State of the Climate Report 2020, CSIRO and BoM

HBS Guy

Head Honcho
Staff member
Summary:

Key points Australia

• Australia’s climate has warmed on average by 1.44 ± 0.24°C since national records began in 1910, leading to an increase in the frequency of extreme heat events.

• There has been a decline of around 16 per cent in April to October rainfall in the southwest of Australia since 1970. Across the same region May–July rainfall has seen the largest decrease, by around 20 per cent since 1970.

• In the southeast of Australia there has been a decline of around 12 per cent in April to October rainfall since the late 1990s.

• There has been a decrease in streamflow at the majority of streamflow gauges across southern Australia since 1975.

• Rainfall and streamflow have increased across parts of northern Australia since the 1970s.

• There has been an increase in extreme fire weather, and in the length of the fire season, across large parts of the country since the 1950s, especially in southern Australia.

• There has been a decrease in the number of tropical cyclones observed in the Australian region since 1982.

• Oceans around Australia are acidifying and have warmed by around 1 °C since 1910, contributing to longer and more frequent marine heatwaves.

• Sea levels are rising around Australia, including more frequent extremes, that are increasing the risk of inundation and damage to coastal infrastructure and communities.
https://www.csiro.au/en/Research/Oa...-the-Climate-2020/Australias-changing-climate

The point about our oceans acidifying and warming is bad news for our coral reefs, especially the now-endangered GBR.
 

HBS Guy

Head Honcho
Staff member
In more detail:

Australia has warmed on average by 1.44 ± 0.24 °C since national records began in 1910, with most warming occurring since 1950 and every decade since then being warmer than the ones before. Australia’s warmest year on record was 2019, and the seven years from 2013 to 2019 all rank in the nine warmest years. This long‑term warming trend means that most years are now warmer than almost any observed during the 20th century. When relatively cooler years do occur, it is because natural drivers that typically cool Australia’s climate, such as La Niña, act to partially offset the background warming trend.
Wow! Every decade after the 1950s was warmer than the decade before!

(We know an idiot collecting what he calls evidence of an ice age now! LOL!)

Continuing:
Warming is observed across Australia in all months with both day and night‑time temperatures increasing. This shift is accompanied by more extreme nationally averaged daily heat events across all months. For example, 2019 experienced 43 extremely warm days, more than triple the number in any of the years prior to 2000. This increasing trend is observed at locations across all of Australia.
So this is a trend. A trend that will not stop for a long time—CO2 is in no way saturated in its warming effect.
http://www.realclimate.org/index.php/archives/2007/06/a-saturated-gassy-argument/
 

HBS Guy

Head Honcho
Staff member
Australia’s climate has warmed by over 1 °C since 1960, which has caused an increase in the frequency of months that are much warmer than usual. Very high monthly maximum temperatures that occurred nearly 2 per cent of the time in 1960–1989 and over 4 per cent of the time in 1990–2004, now occur over 12 per cent of the time (2005–2019). This is more than a sixfold increase over the sixty-year period. Very warm monthly night-time temperatures that occurred nearly 2 per cent of the time in 1960–1989 and over 5 per cent of the time in 1990–2004, now occur around 11 per cent of the time (2005–2019).
More warm to very hot weather. This will increase evaporation of soil moisture which coupled with less rainfall in the south is going to cause problems to our agriculture.

The frequency of extremely cold days and nights has declined across Australia. An exception to this is for extremely cold nights in those parts of southeast and southwest Australia which have seen significant cool season drying, and hence more clear winter nights. The frequency of frost in these parts is relatively unchanged since the 1980s.
Hence Booby just shows his ignorance and idiocy in bleating that I must apologise for cold weather—nothing says that very cold weather no longer happens but it happens significantly less often apart from where drying causes frosts. This applies globally.
 

HBS Guy

Head Honcho
Staff member
Fire weather

Fire weather is largely monitored in Australia using the Forest Fire Danger Index (FFDI). The FFDI indicates the fire danger on a given day based on observations of temperature, rainfall, humidity and wind speed. The frequency of the most dangerous 10 per cent of fireweather days has increased significantly in recent decades across many regions of Australia, especially in the south and east. These increases are particularly evident during spring and summer and are associated with an earlier start to the southern fire weather season.

Climate change is contributing to these changes in fire weather including by affecting temperature, relative humidity and associated changes to the fuel moisture content. Considerable year‑to-year variability in fire weather also occurs. La Niña years, for example 2010–11 and 1999–2000, are associated with wet and cool climate anomalies and a lower number of days with high FFDI values.

There has been an increase in the annual frequency of dangerous bushfire weather days across Australia.   Spatial plot of Australia which shows the change in the number of dangerous bushfire weather days.   For a full description of this figure please contact: helpdesk.climate@bom.gov.au
Enlarge image
There has been an increase in the number of days with dangerous weather conditions for bushfires. This is based on the change in the annual (July to June) number of days between the two periods: July 1950 – June 1985 and July 1985 – June 2020 that the Forest Fire Danger Index exceeds its 90th percentile, which is an indicator of dangerous fire weather conditions for a given location. ©Bureau of Meteorology
Dry lightning that occurs without significant rainfall is the primary source of natural ignition for bushfires. Understanding changes to bushfire ignition in Australia is a current area of active research, including the frequency of dry lightning.


Right whingers were bleating arson caused the fires. There were some arrests like an idiot using an angle grinder outside on an Extreme Fire Warning day. One actual arsonist or would–be arsonist was arrested—no way did he cause all the fires.

A plug for my (present) state: on high fire danger days cops visit known arsonists and convince them not to drive into the Adelaide Hills to start fires. No bushfires in the Adelaide Hills! I hope other police departments follow the SA lead here.
 

HBS Guy

Head Honcho
Staff member
Rainfall

Australian rainfall is highly variable and is strongly influenced by drivers such as El Niño, La Niña, the Indian Ocean Dipole and the Southern Annular Mode. Despite this natural variability, long‑term trends are evident in Australia’s rainfall record. There has been a shift towards drier conditions across the southwest and southeast, with more frequent years of below average rainfall, especially for the cool season months of April to October. In 17 of the last 20 years, rainfall in southern Australia in these months has been below average. This is due to a combination of natural variability on decadal timescales and changes in large‑scale circulation caused by increased anthropogenic greenhouse gas emissions.



Rainfall, during April to October, has been very low over parts of southern Australia in recent decades.  Spatial plot of Australia which shows April to October rainfall deciles for the last 20 years (2000–2019).  For a full description of this figure please contact: helpdesk.climate@bom.gov.au
Enlarge image
April to October rainfall deciles for the last 20 years (2000–19). A decile map shows where rainfall is above average, average or below average for the recent period, in comparison with the entire rainfall record from 1900. Areas across northern and central Australia that receive less than 40 per cent of their annual rainfall during April to October are faded. ©Bureau of Meteorology

Recent years with above-average rainfall in southern Australia were generally associated with drivers of higher than usual rainfall, such as a strong negative Indian Ocean Dipole in 2016, and La Niña in 2010–11. In contrast to southern mainland Australia, cool season rainfall has been above average in western Tasmania during recent decades.

The drying trend in southern Australia has been most evident in the southwest and southeast of the country. Rainfall analyses in these regions can be extended back to around 1890 due to greater data coverage, enabling current droughts to be compared to historical droughts such as the Federation drought (1895 to 1902). The recent drying across these regions is the most sustained large-scale change in observed rainfall since the late 1880s. The trend is particularly strong for the period from May to July over southwest Western Australia, with rainfall since 1970 around 20 per cent less than the average from 1900 to 1969. Since 2000, this decline has increased to around 28 per cent. For the southeast of the continent, April to October rainfall for the period 2000 to 2019 has decreased by around 12 per cent when compared to 1900–1999. This period encompasses most of the Millennium drought, which saw low annual rainfall totals across the region from 1997 to 2009. However, cool season rainfall totals are still around 10 per cent below the 1900–1999 average in the years since the Millennium drought.
Again—this poses obvious problems for agriculture. Expect desalination plants to be used more and more in the future. Sydney used theirs last year. So much for desal plants being white elephants!
 

HBS Guy

Head Honcho
Staff member
UK Met Office: 2020 is nearly as warm as mega El Nino year 2016 despite some La Nina cooling starting late 2020. Only 0.1°C in it.

MetOffice 2020 = 2016.jpeg

This is amazing! A year that is largely ENSO neutral ending with a La Nina system is very nearly as warm as a year 4 years earlier that had a very strong El Nino system for a significant part of the year.

Leads me to think: what is the next El Nino year going to be like? Hope I am in Tassie by then!
 
Last edited:
Top