct fire emissions in 2017 were about 150 million tons of CO2  (plus/minus 30). This, according to Dr Kurtz, is two to three times the emissions from fossil fuel burned in B.C. during an entire year. 

Fossil fuels still the largest emission source on a global scale

The wildfire season in Canada 2023 has broken all previous records.  Although forest fires or not rivalling worldwide emissions from fossil fuels by any means, the numbers from some of the extreme examples of CO2 emissions from Canadian forest fires are staggering. 

In a recent article, Copernicus confirmed to the CBC that the fires in the Northwest Territories in 2023 produced CO2 emissions 277 times the amount of CO produced by human activity during an entire year in the same province. 

The CBC interviewed Mark Parrington, a senior scientist working at the European Union's Copernicus Atmosphere Monitoring Service (CAMS). He said the N.W.T. fires have contributed the most of all the provinces and territories to Canada's total wildfire emissions.

During all of 2023, until Aug. 23, wildfires in Canada have emitted 327 megatonnes of carbon,  according to CAMS data. (one megatonne is a million tonnes.) That is roughly 1200 megatonnes of CO2 from the Canadian wildfire season only up until end August. 

However, as the 2018 CBC points out: the impacts on the atmosphere are even greater than that of the direct emissions from the fire itself: when trees are killed by fires, and left to rot,  they will continue to decompose over the next decades, releasing more carbon dioxide into the atmosphere. Also, dead trees will not be absorbing an carbon dioxide from the atmosphere like living trees would. The combined impact on the greenhouse gas emission balance is larger than just the direct emissions. 

This is, however, very difficult to put exact numbers on, because in most cases, burned areas will eventually reseed themselves, and new trees will grow again, which then re-absorbs some of the released CO2 year by year.

In cases where land erosion occurs after a wildfire, no CO2 is reabsorbed there until reforestation projects are initiated.  

CO2 emissions from human activities by sector:

According to Our World in Data, human energy use in all sectors worldwide makes up 73,2 percent of all greenhouse gas emissions.

Given the recent focus on replacing fossil fuel cars by electric cars, it may seem surprising to see that passenger road transport makes up a relatively small share of the carbon load. Aviation makes up an even smaller share.

The largest CO2-producing activities are from energy use in industry, agriculture and in heating. 

All world transport:16.2%

Road transport (11.9%): emissions from the burning of petrol and diesel from all forms of road transport which includes cars, trucks, motorcycles and buses. Sixty percent of road transport emissions come from passenger travel (cars, motorcycles and buses); and the remaining forty percent from road freight transport

Aviation (1.9%): emissions from passenger travel and freight, and domestic and international aviation. 81% of aviation emissions come from passenger travel; and 19% from freight.

Shipping (1.7%): emissions from the burning of petrol or diesel on ships. This includes both passenger and freight maritime trips.

Rail (0.4%): emissions from passenger and freight rail travel.

Pipeline (0.3%): fuels and commodities (e.g. oil, gas, water or steam) often need to be transported (either within or between countries) via pipelines. This requires energy inputs, which results in emissions. Poorly constructed pipelines can also leak, leading to direct emissions of methane to the atmosphere – however, this aspect is captured in the category ‘Fugitive emissions from energy production’.

Energy use in buildings: 17.5%

Residential buildings (10.9%): energy-related emissions from the generation of electricity for lighting, appliances, cooking etc. and heating at home.

Commercial buildings (6.6%): energy-related emissions from the generation of electricity for lighting, appliances, etc. and heating in commercial buildings such as offices, restaurants, and shops.

Agriculture, Forestry and Land Use: 18.4%

Agriculture, forestry and land use directly account for 18.4% of greenhouse gas emissions. Including refrigeration, food processing, packaging, and transport, this sector accounts for around one-quarter of greenhouse gas emissions.

Energy use in industry:  24,2 percent

These are the  emissions from the energy used by industry, not form the industrial processes themselves. 

Iron and Steel (7.2%):

Chemical & petrochemical (3.6%): energy-related emissions from  manufacturing

Food and tobacco (1%):

Non-ferrous metals: 0.7%

Paper & pulp (0.6%): energy-related emissions from the conversion of wood into paper and pulp.

Machinery (0.5%): energy-related emissions from the production of machinery.

Other industry (10.6%): energy-related emissions from manufacturing in other industries including mining and quarrying, construction, textiles, wood products, and transport equipment (such as car manufacturing).

Direct Industrial processes: 5,2 percent

Cement (3%): carbon dioxide is produced as a byproduct of a chemical conversion process used in the production of clinker, a component of cement.

Chemicals & petrochemicals (2.2%): greenhouse gases can be produced as a byproduct from chemical processes – for example, CO2  can be emitted during the production of ammonia. 

Read more data on greenhouse gas emissions by sector and country