14/11/2020

(AU) BOM And CSIRO State Of The Climate 2020 Shows Australia Is Experiencing Climate Change Now

ABC Weather - Kate Doyle | Clint Jasper

There will be more wild weather in our future, according to the latest
State of the Climate update. (Supplied: Bureau of Meteorology and CSIRO)

Key Points
  • Australia's climate has now warmed 1.44 ± 0.24 degrees Celsius since records began in 1910
  • Fire weather and extreme heat days are up, while stream flows are down. Cool season rainfall continues to decline while heavy rainfall events become more intense
  • The 2020 global slowdown slowed the increase of CO2 concentrations but overall atmospheric carbon has continued to increase
The Bureau of Meteorology and the CSIRO have teamed up for the latest biannual report on the climate, and the findings are clear: Australia is experiencing climate change now, and the warming trend is continuing.

We are now up to 1.44 degrees Celsius of warming since 1910, plus or minus 0.24C, resulting in increased extreme heat days, heatwaves and raised fire danger.

Karl Braganza, manager of the climate environmental prediction service at the Bureau, said the science had been broadly consistent and largely accurate in the way that it had portrayed and projected the climate system for the last several decades.

"What we are seeing now is a more tangible shift in the extremes, so we are starting to feel how that shift in the average is impacting on the extreme events," he said.

2019 saw the most extreme heat days on record. (Supplied: Bureau of Meteorology)

"We don't necessarily feel the 1.44 degree increase in Australia's average temperature but we feel those heatwaves and we feel that fire weather."

In the two years since the last State of the Climate report we have lived through 2019, the hottest year on record, which produced one of the worst fire seasons we have ever seen.

Dr Jaci Brown, research director at the CSIRO's climate science centre, says that in 10 to 20 years' time, 2019 will not be seen as unusual.

"In fact, we think of this decade being hot, but this decade will be one of the coolest in the next hundred years," according to Dr Brown.

Fire threat

This time last year swathes of the east coast were already on fire and Sydney had just faced down catastrophic fire danger.

It fits the trend of the fire season starting earlier and hitting with increasing intensity.

"Absolutely we are saying that Australia should prepare for an increased fire risk," Dr Braganza said.

Fire conditions are worsening. (Supplied: Bureau of Meteorology)

He said the sort of fire events seen since the 2003 fires in Canberra were not one-offs.

"They are the sort of events we should treat as becoming more and more likely as warming continues."

Dr Brown was emphatic: "The message is very clear here. The State of the Climate report shows warming, it shows conditions drying through parts of Australia, and the projections are for hotter and dryer conditions going forward."

Changes in rainfall

Many parts of the country have seen a welcome change, with wetter conditions in recent months, but that does not mean we are out of the woods long-term.

Southern cool season rainfall is expected to continue to decline.

This year might have been a breather from the latest drought, but dry winters over southern Australia
have been common over the last 20 years. (Supplied: Bureau of Meteorology)

Three quarters of hydrologic reference stations across the country show a declining trend in streamflow.

According to Dr Brown, a lot of climate change is locked in, and so adaptation is a big part of what we do from now.

"Australian farmers, for example, are very used to dealing with climate variability and coming up with clever ways to manage and adapt," she said.

"New types of crops, new things to plant, new ways to work together to keep ourselves strong through these next few decades."

In contrast, northern warm season monsoonal rainfall has been above average over the last two decades.

But this rainfall remains inconsistent. Both the last two wet seasons recorded below-average rainfall.

The last few decades have been wet up north, but it has been inconsistent.
(Supplied: Bureau of Meteorology)
As the atmosphere and oceans continue to warm, heavy rainfall is expected to become more intense.

Ocean sinks

As we have pumped CO2 into the atmosphere the oceans have acted as a sink for both CO2 and heat.

But that has not come without an impact upon our oceans.

Surface waters around Australia are estimated to have had a 30 per cent increase in acidity since the 1880s, and sea levels have risen by 25cm globally since 1880 as a result of thermal expansion and ice melt.

Globally, oceans have already risen by an average of 25cm since 1880.
(Supplied: CSIRO)
The rate of sea level rise is increasing. It is now up to an average of 3cm per decade globally, but this is dependent on location.

Australia's northern and south-eastern coasts have been well above the global average, with the north-eastern and southern coastlines closer to average.

Although the total number of tropical cyclones is expected to decrease in the future, warmer oceans, higher sea levels and more intense rainfall all increase the risk posed by tropical cyclones in the future.

2020 slowdown not enough to stem the tide

Even 2020's global slowdown hasn't been enough to stop atmospheric concentrations of CO2 from increasing.

Dr Brown said there was a drop in the rate of increase of CO2, but that the slowdown was indistinguishable from the background variability.

"Another way to think about this is, if you have been eating junk food for 10 years and then you go on a diet for one day and you jump on the scales the next morning expecting to see some change, drop a dress size.

"It is not that simple. This is about a very long-term change"

The last time atmospheric C02 was at the same or higher concentrations than today was way back in the Pliocene,
2.6 million years ago. Global temperatures were 2-3 degrees warmer than today. (Supplied: CSIRO)

CO2 concentrations in our atmosphere are now well above any level reached in the last 800,000 years.

"I think the big challenge for our children and our grandchildren will be how to flatten this curve," Dr Brown said.

This year

Australia is currently under the influence of the La Niña phase of the El Niño Southern Oscillation.

La Niña events are typically associated with wetter-than-average conditions for all but the south-west.

Currently this year's La Niña is not tracking to be as severe as the last major La Niña in 2010/2011, but the Bureau will continue to monitor how the oceans warm over spring.


BOM Severe weather outlookYoutube

There is an increased risk of flooding for the east and north, with an above average risk of cyclones this summer.

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(AU) Climate Change Is Already Here: Major Scientific Report

Sydney Morning Herald - Miki Perkins

Australia is already experiencing climate change and the future holds more extreme fire seasons and“big weather” events such as major flooding, severe cyclones and long-lasting droughts.

That is made clear by the sobering State of the Climate report from the Bureau of Meteorology and CSIRO, released every two years.

Change in the number of dangerous fire weather days
*Change from (July 1950 - June 1985) compared with (July 1985 - June 2020) Source: CSIRO/BOM
It draws on the latest climate data and projections to provide scientifically rigorous analysis of climate change in Australia.

While COVID-19 lockdowns and economic downturns helped reduce global emissions in 2020, this has not been enough to make a discernible impact on carbon dioxide levels in the atmosphere, it finds.

“[It's like] you have been eating junk food for 10 years and you jump on the scales for one day ... this is about a very long change,” said Dr Jaci Brown, director of the climate science centre at CSIRO Oceans and Atmosphere. “The big challenge for our children and grandchildren is how to flatten this curve.”

Measurements taken at the Cape Grim air pollution station in Tasmania show carbon dioxide levels in the atmosphere have been increasing since pre-industrial times, driven by fossil fuel emissions. Around 85 per cent of global CO2 emissions in the decade from 2009 to 2018 were from fossil fuel sources.

The report predicts Australia's future holds further increasing temperatures, greater sea level rise, and less rainfall in eastern and southern Australia. “It’s quite a sobering look ahead,” said Dr Brown.

Climate change is predicted to cause more bushfires. Credit: Nick Moir

Despite years of protracted drought in Australia, a La Nina weather event under way in the Pacific will mean above average rain across most of Australia this summer. Dr Karl Braganza, the BOM’s manager of climate environment prediction, said all of the country should be alert for flooding, except the south-west of Western Australia.

Despite predicted heavier rainfall, Dr Braganza said the bureau was also preparing for an extended fire season. “Australia is fire prone, and southern Australia is fire prone in any given summer, [but] sometimes rainfall shifts the way those fires occur. We tend to have more grass fires than forest fires.”

Australia's climate has warmed, on average, by 1.44 degrees since 1910. Last year was the hottest year on record, with the greatest number of record-breaking hot days: 33 days that exceeded 39 degrees, compared with a total of 24 days between 1960 and 2018. Although 2019 has been the hottest year on record, in the next 100 years, this will be the coolest decade.

Global sea levels have risen 25 centimetres since 1880, and the world's oceans are increasingly acidic, the report finds. The rate of sea level rise is increasing, and is at 3.5 centimetres per decade.

In south-east Australia, there has been a significant drop in rainfall during autumn and winter since the 1990s, meaning a 60 per cent reduction in stream flow. But in northern Australia, monsoonal rainfall is more extreme during the wet season.

Professor Andy Pitman, director of the ARC Centre of Excellence for Climate Extremes at UNSW, said the findings were consistent with 30 years of scientific predictions, and concerns of the scientific community about global warming had only increased with time.

Professor Pitman said it was no longer possible to limit global warming to 1.5 degrees, but it may be possible to contain it to two degrees, the absolute upper limit permitted under the Paris climate agreement.

US President-elect Joe Biden says the US will adopt a 2050 emissions target, like the United Kingdom, New Zealand, Japan and South Korea. Prime Minister Scott Morrison says Mr Biden’s election won’t sway Australia’s position on climate change policy, and Australia would reach zero emissions "as quickly as possible".

Professor Pitman said reaching net zero by 2050 would not be enough to stop global warming reaching two degrees, and even getting to net zero would be "hugely challenging".

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(AU) Prepare For Hotter Days, Says The State Of The Climate 2020 Report For Australia

The Conversation -  | 
Shutterstock/wilsmedia
Authors
  •  is a Climate Projections Scientist at the CSIRO
  •  is Senior Climatologist at the Australian Bureau of Meteorology
The Australian State of the Climate 2020 report reveals a picture of long-term climate trends and climate variability.

The biennial climate snapshot draws on the latest observations and climate research from the marine, atmospheric and terrestrial monitoring programs at CSIRO and Bureau of Meteorology.

We are all still dealing with the lasting impacts of Australia’s hottest and driest year on record in 2019. It was a year of intensifying drought over eastern Australia, high temperature records and the devastating bushfires of summer 2019-2020.

State of the Climate 2020 puts all these events into the longer-term context of climate change trends and key climate drivers.

Australia can expect more dangerous fire weather days. Sean Davey/AAP
Australia’s hottest year on record

Using the best available data, the Bureau of Meteorology estimates Australia has warmed on average by 1.44℃ (±0.24℃) between 1910 and 2019.

Global rates of warming are lower due to the inclusion of the oceans in the global average, with the oceans experiencing a relatively slower rate of warming than continental areas.

The long-term warming trend increases the likelihood of extreme events beyond our historical experience. In 2019, natural climate phenomena that drive our weather, including a strong Indian Ocean Dipole and a negative Southern Annular Mode, added to the local warming trend, setting a record for the Australian average annual temperature.

This annual temperature for Australia is similar to what we might expect in an average year if the world reaches the +1.5℃ warming since pre-industrial times.

The long-term warming trend is also increasing the frequency of extreme warm days. We have seen a rise in the number of days when the Australian average temperature is within the top 1% ever recorded.

Extreme daily mean temperatures are the warmest 1% of days for each month,
calculated for the period from 1910 to 2019. CSIRO/BoM, Author provided

The long-term temperature trend is also lowering the frequency of cooler years. The annual mean temperatures of Australia in the seven years from 2013 to 2019 all rank in the nine warmest years since national records began in 1910.

Barring unpredictable events such as major volcanic eruptions, projections show Australia’s average temperature of 2020-2040 is very likely to be warmer than the average in 2000-2020, as the climate system continues to warm in response to greenhouse gases that are already in the atmosphere.

What’s driving our changing climate?

Australia’s Cape Grim atmosphere monitoring station, in north-west Tasmania, is one of several critical global observing sites for detecting changes in the gas concentrations that make up our atmosphere.

The Bureau and CSIRO’s atmospheric monitoring station at
Cape Grim, Tasmania. CSIRO, Author provided

The increase in greenhouse gas concentrations has been the predominant cause of global climate warming over the last 70 years.

In 2019 the global average CO₂ concentration reached 410ppm, while all greenhouse gases combined reached 508ppm CO₂-equivalent, levels not seen for at least 2 million years.

Emissions of CO₂ from burning fossil fuels are the major source of the increase, followed by emissions from changes to land use. While the ocean and land have absorbed more than half the extra CO₂ emitted, the rest remains in the atmosphere.

The impact of the COVID-19 pandemic has reduced fossil fuel CO₂ emissions in many countries, including Australia.

Over the first three months of 2020, global CO₂ emissions declined by 8% compared to the same three months in 2019. But CO₂ is still increasing in the atmosphere.

Recent reductions in emissions due to COVID-19 have only marginally slowed the current rate of CO₂ accumulation in the atmosphere, and are barely distinguishable from natural variability in the records at sites such as Cape Grim.

Oceans warming and sea levels rising
CSIRO/BoM, Author provided
State of the Climate 2020 can be read on either the Bureau of Meteorology or CSIRO websites. The online report includes an extensive list of references and useful links.

Similar to surface temperatures over the continents, the State of the Climate report says sea surface temperatures are showing a warming trend that is contributing to an increase in marine heatwaves and the risk of coral bleaching.

Important changes are also happening below the ocean’s surface. The global oceans have a much higher heat capacity than either the land surface or atmosphere. This means they can absorb much more of the additional energy from the enhanced greenhouse effect, while warming at a relatively slower rate.

Currently, the oceans are absorbing around 90% of the excess energy in the Earth system associated with increasing greenhouse gases. The related increase in total heat content provides another important way to monitor long-term global warming.

Warmer temperatures cause the water in our global oceans to expand. This expansion, combined with the additional water from melting ice sheets and glaciers, is causing sea levels to rise.

Total global average sea level has now risen around 25cm since 1880, with half of this rise occurring since 1970. The rate of sea level rise varies around Australia, with larger increases observed in the north and the southeast.

The rate of sea level rise around Australia measured using
satellite data, from 1993 to 2019. CSIRO/BoM, Author provided

The oceans are also acidifying due to changes in the chemistry of seawater, related to excess CO₂. The effect of this pH change is detectable in areas such as the Great Barrier Reef and the Southern Ocean.

The wetter and drier parts of Australia

The State of the Climate report shows the trend in recent decades has been for less rainfall over much of southern and eastern Australia, particularly in the cooler months of the year.

The longer-term drying trend is likely to continue, particularly in the southwest and southeast of the continent. Most areas of northern Australia have had an increase in average rainfall since the 1970s.

Natural variability has always been, and will continue to be, part of Australia’s rainfall patterns.

Floods are a regular hazard in Australia. Greg Stonham/Shutterstock
Fire seasons: longer and more intense

The fires of 2019-20 are still very much on everyone’s minds, and the State of the Climate report puts the weather component of fire risk into a longer-term perspective.

Since the middle of last century there has been a significant increase in extreme fire weather days, and longer fire seasons across many parts of Australia, especially in southern Australia.

There has been an increase in the number of days with
dangerous weather conditions for bushfires. CSIRO/BoM, Author provided

The 2020 report highlights many recent changes in Australia’s climate. Most are expected to continue and include:

  • warmer air and sea temperatures
  • increased numbers of very hot days
  • ongoing sea level rise
  • more periods of dangerous fire weather
  • longer and warmer marine heatwaves.

When these extremes occur consecutively within a short timeframe of each other, or when multiple types of extreme events coincide, the impacts can compound in severity.

Understanding these climate risks and how they might affect us will help to ensure the future well-being of our Australian communities, ecosystems and economy.

Hotter, wetter, drier and more bushfires.

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