State of Australian Climate 2024 paints a worsening picture: 13 graphs and maps

 

Australia's climate is worsening, driven by accelerating climate change, according to the latest assessment by the Australian Bureau of Meteorology and the CSIRO. 

Buckle up people. Expect longer, more intense extreme heat events. Heat events kill more people than all other extreme weather events combined. 

Australia has now warmed by 1.51 degrees Centigrade.

South West Australia and South East Australia will get drier. But when it rains, heavy short term rain events are becoming more intense. That means more flash flooding. It also has iimplications for agriculture.

The hotter, drier climate means longer fire season, a more extreme fire season. We are seeing more pyrocumulonimbus (Pyro CB) fires when a bushfire starts generating its own weather firestorm. Larger fires mean more smoke that can travel for hundreds even thousands of kilometres with the air pollution particulates affecting people in distant towns and cities. More people are dying from smoke related conditions.

Current Climate Trends

The eighth biennial State of the Climate report published identifies the following trends:

• Australia’s climate has warmed by an average of 1.51 ± 0.23 °C since national records began in 1910.
• Sea surface temperatures have increased by an average of 1.08 °C since 1900.
• The warming has led to an increase in the frequency of extreme heat events over land and in the oceans.
• In the south-west of Australia there has been a decrease of around 16% in April to October rainfall since 1970. Across the same region, May to July rainfall has seen the largest reduction, by around 20% since 1970.
• In the south-east of Australia, there has been a decrease of around 9% in April to October rainfall since 1994.
• Heavy short-term rainfall events are becoming more intense.
• There has been a decrease in streamflow at most gauges across Australia since 1970.
• There has been an increase in rainfall and streamflow across parts of northern Australia since the 1970s.
• There has been an increase in extreme fire weather, and a longer fire season, across large parts of the country since the 1950s.
• There has been a decrease in the number of tropical cyclones observed in the Australian region since at least 1982.
• Snow depth, snow cover and number of snow days have decreased in alpine regions since the late 1950s.
• Oceans around Australia are becoming more acidic, with changes happening faster in recent decades.
• Sea levels are rising around Australia, including more frequent extreme high levels that increase the risk of inundation and damage to coastal infrastructure and communities.

Future Climate Proijections

The report provides the following information on future climate;

In the coming decades, Australia will experience ongoing changes to its weather and climate. The changes are projected to include:

• Continued increase in air temperatures, with more heat extremes and fewer cold extremes.
• Continued decrease, on average, in cool season rainfall across many regions of southern and eastern Australia, which will likely lead to more time in drought.
• More intense short-duration heavy rainfall events even in regions where the average rainfall decreases or stays the same.
• Continued increase in the number of dangerous fire weather days and a longer fire season for much of southern and eastern Australia.
• Further sea level rise and continued warming and acidification of the oceans around Australia.
• Increased and longer-lasting marine heatwaves that will affect marine environments such as kelp forests and increase the likelihood of more frequent and severe bleaching events in coral reefs around Australia, including the Great Barrier Reef and Ningaloo Reef.
• Fewer tropical cyclones, but with higher intensity on average, and greater impacts when they occur through higher rain rates and higher sea level.
• Reduced average snow depth in alpine regions, but with variations from year to year.

13 Graphs and Maps on Australia's changing climate

1. Temperatures are Rising

 

CSIRO: Australian average annual temperature in observations and global climate models shown relative to the 1850–1900 baseline approximating the pre-industrial era. Past and future coloured bands show the 20-year running average from models for historical conditions and plausible future scenarios to 2040. Black dashed lines show the average warming expected for Australia when the global average temperature reaches 1.5 and 2.0 °C above the pre-industrial era. The panel to the right shows the range of temperatures (one and 2 standard deviations) in various epochs from observations and the 2021–2040 period as simulated by one climate model (the results from which are close to the mean of all models).

2. Extreme Heat days are increasing

CSIRO: Number of days each year where the Australian area-averaged daily mean temperature for each month is extreme. Extreme days are defined as those where daily mean temperatures are the warmest 1% of days for each month, calculated for the period 1910–2023.

There were fewer extremes in the period from 2020 to 2023, which was dominated by La Niña conditions, although the number of extreme heat days in those years (except 2022) was still high compared with most years prior to 2000. Extreme heat has caused more deaths in Australia than any other natural hazard and has major impacts on ecosystems and infrastructure.

The very high monthly maximum temperatures that were recorded under 2% of the time in 1960−1989, are occurring 11% of the time in 2009−2023. That is about 6 times as often.

Similarly, the very high night time temperatures, which are also a major contributor to heat stress, and occurred 2% of the time in 1960−1989, now occur about 10% of the time – 5 times as often.

The occurrence of very cold days and nights has declined across Australia. An exception is for extremely cold nights in parts of south-east and south-west Australia, where the frequency of frost in these parts has been relatively unchanged since the 1980s. In this region, there has been significant cool season drying, and hence more clear winter nights. This results in colder nights due to increased heat loss from the ground.

3. Rising Sea Surface Temperatures

Trends in sea surface temperature in the Australian region (4–46° S and 94–174° E) over 1981–2023 based on the Optimum Interpolation SST (OISST) product derived from various in-situ and satellite observation platforms.

4. Increasing Bushfire Risk

There has been an increase in the number of days with dangerous weather conditions for bushfires. The map shows the change in the number of days per year (July to June) that the FFDI exceeds its 90th percentile of conditions observed from 1950–2024, between 2 periods: July 1950 to June 1987 and July 1987 to June 2024. The FFDI is an indicator of dangerous fire weather conditions for a given location.

5. Changing Rainfall trends 

April to October rainfall deciles for the 30 years from 1994 to 2023. A decile map shows where rainfall is above average, average, or below average for this period compared to all years from 1900 (when reliable national rainfall records began) to 1993. Areas across northern and central Australia that receive less than 40% of their annual rainfall from April to October are faded.

6. Greenhouse Gas emissions continue to Rise

Concentrations of the major greenhouse gases (CO2, methane and nitrous oxide) in the atmosphere over the past 2000 years. Blue data are measured from air extracted from Antarctic ice cores and the overlying compressed snow (firn) layer. Orange data show the modern in situ record measured at Kennaook/Cape Grim Baseline Air Pollution Station. Note the different scales used for the concentration of each gas.

7. Ocean Heat uptake

Estimated change in ocean heat content globally averaged over the full ocean depth, from 1960–2023. Shading indicates the confidence range of the estimates. The measurements contributing to the early part of the record, before 1970, are sparse and trends estimated over this period are small compared to the confidence range and hence are considered less reliable. Source: CSIRO, GEOMAR (Germany) and National Oceanographic Centre (UK), Woods Hole Oceanographic Institute (USA)

8. Southern Ocean in particular is warming

Estimated trend in ocean heat content in the upper 2,000 metres between 2005 and 2023. The highest uptake of heat occurred in regions where the circulation draws heat into the deep ocean, such as the Southern Ocean (data source Scripps Institute of Oceanography, Roemmich and Gilson Argo climatology).

9. Ocean Acidification Increasing

The pH change of surface waters around Australia between 1982 and 2022 (data sourced from the OceanSODA-ETHZ dataset). Calculations are based on data from the Integrated Marine Observing System and other programs.

10 and 11. Sea Levels are Rising but at variable rates around Australia

Global mean sea level change (in cm) from 1900 to 2019 reconstructed with tide gauges from CSIRO (blue line), Palmer et al. (2021; red line) and global mean sea level based on satellite altimetry betweween 1993 and 2023 (yellow line). Shading indicates the confidence range of the estimates.

The rate of offshore sea level rise (in cm per decade) around Australia measured using satellite altimetry from 1993 to 2023, and onshore sea level rise (coastal points) from the multi-decadal tide gauge dataset from the Australian Baseline Sea Level Monitoring Project. The colour scale applies to both the altimetry and tide gauge observations. 

12. Changes to the Cryosphere (Antarctica and the Arctic Sea-Ice)

Antarctic and Arctic sea-ice extent (shown as the anomaly relative to 1981–2010) for January1979 to April 2024 (106 km2). Thin lines are monthly averages and indicate the variability at shorter timescales, while thick lines are 11-month moving averages (centred).

13. Australia's Carbon Budget 2010-2019

When we combine all the land-based CO2 sources and sinks with the fossil fuel emissions, Australia was a net source to the atmosphere of 200 million tonnes of CO2 per year between 2010 and 2019.

If we count the CO2 sinks from coastal ecosystems, the contribution to the atmosphere is smaller. This means CO2 sinks partially offset fossil fuel emissions, albeit with large uncertainties. Australia also transfers large amounts of carbon embedded in its fossil fuel exports, the emissions of which are accounted for in the country where the combustion occurs. 

This new assessment of the Australian carbon budget shows that the net annual carbon balance of the entire continent is highly variable from year to year, owing to changes in the behaviour of natural CO2 sinks. Australia can be a large net source of CO2 in one year, to carbon neutral the next, to a large net CO2 sink in the next year. This ‘boom and bust’ dynamics of Australia’s carbon budget, largely driven by the responses of the land CO2 sinks to rainfall and fire, underscores the potential large impacts of future climate change on Australia’s net carbon balance.

References

CSIRO/BOM 2024 State of the Climate Report https://www.csiro.au/en/research/environmental-impacts/climate-change/state-of-the-climate

Previous State of the Climate Reports I have reported on. BOM and CSIRO have been warning of accelerating climate impacts for Australia for more than 20 years:

Climate Citizen, April 2014, Climate change gives a clear signal in 2014 State of the climate Australia report https://takvera.blogspot.com/2014/03/climate-change-gives-clear-signal-in.html

Climate Citizen, March 2010, Scientists affirm Australia's climate already changing https://takvera.blogspot.com/2010/03/scientists-affirm-australias-climate.html

Climate Citizen, November 2004, CSIRO warns: Australia to get hotter, wetter, with more extreme weather https://takvera.blogspot.com/2004/11/csiro-warns-australia-to-get-hotter.html