Drawing on growing evidence for fire in the rock record Andrew Scott gives an account of the important role of fire over the past 400 million years of Earth history. He describes the remarkable information we can extract about past climate, environment, and vegetation from fossil charcoal, including the finest details of ancient flowers and discusses early human use of fire.
On this journey he explores the impacts of wildfires on landscapes and ecosystems, and the ways of tackling growing problems of fire associated with climate change and invasive species. Raging wildfires have devastated vast areas of California and Australia in recent years, and predictions are that with global warming, and human settlements encroaching on flammable vegetation, we can only expect the problem to increase. But wildfire is nothing new. Since plants spread on land, large-scale fires have played their part in shaping life on Earth. To manage fire effectively, we need to understand its long history as a force of nature.
**Twenty things you might not know about wildfire**
- There is a fire burning somewhere in the world every minute of every day. There are 8 million lightning strikes on Earth daily. Humans are responsible for more than half of ignitions today but before human evolution lightning strikes were the main ignition source.
- Evidence of wildfire is first found on Earth 420 million years ago.
- The first mega-fire known from fossil charcoal deposits burned across Ireland 350 million years ago and covered an area the size of Holland, Belgium and Luxembourg combined.
- Of the 51 fires during the 1988 fire season in Yellowstone National Park, all but 9 were started naturally by lightning strike.
- African savannas need regular fire to keep habitats open.
- Some types of vegetation have evolved with fire and need it to survive, including Eucalyptus forest in Australia and chaparral in California.
- Some conifer cones such as the jack pine need fire to open their cones for the seeds to be shed.
- Smoke from fires in southern Africa triggers a seed germination response for some plants in the Fynbos.
- Fire and the amount of oxygen in the atmosphere are interlinked. With 15% oxygen there is no fire; above 30% fires would destroy most vegetation.
- There have been ‘high fire’ periods in Earth’s history, such as the Cretaceous, 100 million years ago, when atmospheric oxygen levels were high, and fires burned hotter and were more widespread.
- Some dinosaur graveyards were the result of post-fire erosion/flooding such as that recently witnessed in California.
- Fires were frequent across Antarctica 100 million years ago.
- Many fire-adapted traits in the Eucalypts, Pines, and Proteas evolved during the Cretaceous high fire period.
- Coal is formed from fossil peat but it is the charcoal from contemporary wildfires that rubs off on your hands when handling black coal.
- The amount of charcoal in a coal can provide information on the oxygen concentration in the atmosphere through time.
- Charcoal, the residue of burnt plants from a fire, preserves detailed morphological and anatomical information of the plant tissues.
- Delicate structures such as flowers have been found preserved as charcoal following wildfires. Such charcoalified flowers have been found in rocks 100 million years old.
- The earliest known conifer was found preserved as charcoal from a fire that swept across Yorkshire 315 million years ago.
- Today, the spread of invasive grasses is altering many of the world’s fire regimes.
- More fires occur during periods of rapid climate change, and with global warming large wildfires are only likely to increase.
Andrew Scott tells the whole story of fire’s impact on our planet’s atmosphere, climate, vegetation, ecology, and the evolution of plant and animal life. It has caused mass extinctions, and it has propelled the spread of flowering plants.
The exciting evidence we can now draw on has been preserved in fossilized charcoal, found in rocks hundreds of millions of years old, from all over the world. These reveal incredibly fine details of prehistoric plants, and tell us about climates from deep in earth’s history. They also give us insight into how early hominids and humans tamed fire and used it.
Looking at the impact of wildfires in our own time, Scott also looks forward to how we might better manage them in future, as climate change has an increasing effect on our world.
Andrew Scott is Emeritus Professor of Geology and a Leverhulme Emeritus Fellow at Royal Holloway, University of London. He has co-authored and edited several books on fire, most recently Fire on Earth: An Introduction. He appears regularly on radio and television science programmes.
The book will be published 22 March 2018 at £20 in hardback and available from www.oup.com