Australia is on track for up to 1.7C of warming this century if the world curbs its greenhouse emissions, but under a worst-case scenario could see anything from 2.8C to 5.1C of warming by 2090, according to new climate change projections released by the CSIRO and the Bureau of Meteorology.
The projections are the most comprehensive ever released for Australia. They are similar to those published in 2007, but based on stronger evidence, with more regional detail. These projections have been undertaken primarily to inform the natural resources management sector, although the information will be useful for planning and managing the impacts of climate change in other sectors.
The new report draws on climate model data used by the Intergovernmental Panel on Climate Change (the IPCC). The Fifth IPCC Assessment Report (AR5), released in 2013 and 2014, used a range various greenhouse gas and aerosol scenarios to project future climate change.
Over the past 10 years, carbon dioxide emissions have been tracking the highest IPCC emission scenario (known as RCP8.5). If there is limited international action to reduce emissions, then projections based on the highest scenario may be realised.
However, if emissions are significantly reduced over the coming decades, then intermediate emissions (RCP4.5) might be feasible. Following the low emissions scenario (RCP2.6) would be very challenging given the current trajectory of carbon dioxide emissions.
How does Australia compare?
By late in this century (2090), Australia’s average warming is projected to be 0.6 to 1.7C for a low emission scenario, or 2.8 to 5.1C under a high emission scenario.
The warming under the high scenario is similar to the global average warming of 2.6 to 4.8C under the high emission scenario reported by the IPCC AR5. However, inland areas of Australia will warm faster than coastal areas.
The new projections should be viewed in the context of what has already been observed. Australia has become 0.9C warmer since 1910. Rainfall has increased in northern Australia since the 1970s and decreased in south-east and south-west Australia.
More of Australia’s rain has come from heavy falls and there has been more extreme fire weather in southern and eastern Australia since the 1970s. Sea levels have risen by approximately 20 cm since 1900.
In future, Australia’s average temperature will increase and we will experience more heat extremes and fewer cold extremes. Winter and spring rainfall in southern Australia is projected to decline while changes in other regions are uncertain.
For the rest of Australia, natural climate variability will predominate over rainfall trends caused by increasing greenhouse gases until 2030. By 2090, a winter rainfall decrease is expected in eastern Australia, but a winter rainfall increase is expected in Tasmania.
Historical climate data can be used as an analogue for the future. The analogue could be a location that currently has a climate similar to that expected in another region in the future.
For example, for a warming of 1.5-3.0C and a rainfall decrease of 5-15%, Melbourne’s climate becomes similar to that of Clare in South Australia, Sydney becomes more like Brisbane, and Brisbane becomes more like Bundaberg in inland Queensland.
Extreme rainfall events that lead to flooding are likely to become more intense. The number of tropical cyclones is projected to decrease but they may be more intense and possibly reach further south. Southern and eastern Australia is projected to experience harsher fire weather. The time in drought will increase over southern Australia, with a greater frequency of severe droughts.
A projected increase in evaporation rates will contribute to a reduction in soil moisture across Australia. There will be a decrease in snowfall, an increase in snowmelt, and therefore reduced snow cover.
Sea levels will continue to rise throughout the 21st century and beyond. Oceans around Australia will warm and become more acidic.
What will Australia look like?
Freshwater resources are projected to decline in far south-west and far south-east mainland Australia. Rising sea levels and increasing heavy rainfall are projected to increase erosion and inundation, with consequent damage to many low-lying ecosystems, infrastructure and housing.
Increasing heat waves will increase risks to human health. Rainfall changes and rising temperatures will shift agricultural production zones. Many native species will suffer from reduced habitats and some may face local or even global extinction.
The most vulnerable regions/sectors are coral reefs, increased frequency and intensity of flood damage to infrastructure and settlements, and increasing risks to coastal infrastructure and low-lying ecosystems.
While reductions in global greenhouse gas emissions would increase the chance of slowing climate change, adaptation is also required because some warming and associated climate changes are unavoidable.
The coastal city of Newcastle is in the midst of a media frenzy, thanks to a string of shark sightings close to popular swimming beaches.
A 15 kilometre stretch of beaches has now been shut for a record six consecutive days, with lifeguards and police craft reporting shark sightings seemingly by the hour. Of most concern have been a purportedly 5 metre, 1,700kg White shark that has been lingering along the coastline; and what is suspected to be a 3 metre tiger shark that was photographed attacking and killing a small dolphin only 50 metres from the shore yesterday (warning: graphic images).
While no attacks on humans in the area have yet been recorded, the sharks have become national celebrities in their own right, with widespread media coverage and commentary. There has even been a Twitter account set up for the @Newy_Shark (which is one account you probably don’t want to be “followed” by).
So what’s the deal here? Are we seeing the real-life return of Jaws? Has a curse been struck down upon the town of Newcastle by Poseidon himself? Is a Sharknado next?
Our resident White shark expert, Barry Bruce, knows a thing or two about these ancient predators. He is one of Australia’s pre-eminent authorities on the species and is the head of our White Shark Research Program. But he is perhaps most famously known for having one of Finding Nemo’s most famous characters named after him.
According to Barry, the story behind Newcastle’s shark saga is far less salacious. Thankfully, we’re not gonna need a bigger blog.
The coastline just north of Newcastle (stretching from the appropriately named Stockton Bight to the even tastier-sounding Seal Rocks) is famously known as being a nursery ground for White sharks. These juveniles are usually about 2-3 metres in length, and a tagging program undertaken by Barry and his team has shown that they are more than prevalent in the area.
Seeing a larger sized White in this area, like the infamous #NewyShark, is slightly less common, but still not at all unusual.
Large White sharks are well known to move up and down the New South Wales coastline, stopping in certain areas when food is prevalent. White sharks have been exhibiting this exact behaviour for countless millennia – it is only when they stop near a heavily populated area like Newcastle that we would notice.
But these are nomadic creatures, and they won’t stay in one spot for too long. We know through collaboration with our colleagues in New Zealand that white Sharks will travel as far north as the Great Barrier Reef – and even across the Tasman to NZ – in a span of just months.
Barry puts the current concentration of sharks in Newcastle purely down to natural variability. Sharks go where the food goes – if there are more sharks in one area at one point in time, it means there will be less in others.
And while we’re in the mood for debunking myths, here’s another one: dolphins are just as much a food source for sharks as are any other species of their size. While it is uncommon for us to observe – and the images were undeniably distressing – sharks are well-known to attack dolphins. Unfortunately, what Flipper taught us was wrong.
More than anything, Barry says that this is a positive advertisement for the health of marine ecosystems in Australia. That there is a large enough food source to sustain shark populations is a good thing, and should be celebrated.
But of course, it is important for beachgoers to take advice from authorities when entering the water. While this is a natural spectacle that should be enjoyed, it is advisable to do so from a distance – and on land. In time it will run its course, and we can all return to the water.
White shark fast facts:
- A common mistake people make is calling these awesome creatures, ‘Great White Sharks’, it’s actually just ‘White shark’ (Carcharodon carcharias). But we still think they’re still pretty great.
- Sharks play a vital ecosystem role as top predators. Declines in top predators can cascade through the food web, seeing some species groups increase while eliminating others.
- We have one of the most comprehensive White shark research programs in the world, with over 250 tagged White sharks in Australian waters. Check out a few shark tracks on our website.
- Our tagging program provides us with a good idea of migration patterns – we know for example that there is an East and a Southwest population.
- Our research on White sharks is a collaborative project funded under the Australian Government’s National Environmental Research Program.
- We tag these beauties in a very humane way – in a sling, in the water:
The latest round of bushfires, which claimed 27 homes in the Adelaide Hills, has once again highlighted the importance of planning for the worst. Mercifully, no human lives were lost, and it will be important to learn whatever lessons we can to avoid future tragedies.
My colleagues and I analysed 825 deaths in 260 Australian bushfires from 1901 to 2011, and our research has revealed some compelling evidence to help guide residents to plan for future bushfires.
Most people (58%) lost their lives when caught out in the open. Strikingly, 72% of those people were within 200 m of their own homes (this statistic is based only on cases where details are accurately known).
I encourage you to imagine what circumstances and decisions might have led to these outcomes. Do a large number of people simply wait to see if the fire is really going to arrive on their doorstep?
Bushfire deaths within a house are most prevalent during our most severe fire events, representing 75% of all fatalities during bushfires that occurred on days with “catastrophic” (code red) fire danger conditions. This is despite them representing only 27% of all bushfire deaths.
Of those who died inside homes, 92% were in rooms that did not have a door that led directly to the exterior of the house (once again, this is based only on cases where circumstances are accurately known). This raises uncomfortable questions: why did these people apparently not try to leave the home as the house fire developed? Were they monitoring the conditions outside as the fire passed? Had they thought about which exit was the safest?
Homes under attack
When a fire arrives at a property, the house will experience “ember attack”. This attack is strongest as the main fire arrives and will persist for a long time after it has passed, and may also start to happen before the fire actually arrives. If the house is close enough to the bush it may also be affected by radiant heat, and if very close then direct flame contact is possible, although most houses are lost without any direct interaction from a bushfire front – which goes some way to account for the seemingly random loss patterns that occur.
Given the timing and intensity of ember attack, it is no surprise that our data show that houses can ignite before, during, and after a fire front’s passage – with the most likely time being during and immediately after the fire front has passed.
For the relatively small number of houses that ignite before the fire front arrives, the occupants may be faced with life-threatening conditions both inside and outside at the same time. There are also a few cases were houses are built so close to the bush or other combustible elements that even the low-level fire that persists after the main fire front has passed is too intense to survive outside.
Nevertheless, for the vast majority of homes that burn in bushfires, it is likely that at any given time, conditions would be survivable either inside or outside the house. That means that, with the right strategy, lives should not be lost.
Designing a lifesaving strategy
It is interesting to note that the current building codes for bushfire-prone areas include specific fire weather severity limits beyond which these standards may no longer be effective. The standards aim to reduce the risk that a building will catch fire, but they also rule out any guarantee that it won’t. The code also doesn’t address the issues of how fast burning homes might succumb, or of how to provide a safe or effective exit path from the building.
So even if your bushland home is fully up to code, you need to plan for a wide range of scenarios. Fire agencies across Australia have stressed the importance for people living in bushfire-prone areas to develop a fire survival plan, and your local fire agency is the best place to start on developing a plan and educating yourself about the specific local fire conditions you might face.
Once a plan has been developed I encourage residents to test their fire plan by checking whether it answers the following questions:
- At what level of forecast fire weather severity will you retreat to a non-bushfire-prone area for the day?
- Do you understand the local potential fire severity for weather conditions below this level?
- For any given circumstances, what are the signs or triggers that indicate that it is no longer safe to evacuate to a non-bushfire prone area? For some isolated communities this will be when fire weather severity passes a certain level; for other, less isolated residents it will be when they are no longer certain that the roads are moving freely and fire will not impact their travel route.
- What and where is your personal protective equipment and firefighting tools?
- Is the property free from combustible items under or adjacent to the home?
- Is the home in an acceptable state of repair to survive a bushfire?
- Which areas would be the safest external location to move to if it becomes impossible to stay in the house?
- Does the path leading to this cleared area involve walking over or past combustible elements such as vehicles and decking?
- How do I monitor all rooms and cavity areas of the home for signs of ignition of fire development inside the house?
- What do you have on hand to monitor and put out these fires (stored water, ladders to monitor internal roof space, etc.)?
- If you can’t put them out, which exit path is the most appropriate?
A deep understanding of the nature of bushfire threat is your best tool in assessing and managing your own risk.
By Leon Braun
“’Twas the night before Christmas, when all thro’ the house
Not a creature was stirring, not even a mouse …”
CSIRO scientists are keeping their eyes peeled for more than just Santa Claus this Christmas. With unusually high numbers of mouse sightings in Victoria this spring, CSIRO ecologist Peter Brown and colleagues at various Australian and New Zealand research agencies are monitoring mouse populations to see whether 2015 will bring a sigh of relief or send people scurrying for cover under a deluge of tiny, furry bodies.
While taken individually, mice can be rather cute (think Mickey, Mighty and Danger), en masse they can be absolutely devastating. In 1993, Australia’s worst ever mouse plague caused an estimated $96 million worth of damage, destroyed thousands of hectares of crops, blighted piggeries and ravaged poultry farms. The whiskered marauders chewed their way through rubber and electrical insulation, damaged farm vehicles, ruined cars and buildings. Another plague in 2010/11 was almost as bad, affecting 3 million ha of crops in NSW’s central west and the Riverina, as well as parts of Victoria and South Australia.
Along with economic hardship and disease, plagues bring severe psychological distress for people living through them.
“The sheer stress of dealing with mice in your kitchen every night takes its toll,” Peter says. “They’re everywhere: chewing, defecating, breeding.”
The good news is that with sufficient warning it is possible to prepare for mouse plagues, and to minimise the damage they cause, through early baiting and removing food supplies and cover. Over the years, our scientists have become increasingly accurate at predicting mouse plagues (they got it right in 1994 and 2001-2003) and have developed an ever more sophisticated range of tools to assist them. The latest weapon in their arsenal is “MouseAlert“, a citizen science website where keen-eyed rodent reporters can notify CSIRO about mouse sightings. The website is optimised for mobile phones, and Peter and his team hope to have an app out soon.
“Numbers are everything when you’re trying to predict a plague,” Peter says. “Traditionally we’ve used traps and chew cards [thin pieces of cardboard soaked in vegetable oil], but they have disadvantages, not least the fact that we’re not physically able to put them everywhere. MouseAlert allows us to capture data over a much wider area and potentially spot a plague well before it becomes a problem.”
Equally important as sightings, Peter says, are reports of where mice haven’t been.
“The jump from zero sightings to one or two can be an important indicator that mouse numbers are increasing,” he says. “By participating in citizen science, the public can help us identify these trigger points.”
So how are things looking this year? A little ominous, actually. Unusually high numbers of mice were seen in western Victoria in September. Depending on how much rain we get, they could build up to plague proportions by March or April next year. That’s why Peter wants mouse watchers to keep their eyes peeled:
“If it looks like there’s going to be a plague, we want to be able to give farmers plenty of time before sowing to prepare – or else put their minds at ease if it looks like there isn’t.”
So if you do see a mouse this Christmas Eve – stirring or not – get over to MouseAlert and report it. The pantry you’re saving could be your own!
This is our first of three Christmas-themed posts – enjoy!
The holiday period can seem like a month-long headache for us humans. As a species we go into overdrive: preparing our offices for hibernation while we hurriedly fossick for gifts and forage for Christmas feasts. Many of us also dedicate time gathering our familial herds – for better or for worse – while a lucky few are even able to migrate north (or south or east or west) for the summer.
But we’re not the only ones that get busy at this time of year. There are countless thousands more animals and plants that are saddled with similar chores to us (albeit without the seafood dishes and Christmas crackers). They too must weather the blistering heats, and keep themselves and their relatives cool, fed, and hydrated.
Here’s a brief low-down on what the holiday season means for Australia’s non-human residents.
Running a kingdom is tough work: workers and soldiers must be kept inline, and young, vulnerable individuals must be cared for and nourished. And when the population grows into the thousands or millions, the exposed Australian landscape is no place for such an empire.
Termites build their colonies in locations where they can moderate the temperature and humidity with organic air-conditioning. All-year round, colonies are maintained at a consistently high temperature and humidity, sometimes as high as 36oC. Since these conditions are critical to survival, termites scarcely expose themselves.
As our year closes to an end, the summer sun heats up our country, releasing water into the air, thus bringing our above-ground climate to the temperature and humidity loved by termites. The termites use this climatic window as an opportunity to expand their empires.
Starting in November when the conditions are just right, sexually active termites grow ephemeral wings and leave the nest. The air becomes filled with pioneering couples, searching for the ideal log or mound to start the next generation. 95% of couples will not survive their first week, likely ending up in ponds, pockets, and ear canals.
For the few lucky couples that make it, they will begin their new colony and reign for up to 45 years together, as king and queen, producing offspring to take flight each Christmas.
The journey of the “Christmas beetles, the quintessential insect of the summer festive season…” is also one of patience and timing, with the insects spending their lives underground as grubs before metamorphosing as those brilliant, clumsy creatures we know and love. Their full story has already been covered by us, here.
You’ve probably heard enough from these birds to last you a lifetime, but, after reading their plights, their cacophonous calls might seem slightly more bearable. If you are on the eastern or northern coast, the two birds you’re likely to hear this time of year are both cuckoos: the Pacific koel and the channel-billed cuckoo.
The channel-billed cuckoo is an enormous bird with a very distinct and coarse ‘hoink’. The channel-bill can often be heard hoinking as it flies gracefully overhead.
For both of these species, ’tis the season to be breeding. In spring and summer the birds fly to northern and eastern Australia all the way from Indonesia and New Guinea. And over the holiday period they meet up on our shores and seek out a nest. Since they are cuckoos, they make their living off the backs of others. They don’t make their own nests but take advantage of the onerous nest making of other species.
An ‘eggnant’ cuckoo will seek out the nest of a host bird species, such as a wattle bird for the koel and a currawong for the channel-bill. To salt the wound, some cuckoos will destroy any already-present host eggs.
Upon hatching, the cuckoo chick squawks incessantly to the host mother for food. And since the mother and child are different species, a parasitic cuckoo chick can be many times larger than the host, forcing the host mother’s beak to the grindstone to gather enough food for her gargantuan faux-spring:
The offspring is raised until its large enough to make the flight back up north to Indonesia early the next year.
These birds can survive in urban environments, so if you keep out a sharp ear and eye, you may be able to spot one.
These cuckoos, the koel and the channel-bill, are obligate parasites – meaning they cannot complete their lifecycle on their own and without the manipulation of their host. So don’t be angry at those slacker cuckoos, they’re simply doing what has worked for them for myriad generations, what is best for their kids.
If, every summer, your oxygen supply were to disappear for a few months, how would you cope? Not well, we imagine. For aquatic animals who live in temporary billabongs in Australia, this is exactly what happens each holiday season or dry spell. Under such extreme pressures, natural selection has generated wonders, wonders like our salamanderfish:
Salamanderfish are difficult to find – especially over Christmas. They are just 7 cm long and only exist in the southern-most, western-most corner of our country in freshwater pools only present for part of the year.
When there is water for the salamander fish, it is highly acidic and tannin-rich. Tannins are the chemicals that leach from leaves, giving tea its characteristic colour and flavour. And speaking of tea, salamanderfish live in water that is so acidic, its pH is somewhere between that of a cup of tea and lemon juice.
Over summer they have an interesting…what’s the opposite of a ‘sea change’? For salamanderfish, the holiday season is an upheaval of their fishy lifestyles. When their ponds dry up, they bury half a metre underground, create a membranous cocoon, and chillax under the sand for months at a time, waiting out rains and summer’s end.
Taking a quick summer tour around the rest of the country, on the Western Australian, Northern Territory and Queensland coast, green, flatback, and loggerhead sea turtles are coming ashore to lay their eggs, and some earlier laid hatchlings are digging free and making the treacherous trip back to the ocean.
All around the country male frogs such as the corroboree and motorbike frogs are preparing their nests and vocal chords to catch the attention of female suitors to produce offspring in the new year.
On the south eastern tip of Australia, male brown fur seals are competing fiercely for territory. Female fur seals are arriving to pick suitors with territory close to the water’s edge. Many fur seals are breeding, and many are giving birth, since their gestation period is around a year.
On the Great Barrier Reef, corals of all shapes and sizes are releasing clouds of eggs and sperm into the waters, a gambit that relies on the currents for fertilisation.
The wet season on Christmas Island means a lot for one species of crab. Since crabs use their gills to breathe, the humid summer air allows the Christmas Island red crabs to make their annual migration from the forest to the coastline to meet and breed.
And along the eastern coast, the blue blubber jellyfish (Catostylus mosaicus) or ‘jelly blubber’ populations are blooming with the increase in temperatures and prey: fish larvae, plankton, and crustacean larvae.
So over the next few weeks when you are stressing out at the bustling shopping centre, or fussing over a stove with four occupied hot plates, remember those starry-eyed termite couples with a miniscule chance of survival, the cuckoos using their wrists to fly here from Indonesia, and the salamanderfish lying underneath kilos of mud awaiting the next storm cell.
By Leon Braun
It’s downtrodden, underfoot and often under appreciated, yet so crucial to our existence that one of our scientists describes it as “the complex natural medium that supports all life on Earth”. It holds our crops, stores and purifies our water, and provides habitat for amazing creatures like the giant Gippsland earthworm, which can reach up to 3 m in length. But most of us only think about it when we’re trying to get it out of footy socks on laundry day.
It’s soil – and today (and all next year) it gets a bit of long-overdue recognition. December 5 is World Soil Day, and the United Nations has declared 2015 to be International Year of Soils. That’s a good thing, because globally, soils are under threat: from erosion, poor land management and urbanisation. At the same time, we need soils more than ever to produce the food we need for a growing population, to help manage climate change and to ensure ecosystem health.
Luckily for Australia’s soils, they have CSIRO looking out for them. We started researching soils in 1929, published the first soil map of Australia in 1944, and have been working hard ever since to improve our understanding and management of soils. We’re looking at ways to make agricultural soils more productive and to ensure they’re used sustainably, so future generations can continue to reap their bounty. And we’re working internationally too, so it’s not just Australia that benefits.
Our latest achievement (with allies from around the country) is the Soil and Landscape Grid of Australia, a digital map of Australia’s soils with two billion ‘pixels’ of about 90 by 90 metres, down to a depth of two metres below the surface. It contains information such as water holding capacity, nutrients and clay, and has applications for everyone from farmers deciding where to plant their crops to conservationists looking for habitats for endangered native species. You can read more about it here.
We’re also home to the Australian National Soil Archive, which has just gotten a new home in Canberra. The archive contains about 70,000 samples from almost 10,000 sites across Australia, the oldest dating back to 1924. Each sample represents a time capsule of the Australian landscape at the time it was collected, so we can measure things like caesium dispersal from the British nuclear tests at Maralinga and the impact of phosphate-based fertilisers on agricultural land. The archive is a vital national asset for soil researchers and industry, and has even been used by the Australian Federal Police to examine the potential of new forensic methods. Finally, data from the archive powers our first official app, SoilMapp, which puts information about Australian soils at your fingertips. This is incredibly useful, whether you’re growing canola on a farm in Western Australia or planning a major roads project in Victoria.
So as you go through your day today, eat your lunch, wipe your shoes, just remember: it takes 2000 years to form 10 centimetres of fertile soil suitable for growing our food, but just moments for that soil to blow away or get covered in a layer of asphalt. Something to think about next time you sit down to a meal – or do your laundry.
By Dr Helen Cleugh, Science Director, CSIRO Oceans and Atmosphere Flagship
The World Meteorological Organization reports that 2014 is on track to be possibly the world’s hottest year on record. Meanwhile, there’s been a lot of public commentary lately about the so-called “hiatus” in global surface temperature over the past 18 years, recent sea-level rise, and what it all means.
So what do CSIRO’s research and observations tell us?
They show that average surface air temperatures have continued to rise during the past two decades, but not as fast as in preceding decades. In other words, while the rate of temperature increase is lower, the temperatures themselves are not lower.
It is also important to note that when climate scientists use the term “global-mean surface temperature” they refer to near-surface air temperatures. Surface air temperature is an incomplete measure of warming of the planet; oceans store huge amounts of heat, with about 93 per cent of the extra heat stored by the Earth over the past 50 years being found in the oceans.
The ocean today is warmer, and sea levels higher, than at any time since the instrumental record began. As the oceans warm, they expand and sea levels rise. Using a combination of coastal tide-gauge and satellite-altimeter data, CSIRO and others have shown that, globally, sea level has been rising since the late 1800s. Global-averaged sea level rose at an average rate of about 1.6 mm per year over the 20th Century, but this rate has accelerated to about 3 mm per year as measured by satellite altimetry and tide gauges since 1993. So the rate of sea-level rise has not slowed; it has increased.
Our measurements across the land, atmosphere and oceans show that warming has continued unabated throughout the past 18 years.
Last year was Australia’s warmest year on record, followed by 2005 and 2009. For global land and ocean temperatures, 2013 tied with 2003 as the fourth warmest year globally; and 13 of the 14 warmest years ever measured occurred in the 21st Century. As reported by the World Meteorological Organization, this year is shaping up to be the world’s warmest year – the year to the end of October is the planet’s warmest on record.
It is not unusual to see changes in the rate of surface warming. Over the past 120 years, there have been decades where global-mean air temperature has warmed more rapidly, and decades where relative cooling has occurred.
Increases in greenhouse gases provide a warming effect but, due to natural variability, climate trends based on short records are very sensitive to the beginning and end dates, and do not reflect long-term climate trends.
The rate of warming in any shorter period fluctuates because of factors such as short-term natural variability, ocean absorption of heat from the atmosphere, volcanic eruptions, changes in the 11-year solar cycle, and so on. This does not change any conclusion about the long-term trend of warming due to human activities, which have increased the concentration of greenhouse gases in the atmosphere.
CSIRO research has shown that there is less than 1 chance in 100,000 that global mean air temperature over the past 60 years would have been as high without human-caused greenhouse gas emissions. That is, the probability of global temperature increases being due to human activity exceeds 99 per cent.
The world is not cooling.
*Note (1) net increase in glacier volumes have regional variation (almost all glaciers worldwide losing mass but some gaining) but overall net loss; and (2) net decrease in global sea-ice extent has regional variation (over the period 1979–2012 it is very likely that the annual mean Arctic sea-ice extent decreased 3.5 to 4.1% per decade, and it is very likely that the annual mean Antarctic sea ice extent increased by 1.2 to 1.8% per decade) but overall net loss. Source: CSIRO and Bureau of Meteorology.
This article was originally published in The Canberra Times.