How many fires are caused by climate change?

This is a great question, but one that science can’t fully answer yet. There are several ingredients necessary for fire, which means it is often difficult to say that a particular fire was caused only by climate change. For bushfires to occur, there needs to be:

• fuel to burn, which is typically leaf litter and twigs, grasses, shrubs and trees;
• the fuel needs to be dry enough to catch on fire;
• an ignition source, such as a camp fire that somebody failed to put out, lightning, or a downed powerline, and
• fire weather: typically hot, dry, windy weather that causes a fire to spread quickly. 

Because all these ingredients are required for a bushfire, it is difficult to say how many fires are specifically caused by climate change. We do know, however, that climate change is affecting each of these ingredients. Climate change is leading to changes in plant growth (fuel) and causing fuels to dry out more quickly because the air is hotter and drier. Climate change seems be leading to more ignitions from dry lightning (lightning that occurs when it is not raining). Climate change is certainly causing more dangerous fire weather (hot, windy weather) and fire seasons that start earlier in the year and finish later.

So, although science cannot yet say how many fires are caused by climate change, we can be confident that climate change is leading to more large forest fires around the world.