More and more species are migrating towards cooler regions in response to climate change. This is having a noticeable impact on humankind as the migration includes disease-transmitting insects and crop-destroying pests. Barbara Barkhausen reports from Sydney.
Species are reacting to climate change in different ways in different parts of the world. In Australia, for instance, the effects of warmer temperatures are already clearly visible.
Fish such as snapper are migrating from the north towards the cooler waters of Tasmania. In the northeastern part of the country, the Bramble Cay melomys has become the world’s first mammal to go extinct due to climate change. And the Great Barrier Reef is now experiencing coral bleaching for a second year in a row.
Climate change isn’t just about warmer temperatures. Sea levels are also rising, oceans are becoming more acidic and extreme weather events such as storms, floods and droughts are becoming more frequent – all of which are forcing animals to migrate.
“As their local environment changes, many plants and animals are responding by moving to higher altitudes, greater depths in the oceans, or towards the poles,” said Gretta Pecl, a marine ecologist at the University of Tasmania, who led a recent international study on how humans are being affected by climate-driven migration.
“Human survival depends on other life on earth so the redistribution of the planet’s living organisms is a substantial challenge for people worldwide.”
17 kilometres in 10 years
Scientists representing over 40 different institutes around the world participated in the study, which was recently published in the journal Science.
“Previous studies have shown that land-based species are moving polewards by an average of 17 kilometres per decade,” wrote the scientists.
Marine species are migrating at an even more astonishing rate: 72 kilometres per decade. The signs of this are already clearly visible in the oceans – and in turn affecting human activities. As corals die off from warmer temperatures, jellyfish infest waters used for recreation and urchins destroy fish habitats in kelp forests.
Nothing like it in 25,000 years
According to the international research team, there hasn’t been a comparable mass species migration in the past 25,000 years since the peak of the last ice age. And it is having an effect on ecosystems around the world, human health and culture in the process.
Coastal communities that depend on local fish stocks will lose or gain food sources depending on where they are located. And changes in distribution of fish and reindeer are impacting food security and traditional knowledge systems of indigenous Arctic peoples.
Winners and losers alike
“While some species favour a warmer climate and are becoming more abundant, many others that humans exploit or interact with face depletion or extinction,” explained Pecl.
For instance, pests will attack crops in what were once cooler regions, while disease-transmitting insects – such as malaria-carrying mosquitos – will spread into regions where people have not had prior exposure.
“The shifts will leave ‘winners’ and ‘losers’ in their wake, radically reshaping the pattern of human wellbeing … and potentially leading to substantial conflict,” warn the researchers.
New international guidelines needed
Economic factors, health risks or conflicts over fish stocks could ignite conflicts around the world.
An example of this is the ‘mackerel wars’ between Iceland and the European Union, which broke out after the mackerel had left their former homes and moved northwards in search of cooler waters, ending up around Iceland. The result: Iceland’s catch jumped from 1,700 in 2006 to 120,000 in 2010, leaving its EU neighbours to the south empty handed and crying foul.
To prevent even worse conflicts in the future, the researchers are calling for a revision of current international treaties and guidelines to take better consideration of species range-shifts.
“A dynamic, multi-level legal and policy approach is needed to address the impacts across local, national and international boundaries,” said Roger Griffis, a fisheries biologist with the American National Oceanic and Atmospheric Administration (NOAA) and co-author of the study.
Coastal communities that depend on fish stocks for their livelihoods could find themselves empty handed as fish move northward in search of cooler waters.
Image credit: Harold Meerveld, flickr/Creative Commons