In the air, on land and under the sea, species are battling a devil’s brew of climate change and human activity that’s rapidly altering their ranges, migration times and feeding grounds. As waters and the weather warms, rainfall patterns change and the rapidly expanding human population encroaches increasingly into remaining habitats, birds, insects, fish and even plants are being pushed towards the poles in their relevant hemispheres, and to higher elevations too.
Nowhere is this more apparent than in the key East Asian-Australasian flyway migration route, used by more than 200 species of water bird, which move from feeding areas in Australia and New Zealand to breeding grounds in the Russian and Alaskan Arctic via stop-over wetlands along the coastlines of East Asia.
“The main issue for the flyway at the moment is habitat loss”, says Richard Fuller of the School of Biological Sciences at the University of Queensland. The coastlines along the flyways – particularly in the middle section where birds pause en route to the Arctic – have been heavily developed over the last 50 years. “Any sea level rise that happens now is really going to squeeze out the remaining habitat”, says Fuller.
Species under dire threat include the Great Knot and Eastern Curlew, formerly abundant but now categorised as globally threatened. The highly threatened Spoonbilled Sandpiper is also declining due to the loss of important flyway stop-over sites for feeding and roosting.
The answer to these problems, Fuller says, is careful planning and targeted action to mitigate climate change through global agreements, while adapting to its inevitable impacts on already fragile ecosystems.
“We can use techniques in decision theory and conservation planning to work out where we can invest our limited resources – and that includes political will – in protecting the habitats that we do have left. Mitigation is vitally important longer term, but we need adaptation right now to save habitat before it is too late.”
In March, Working Group II of the Intergovernmental Panel on Climate Change published its fifth report on assessing and managing the risks of climate change. It stated that many land and water species had already shifted their geographic ranges, migration patterns and numbers in response to climate change. It also warned that the current pace of anthropogenic change in the climate was far faster than the natural rate, which had itself led to major ecosystem shifts and species extinctions in the past.
While the picture for migratory species is overwhelmingly negative, some have managed to adapt to the accelerating rate of change by altering their range, diet or even genetic make-up. At least one species of coral in the Pacific, for example, acclimatised to the warming temperature of the ocean and its higher acidic content (due to increased C02 absorption) by apparently activating genes that were previously dormant, according to a team of Stanford University scientists.
While in Mexico and California, the Quino Checkerspot butterfly has defied predictions of its imminent demise due to habitat loss caused by climate change. It has simply moved its range to higher altitudes and changed its diet to a totally different plant. But it remains to be seen how long such measures will last, and what impact they might have on other species.
Steve Brooks, an entomologist at London’s Natural History Museum, says many insects are highly mobile and adaptable, moving their ranges and colonising new territory as the climate changes. “Some insects are better colonisers than others … the less fussy, the bigger the range.”
But there can be a downside to this – as in the case of the Harlequin ladybird, dubbed the most invasive ladybird in the world. It first arrived in the UK in 2004 from Continental Europe, where it was introduced from Asia as a natural form of aphid control. It now covers a large area of the country and there is evidence that indigenous ladybirds are starting to decline as a result.
New research has found that birds migrating between the Arctic and South America could also be carrying plant fragments in their plumage and distributing them across the tropics, thereby establishing new plant colonies in areas where they have previously been absent – a kind of long-range version of localised seed dispersal. If the findings are applied to entire populations of migratory birds, it means they could potentially be transporting hundreds of thousands of plants parts around the world. The disruption of their migratory patterns could therefore have a knock-on effect on how, when and where new plant populations are established.
Even trees, not known for their mobility, are on the move: in northern Norway, conifer species have been found 100 kilometres north of what was previously the northern edge of their range.
Fish are altering their ranges too. In the northern hemisphere they’re expanding northwards and in the southern, southwards. Species of fish once confined to the Mediterranean such as Seabass, Red Mullet and Anchovies can now be found as far north as Scotland due to the fact that the seas around the country have warmed, according to John Pinnegar, programme director of the Marine Climate Change Centre at the UK government’s Centre for Environment, Fisheries and Aquaculture Science.
This has inevitably led to disputes between fishing fleets who find that either they now have access to fish that were previously not within reach, or that the fish they used to catch are no longer where they used to be. “Mackerel – usually found around Scotland and Norway – has recently shifted its distribution north to Iceland and the Faroe Islands”, says Pinnegar. “There is a battle raging over who has the right to catch them.” They’re also causing the collapse of the local sand eel population, on which puffins depend for feed.
French and Spanish fishermen recently argued for the right to catch anchovies of the cost of Southern England, claiming that the usual populations they take from the Bay of Biscay had simply moved north. But the row was defused when it was found that the anchovies now teeming in the Channel were genetically different from those in the Bay of Biscay: a small and previously overlooked indigenous population had boomed in the warming waters.
For certain industries, for the moment at least, the changes come with new profit potential. A thriving seabass and squid fishery has also begun to develop in northern England, and anglers are catching colourful triggerfish more commonly associated with tropical waters. On the other side of the globe, Australian winegrowers are moving south into Tasmania, where grapes associated with warmer climates can now be grown.
As accelerating climate change alters the physical distribution and abundance of more species, value chains will need to adapt. Can collaborations to secure the future of land and marine resources take shifting populations – and new demands on them – into account?
Jeremy Lovell is a freelance writer specialising in energy, environment and climate change.
Photo credit: Tsuguliev/iStock/Thinkstock, Shutterstock