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State of the Climate 2024 ANRTranscript
BRoll State of the Climate 2024 ANR
Dr Karl Braganza: Hi, I'm Doctor Karl Braganza, National Climate Manager at the Bureau of Meteorology.
Interviewer: What are the key findings in the report?
Dr Karl Braganza: The key finding of the report is that greenhouse gases such as carbon dioxide, are at the highest levels seen on Earth in at least 2 million years, and this is causing Australia to continue to warm. Australia's terrestrial climate has warmed by around 1.5 degrees since national records began, while sea surface temperatures have increased by just over one degree. Eight of the nine warmest years on record in Australia have occurred since 2013. Rainfall patterns are changing too, South West and South East Australia are experiencing a drying trend in total rainfall in the cooler months. We are also seeing heavy rainfall events become more intense.
Interviewer: What has changed since the last report?
Dr Karl Braganza: The long term trends identified in the previous reports are continuing. Australia's weather and climate has continued to change with an increase in extreme heat events, longer fire seasons and sea level rise. We have also seen some seen some significant new climate records in the past two years. This includes the extraordinarily low Antarctic sea ice extents that occurred through 2023 and globally, 2023 was the warmest year on record. However, Australia's warmest year remains as 2019.
Interviewer: Does this data show that we've crossed the Paris Agreement threshold of 1.5°C?
Dr Karl Braganza: This report doesn't show that we've crossed the global 1.5 degree threshold of the Paris Agreement. Temperatures over the continental land masses have warmed more rapidly than the oceans, and the threshold for the Paris Agreement is the warming from both land and ocean temperatures average globally.
Interviewer: How is climate change impacting extreme rainfall and floods?
Dr Karl Braganza: For rainfall, we're observing different changes in different parts of the country. In South West and South Wast Australia, we've seen a noticeable drop in rainfall between April and October. In contrast, parts of northern Australia are seeing increased rainfall during the summer wet season. Overlaying these seasonal rainfall changes are increases in rainfall extremes, particularly extremes in hourly rainfall totals such as those you see during thunderstorms or weather systems such as East Coast lows. These are likely to increase by about 15% per degree of global warming. Extreme rainfall is one of the major drivers of flood risk in Australia.
Interviewer: How is climate change impacting tropical cyclones?
Dr Karl Braganza: There has been a decrease in the number of tropical cyclones observed in the Australian region since at least 1982, but a greater proportion of future storms that do occur are likely to be of high intensity. Climate change, particularly a warmer atmosphere, warmer sea surface temperatures and higher sea levels will also amplify heavy rainfall in future storm surge events associated with tropical cyclones.
Interviewer: How is climate change affecting bushfire seasons?
Dr Karl Braganza: There has been an increase in extreme fire weather and in the length of the fire season across large parts of the country, especially in southern Australia. Natural variability will continue to play a role from year to year, but with an added contribution from climate change. Extreme drought years like those we saw in 2017 and 2019, will increasingly be followed by catastrophic fire weather, such as we experienced during the Black Summer of 2020 as the climate system warms.
Interviewer: What does the report say regarding snowfall?
Dr Karl Braganza: The snow depth, snow cover and extent of the season are shrinking due to climate change. Snow depth is closely related to temperature and the observed declines are associated with global warming trends.
Dr Jaci Brown: Hi, I'm Doctor Jaci Brown, Climate Research Manager at CSIRO.
Interviewer: Why does this report matter?
Dr Jaci Brown: The State of the Climate report is the eighth in the series, released every two years. The report is designed to provide a trusted source of information for all Australians to know how their climate is changing.
Interviewer: What does the report tell us?
Dr Jaci Brown: Australia has warmed 1.5 degrees since 1910 and that impacts our heat waves, droughts, rainfall intensity and sea level rise.
The concentration of greenhouse gases in the atmosphere is continuing to rise, however, recent data suggests that emissions from human activities is stabilising. The consequences of increasing greenhouse gases are warmer weather, drier conditions in the South East and South West of Australia and more days conducive to bushfires.
Interviewer: What do these changes mean for the average Australian?
Dr Jaci Brown: Climate change is already happening and the changes being experienced will now become more frequent into the future. Heatwaves, bushfires, intense rainfall, coastal inundation and the time to recover between events will become shorter. This will likely impact lifestyle choices, food production and consumption, insurance premiums, energy costs, health, particularly for the elderly and vulnerable.
Interviewer: How is this report put together?
Dr Jaci Brown: Climate scientists from CSIRO and the Bureau of Meteorology draw together the latest atmospheric and ocean monitoring to describe variability and changes in Australia's climate. An important source of greenhouse gas data is the Kennaook Cape Grim Baseline Air Pollution Station in Tasmania. This station has provided a continuous record of greenhouse gases since 1976.
Interviewer: What is the impact of warmer and more acidic oceans?
Dr Jaci Brown: The oceans take up 90% of the energy from climate change, and this is evident in rising sea surface temperatures, marine heatwaves and sea level rise. Marine heatwaves are seriously affecting coral reefs, particularly the Great Barrier Reef. Five mass coral bleaching events have occurred on the Great Barrier Reef in the last ten years. Recovery is possible between events, but with future warming more frequent, extensive, intense and longer lasting marine heatwaves are likely and this can lead to more coral bleaching and pressure on fisheries.
Interviewer: Can you talk through what we are seeing with sea level rise?
Dr Jaci Brown: Global sea levels have risen 22cm since 1900. The rate is increasing and is now approaching four centimetres per decade, but it doesn't rise evenly everywhere. Bigger increases are occurring to the north of Australia and in the South East. About one third of the sea level rise is due to water warming and expanding, and the remaining is from ice melting and less water being stored on land. The East Australian Current is strengthening and moving closer to Tasmania, causing a warming of the surface water.
Interviewer: Are our greenhouse gases reducing?
Dr Jaci Brown: Global average concentrations of greenhouse gases are continuing to rise and are rising at globally unprecedented rates. In 2023, the concentration of annual mean carbon dioxide levels was 419.2 parts per million. The current level of greenhouse gases is 50% more than it was in 1750. Methane emissions continue to increase. Methane makes a significant contribution to warming because it is 81 times more powerful than carbon dioxide as a greenhouse gas.
Interviewer: What do these findings mean for Australia's net zero targets?
Dr Jaci Brown: The Paris Agreement target to limit global warming to well below two degrees, preferably 1.5, will be exceeded if greenhouse gas emissions do not decline. If we continue at the current rate of emissions for the next seven years, we will likely lock in 1.5 degrees of global warming.
Dr Karl Braganza: Hi, I'm Doctor Karl Braganza, National Climate Manager at the Bureau of Meteorology.
Interviewer: What are the key findings in the report?
Dr Karl Braganza: The key finding of the report is that greenhouse gases such as carbon dioxide, are at the highest levels seen on Earth in at least 2 million years, and this is causing Australia to continue to warm. Australia's terrestrial climate has warmed by around 1.5 degrees since national records began, while sea surface temperatures have increased by just over one degree. Eight of the nine warmest years on record in Australia have occurred since 2013. Rainfall patterns are changing too, South West and South East Australia are experiencing a drying trend in total rainfall in the cooler months. We are also seeing heavy rainfall events become more intense.
Interviewer: What has changed since the last report?
Dr Karl Braganza: The long term trends identified in the previous reports are continuing. Australia's weather and climate has continued to change with an increase in extreme heat events, longer fire seasons and sea level rise. We have also seen some seen some significant new climate records in the past two years. This includes the extraordinarily low Antarctic sea ice extents that occurred through 2023 and globally, 2023 was the warmest year on record. However, Australia's warmest year remains as 2019.
Interviewer: Does this data show that we've crossed the Paris Agreement threshold of 1.5°C?
Dr Karl Braganza: This report doesn't show that we've crossed the global 1.5 degree threshold of the Paris Agreement. Temperatures over the continental land masses have warmed more rapidly than the oceans, and the threshold for the Paris Agreement is the warming from both land and ocean temperatures average globally.
Interviewer: How is climate change impacting extreme rainfall and floods?
Dr Karl Braganza: For rainfall, we're observing different changes in different parts of the country. In South West and South Wast Australia, we've seen a noticeable drop in rainfall between April and October. In contrast, parts of northern Australia are seeing increased rainfall during the summer wet season. Overlaying these seasonal rainfall changes are increases in rainfall extremes, particularly extremes in hourly rainfall totals such as those you see during thunderstorms or weather systems such as East Coast lows. These are likely to increase by about 15% per degree of global warming. Extreme rainfall is one of the major drivers of flood risk in Australia.
Interviewer: How is climate change impacting tropical cyclones?
Dr Karl Braganza: There has been a decrease in the number of tropical cyclones observed in the Australian region since at least 1982, but a greater proportion of future storms that do occur are likely to be of high intensity. Climate change, particularly a warmer atmosphere, warmer sea surface temperatures and higher sea levels will also amplify heavy rainfall in future storm surge events associated with tropical cyclones.
Interviewer: How is climate change affecting bushfire seasons?
Dr Karl Braganza: There has been an increase in extreme fire weather and in the length of the fire season across large parts of the country, especially in southern Australia. Natural variability will continue to play a role from year to year, but with an added contribution from climate change. Extreme drought years like those we saw in 2017 and 2019, will increasingly be followed by catastrophic fire weather, such as we experienced during the Black Summer of 2020 as the climate system warms.
Interviewer: What does the report say regarding snowfall?
Dr Karl Braganza: The snow depth, snow cover and extent of the season are shrinking due to climate change. Snow depth is closely related to temperature and the observed declines are associated with global warming trends.
Dr Jaci Brown: Hi, I'm Doctor Jaci Brown, Climate Research Manager at CSIRO.
Interviewer: Why does this report matter?
Dr Jaci Brown: The State of the Climate report is the eighth in the series, released every two years. The report is designed to provide a trusted source of information for all Australians to know how their climate is changing.
Interviewer: What does the report tell us?
Dr Jaci Brown: Australia has warmed 1.5 degrees since 1910 and that impacts our heat waves, droughts, rainfall intensity and sea level rise.
The concentration of greenhouse gases in the atmosphere is continuing to rise, however, recent data suggests that emissions from human activities is stabilising. The consequences of increasing greenhouse gases are warmer weather, drier conditions in the South East and South West of Australia and more days conducive to bushfires.
Interviewer: What do these changes mean for the average Australian?
Dr Jaci Brown: Climate change is already happening and the changes being experienced will now become more frequent into the future. Heatwaves, bushfires, intense rainfall, coastal inundation and the time to recover between events will become shorter. This will likely impact lifestyle choices, food production and consumption, insurance premiums, energy costs, health, particularly for the elderly and vulnerable.
Interviewer: How is this report put together?
Dr Jaci Brown: Climate scientists from CSIRO and the Bureau of Meteorology draw together the latest atmospheric and ocean monitoring to describe variability and changes in Australia's climate. An important source of greenhouse gas data is the Kennaook Cape Grim Baseline Air Pollution Station in Tasmania. This station has provided a continuous record of greenhouse gases since 1976.
Interviewer: What is the impact of warmer and more acidic oceans?
Dr Jaci Brown: The oceans take up 90% of the energy from climate change, and this is evident in rising sea surface temperatures, marine heatwaves and sea level rise. Marine heatwaves are seriously affecting coral reefs, particularly the Great Barrier Reef. Five mass coral bleaching events have occurred on the Great Barrier Reef in the last ten years. Recovery is possible between events, but with future warming more frequent, extensive, intense and longer lasting marine heatwaves are likely and this can lead to more coral bleaching and pressure on fisheries.
Interviewer: Can you talk through what we are seeing with sea level rise?
Dr Jaci Brown: Global sea levels have risen 22cm since 1900. The rate is increasing and is now approaching four centimetres per decade, but it doesn't rise evenly everywhere. Bigger increases are occurring to the north of Australia and in the South East. About one third of the sea level rise is due to water warming and expanding, and the remaining is from ice melting and less water being stored on land. The East Australian Current is strengthening and moving closer to Tasmania, causing a warming of the surface water.
Interviewer: Are our greenhouse gases reducing?
Dr Jaci Brown: Global average concentrations of greenhouse gases are continuing to rise and are rising at globally unprecedented rates. In 2023, the concentration of annual mean carbon dioxide levels was 419.2 parts per million. The current level of greenhouse gases is 50% more than it was in 1750. Methane emissions continue to increase. Methane makes a significant contribution to warming because it is 81 times more powerful than carbon dioxide as a greenhouse gas.
Interviewer: What do these findings mean for Australia's net zero targets?
Dr Jaci Brown: The Paris Agreement target to limit global warming to well below two degrees, preferably 1.5, will be exceeded if greenhouse gas emissions do not decline. If we continue at the current rate of emissions for the next seven years, we will likely lock in 1.5 degrees of global warming.