Climate Change

Climate crisis is already affecting the Brazilian Amazon

The population of pink dolphins in the Mamirauá Sustainable Development Reserve, fell by 65 per cent between 1994 and 2016; dolphins are a good indicator of the degree of conservation of habitat

By Mariana Paschoalini Frias
Published: Thursday 26 October 2023
Small canoe stranded in the nearly dry bed of the Tapajos river in Alter do Chao, Santarem, Brazil, during the Amazonian drought in the second half of 2023. Photo: iStock

If the Amazon were a country, it would be the seventh-largest in the world. Its biodiversity is also great. The territory is home to a huge number of plants and animals and most of these species have not even been studied by scientists. So far, at least 40,000 plant species, 427 mammals, 1,294 birds, 378 reptiles, 427 amphibians and around 3,000 fish in the region have been scientifically classified.

However, all this untapped natural wealth is at risk. The latest edition of the Living Planet Report reveals an average drop of 69 per cent in the monitored populations of vertebrates — mammals, birds, amphibians, reptiles and fish — over the last four decades.

Since 1970, the world has lost a third of its remaining wetlands, while freshwater wildlife populations have fallen by an average of 83 per cent. In the Latin American and Caribbean region, monitored populations have shrunk by an average of 94 per cent. In Brazil, the population of pink dolphins in the Mamirauá Sustainable Development Reserve, in the state of Amazonas, fell by 65 per cent between 1994 and 2016.

Since September 23, 2023, pink dolphins and Tucuxis from the Lake Tefé region in the interior of the state of Amazonas have been turning up dead on the shores of the lake. By October 20, 154 dead individuals had been recorded. Histological analysis and molecular diagnosis of 17 individuals did not indicate the cause of the mass deaths. The most likely hypothesis is overheating of the water. Measurements taken by the Mamirauá Institute reached 40 degrees in some areas — 10 degrees above the average recorded historically.

This year, the abnormal warming of the Atlantic Ocean has contributed to the drying up of the region’s rivers and, combined with El Nino, the drought could be prolonged, affecting wildlife and more than 500,000 people, making it impossible to access food, medicine and water.

This is a preview of what could happen if we fail to keep the planet’s temperatures at safe levels. The loss of nature, water and food insecurity are likely to worsen with the reduction of water accelerated by climate change.

The crisis with the Amazon river dolphins shows that further studies on the impacts of climate change on wildlife are urgently needed. It is not yet known what the consequences will be for the surviving animals of this population in Lake Tefé. The deaths are a wake-up call, because like the jaguars, the presence of dolphins is a good indicator of the degree of conservation of the habitat.

In the past, animals have had thousands or millions of years to adapt to changes on the planet. But now these changes are happening very quickly. We fear that there won’t be enough time for the animals to change their habits and adapt to the new temperatures.

With warmer scenarios such as those predicted by the Intergovernmental Panel on Climate Change (IPCC), the tendency is for stronger animals to migrate to regions with more bearable temperatures. However, this movement can have an impact on the entire chain, whether it’s a dispute over territory or resources. Animals can suffer greater stress, changes in physiology, size, reproduction and insufficient food collection.

Ultimately, we can consider extinction, especially for smaller species. In the Caatinga biome, for example, there is already the prospect of the extinction of more than 90 per cent of mammals, according to a study published in the journal Global Change Biology.

Water and thermal stress, nutrient depletion and altered population dynamics directly affect the survival of species. The increase in temperature caused by global warming and the reduction in vegetation favours the evaporation of water, reducing air humidity and increasing the possibility of savannization. The instability of rainfall can lead to extreme events of drought or flooding, which can cause animal and human mortality. Warmer environments, for example, can encourage the spread of invasive species, pests that affect forests and diseases that affect people.

The reduction in vegetation cover, the rise in temperature, the decline and quality of water are determining factors for the survival of animals and people. It is urgent that humanity complies with the Paris Agreement and reduces greenhouse gas emissions. In Brazil, this choice necessarily involves reducing deforestation and opting for clean energy.

Mariana Paschoalini Frias, Conservation Analyst at WWF-Brazil and coordinator of the South American River Dolphins Initiative (SARDI)

Views expressed are the author’s own and don’t necessarily reflect those of Down To Earth

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