Hottest Financial Year On Record BOM Data Shows

ABC Weather - Kate Doyle

Daytime temperatures have been above average across the country over the last year. (Supplied: Bureau of Meteorology )

The data has come through from the financial year and it was hot with maximum temperatures the warmest on record from July to June.

Minimums were also above average but not record-breaking, at only 0.72 degrees above the long term average.
The Bureau of Meteorology's David Jones said it was quite remarkable how consistent the temperature anomalies were.

Australia is getting warmer says Dr Jones from the Bureau of Meteorology. (ABC Regional: Rae Allen)

"The only part of Australia that saw temperatures almost average was the far north west corner," he said.
For example, places up and around Wyndham in north-west Western Australia but even there, Dr Jones said it was still pretty hot, just not much hotter than average.
"Once you got into the east it was a very warm year," he said.
"Not all, but certainly large parts of Queensland, New South Wales, and parts of South Australia saw either record hot conditions or near-record hot conditions for the year."

Why such a warm year?
Dr Jones said part of the story was the lack of rain.
"Many people in eastern Australia know we were in the grip of a drought in many areas and of course, droughts do contribute to above average temperatures, particularly during the day," he said.
"But the other story is obviously 'the trend'."

Financial year (July to June) maximum temperature anomaly for Australia from 1910-11 to 2017-18 (Supplied: Bureau of Meteorology )

You know, 'the trend'. Yes, we are talking about global warming.

"Australia is getting warmer so when you have a drought and you've got a trend you set these records," Dr Jones said.

What happened to La Nina?
But wait. It was a La Nina for a large part of this financial year! La Nina usually means wet and cold conditions for the east coast, doesn't it?
It does sometimes, according to Dr Jones.

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What El Nino and La Nina
mean for Australian and world weather

A Pacific Ocean phenomena

with impacts around the world

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"Firstly we did have a La Nina, but it was a fairly weak La Nina, so its overall influence was pretty modest," he said.
"The other thing too was, with the trend going upwards for temperatures, even La Ninas nowadays tend to often be warmer than average."
So this year's La Nina didn't have a big enough impact to compensate for 'the trend'.
'The trend' becomes apparent when you look at the data. There is proxy data going back a lot further but even just looking at the last century we can see a lot of the story, according to Dr Jones.
"We see that up until about 1950 Australian temperatures went up and down," he said.
"Droughts tend to be warmer, wet spells tend to be cooler, but then subsequently in the 1950s, it started to become warmer.

"So 'the trend' that we talk about is mainly in temperature and it's been going on now for the best part of 50 to 100 years."

Rainfall was down as well

Much of the east coast has been dry over the last 12 months but it has been a wet year for the north west thanks to all those cyclones over summer. (Supplied: Bureau of Meteorology )

"Unfortunately it was a pretty lean year for rainfall across most of those areas where people live," Dr Jones said.
"Eastern Australia in particular was pretty dry.
"I guess one thing that has been a bit unusual about this dry spell, this drought, is it's really come quite close to the coast.
"Obviously our inland areas do have these cycles of droughts and they can be very harsh."

Rainfall was below average nationally this financial year but not by much. (Supplied: Bureau of Meteorology )

But he said this one is also affected some fairly highly populated, usually quite reliable, rainfall regions.
"Areas around Sydney for example [and] the Tablelands through NSW [there were] very dry conditions and] in some spots actually record dry," he said.
It wasn't dry everywhere though.
The north-west corner of the country had a wet year thanks to all of those cyclones this wet season.
The financial year does an excellent job of capturing the northern Australian wet season; for example, 1973-74 and 2010-11, the standout years on the above graph, were the La Nina years of the big Brisbane floods.

Is there a cool change in sight? 

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Dr Jones said it did not "look too good" for a cool change and there is there is an El Nino watch on at the moment.
"Basically what we are saying is there's about a 50 per cent chance of an El Nino and that's been reflected in our forecast for dryer than average conditions," he said.
"At this point, people are looking for above average rainfall [and] unfortunately, we don't think that's likely."
When you look at temperatures, the warm conditions are likely to continue, particularly during the daytime with most of Australia expected to be above average.
"No real surprises there but I guess we'd all like to see a little bit more normal coming to our climate," Dr Jones said.

The Bureau of Meteorology's outlook for July - Sep 2018

Links

• As BOM declares a 50 per cent chance of El Nino this spring, should we be worried?
• Winter is coming — but it's looking warm and dry for south-east Australia, BOM says
• State of the drought: How bad is it and why has it been so dry?

Ecosystems Across Australia Are Collapsing Under Climate Change

The Conversation - Rebecca Harris | David Bowman | Linda Beaumont

Widespread mangrove dieback in the Gulf of Carpenteria. JAMES COOK UNIVERSITY/AAP

To the chagrin of the tourist industry, the Great Barrier Reef has become a notorious victim of climate change. But it is not the only Australian ecosystem on the brink of collapse.
Our research, recently published in Nature Climate Change, describes a series of sudden and catastrophic ecosystem shifts that have occurred recently across Australia.
These changes, caused by the combined stress of gradual climate change and extreme weather events, are overwhelming ecosystems’ natural resilience.

Variable climate
Australia is one of the most climatically variable places in the world. It is filled with ecosystems adapted to this variability, whether that means living in scorching heat, bitter cold or a climate that cycles between the two.
Despite land clearing, mining and other activities that transform the natural landscape, Australia retains large tracts of near-pristine natural systems.
Many of these regions are iconic, sustaining tourism and outdoor activities and providing valuable ecological services – particularly fisheries and water resources. Yet even here, the combined stress of gradual climate change and extreme weather events is causing environmental changes. These changes are often abrupt and potentially irreversible.
They include wildlife and plant population collapses, the local extinction of native species, the loss of ancient, highly diverse ecosystems and the creation of previously unseen ecological communities invaded by new plants and animals.
Australia’s average temperature (both air and sea) has increased by about 1°C since the start of the 19th century. We are now experiencing longer, more frequent and more intense heatwaves, more extreme fire weather and longer fire seasons, changes to rainfall seasonality, and droughts that may be historically unusual.
The interval between these events has also shortened, which means even ecosystems adapted to extremes and high natural variability are struggling.
As climate change accelerates, the magnitude and frequency of extreme events is expected to continue increasing.

What is ecosystem collapse?
Gradual climate change can be thought of as an ongoing “press”, on which the “pulse” of extreme events are now superimposed. In combination, “presses” and “pulses” are more likely to push systems to collapse.
We identified ecosystems across Australia that have recently experienced catastrophic changes, including:

• kelp forests shifting to seaweed turfs following a single marine heatwave in 2011;
• the destruction of Gondwanan refugia by wildfire ignited by lightning storms in 2016;
• dieback of floodplain forests along the Murray River following the millennial drought in 2001–2009;
• large-scale conversion of alpine forest to shrubland due to repeated fires from 2003–2014;
• community-level boom and bust in the arid zone following extreme rainfall in 2011–2012, and
• mangrove dieback across a 1,000km stretch of the Gulf of Carpentaria after a weak monsoon in 2015-2016.

Of these six case studies, only the Murray River forest had previously experienced substantial human disturbance. The others have had negligible exposure to stressors, highlighting that undisturbed systems are not necessarily more resilient to climate change.
The case studies provide a range of examples of how presses and pulses can interact to push an ecosystem to a “tipping point”. In some cases, a single extreme event may be sufficient to cause an irreversible regime shift.
In other systems, a single extreme event may only be sufficient to tip the ecosystem over the edge when gradual declines in populations have already occurred. More frequent extreme events can also lead to population collapse if a species does not have enough time to recover between events.
But not all examples can be directly linked to a single weather event, or a series of events. These are most likely caused by multiple interacting climate “presses” and “pulses”. It’s worth remembering that extreme biological responses do not always manifest as an impact on the dominant species. Cascading interactions can trigger ecosystem-wide responses to extreme events.

The cost of intervention
Once an ecosystem goes into steep decline – with key species dying out and crucial interactions no longer possible – there are important consequences.
Apart from their intrinsic worth, these areas can no longer supply fish, forest resources, or carbon storage. It may affect livestock and pasture quality, tourism, and water quality and supply.
Unfortunately, the sheer number of variables – between the species and terrain in each area, and the timing and severity of extreme weather events – makes predicting ecosystem collapses essentially impossible.
Targeted interventions, like the assisted recolonisation of plants and animals, reseeding an area that’s suffered forest loss, and actively protecting vulnerable ecosystems from destructive bushfires, may prevent a system from collapsing, but at considerable financial cost. And as the interval between extreme events shorten, the chance of a successful intervention falls.
Critically, intervention plans may need to be decided upon quickly, without full understanding of the ecological and evolutionary consequences.
How much are we willing to risk failure and any unintended consequences of active intervention? How much do we value “natural” and “pristine” ecosystems that will increasingly depend on protection from threats like invasive plants and more frequent fires?
We suspect the pervasive effects of the press and pulse of climate change means that, increasingly, the risks of doing nothing may outweigh the risks of acting.
The beginning of this century has seen an unprecedented number of widespread, catastrophic biological transformations in response to extreme weather events.
This constellation of unpredictable and sudden biological responses suggests that many seemingly healthy and undisturbed ecosystems are at a tipping point.

Links

• It's official: 2016's Great Barrier Reef bleaching was unlike anything that went before         
• Recent Australian droughts may be the worst in 800 years
• Climate change could alter ocean food chains, leading to far fewer fish in the sea
• What is a pre-industrial climate and why does it matter?
• How the land recovers from wildfires – an expert’s view
• How climate change is increasing the risk of wildfires
• The US natural gas industry is leaking way more methane than previously thought. Here’s why that matters
• Crop insurance is good for farmers, but not always for the environment