At this point, you are likely asking yourself: Why are fires in decline? The surprising answer is that it is likely the result of the combination of modest warming and increasing CO2!
A study by scientists with the Canadian Forest Service compared temperatures and CO2 concentration versus frequency of forest fires over the last 150 years in North America and northern Europe. The authors demonstrated a link between more CO2 in the air and fewer fires worldwide. They attributed the decline in forest fires to the combined effect of CO2 fertilization and rising temperature, leading to greater soil moisture. Higher levels of atmospheric CO2 means that plants lose less water via the process of transpiration, which results in less moisture being drawn from soil. The Canadian scientists’ summary is worth reading:
Despite increasing temperatures since the end of the Little Ice Age (ca. 1850), wildfire frequency has decreased as shown by many field studies from North America and Europe. We believe that global warming since 1850 may have triggered decreases in fire frequency.
