State of the Climate 2018: Bureau of Meteorology and CSIRO


Michael Grose, CSIRO and Lynette Bettio, Australian Bureau of Meteorology

The Australian Bureau of Meteorology and CSIRO have released their fifth biennial State of the Climate report.


State of the Climate 2018 is the latest biennial snapshot of climate change in Australia. It focuses on observed long-term trends that are happening now and are likely to continue into the near future, as well as significant climate events that have occurred over the past two years. These changes are described through the latest observations from CSIRO and Bureau of Meteorology marine, atmospheric and terrestrial monitoring programs.

The report also summarises the latest climate research from Australia and around the world. This will help inform a range of economic, environmental and social risk assessments and responses by government, industry and communities.




Read more:
State of the Climate 2016: Bureau of Meteorology and CSIRO


Multiple lines of evidence show the climate system changing in ways that are discernible from natural variability, and consistent with a human influence on climate. These changes are having an impact on our natural and built environment.

In particular, climate change is being felt through an increase in the frequency and severity of high-impact weather events such as heatwaves, extreme fire weather conditions, coastal inundation and marine heatwaves. These trends are projected to continue.

Some of the report’s major findings are described below.

Passing major milestones

Australia’s average air temperature has warmed by just over 1℃ since national records began in 1910. Oceans around Australia have also warmed by around 1℃ since 1910.

Annual mean temperature over Australia and the seas surrounding Australia.
Bureau of Meteorology, Author provided

Atmospheric concentrations of carbon dioxide are rising globally. Emissions from the burning of fossil fuels continue to increase, and are the main contributor to the rise in CO₂, with some contribution from changes in land use.

Atmospheric CO₂ concentrations measured at Cape Grim, Tasmania (one of three main global measuring stations, alongside Mauna Loa, Hawaii, and Nunavut, Canada), have persisted at levels above 400 parts per million (ppm) since 2016. What’s more, the combined concentration of all greenhouse gases exceeded the equivalent of 500 ppm CO₂ in mid-2018. These milestones haven’t been crossed for at least 800,000 years, and likely 2 million years.

Changes in the atmosphere and land

Australia’s warming trend has led to an increase in the frequency of extreme heat events. For example, very high monthly maximum temperatures that used to occur around 2% of the time (based on the average for 1951–80) now happen about 12% of the time (2003–17).

Other elements of Australia’s climate have also shown long-term changes. New analysis techniques now provide a more detailed picture of changes to fire weather through time. The annual total of daily values of the Forest Fire Danger Index is increasing over large areas of Australia. Most regions also saw an increase in the most extreme 10% of fire weather days, and fire seasons have lengthened.

Rainfall in April–October has been steadily decreasing in Western Australia’s Southwest, and has decreased since the 1990s in southeast Australia. In contrast, rainfall has increased in parts of northern Australia since the 1970s.

The observed long-term reduction in rainfall across southern Australia has led to even greater reductions in streamflow. Long-term average streamflow has decreased in most regions of southern Australia, and increased in regions of northern Australia.

A warmer atmosphere can hold more moisture, and this is an important driver of the observed increase in the intensity of short-duration rainfall, sometimes linked to flash flooding. Southern Australia is projected to experience decreases in average rainfall and more time spent in drought. Meanwhile, most of the country can expect an increase in rainfall intensity.

Historically, significant weather and climate events are often the result of the combined influence of several extreme factors at once. Higher temperatures during periods of below-average rainfall, for instance, can exacerbate drought conditions. Temperature, dryness and wind come together to create dangerous bushfire conditions.

Trend in the annual sum of Forest Fire Danger Index, 1978–2017.
Bureau of Meteorology, Author provided

Changes in the ocean

The warming in Australia’s oceans has contributed to longer and more frequent marine heatwaves – defined as periods when sea surface temperatures are much warmer than average. The world’s oceans are a crucial moderator of the climate, taking up more than 90% of the extra heat in the system – most of it is absorbed by the Southern Ocean.

Sea levels continue to rise through the combined effects of warming oceans and melting ice from land-based glaciers and ice sheets. Global average sea level has risen by more than 20cm since 1880, but the rate varies from place to place. About 25% of the CO₂ emitted by human activity diffuses into the oceans, making them more acidic in the process.

The past two years, 2016 and 2017, have seen back-to-back bleaching events in parts of the Great Barrier Reef, linked to marine heatwave events. These changes are very likely linked to warming oceans, and primarily driven by the human influence on the climate.

Global sea level change from 1880 estimated from tide gauges and satellites.
CSIRO, Author provided

Well-established scientific theory and climate model studies both show that the warming would largely not have occurred without the increase in greenhouse gas concentrations. In addition, the current increase in temperatures accords with projections made nearly 30 years ago. Warming is projected to continue into the future as the effect of past emissions continue, and more greenhouse gases are emitted. Australia is projected to experience increases in sea and air temperatures, with more hot days and marine heatwaves, and fewer cool extremes.

It takes time for the climate system to warm in response to increases in greenhouse gases, and the historical emissions over the past century have locked in some warming over the next two decades, regardless of any changes we might make to global emissions in that period. However, by the mid-21st century, higher ongoing emissions of greenhouse gases will lead to greater warming and associated impacts, and reducing emissions will lead to less warming and fewer associated impacts.

Australian average annual temperature 1861-1900 period in observations and global climate models.
CSIRO, Author provided

State of the Climate 2018 can be read on either the Bureau of Meteorology or CSIRO websites. The online report includes an extensive list of references and useful links.

You can also watch accompanying behind-the-scenes videos on our research on climate extremes and ocean warming.The Conversation

Michael Grose, Climate Projections Scientist, CSIRO and Lynette Bettio, , Australian Bureau of Meteorology

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Advertisements

The BOM outlook for the weather over the next three months is ‘neutral’ – here’s what that really means



File 20180327 188622 twb5im.jpg?ixlib=rb 1.1
It’s more important to know whether there’ll be any weather than what the weather will be.
Photo by Loren Gu on Unsplash, CC BY-SA

Andrew B. Watkins, Australian Bureau of Meteorology and Felicity Gamble, Australian Bureau of Meteorology

Today the Bureau of Meteorology releases its end-of-month seasonal outlook for April to June, updating the initial outlook released on March 15. But you might not have seen much media coverage of it, because we’re not seeing big swings towards the attention-grabbing climate drivers like El Niño or the Indian Ocean Dipole, which can dominate Australia’s climate.




Read more:
Dipole: the ‘Indian Niño’ that has brought devastating drought to East Africa


There are times when the main drivers of our climate are not strong enough to push us towards a season dominated by unusually wet or dry, or hot or cool, weather. This can also happen if different climate drivers are having opposite impacts – they can cancel each other out.

Without a strong push one way or another, our outlook maps are often white. This is a neutral or “50:50” outlook map.

The rainfall outlook map for April–June 2018, issued March 15 (left), shows most of Australia in the neutral/50:50 range (so coloured white). In contrast, the rainfall outlook map for October 2015 (right) shows a low chance of exceeding the median (so brown dominates the map).
Bureau of Metereology

A 50:50 outlook map doesn’t mean we’re taking a guess, or that there’s no indication of what’s happening with our weather and climate. In fact, it’s giving us some key information.

What does a neutral outlook mean?

Let’s focus on rain. A neutral climate outlook means there is a 50% chance of above-average rainfall. In other words, there is an equal chance of getting above-average or below-average rain over the coming season.

But it doesn’t mean that the most likely rainfall is spot-on average. Have a look at the graph below for rainfall in the Murray—Darling Basin. It shows rainfall over 116 years, ordered from lowest to highest. Years with no strong climate driver, or no strong push from the climate system one way or another, are in blue.


Bureau of Meteorology

Most winter–spring periods (29 out of the 40 years, or about three-quarters of all years) fall within the middle 50% of past rainfall totals, as indicated by the 25th and 75th percentile lines. But within that middle 50%, the rainfall in neutral years is fairly evenly spread — it isn’t clustered right in the middle, or dead on average.

This means two things.

First, it means that a neutral year will typically bring quite variable rainfall, with periods of rainfall above or below average. We also know that the above or below patterns tend not to be as widespread across the continent as during stronger La Niña or El Niño periods.

Second – and importantly – it also means there is less chance of extremely wet or extremely dry conditions over large areas; that’s a good sign if drought or flood is a concern.

What doesn’t a neutral outlook mean?

A neutral outlook certainly doesn’t mean climatologists are having a bet each way. We can think about this in terms of a football game.

Some footy games we are fairly sure will be a one-sided affair — based on previous match performance, players’ injuries, whether it’s a home or away game, and so on. On other occasions, those factors aren’t in play and the teams are very evenly matched, so the result could go either way. It doesn’t mean we don’t know much about footy or about the teams that are about to play – it’s just that there is no strong indication that one team is far better than the other.




Read more:
A chaotic beast, probably: wacky weather and climate forecasting


What can I do with a neutral outlook?

So what should you look at during neutral periods to get an idea of what’s possible for the upcoming season? Well, there’s lots of additional information on our climate outlooks website.

For a start, think about your local rainfall at a particular time of year, and what range you typically have in years without flood or drought. Use our rainfall ranges information to see your current rainfall accumulation, and what result you’ll get in a few months’ time if a typical range (wet, dry or average) of rain falls over the season.

The seasonal outlook itself may also be useful. For example, if you need a certain amount of rainfall, say 100mm over the next season, you can check out the likelihood of that happening. Or looking at it the other way round, what rainfall amount has a 25% (less likely) or 75% (more likely) chance of occurring, as shown below.

BOM seasonal outlook.

Other tools worth worth looking at in neutral periods include streamflow forecasts, which can tell you if streamflows are likely to be high, low or average in your region, and soil moisture guidance, to assess your soil moisture for daily and monthly periods.

And, of course, you can find the typical rainfall range for your area in our Climate Data Online. Select “Weather and Climate” at the top and “Monthly” statistics.

BOM Climate Data Online.

All of us – including climatologists – wish the outlooks were always clearly wet or dry, or hot or cool. It would certainly make all our lives a lot easier! But when the climate drivers are not strong, or oppose each other, there’s rarely any chance of a big push towards one outcome – and that information is still useful for making decisions.

A neutral outlook indicates a 50% chance of above-average rainfall. This means there is more chance of good rain than in a season with only 25% probability, but less chance than a season with 75%.

If your appetite for risk is high – if you are a farmer with good soil moisture, full dams and lots of money in the bank – 50% may be enough for you to take a punt on a riskier crop. But if times are tough, 50% may not be anywhere near high enough, so you’d make a more conservative decision. No number is ever too small if the return is high enough: most of us have bought a lottery ticket even though the odds might be one in a million.




Read more:
Curious Kids: What causes windy weather?


At the end of the day, a 50% chance is a number just like any other. When combined with your knowledge of what a typical range of outcomes may be, other bureau information at your fingertips, and your appetite for risk, it can still help you make a climate-smart decision.


You can stay on top of what’s happening with the climate by subscribing to the Bureau of Meteorology’s Climate Outlooks.

The ConversationThis is an edited version of a post that appeared on the Bureau of Meteorology’s blog.

Andrew B. Watkins, Manager of Long-range Forecast Services, Australian Bureau of Meteorology and Felicity Gamble, Senior climatologist, Australian Bureau of Meteorology, Australian Bureau of Meteorology

This article was originally published on The Conversation. Read the original article.

CSIRO climate cuts will trash a decade of hard work with the Bureau of Meteorology and universities


Gregory Ayers, Monash University

A dozen years ago, climate science in Australia was academically excellent, but was being done in small groups, none able by itself to answer the large, complex scientific questions that were beginning to confront Australia, such as understanding the adverse trends emerging in temperature and rainfall.

We weren’t alone – all countries were grappling with their own issues, as the scale of the climate challenge was made starkly clear by a succession of reports from the Intergovernmental Panel on Climate Change.

So, early in the new century, a handful of people leading the key separate parts of Australia’s system began working together to create a truly strategic, truly national climate science capability.

CSIRO led from the front. Its executives knew that CSIRO alone could not meet the nation’s climate science needs, so they worked with government departments to support the development of a larger national architecture.

Gradually, the project took shape. In 2005, CSIRO merged its atmospheric and marine research divisions, creating a unified division focusing on a single national climate modelling system, rather than two separate ones. Sensible move.

The following year, CSIRO championed integration of all state and national marine observing systems into one federal system, the Integrated Marine Observing System.

CSIRO also turned its attention overseas, joining with the Bureau of Meteorology to adopt the UK Met Office’s state-of-art Unified Atmospheric Model as our national weather forecasting model, for an immediate improvement in forecasting skill.

Since this model could be run in climate mode as well as weather mode, we now had both agencies’ scientists supporting a single, world-leading atmospheric climate model that was also the national weather forecasting model. It was a superbly efficient outcome. The pieces of a truly national climate science program were falling into place.

Universities on board

Meanwhile, in 2007 CSIRO and the Bureau launched a joint venture now called the Collaboration for Australian Weather and Climate Research. The idea was to create a single large government-funded climate science program that, for the first time, would be easy for top university climate scientists to engage with.

CSIRO already had a fruitful collaboration with Antarctic climate researchers at the University of Tasmania, but what was needed was for all universities doing significant climate science to become engaged in the national endeavour.

This was harder than it sounds; government research agencies are typically driven by specific missions related to the agency’s charter, whereas university research often focuses on investigating science questions framed by individual specialisations and academic prowess.

As chief of CSIRO’s Marine and Atmospheric Research Division at the time, I was seconded into the federal Department of Climate Change to draft a blueprint for a national climate research agenda that would include universities along with government scientists. It gave rise to the National Framework for Climate Change Science, which was adopted by the Rudd government in 2009 and still remains current.

With the framework in place, CSIRO, the Bureau and universities signed up to use Australia’s new National Computational Infrastructure for climate research. In 2011, the Australian Research Council funded the creation of the Centre of Excellence for Climate System Science, which drew together the best university-based climate research. With everything now in place in 2012 the federal government turned the 2009 climate science framework into an implementation plan to deliver on the research goals.

More than a decade in the making, Australia finally had a truly national, unified collaboration set up to deliver as fruitfully as possible on our nation’s climate science needs.

All of that hard work, planning and organisation is now at risk.

Climate cuts

The implementation plan contains a series of tables listing the priority policy questions to be answered, and who is best placed to deliver the scientific research needed to answer them. CSIRO appears in every one. If you mentally remove the word CSIRO from the document, it’s clear that if CSIRO leaves the climate science stage (and while the precise number of job cuts remains uncertain it is set to be significant) it will leave Australia’s federally endorsed climate science agenda gutted, and totally unachievable.

This brings us to the misconception promulgated by CSIRO chief executive Larry Marshall as a rationale for the CSIRO cuts: that human-induced climate change is now confirmed, so there is now less need for climate science and more need for research into adaptation and mitigation measures.

The implementation plan makes it clear that mitigation and adaptation would also suffer badly from CSIRO’s climate cuts, as they would no longer be built on the national climate science framework set up precisely to enable and support those activities.

CSIRO was the main agency behind Australia’s world-leading climate science framework – a setup that serves this nation’s climate science policy needs superbly, and one of the areas in which Australia punches above its weight internationally.

Why would CSIRO retreat from one of its own (and Australia’s) most effective scientific endeavours? Why stop now, after working tirelessly for more than a decade to create a unified national platform that provides essential advice to local, state and federal governments, as well as industry, commerce and the environmental sector? I don’t know. It makes no sense.

CSIRO’s decision to pull away from climate change science is against the national interest. It should not proceed.

The Conversation

Gregory Ayers, Atmospheric Scientist and Advisory Board Chair, School of Biological Sciences, Monash University

This article was originally published on The Conversation. Read the original article.

Declining rainfall in parts of Australia, but still plenty of water available: BOM report


Malcolm Watson, Australian Bureau of Meteorology

The Millennium Drought ended more than five years ago, but several years of below-average rainfall and El Niño have brought drought back to many parts of Australia. Our latest report on water in Australia shows rainfall is continuing to decline in eastern Australia and increase in the north.

However in urban areas, where water use has not changed significantly since the Millennium Drought, more water is available for use thanks to technologies such as desalination and recycling.

In a recent article on The Conversation, the Bureau of Meteorology put the case that Australia can now better manage water resources using new water information capability.

Last week the Bureau released a new assessment report on our national water availability and use. Water in Australia 2013–14 examines climatic conditions and the physical hydrology to create the most recent national assessment of Australia’s water resources.

The main findings are outlined below.

Water resources

Since 1950, rainfall has increased in Australia’s north and northwest, but declined along the west coast and most of eastern Australia. This pattern was reflected in 2013–14.

Rainfall affects streamflow and groundwater replenishment, which in turn affects our available water resources.

In southern Queensland and northern New South Wales, a severe drought, which started in 2012, continued in 2013–14. As expected, streamflow in these areas was very much below average in drought-impacted areas.

Annual rainfall, runoff and streamflow conditions, 2013–14
Australian Bureau of Meteorology

The volume of groundwater stored in aquifers is very large compared with surface water and responds more slowly to external influences. As a result, most bores across the country had average groundwater levels in 2013–14.

In South Australia and Queensland, more than one-third of all bores had an above-average level. Below-average groundwater levels were present in 5–20% of bores in each State and Territory.

Water availability

Australia has extensive water supplies and their use is managed by various institutional arrangements. Water availability is being increased by using recycled and desalinated water. At the same time, greater protection is being afforded to the environment through the purchase of entitlements from water users and investments in water-saving infrastructure.

https://datawrapper.dwcdn.net/5YaAM/1/

Status of Australia’s major water storages at 30 June 2014
Australian Bureau of Meteorology

Since the Millennium Drought, Australia’s water market has thrived, facilitating the buying and selling of water rights to allow water to be moved and put to more effective use. Entitlement trade increased in 2013–14 to about 2400 gigalitres (GL), and can partly be attributed to entitlements being transferred to the Commonwealth for the environment and partly to declining water storage levels that prompt buyers into the market to secure more water. Allocation trade in 2013–14 was around 5500 GL.

As well as ensuring sustainable water supply for human needs, water resources are managed to ensure that environmental needs are met. Environmental water holders in the Murray–Darling Basin held 3192 GL of surface water entitlements at the end of 2013–14 (increasing from 3160 GL at the end of 2012–13). Of the total allocated environmental water available in 2013–14, 68% was delivered for environmental purposes and 27% was carried over to 2014–15.

Water use

Total water use across Australia was estimated at 23 500 GL in 2013–14. Irrigation (57% of total use) and urban consumption (17% of total use) were the top two water uses.

Estimated total water use in Australia, 2013–14
Australian Bureau of Meteorology

The main irrigation use in 2013–14, at just over 9500 GL, was in the Murray–Darling Basin. The estimated total surface water use for irrigation in the Murray–Darling Basin decreased from 11 000 GL in 2012–13 to about 8400 GL in 2013–14—a drop of 24%.

Groundwater use for irrigation increased by 18%, to 1100 GL, because of drier conditions and limited surface water allocation announcements — particularly in the northern Basin.

Outside the Basin, 3900 GL were used for irrigation, mainly in the Queensland and Victorian coastal regions, the coastal regions surrounding Perth and Adelaide, northeastern Tasmania, and in the Ord irrigation scheme in northern Australia.

Urban residential use in 2013–14 was 185 kilolitre per property, up 3% from 2012–13. However, use per property has not increased significantly from the levels at the end of the Millennium Drought. Total water use in 2013–14 in the major cities showed no significant changes from the recent past.

Though water availability exceeded use in 2013–14, shortages were experienced across large parts of the continent. With Australia’s highly variable and changing climate there will be ongoing challenges to meet the water needs of our nation.

The Bureau’s wide variety of water products are available at: www.bom.gov.au/water, including the Monthly Water Update, Regional Water Information, National Water Account and Water in Australia.

The Conversation

Malcolm Watson, Manager Water Assessment and Analysis, Australian Bureau of Meteorology

This article was originally published on The Conversation. Read the original article.