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The record-setting and deadly fire season in Australia took a dramatic turn in the last week of December and first week of January. Residents of southeastern Australia told news media about the daytime seeming to turn to night, as thick smoke filled the skies and intense fires drove people from their homes. In the coastal tourist town of Mallacoota, fire blocked the main road out of the area. Seeking safety, residents, tourists, and firefighters huddled on beaches and the wharf as wind-driven fires advanced. Tens of thousands of people were evacuated from the provinces of Victoria and New South Wales "the largest evacuation of people out of the region ever," according to NSW Transport Minister Andrew Constance.

Three weeks into November 2019, springtime bush fires continued to blaze across southern and eastern Australian states. As of November 20, government agencies counted 45 fires in South Australia and 49 in New South Wales, and dangerously dry and windy weather was fanning flames in Victoria and Queensland. The fires sent smoke rising high into the atmosphere and half-way around the world, with satellites detecting aerosols and other smoky pollutants crossing the Pacific and moving over the South Atlantic Ocean. Locally, the smoke blanketed the Sydney metropolitan area, significantly degrading air quality.

As wildfires consume wood, vegetation, homes, and other materials, they emit many gases and particles, including carbon monoxide, carbon dioxide, hydrocarbons, nitrogen oxides, organic carbon, and fine particulate matter (PM2.5). Black carbon is a type of aerosol that is especially harmful to humans and animals because the particles are small enough to enter the lungs and bloodstream.

Carried by the wind, dust and ash particles from Australia painted some glaciers in New Zealand with a brown-orange tint. Australian dust on New Zealand snowfields is relatively common, The smoke plumes from the Australian fires had risen as high as 12 to 13 kilometers (7 to 8 miles) in the atmosphere. That is unusually high for wildfires. This event is interesting because we still dont have a confirmed pyrocumulonimbus cloud to explain the lofting, said Mike Fromm, a fire researcher at the U.S. Naval Research Laboratory. In spite of this being a well-observed plume event, it is still not clear how so much smoke got so high so fast.

A March 2020 scientific study showed climate change was 30% more likely to have triggered the recent devastating bushfires in Australia. The study was conducted by an international group of scientists from Europe, Australia and the United States for World Weather Attribution, an independent agency that analyzes the possible influence of climate change on extreme weather events. Using the latest high-resolution computer models, the scientists found that temperatures are 1-2 degrees Celsius higher than in 1900, and the risk for fire is four times more likely compared with the conditions in the same year.

On The Beach On The Beach

Australia is a land well used to nature's extremes. Australia is the worlds second-driest continent and is the world's driest inhabited continent. There is an average annual rainfall of less than 600 millimeters (24 inches) for more than 80 percent of the country.

A recent heat wave saw temperatures reach almost 49 degrees Celsius (120 Fahrenheit) in Western Australia, while a cyclone has menaced coastal areas in the Northern Territory. Bushfires have also blanketed the Tasmanian state capital, Hobart, with a threatening haze. In August 2018, a drought was officially declared in the entire Australian state of New South Wales.

By 2018 the resilience and ingenuity of its farming communities were being severely tested. South-eastern Australia was in the grip of a drought worse than many can remember. Last month was the second-hottest July on record, and the driest since 2002. Farmers in eastern Australia were in the grip of the worst drought in memory. Some landholders had not seen decent rain for seven years and the government promised more help to hard-pressed communities. In New South Wales state, about 99 per cent of farmers were dealing with drought conditions and were not producing enough food to feed their animals. Most of the nation's most populous state, New South Wales, was in drought. In some parched areas, storms of dust forced children to wear protective masks on farms.

As 2019 begins, communities in Queensland state in Australia faced their seventh year of drought. Farmers are suffering. Regional towns struggled. And local officials said more government relief was needed, including additional spending on roads and rail. Record-breaking rainfall may have soaked parts of northern Queensland in December 2018, but nearly 60 percent of Australias second-largest state, which is 2 times the size of the U.S. state of Texas, was bone dry. Some regions are entering their seventh year of drought. For many farmers on the frontline of the so-called Big Dry, the lack of rain is causing financial distress. Agricultural profits in Queensland are expected to fall in 2019. Grain producers and dairy farms are predicted to be the hardest hit.

The so-called Big Dry' did not affect all regions of the country. In July 2018, parts of Western Australia, the Northern Territory, Queensland and most of the island state of Tasmania received above average rainfall.

Australia is a continent that experiences a variety of climates due to its size. The temperature can range from below zero in the Snowy Mountains in southern Australia to extreme heat in the Kimberley region in the north-west of the continent. Due to the size of the continent, there is not one single seasonal calendar for the entire continent. Instead there are six climatic zones and this translates as two main seasonal patterns.

There is a Summer / Autumn / Winter / Spring pattern in the Temperate zone, also affecting the Desert and the Grassland climatic zones and, a Wet / Dry pattern in the tropical north which includes the Equatorial, Tropical and sub-tropical zones. The Temperate zone occupies the coastal hinterland of New South Wales, much of Victoria, Tasmania, the south-eastern corner of South Australia and the south-west of Western Australia.

The seasons in the temperate zone are described in terms of European seasons applied to the southern hemisphere. This means that the Australian Christmas takes place at the height of summer. It also means that the mid-year break for students happens in winter. The long end of year break for students is commonly known as the 'summer holidays', or the 'Christmas holidays'.

There are three climatic zones in the tropical areas of Australia:

  • Equatorial the tip of Cape York and Bathurst and Melville Islands north of Darwin
  • Tropical across northern Australia including Cape York, the Top End of the Northern Territory, land south of the Gulf of Carpentaria, and the Kimberley region
  • Sub-tropical the coastal and inland fringe from Cairns along the Queensland coast and hinterland to the northern areas of New South Wales and the coastal fringe north of Perth to Geraldton in Western Australia.

The tropical regions of Australia, in the north of the country, including the equatorial and sub-tropical zones have high temperatures and high humidity and distinct wet and dry seasons. In the Australian tropics the wet season, called the monsoon season, lasts about six months, between November and March. It is hotter than the dry season, with temperatures between 30 and 50 degrees Celsius. This is because of the high humidity during the wet, which is caused by large amounts of water in the air. During the wet there is a lot of rain, which frequently causes flooding.

The dry season lasts about six months, usually between April and October. Temperatures are lower and the skies are generally clearer during the dry. The average temperature is around 20 degrees Celsius.

The great Australian droughts of the twentieth century have mostly been closely linked with the major swings in the Southern Oscillation Index (SOI) with drought in eastern Australia coinciding with the El Nio (warm central and eastern Pacific Ocean) phase of the El Nio-La Nia cycle.

Since the 1950s, Australian temperatures have, on average, risen by about 1C with an increase in the frequency of heat waves and a decrease in the numbers of frosts and cold days, except in the regions immediately to the west and north-west of Sydney. Since 1900, the sea temperatures are showing to be two degrees warmer.

High sea surface temperatures have repeatedly bleached coral reefs in north-eastern Australia since the late 1970s and more recently in Western Australia. The 2016 bleaching event was the most severe on record and affected most of the reef. Research warned in March 2017 that Australias Great Barrier Reef can be saved only if urgent steps are taken to tackle climate change. The study, published in the journal Nature, said parts of the worlds largest coral system will never fully recover from repeated bleaching, caused by spikes in the water temperature. The Great Barrier Reef faces localized threats, such as the run-off of pesticides from farms and overfishing, but scientists believe its future depends on immediate efforts to reduce global warming.

During 19012010, global average sea level rose by 190 mm. Since the early 1970s, glacier mass loss and ocean thermal expansion from warming together explain about 75% of the observed sea level rise. Continued net emissions of greenhouse gases will cause further warming and changes in all components of the climate system. For the period 20812100, relative to 19862005, expected changes include:

  • Global warming of 0.3 C 1.7 C under a low emissions scenario through to 2.6 C 4.8 C under a high emissions scenario
  • Sea level rise of 0.26 to 0.55 m under a low emissions scenario through to 0.45 to 0.82 m under a high emissions scenario.
  • More and longer heat waves.
  • More intense and more frequent extreme rainfall over most of the mid-latitude land masses and over wet tropical regions.

Some of the largest projected climate change impacts will be felt through changes to extreme weather. For example, an increase in extremely hot days will lead to greater energy demand for air conditioning, more black-outs, more heat-related deaths, increased fire risk and transport disruption. Fewer extremely cold nights will lead to reduced energy demand for heating, less cold-stress, less frost-damage to crops, less snow and reduced yield for stone fruit and apples.

Australian average surface air temperature has increased by around 1 C since 1910, with warming over most areas since 1950. In recent decades, months warmer than average have occurred more often than months colder than average. Heat waves have increased in duration, frequency, and intensity in many regions. Since 2001, the number of extreme heat records in Australia has outnumbered extreme cool records by about 3 to 1 for daytime maximum temperatures and about 5 to 1 for night-time minimum temperatures. Many heat extremes have been shown to be much more likely due to human influence, including numerous heat records set from 2013 onwards.

Atmospheric circulation has changed, partly due to human influence: in some seasons the edge of the tropical zone and the weather band in southern Australia known as the storm track have both moved south. In other words, the tropics are expanding. Annual-average rainfall in many regions of southern and eastern Australia has decreased since the 1950s, particularly in southwest Western Australia. Annual-average rainfall increased in much of northern Australia since the 1950.

Decreases in heavy rainfall have tended to occur in southern and eastern Australia, while increases have occurred in northern Australia. Heavy daily rainfall has accounted for an increased proportion of total annual rainfall over an increasing fraction of the Australian continent since the 1970s.

Annual total rainfall varies substantially from year to year. Rainfall is projected to increase in some areas and seasons, and decrease in others, and in some areas substantial change is possible but the direction of change is unclear. Projected changes are generally larger for the higher emissions scenarios. Southern Australian rainfall is projected to decrease, mainly in the cooler months, but with some regional exceptions. Substantial increase or decrease is possible in northern Australia, but more research is needed to understand which is more likely.



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Page last modified: 20-09-2021 15:48:01 ZULU