Fire

Fires come both good and bad. You will find many kinds of them here. Where people are, there will always be more fires because we cause them. In the cold-temperate part of the northern hemisphere 55% of all wildfires are caused by people. These are forest fires with evergreen/needle trees, and commonly they are extinguished fairly fast. The remaining 45% are caused by lightning and they take much longer time to extinguish since they are located in more remote terrain generally. The spruce and pine trees of the northernmost forests are annihilated by natural fires twice per century — not simultaneously but area by area. The spruce and pine forests 1000 km southwards are destroyed 4-5 times per century in this natural process of forest rejuvenation. The largest burnt forested areas in this cold-temperate climate zone are in Russia and some people are killed every year by these fires. Chiefly south of this zone about 100 people per year are killed by forest and bush fires in China alone, where also 1 million hectares of land are damaged or destroyed by such fires.

In the dry regions of the globe lightning is responsible for most bush fires and grass fires. The trees destroyed are often palms or in Australia Eucalyptus. In parts of Java lightning occurs more than 300 days per year, yet wildfires are very rare there, but occur when one of the island's >40 active volcanoes erupts. Lightning strikes the earth 8 million times per day. Conclusion: It is not enough with thunderstorms and flashes of lightning to get a wildfire. A stroke of lightning will cause a fire only when it hits something dry and flammable.

Geologists are also interested in fires caused by lightning because coal seams that are exposed in mountain slopes are ignited by lightning strokes and burn during decades — possibly centuries. Natural pollution of this kind exists in Alaska. In Greenland a coal seam caught fire by heat and sparks of friction when a fault cut trough the coal seam.

In Southeast Venezuela lies the 11,000 km² Great Savanna with its biologically famous tepuis or mesas/table top mountains and the water of the highest waterfall on earth jumps freely 979 m down to the savanna plain were the rivers carry a strange water — coloured like a good tea. Around 20 years ago, three thick charcoal beds discovered in a vertical soil profile were studied and analysed in detail. The charcoal beds were what was left of three forests with 30-40 m tall trees after a period of long drought that ended with fires caused by lightning over wide areas, leaving only pieces of charcoal. This forest had a very diversified flora and fauna as revealed by pollen analysis and other microscopy investigations. This first fire disaster took place ca. 480 CE.

After some decades the annihilated forest got new vegetation when a soil layer had been formed, a less than 20 m high savanna forest dominated by one species of palms and a low-diversity flora and fauna. Given time it evolved slowly to a new 30-40 m high forest almost identical with that of the buried charcoal bed below its roots. A high-diversity fauna and flora developed again, until 800 CE when — after another long drought, lightning set the forest ablaze, leaving nothing but the second charcoal bed. Similar ecological effects repeated the story. A monospecific palm savanna with a low-diversity flora and fauna on top of the second charcoal bed evolved to an ecologically diverse rain forest. Until...a third drought period ended by the third charcoal bed ca. 1000 CE.

When people moved into this area in the 19th century, they burnt the 30-40 m high-diversity rainforest because they wanted to grow food and have livestock. They did not know any of the natural history of what we now call the Great Savanna.

I started building my database 30 years ago because — at that time living in the tropics where all biological processes run faster than in cold areas — we realized that the past can teach us about the impact human activities today will have in the coming years. Global warming — irrespective of its natural cause or pushed further by man — can be met with better education where science has a greater role.

Almost all fires in high-income countries are related to their population density. A growing population means more fires — until we start educating our children about how to avoid causing fires. It is time for politicians in Europe and Asia to wake up.