The total emissions of greenhouse gases and airborne particles caused by wildfires are almost 70% higher than previously assumed. Researchers at Wageningen University & Research discovered this in a long-term study conducted in collaboration with NASA, BeZero Carbon, and American universities in Maryland and Irvine, California. It turns out that far more small fires occur worldwide than previously believed. This is because satellites had not adequately recorded these smaller fires, and many were not included in the data. Satellite data are crucial for determining the size of fires and the amount of vegetation lost. We now see a new picture: the latest satellite data reveal a significantly altered view.

Small Fires, High Emissions

These newly recorded fires occur mainly in areas with high population density. Wildfires therefore have an even greater impact on air quality than previously thought. Fires emit not only greenhouse gases but are also a major source of airborne particles in many regions. The newly detected fires are so numerous that they play a major role in global wildfire emissions, which now appear to be nearly 70% higher than earlier estimates.
Researchers are mapping where wildfires occur and what their emissions are. This includes not only forest fires but also fires in grasslands and agricultural land. A new version of the Global Fire Emissions Database (GFED) has recently been released, and the results have been published in Nature Scientific Data.

Improved Satellite Data
According to lead researcher Guido van der Werf (Wageningen University & Research), ‘Our estimates of emissions have never changed so dramatically as they have now. Although our data have been refined over the years, our estimate of annual emissions was always around 2.0 gigatonnes of carbon, or about 20% of fossil fuel emissions. Now it is almost 70% higher, around 3.4 gigatonnes.’ The main reason is improved satellite data. Previously, satellite data divided the world into blocks of 500 by 500 metres, whereas now it is partly 20 by 20 metres.

Forest Fires Cause the Most Damage

Emissions from forest fires represent a relatively small share of total landscape fires, but they are the category causing the most damage. On average, emissions from these forest fires in the new database are not much higher than in previous versions, because these fires were already well recorded with older satellite data. However, researchers observed that forest fires have become more frequent and more intense over time, partly due to climate change.

Further research Needed

GFED data are widely used in climate models and are an important dataset for air quality research. Whether these new insights will also lead to a different understanding of the interaction between climate change and wildfires will be investigated in the coming years. What is already clear is that higher emissions have negative consequences for air quality: simply put, more fine particles and soot enter the atmosphere, especially in areas where many people live.