Defending Biodiversity A Top Priority
Half of the world’s population lives in areas that are highly vulnerable to climate change. That means that 3.6 billion people could become refugees in search of food, water and shelter. Such a mass migration will not end well.
A quarter of the world’s natural landscapes now face longer fire seasons as a result of global warming and changes in precipitation. Scientists have shown that degraded ecosystems are more likely to burn.
Global warming and biodiversity loss promote more deadly wildfires. As both problems escalate, scientists are racing to understand all of the ways that climate change and biodiversity loss are already compounding one another – and how the world can deploy solutions that tackle both.
Many of the options on the table for tackling climate change, such as stopping deforestation and restoring natural ecosystems, would come with obvious benefits for biodiversity. However, other proposed climate solutions, such as burning crops for energy, ar not the answer.
Addressing climate change will be crucial for the natural world. One in 10 species is likely to face a very high risk of extinction at 2C of global warming, the upper limit of the Paris Agreement. This rises to 15 percent at 5C.
Though the overlap between the two challenges is becoming clearer, politicians still tackle each problem separately. The next biodiversity summit, COP15, is due to take place in China later this year after several postponements, while the next climate summit, COP27, will take place in Egypt in November.
Both climate change and biodiversity loss are already causing severe impacts for people.
Average global temperatures have risen by 1.2C since the start of the industrial era, while CO2 in the atmosphere is at its highest level in at least two million years, according to the world’s climate authority, the Intergovernmental Panel on Climate Change (IPCC).
This has caused an increase in weather and climate extremes in every world region.
Human-caused climate change is already influencing the severity of extreme events, such as heat waves, floods and wildfires. For example, the deadly heat sweeping India and Pakistan in 2022 was made 30 times more likely by climate change. In addition, extreme flooding in Western Europe in 2021, which killed 220 people in Germany and Belgium, was made up to nine times more likely by climate change.
Depending on what actions humanity takes to tackle climate change, 50-75% of the global population could face “life-threatening” extreme heat by the end of the century, the IPCC says. Tropical coral reefs, which provide food or income to half a billion people, are projected to disappear if temperatures exceed 1.5C, the aspiration of the Paris Agreement.
The world’s most marginalized communities are suffering disproportionately from the impacts of climate change. This is despite the fact that most emissions come from a wealthy few. Carbon Brief analysis shows the US and Europe have together produced nearly half of all the CO2 that has been released into the atmosphere since the start of the industrial era.
The loss of biodiversity across the world is also having a major impact on people.
While many people associate the term “biodiversity” with iconic species and tropical forests, it actually covers much more than this, explains Dr Nathalie Pettorelli, a senior research fellow at the Zoological Society of London’s Institute of Zoology.
“Biodiversity is everything that defines our living world,” she said. “It’s not only species – it’s ecosystems, it’s habitats, it’s the genetic makeup of individuals. It’s how communities assemble to be something bigger than the sum of their parts.”
The variety of living things found on Earth is crucial to human survival, explains Dr Charlie Outhwaite, a postdoctoral research associate at the Centre for Biodiversity and Environment Research at University College London.
“It’s not just nice to have biodiversity on the planet, it also provides a lot of important things,” Outhwaite said. “Biodiversity is important for the pollination of crops, for maintaining nutrients in the soil and for maintaining water quality that we need to water crops. If we lose biodiversity, we lose a lot of the benefits that humans rely on.”
While the pace of climate change can be measured through global temperature rise and increasing greenhouse gas emissions, understanding the extent of human-caused biodiversity loss is far more complex. This is largely because humans can affect biodiversity in myriad, far-reaching ways – for example, by destroying habitats, causing species extinctions or converting diverse ecosystems to monocultures. (Climate change also poses a major risk to biodiversity.) While human-caused climate change became evident in the 1800s, biodiversity loss has occurred since the dawn of human civilization. We simply filed it under the theme of evolution.
Biodiversity loss is now at an unprecedented level because of human activities. An important report released in 2019 from the world’s biodiversity authority, the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), found that one million animal and plant species now face extinction. At least 680 vertebrate species have already been driven to extinction since the 16th century.
A separate report from the United Nations Convention to Combat Desertification (UNCCD) released this year found that human activities have already altered 70 percent of the Earth’s land surface, degrading up to 40 percent of it. Four of the nine “planetary boundaries” – limits on how humans can safely use Earth’s resources – have already been exceeded, according to the report. The report also said that, across the world, populations of mammals, birds, amphibians, reptiles and fish decreased by an average of 68 percent between 1970 and 2016. In tropical central and South America, animal populations fell by 94 percent.
This biodiversity loss has consequences for people. An estimated $44tn – roughly half the world’s annual economic output – is currently being put at risk by the depletion of natural resources, according to the UNCCD. The loss of pollinator species specifically threatens global crops worth $577bn per year. The loss of coastal habitats that provide a natural buffer against extreme weather events has put 100-300 million people at an increased risk of floods and hurricanes. If the unsustainable use of land continues to 2050, an additional 16m square kilometers – an area the size of South America – could be degraded globally.
And research shows that climate change could become the largest risk facing biodiversity sometime this century. Much like climate change, the global challenge of biodiversity loss is defined by large geographic and economic disparities. According to the UK Natural History Museum’s biodiversity intactness index, high levels of biodiversity loss has occurred in regions including the UK and Ireland, parts of western Europe and stretches of North America. By contrast, areas with high levels of biodiversity tend to be found in sub-Saharan Africa, South America and parts of Asia.
Meanwhile, marginalized groups today play a disproportionate role in protecting the world’s biodiversity. For example, Indigenous peoples represent around 6 percent of the global population, yet act as stewards over 40 percent of intact ecosystems and protected areas.
Humans are responsible for driving both climate change and biodiversity loss.
For example, in 2019, CO2 from the fossil fuel industry accounted for 64 percent of all human-caused greenhouse gas emissions. Fossil fuel extraction also poses a major threat to biodiversity, both directly through the destruction of ecosystems and indirectly by driving climate change.
Humans’ impact on land – primarily for food production – is also a major driver of both climate change and biodiversity loss. Food systems – a catch-all term to describe the way humans produce, process, transport and consume food – are the leading driver of biodiversity loss and also account for 29 percent of human-caused greenhouse gas emissions, according to UNCCD.
Animal agriculture has a large climate impact. Meat and dairy accounts for around 14.5 percent of global greenhouse gas emissions, according to the UN’s Food and Agricultural Organization (FAO). Beef has a greater climate impact than any other food. One major reason for this is cows are ruminant animals, meaning they belch out the potent greenhouse gas methane when digesting food.
Another reason is that meat production requires vast areas of land to be converted for grazing or to grow animal feed. Because of this, livestock production takes up nearly 80 percent of global agricultural land, despite supplying less than 20 percent of the world’s calories. This land conversion also makes animal agriculture a profound driver of biodiversity loss. A study published in 2018 found that the mass of animals raised for slaughter on Earth now outweighs wild mammal populations by a factor of 15-to-1.
The destruction of tropical forests for livestock production has a particularly severe climate and biodiversity impact. This is because tropical forests store a quarter of all land carbon and supporting two-thirds of the world’s biodiversity.
In addition to cattle rearing, tropical forests are also cleared for palm oil production, logging, mining and other exploitative activities. A recent report found that, in 2021 alone, humans cut down 3.75m hectares of tropical forest – creating emissions equivalent to those caused by India’s annual fossil fuel use. In addition to tropical forests, humans are fast degrading other carbon-rich and diverse ecosystems, including tropical mangroves, grasslands and underwater kelp forests.
At the root of both climate change and biodiversity loss is overconsumption of Earth’s resources, says Professor Katharine Hayhoe, a climate scientist and chief scientist at the Nature Conservancy.
“The interlinking nature of these crises is all due to humans’ unsustainable use of resources,” she said. “We have been living as if the world were infinite and flat. And it isn’t.”
In addition to climate change and biodiversity loss sharing common drivers, each global challenge can worsen the other. While humans’ impact on land remains the chief driver of biodiversity loss, climate change is playing an increasingly large role. The IPCC’s most recent assessment of the impacts of climate change concluded that warming has already caused “substantial damages and increasing irreversible losses to land ecosystems across every region of the world.”
“The climate is changing faster now than any time in the history of humans on this planet,” she said. “It’s changing faster than all plant and animal species that currently exist have ever experienced as well. So climate change is a threat multiplier for biodiversity.”
As temperatures increase and rainfall changes, some species are being forced to seek out new areas with climate conditions they are able to tolerate. A scientific review of 40,000 species across the world published in 2008 found that around half are already on the move as a result of changing climate conditions.
Many species are seeking cooler temperatures by moving towards Earth’s poles. Land animals are moving toward the poles at an average rate of 10 miles per decade, whereas marine species are moving at a rate of 45 miles per decade.
This global movement of species in response to warming will have far-reaching consequences for ecosystems, explains Professor Hans-Otto Poertner, head of biosciences at the Alfred Wegener Institute (AWI) and co-chair of the IPCC’s climate impacts assessment.
“It’s habitat modification – by the warming climate making species move to higher altitudes, higher latitudes or deeper waters. This does not happen to the same extent for all species. So we’re getting new ecosystems. The projection is that this leads to a decline in species numbers, abundance and overall biomass.”
The reshuffling of ecosystems could be creating new risks, including increased opportunities for animals to spread their viruses. Increased virus sharing between animals could in turn boost the chances of a “zoonotic spillover” – the passing of harmful pathogens from animals to humans. Read the full story via the link below and thanks to Carbon Brief.
