Climate warming, the rising sea level, the prominent increase of other extreme climates and natural disasters, as well as the loss of biodiversity . . . global climate changes have continuously threatened people’s living environment in recent years. Feb. 2 each year marks World Wetlands Day. Scientists have found that the unique ecological functions the wetland ecosystem possesses are closely related to global climate changes. The growth and decline of wetlands will affect the content of greenhouse gases in the planet’s atmosphere, which influences the trend and speed of global climate change.

Studies have shown that though wetlands only account for 5–8 percent of the world’s land area, they store about 525 Gt of carbon, accounting for about 35 percent of the world land carbon pool. Among them, peat bogs, which take only 3 percent of the global surface area, possess a carbon pool twice that of the global forest ecosystem. For example, in West Siberia, in Northwestern Europe, between the five Great Lakes of North America and Canada’s Hudson Bay, and in China’s Tibetan Plateau, low temperatures slow the decomposition of the soil’s organic matter, the accumulation of which forms good storage for carbon. The mangrove forest is another type of wetland that has high carbon storage capacity, and its carbon sequestration rate is 50 times that of tropical forests. 

In addition, wetlands have the sponge-like function of absorbing floods, providing a source of water, which notably enhances our ability to counter the negative effects of global climate change, such as resisting storm surges, floods and droughts as well as protecting the coastal zone.

The wetlands in coastal zones, especially mangrove forests, while providing food and livelihood for humans, are also an important lifeline for protecting the lives and properties of people living in coastal areas. After the 2004 Indian Ocean Tsunami occurred, people were to find that in those coastal zones where the mangrove forest was well protected, the loss in lives and property was quite small, which has led the world to this profound realization of the function of the mangrove forest. In the 1990s, wetlands along the middle reaches of the Yangtze River once suffered from large-scale reclamation, severely impairing the wetlands’ ability to store and regulate floods. This was one of the main reasons for the heavy losses of the disastrous flood that afflicted the Yangtze River basin in 1998. This once again proved the wetlands’ importance. 

Valuable as they are, wetlands have become the most damaged ecosystem in the last several decades of societal development. According to an estimate in the Ramsar Convention on Wetlands, global wetlands have decreased by 35 percent since 1970. The animal and plant species that inhabit wetlands have also remarkably declined, one fourth of which are endangered. Currently, wetlands also face threats from drainage, pollution, invasion by external species and global climate change, becoming increasingly vulnerable.

Though wetlands are able to store carbon, when undermined they become a source of greenhouse gasses. In their natural state, the carbon storage effect of wetlands outweighs the greenhouse gasses they release, which is manifested as carbon accumulation. However, the alterations of the water, vegetation, temperature and other factors of wetlands may possibly incur qualitative changes in wetlands’ carbon storage ability. 

Studies have shown that since modern times, as people’s exploitation and use of wetlands have increased, the carbon storage function of some wetlands has been converted and they nevertheless have become a source of greenhouse gasses, releasing a substantially higher amount of carbon substances.

As the scientific study on wetlands deepens, the role that wetlands play in carbon cycling is increasingly valued. The Ramsar Convention on Wetlands thus calls for countries to strengthen the study on wetlands and global climate change and to formulate corresponding national policies for wetland protection. In recent years, the Chinese government has also placed a higher premium on countering climate change through wetlands, and it has identified increasing wetlands’ carbon storage to promote green low-carbon development an important part of ecological progress. In face of the global climate change that may shake the foundation of human society’s long-term sustainable development, wetland protection offers a natural solution. 

This article was edited and translated from Guangming Daily. Lei Guangchun is dean of the School of Nature Conservation at Beijing Forestry University.

(Edited by Bai Le)