From the elephant in Africa to the caribou in Alaska, from the heaviest animal on earth, the blue whale, to the less-than-feathery dragonfly: there are migratory animals on the move every day all over the world. They run, fly, crawl and swim to wherever the climate promises them the most food. Migratory birds trade the European winter for the insect-rich African spring, polar bears migrate to the edges of the sea ice in autumn to hunt seals, and millions of zebras, wildebeests and gazelles follow the rain through the African savannahs in search of fresh greenery and water.
But regardless of whether it is the migration of millions of birds, the lonely journey of sea turtles through the oceans or the mass migration of ungulates through steppes, savannahs and prairies: the global system of animal migration is becoming increasingly out of step due to climate change, experts point out in a report on Sunday COP28 world climate conference presented in Dubai, report commissioned by the United Nations. Global warming is already having catastrophic effects on animal migration and thus on the populations of numerous species on all continents and among all animal groups, according to the report.
Migratory animal species suffer particularly badly from the consequences of climate change because they are affected by the changes associated with global warming in different places and in different habitats. In their breeding and rearing regions, at resting places and in the wintering area itself. “The dangers from climate impacts such as rising sea levels, droughts, storms or floods are increasing for migratory species,” warn the experts.
According to the researchers, far-reaching effects on animal migration have now been demonstrated in all ecosystems and for all forms of climate change. For example, dry wetlands and riverbeds that have dried up after a hot summer are already posing major problems for migrating waterfowl and migrating fish. For some species, these can become an existential threat. According to calculations, more than every second wetland along the bird migration route between Europe and Africa will fall victim to drought by the turn of the century.
Species that commute across continents are particularly badly affected
The consequences of global warming are also clearly visible in the world’s oceans and in the Arctic regions. The rise in temperature is changing the metabolism of fish there and is leading to a sharp decline in krill populations in Antarctica. The result of the decline of small crabs is a lack of food for fish and, as a result, for the animals that live on them and migrate after them: This affects predatory fish, whales, penguins and seabirds.
According to the analysis, species that commute over huge distances across continents are particularly affected. They have to cope with the fact that warming is changing the timing of nature very differently from region to region. Migratory birds from Europe, for example, have spent millions of years of evolution developing an internal clock that ensures that they return from Africa to raise their young exactly when insect development is at its peak. Because climate change is causing vegetation to develop ever earlier, this interaction is getting out of sync. As spring moves forward, the peak of the insect boom is already over when the young birds hatch from their eggs. The consequences are malnutrition or the death of many young animals.
More and more studies show that animals all over the world and in all habitats are trying to adapt. Birds return from winter quarters earlier, and African wild dogs give birth later to protect them from the heat. Whales that feed in Antarctica and reproduce in the tropics are also now arriving at their breeding grounds earlier. But the adaptations come at a price: Because migratory birds shorten their resting times, they often reach their destination in poor condition and have lower breeding success. And in wild dogs in Africa, researchers found that later whelping times lead to more heat-related deaths among young animals during the growing phase. Heat stress is already killing large numbers of seabirds and fish. More and more animal species are reacting to rising temperatures by fleeing towards the poles. The phenomenon is also evident in Europe, where the distribution of all 600 bird species has shifted northward by an average of almost 30 kilometers in recent decades – by one kilometer per year.
“The impacts of climate change have the potential to disrupt the functioning and cohesion of ecosystems worldwide,” the UN report warns. This would also mean that natural services essential to humanity’s survival would be at risk: birds, insects and bats pollinate more than two thirds of the world’s crops. They spread seeds on their migrations and thus create climate-stable forests – and they themselves actively contribute to climate protection.
Marine fish and whales store large amounts of carbon in their bodies, while the huge herds of ungulates in African savannahs and Asian steppes bind carbon through their grazing behavior. Scientists believe that through better protection, especially of migratory wild animals, more than six billion tons of additional carbon dioxide can be bound in ecosystems every year – almost as much as the Intergovernmental Panel on Climate Change calculates that must be removed from the atmosphere as “negative emissions.” to keep global warming within the Paris climate targets. An intact system of animal migration creates a win-win situation for the climate and wildlife, believes the head of the UN Convention for the Protection of Migratory Animals, Amy Fraenkel: “There can be no ‘net zero’ without restoring nature.”