Question: How does climate change impact wildfires?

Matt Kasoar answered on 11 Mar 2022: last edited 11 Mar 2022 5:55 pm

Thanks for the question! So we’d love to know for sure (and this is why we’re working on studying it!) – there are a few ways that climate change can impact fires, some obvious and some less obvious which is why disentangling the total effect is a challenging but really important problem!

If all the plants etc. stayed the same and it was just the climate that changed, then warmer and dryer conditions will increase the risk of wildfires igniting and spreading, since all the wood will be more flammable. And in many parts of the world this is what we expect to happen – and indeed are already seeing it happen, e.g. California, Greece, Australia, and Siberia just in the last couple of years have all had really bad wildfires which coincided with record heatwaves and dry conditions. As climate change gets worse if we keep emitting greenhouse gases, these conditions are expected to become more frequent – the world will be warmer, heatwaves and droughts will both be more common and more intense, which will result in more dangerous fire weather conditions.

But. It gets more complicated than this because ecosystems are affected by climate change as well. E.g. you can’t have a big fire if there’s nothing growing there to burn. So if a forest or grassland becomes a desert because it’s too hot and dry for plants to grow there, then you won’t have wildfires there anymore even though the weather conditions might be perfect for fires to start. Or, if you have a dense forest which used to only have fires occasionally, but starts having big fires every year because of more frequent hot weather, then lots of those trees won’t get a chance to grow back and the ecosystem might change to a more sparse forest or shrubland, with plant species which are more adapted to fire and burn less easily.

Finally, humans have a big impact on fire. For thousands of years we’ve used fire for hunting, grazing, and agriculture, but as we increasingly become industrialised and urbanised, this happens less as farmers start to use machinery more, and governments introduce air quality laws to stop burning of agricultural waste etc. So in some developing economies which are undergoing that transition right now, the amount of fire might go down even as climate change gets worse, because humans aren’t using fire for farming anymore.

So yeah… It’s a complicated question!! In places like North America and Europe fires will almost certainly get worse (as we’re already seeing) as heatwaves become more frequent, at least until there’s a change in the dominant ecosystems which might happen eventually. In other places like Africa where there’s already good conditions for fire every year, the amount of fire is probably going to go down – but this is because of population growth and increasing urbanisation rather than because of climate change