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Welcome to the Pyrocene: Living with Fire in a Changing World

Since 2023, global fires have intensified and are even reshaping the earth’s ecological landscape to some extent. The Canadian forest fire is one of the most representative fire events. In addition, the Maui fire in Hawaii, large-scale fires in the Pantanal wetland in western Brazil, and forest fires in Greece… have turned 2023 into an unusual “fire year.” Stephen Pine, an emeritus professor at Arizona State University who specializes in environmental history, believes that humans have entered the “Pyrocene”.

Nature that “walks with fire”

Today, with frequent fires, the plants in nature are most affected. However, plants are much more tolerant of fire than we think. Charcoal fossils 400 million years ago prove that plants had to face the threat of fire a long time ago; some studies also show that gymnosperms partially adapted to fire about 100 million years ago, while angiosperms developed during the Cretaceous. The widespread spread is also related to the high oxygen content in the atmosphere and frequent fires at that time.

Over the centuries, adaptations to fire gave some plant lineages a competitive advantage. For example, Pinus, as the largest genus among gymnosperms, contains more than 100 species and occupies vast coniferous forests in the northern hemisphere. Its spread and diversification are closely related to its adaptation to fire.

In addition, fire and climate are also inextricably linked. For example, a Mediterranean climate with hot and dry summers and mild and rainy winters can easily cause forest fires. Today, the world’s five Mediterranean climate zones together account for about 1.2% of the world’s land area, but are home to about one-sixth of the world’s plant species. In a Mediterranean climate, frequent fires almost always occur in hot and dry summers, which makes fires highly periodic and predictable, thereby changing the evolutionary direction of local plants.

So, how to make good use of the relationship between fire and species renewal? A review article published in Trends in Ecology & Evolution on July 19, 2023 pointed out that by synthesizing a large number of studies on the rapid evolution of animals in response to fire, an interdisciplinary expert team The team hopes to use what is known to help promote evolution-based conservation programs. In this way, they believe, they can try to exploit the way fire affects animals and in turn protect vulnerable species. In other words – work with evolution, not against it.

The climate crisis brought about by the Pyrocene

Another topic that people are concerned about is how the frequent fires around the world since 2023 will affect plant species? The answer may not be optimistic.

Liu Junyan, head of Greenpeace’s climate risk project, said: “In recent years, global wildfires have become more frequent, which has far exceeded the scale of wildfires as a natural phenomenon.” In the natural state, the burning of wildfires contributes to the sustainability of forests. Continuous development is a normal cyclical process. But now, as wildfires intensify, that cycle is broken.

For example, the fires in Australia and the Amazon forest are so large that it is basically impossible for the forests in these areas to recover in the next few years, making it impossible to form a self-cycle. It can be seen that frequent and intensified wildfires will have a very serious impact on the ecosystem and global climate.

So can the increasingly frequent fires around the world be avoided? In fact, as early as February 2022, the United Nations Environment Program released a report titled “Spreading Like Wildfire: The Growing Threat of Extreme Fires.” The report points out that climate change and land use changes are expected to cause wildfires to become more frequent and more intense; it predicts that global extreme wildfires will increase by 14% by 2030, by 30% by 2050, and by 50% by the end of the 21st century. In addition to countries and regions that have experienced frequent wildfires in the past, the risk of wildfires in some areas that have not been affected by wildfires before, such as the Arctic, is also increasing.

Against this background, on December 7, 2023, on the occasion of the 28th United Nations Climate Change Conference, the Chinese Academy of Sciences released the “Blue Book on Forest Fire Carbon Emission Research (2023)” (hereinafter referred to as the “Blue Book”). The blue book shows that in the 22 years from 2001 to 2022, global forest fires emitted a total of 33.9 billion tons of carbon dioxide, and the average annual forest fire area was 46.95 million hectares, which was 11 times the average annual growth area of ​​artificial forests during the same period. Forest fires have become a problem that cannot be ignored Sources of carbon emissions, experts call for including forest fire carbon emissions into the global carbon accounting system, while strengthening the prevention and management of extreme forest fires, deepening relevant scientific research and international cooperation, and jointly actively responding to global climate change.

It can be seen that in the current “Pyrocene”, as long as all countries in the world assume their respective responsibilities and adopt relevant measures such as forest fire control and climate action, they can minimize a series of serious disasters caused by climate change.

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