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ePaper created 2015-12-01, 11:33:23 | version 1.43.00
akzente 3/15 21 in focus Climate zones are shifting, causing palpable and perma nent changes to habitats. This has a dramatic impact on bird populations in particular. Due to higher tempera tures, some species are no longer migrating to warmer climes and are now starting to dominate certain habitats. This alters the local species composition and accelerates population decline. Flyways are also changing, increasing birds’ exposure to parasites. What’s more, pathogens such as certain strains of the flu virus are spreading to more northerly regions with the migration of waterfowl and have already caused outbreaks of disease – known collec tively as ‘avian flu’ – in a number of countries. Crops such as coffee at risk in many regions An even greater concern for scientists is the collapse of entire habitats and the associated ecological risks. Many flora and fauna currently face a rapidly growing threat of extinction. According to a recent meta-analysis, even if global warming is held down to 2° C, at least 5 per cent of species will still face extinction, and with a tempera ture rise of more than 4° C, 16 per cent of today’s species, both flora and fauna, will be at risk. Indeed, the figure may be very much higher. Warming is already threaten- ing the food sources of Adélie penguins in the Antarctic, for example. They mainly eat krill – tiny organisms that live under the ice. As the ice melts, the penguins are forced to travel long distances to find food, but young birds in particular often lack the reserves of energy that this requires. This is causing a sharp population decline in a number of colonies. Warming affects not only wild species, but also many commercial crops. According to a recent study, climate change poses a threat to the production of Arab- ica coffee, which accounts for approximately 75 per cent of the world market, in the main coffee-growing regions in Brazil, Viet Nam, Indonesia, Colombia and Central America. Warming of 2° C or more and changing hydro- logic cycles are detrimental to plant growth and make crops more vulnerable to pests. The coffee output of Brazil alone could well decrease by 25 per cent within the next 15 years. As coffee is the second most traded commodity after oil, this will threaten the livelihoods and survival of many of the world’s 25 million coffee farmers. Wheat production will also be adversely af- fected by higher temperatures. Many cereals do not thrive in heat, and this applies particularly to wheat, an important element of the ‘green revolution’. Studies show that global wheat production will suffer losses of 6 per cent for each degree centigrade of global warming. Even without drought and lack of nutrients, it seems that warmer temperatures will cause massive falls in out- put, potentially wiping out the higher yields that hu- mankind has worked so hard over many decades to achieve. But human communities also face immediate threats, including more frequent extreme weather events, droughts and floods. Climate change also ex- poses human communities to new indirect threats, for example by expanding the range of the subtropical Asian tiger mosquito and now the Bush mosquito to Europe. Many medical experts consider that the spread of these mosquitoes, which transmit dengue fever, West Nile virus and the viral disease Chikungunya, creates a seri- ous risk of infection in Europe. In 2007, researchers found larvae laid by these mosquitoes at a motorway service station in Baden-Württemberg in Germany. Since then, mosquitoes at all developmental stages have been found further afield, not only along motorways. So far, no confirmed cases of mosquito-borne diseases have originated in Germany, but the risk is increasing. The Tiger mosquito is by no means exceptional: hundreds of studies conducted in recent years on the spread of diseases – from malaria to crop infestations – have confirmed the close link between climate change and health risks. Studies in South-East Asia, Peru and Colombia have shown that malaria cases increase dra- matically during and after El Niño years. The World Health Organization (WHO) predicts a further spread of heat-loving parasites and vectors of diseases such as Leishmaniasis in South America and along the Mediter- ranean coast. This particular disease affects both humans and animals and can be fatal. But nowhere is climate change more obvious than around the polar ice caps and in mountain glacier regions. In the Arctic, average temperatures are currently rising twice as fast as in more temperate climes, and the average sea ice thickness per year in the central region of the Arctic basin has decreased by 65 per cent since 1975. In February 2015, the Arctic sea ice maximum extended for just 14 million square kilometres – an all-time low for » foto:GettyImages/NationalGeographicCreative(S.20) Smokestacks: atmospheric concentrations of greenhouse gases are still increasing, partly due to the burning of fossil fuels. The IPCC’s latest report leaves little room for doubt that global warming is human-induced. It can only be avoided with a radical transformation of energy systems. www.ipcc.ch akzente 3/1521