My Science School

Over the last few decades, there has been a significant spike in the number of wildfires. Greenhouse gas emissions have led to an increase in global temperature. As warmer temperatures hasten evaporation, the land subsequently turns drier, enhancing the chances of wildfires.

A 2019 Australian government report on wildfires and climate change said human-caused climate change has resulted in more dangerous weather conditions for bushfires in recent decades for many regions of Australia.

 Heatwave and drought

Fire season in Australia is always dangerous. But conditions have been unusually severe this year. Australia is experiencing one of its worst droughts in decades. Meanwhile, a heatwave last December broke the record for highest nationwide average temperature, with some places sweltering under temperatures well above 40 degrees Celsius.

Fire season has changed

With climate change, weather conditions are growing more extreme, and for years, the fires have been starting earlier in the season and spreading with greater intensity in Australia. The fire season is starting earlier and is about two to four months longer, especially in south and east Australia. The normal peak fire season is later in summer, which is January and February. Australia is just entering its summer season, meaning the country could be months away from finding relief.

 

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 Though it is estimated that nearly half-a-billion animals have been affected in one State alone, it is difficult to get the exact number until fires subside enough to allow surveys of the burned areas. Fires have been part of the Australian landscape for thousands of years. Many species and ecosystems have evolved to cope and later populate nearby unaffected land. But as climate change fuels longer five seasons and more frequent, intense fires, it could become increasingly difficult for animals to adapt newer escape strategies and for ecosystem to bounce back.

In the line of fire

Smaller mammals and reptiles can escape the blazes by burrowing underground or hiding in rocks.

But some are not good at coping heat or stress. Wombat, the small, stubby-legged marsupial, can’t run very fast or far. Kolas are particularly vulnerable to bushfires as their slow movement and tree-dwelling lifestyle make it difficult for them to escape. Koalas and kangaroos are primarily killed directly by the fires. In this season, nearly a third of all koalas in New South Wales have died and about a third of their habitat has been destroyed according to a government estimate.

Ecosystems are built on balance – once one element is thrown off, everything is affected. Even if animals don’t die from the flames or smoke, they would eventually do from the fire’s aftermath. After their habitat is destructed, there will be no shelter or food left to survive on. These animals’ recovery depends not only on their population size, but also on the condition of their habitat.

 

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An uncontrolled fire in an area of combustible vegetation that spreads quickly, wiping out large areas of land is called a wildfire. A wildfire can also be termed a forest fire, a grass fire, a peat fire or a bushfire depending on the type of vegetation.

During summer, when there is no rain for months, the forests become littered with dry leaves and twigs, which could burst into flames ignited by the slightest spark.

Natural causes: Lightening is the most common cause of bushfire. There are three conditions for a bushfire to spread – fuel, oxygen and a heat source. In the forest, anything that is flammable is a fuel. This includes tall, dry grass, bushes and trees. High temperature, drought and dry vegetation are a perfect combination for igniting a forest fire.

Human-made disaster: Human neglect such as downed powerlines, sparks from tools or forest machinery, abandoned campfires and discarded cigarette butts can spark fires. People also tend to clear forests by setting them on fire to pave way for cultivation. Sometimes they set fire to scare away wild animals and the fire could spread and turn disastrous.

In Australia:

Summer is the season of fire in Australia with hot, dry weather making it easy for blazes to start and spread. Most of the time, it is natural causes such as lightning that trigger a fire, but sometimes human are also to blame. New South Wales police have charged at least 24 people with deliberately starting bushfires, and have taken legal action against 183 people for fire-related offences since November, according to reports.

 

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Bushfires are almost an annual affair in Australia, but this fire season has been unprecedented in scale and intensity.

A series of massive bushfires has been burning across Australia since September 2019 and they intensified early this month, with a number of towns evacuated.

At least 27 people have been killed, 1200 homes destroyed, and 18 million acres of land – bush, forest and parks – have been burned. Of all the States, New South Wales has been the hardest-hit. Nearly half-a-billion creatures, including birds, mammals and reptiles, have been affected by the fires in New South Wales alone and millions of them are possibly dead, according to scientists. Many large cities have been shrouded in smoke for weeks. State and federal authorities are struggling to contain the massive blazes, even with firefighting assistance from other countries.

Why are the fires so bad? Persistent drought and record temperatures are the major drivers of the fire, but the role played by climate change in making natural disasters go from bad to worse should not be overlooked, say scientists.

 

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According to a study, at the current rate of warming, the area of ice-free land in the Antarctic peninsula, in the west, is set to rise by 300% in the next century. That means invasive species will have more land and more water (thanks to melting ice) species of fly will face-off against invaders. The exact effect is difficult to predict precisely, say scientists.

Antarctica is home to species that can gather in greater densities than those in temperate or tropical climates, said Convey, pointing to microscopic arthropods known as Collembola, a million of which can squeeze into a square meter.

The thousands of researchers and 50,000 tourists who visit the remote continent every year risk upsetting this balance by bringing plant and insect life with them.

One type of grass, Poa annua, has already managed to carve out a beachhead on some islands, and humans have brought with them two species of fly.

Some species do manage to arrive by natural means from the tip of South America 1,000 km (600 miles) away, but they do not manage to establish themselves permanently.

The thousands of researchers and 50,000 tourists who visit the remote continent every year risk upsetting this balance by bringing plant and insect life with them.

One type of grass, Poa annua, has already managed to carve out a beachhead on some islands, and humans have brought with them two species of fly.

Some species do manage to arrive by natural means from the tip of South America 1,000 km (600 miles) away, but they do not manage to establish themselves permanently.

 

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• Specimens of non-native species of flies, spiders, caterpillars, butterflies, wasps, beetles, moths, slugs, bugs, ants, moss and grass have been found in Antarctica over the years. Ground beetles, in particular, have been extremely invasive, preying on native insects.


• In a study, scientists found that foreign plants such as annual bluegrass, chickweed and yellow bog sedge, were establishing themselves in Antarctica. They found that seeds and other detachable plant structures were stuck to cold-weather gear that travellers and researchers brought to the continent. Disturbingly, 49% to 61% of foreign plants that reach Antarctica are cold-adapted and can withstand and colonise in extreme conditions.


• Scientists with the British Antarctic Survey have discovered that a species of fly originally from South Georgia – the chironomid midge, has flourished since its accidental introduction to Signy Island in the Antarctic in the 1960s. It has expanded to more than 650 feet away from its original site, and in some areas is more numerous than any of the native insects. The fly likely travelled unnoticed on the plants brought to Antarctica for research. In the 1990s and early 2000s, its population started to explode.


• Some species do manage to arrive by other natural means. But it is humans who bring in 99% of invasive species, say scientists.


• Transport of invasive species can be minimized by careful cleaning and checking of clothing, footwear, construction materials, food, equipment and vehicles sent to Antarctica.

 

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Invasive species cause harm to the ecosystem in many ways:

• In the absence of natural predators, a new and aggressive species can breed, spread quickly and overrun the local habitat. Native species may not have evolved defences against the invader, further boosting the invaders’ growth.


• The threats from an invasive species also include preying on native species and outcompeting them for resources, thereby restricting the growth of native species.


• Some invasive species are capable of changing the conditions in an ecosystem, such as the soil chemistry.


• Invasive species can change the food web in an ecosystem by destroying native food sources.


• People who depend on the ecosystem’s native resources will also be affected.

 

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• Some species arrive in a new area through migration.


• Some are spread unintentionally by human activities. When people travel, they often inadvertently carry alien species along. For instance, insects may arrive in a new place by travelling on luggages.


• Some species are introduced on purpose as pets or to combat pests, which turn out to be invasive in the new place.


• Ships can carry aquatic organisms in their ballast water, while smaller boats may carry them on their propellers. Insects can get into wood, shipping palettes, and crates that are shipped around the world.


• Some ornamental plants can escape into the wild and become invasive.


• Illegal smuggling/trading of fruits and vegetables across borders can introduce not only potentially harmful new plant species but also any insects and parasites that may live in them.


• Higher average temperatures and changes in rain and snow patterns caused by climate change will enable some invasive plant species—such as garlic mustard, kudzu, and purple loose strife—to move into new areas. 

 

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Invasive species are organisms that migrate to or are introduced to a new geographical location, where they pose a threat to the environment. They could be insects, plants, animals or pathogens. These species start to grow and multiply quickly in the absence of natural predators from their original homes.

Invasive species are capable of causing extinctions of native plants and animals, reducing biodiversity, competing with native organisms for limited resources, and altering habitats. This can result in huge economic impacts and fundamental disruptions of coastal and Great Lakes ecosystems.  The impacts of invasive species on our natural ecosystems and economy cost billions of dollars each year. Many of our commercial, agricultural, and recreational activities depend on healthy native ecosystems. They can harm the environment, the economy, or even human health. Species that grow and reproduce quickly, and spread aggressively, with potential to cause harm, are given the label “invasive.”

 

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