Without ambiguity or periphrasis, the answer to the question at the head of this article is yes . Of course, anthropogenic climate change is directly related to forest fires. It is a fact that human-driven weather modification events over the past few decades have an influence on when, where, and how many wildfires start and, especially, how they spread.

Fire without human influence

Fire regime is an ecological term that refers to the frequency, size, intensity, seasonality, and type of fires. Some of these components are very relevant in certain types of ecosystems.

If fires in an environment increase in frequency , the selective pressure represented by natural selection favors certain species that reproduce quickly and are benefited by the fire. The size determines the irregularity of the landscape and the distance that living beings will have to travel to regenerate the devastated environment. Intensity , measured as the amount of energy released in the fire, can change significantly depending on weather conditions or the plant composition of the ecosystem. Seasonality can influence the other factors; a fire during the dry season does not have the same consequences as one that occurs during the rainy season.

Different types of fire affect different strata of the ecosystem; Burning the crowns and maintaining the undergrowth has different consequences than burning the scrub, but the trees survive.

Fire is one of the dominant disturbances in forests in many regions of the world. Naturally, and without human influence , forest fire acts as a primary process on the composition and structure of the vegetation, helping, as large herbivores do, to shape the mosaic of the landscape and decisively influencing the cycle carbon from ecosystems.

Ecosystems, as complex entities that present emergent properties —that is, their total properties are greater than the simple sum of the properties of their components—, have a certain resilience and capacity to adapt to these disturbances. It is common for the different types of ecosystem to adapt to the fire regime that occurs in their environment. And, therefore, a change in the fire regime can have unexpected consequences, altering the way the ecosystem reacts. If the change is drastic and happens in a short time, the ecosystem fails to readjust to the new fire regime, with devastating consequences.

Human influence on fire

Currently, human activity is the main cause of forest fires in Spain. More than 80% of Spanish forest fires are caused by human hands –intentionally or accidentally– and this is behind more than 87% of the forest area burned.

If we consider, therefore, the human being as the main cause of forest fires in Spain, it is evident that we become an agent that modifies the fire regime . We increased the frequency and modified the types of fires in the different ecosystems. In addition, while natural fires generally occur in ecosystems already adapted to these dynamics, and are usually limited in time and space, fires caused by human activity are usually larger and more intense.

On the other hand, certain disturbances caused by humans can act in synergy with fire, also altering the fire regime of an ecosystem. Among them, the change of land use, deforestation for agricultural or forestry purposes, urban development or the installation of infrastructures and, of course, the introduction of certain invasive exotic species of a pyrophytic nature, such as eucalyptus, in environments not adapted to fire.

Climate change, another factor caused by the human hand

While many human activities have direct effects on fire, its intensity and frequency, there are also other actions that indirectly affect fires. And anthropogenic climate change is the main intermediary in this relationship. In fact, forest fires are closely linked to the weather , both in their origin and in their spread.

One of the effects of climate change is the change in the frequency and distribution of storms . These changes may cause more wildfires caused by lightning, or to happen in places where they did not happen before.

Prolonged drought , another effect of climate change in some regions, favors fires to start and spread more easily, and have greater intensity. The fact that there are more and more long-lasting, more frequent and larger heat waves is another perfect ingredient for increasing the frequency and intensity of fires.

In addition, changes in the distribution of the seasons can alter the seasonality of the fires, causing even ecosystems prepared for the presence of fire at certain times of the year to face the devastation of the flames at a time of the year other than habitual, and for which they are not adapted.

The researchers caution that in the future, under a warmer climate, the overall fire regime is expected to become increasingly severe, with more areas burned and a longer fire season . Although, of course, it will not affect all places equally, and there will be great spatial and temporal variation in the response of fire activity to climate change.

References:

Aponte, C. et al. 2016. Forest fires and climate change: causes, consequences and management options. International Journal of Wildland Fire, 25(8), i. DOI: 10.1071/WFv25n8_FO

Flannigan, M. D. et al. 2000. Climate change and forest fires. Science of The Total Environment, 262(3), 221-229. DOI: 10.1016/S0048-9697(00)00524-6

Flannigan, M. D. et al. 2006. Forest Fires and Climate Change in the 21ST Century. Mitigation and Adaptation Strategies for Global Change, 11(4), 847-859. DOI: 10.1007/s11027-005-9020-7

MAP. 2019. Forest fires in Spain: Decade 2006-2015 (NIPO: 003-19-031-5). Ministry of Agriculture, Fisheries and Food.