Justin Welbergen, a biologist from Cambridge (UK), will never forget how hundreds of flying foxes died before his eyes. It happened in January 2002 in the north of the Australian state of New South Wales
The scientist observed one of the fruit bat colonies - studied them for his dissertation. It was unbearably hot - the air temperature had just risen to + 43C. Usually, the animals dozed or made noise, sitting on the treetops, but that day they behaved very strangely.
“I noticed their haggard appearance,” Welbergen recalls. - They could not sit still, all the time flapping their wings and breathing heavily. Some licked their paws, trying to cool off. And suddenly they began to fall from the trees, as if a shower were pouring from their bodies. Those who did not die when hitting the ground died soon after. Others fell already dead. It was a real nightmare."
In a single day, the colony that Welbergen watched lost two thousand animals, the same thing happened in other areas. Since 1994, extreme heat in Australia has cut the population of flying foxes by a total of 30,000, with the bulk of the fatalities being young and adult females. “What I saw was a terrible insight for me. Previously, I did not think that such a rise in temperature could be fatal for fruit bats,”says the scientist.
Unfortunately, this seems to be just the beginning. It is highly likely that in the future, heat waves, floods, droughts, hurricanes and similar natural phenomena will begin to repeat more and more often. All this will have the most negative impact on the fauna and ecosystems in general and will most likely lead to the extinction of some species.
The situation becomes extraordinary
Today, there is no doubt that the climate on the planet Earth is getting warmer. Previously, prolonged periods of heat were rare enough, but now, according to forecasts, their frequency will increase, while the thermometer will show unprecedented numbers.
Statistician Claudia Tebaldi and climatologists from the National Center for Atmospheric Research in Boulder, Colorado, USA have determined the nature of the coming temperature changes. A computer model created by scientists confirms that over time, abnormal heat will become common, if not commonplace.
The extreme heat can damage ecosystems around the globe, but biologists are especially concerned about the fate of tropical rain forests. The fact is that they are home to many species that are not able to adapt to such climate change. Myriads of birds, mammals, lizards and frogs will be threatened with extinction, for which the cool and humid jungle is the only possible habitat.
"If it suddenly gets too hot, all these creatures literally have nowhere to go," says Stefan Williams of James Cook University in Townsville, Queensland, Australia, who studies the impact of global warming on the wildlife of the Australian tropics. "Our calculations show that if the temperature rises by two or three degrees, many species will disappear."
Most likely, the death sentence for animals will not be the gradual heating of the planet's surface, but the so-called heat waves. It was they, scientists believe, that led to a catastrophic decline in the number of white lemur ring-tailed possums (Hemibelideus lemuroides, see photo below) in northern Queensland. After an abnormally hot winter of 2005 for four years, no one has seen these cute marsupials accustomed to living in cool rain forests at an altitude of 1100 meters above sea level. After combing up and down the former habitat of possums, the researchers found only four surviving individuals. “Another such heat wave, and this species will disappear from the face of the Earth forever,” Williams concludes bitterly.
In other areas of the tropical belt, the situation is no better. As a group of researchers led by Barry Sinervo from the University of California at Sites Cruz (USA) found out, extremely strong warming in Mexico is forcing the lizards to leave their habitats. The number of one of the species of these reptiles has decreased in comparison with 1975 by 12%.
The scorching sun does not spare the inhabitants of hot, humid lowlands - today they are forced to live on the verge of the temperature limit that is permissible for them. Robert Colwell of the University of Connecticut (USA) argues that
further warming could cause serious damage to vast areas of the Amazon and Congo Basins. The animals of these places have nowhere to hide from the heat, because the nearest mountains are at a distance of thousands of kilometers.
Heat waves are not the only future challenges. According to climate models, disasters such as floods caused by heavy rains will also become more frequent. “The point is that a warm atmosphere holds more moisture than a cold one,” Tebaldi explains. “Hence the increase in precipitation.”
It is possible that showers do not pose a threat to the animal world. However, warming the atmosphere can lead to the onset of unexpected dry periods where they have not been observed before.
For example, in 2005, an abnormal drought was noted in the Amazon region. As a rule, such phenomena are due to the Pacific El Niño phenomenon and are typical for the eastern and southern regions of the river basin. But this time the heat had a completely different origin. The reason for this was the unusually high water surface temperature in the Atlantic Ocean. At the same time, the western part of the region suffered the most, especially the regions of Peru and partly Brazil.
Initially, these are very humid places, and life there is not able to withstand such harsh conditions. As a result, large tracts of rainforest were killed. There was no mass extinction of animals recorded here, but the trees, withering, released huge amounts of carbon into the atmosphere. “The 2005 drought came as a complete surprise to climatologists,” comments Thomas Lovejoy, an Amazon forest specialist at the Hannz Research Center in Washington DC, USA.
The same unprecedented conditions that led to the drought triggered Hurricane Katrina, devastating New Orleans. Every year, tornadoes, cyclones and typhoons wreak havoc in different parts of the world, and many scientists agree that global warming can only make things worse.
“At their core, cyclones are giant steam engines,” says Jonathan Knott, a hurricane expert at James Cook University. - Over the past hundred years, storms of incredible strength have become more frequent in the Atlantic Ocean - the fourth and even the fifth category on the five-point Saffers-Simpson scale. This is directly related to the rise in temperature near the surface of the water."
Such powerful vortices can cause serious damage to forests in coastal zones, as well as cause colossal damage to coral reefs. Usually ecosystems are able to recover even after severe disasters. But will they have enough time for this if hurricanes follow one another? How will the flora and fauna of the planet react to repeated repetitions of destructive weather events? These formidable questions imply equally formidable answers. At the same time, judging by the latest data, such events play a key role in the dispersal of living organisms around the globe. For example, the geographical distribution of many birds is in direct proportion to their ability to withstand extreme high temperatures. The same can be said for trees.
The most dangerous feature of extreme weather events is their absolute unpredictability. It is only clear that they will become more frequent, but no one is able to predict their exact time and place. All computer models allow you to see a picture of changes on a global scale, but not events in specific regions. In fact, this is a blindfold game. If you want to know the date of the next severe drought in the Sahel, the devastating flood in Pakistan or the dollar in Australia, you can just as well tell fortunes on the coffee grounds.
What to do?
First of all, it is desirable to reduce greenhouse gas emissions. “Reducing emissions will help us buy time and find a way to deal with changes in nature,” said Luke Shue, climate modeling specialist at James Cook University. "If we do not take this important step, then all our efforts will be in vain before the speed and scale of the upcoming processes."
Secondly, it is necessary to create protected areas, as large as possible, so that they include the widest range of microclimatic conditions. Mountain areas are best suited for the role of a refuge in an extreme situation (Nature, vol. 462, p. 1052). These are natural islands of safety that reduce
the destructive impact of the external environment. Perhaps it was thanks to their protection that a handful of lemur possums managed to avoid the fate that befell their fellows. It is also important that reserves are provided with reliable water sources in case of drought.
Among other things, other negative factors, such as hunting and fires, need to be minimized. Indeed, the main reason for the extinction of species is seen precisely in the total effect of many adverse influences.
Measures aimed at nature conservation will entail additional benefits: thanks to them, the process of release of greenhouse gases into the atmosphere will slow down. This can significantly slow down global warming, because as a result of deforestation of tropical forests, 5 billion tons of carbon dioxide are released into the atmosphere annually, which is about 17% of world emissions. By protecting protected areas, we will not only make ecosystems more resilient to destructive forces, but we will also directly confront climate change.
So, warming on the planet creates new, unpredictable dangers for the animal world.
And if a person does not limit his harmful activities, he must be prepared for the most serious consequences. In this case, the death of flying foxes is only the beginning of the end.
NewScientist №3 2011