The Bureau of Meteorology (BOM) and the Commonwealth Scientific and Industrial Research Organisation (CSIRO) have released their eighth “State of the Climate” report.
Climate change will bring more frequent extreme heat, rainfall, fires, and droughts to Australia, according to a new report.
The organisations tracked rising land and ocean temperatures in Australia and globally.
Temperature
Since records began in 1910, Australia has become 1.51°C warmer, according to the “State of the Climate” report.
Every decade after 1980 has been warmer than the decade before. 2019 was the country’s hottest year.
High night-time temperatures are five times more frequent than they were in the second half of the 20th Century.
Fire danger
The risk of bushfires across Australia has increased, and the fire season begins earlier in the year.
Southern parts of Australia have seen trends of hot temperatures with thunderstorms, which pose higher fire risks due to lightning strikes. Lightning without a lot of rainfall, or ‘dry lightning’, also increases the threat of bushfires.
Increased rainfall earlier in the year can also impact the number of fires, as it boosts the growth of vegetation, giving fires more fuel.
Rainfall
South-western parts of Australia have experienced some of the country’s biggest rainfall declines. Since 1970, rainfall has decreased by 16% during the cooler months. Meanwhile, rainfall across northern parts of Australia in the warmer months has been above average.
The report found “heavy short-term rainfall events” are more intense than they used to be. This impacts urban areas with large amounts of concrete, increasing the risk of flooding.
Snowfall has also continually decreased across Australia since the 1950s.
Sea surface temperature
The sea surface temperature has increased by 1.08°C on average since 1900. Nine of the 10 hottest years for the sea surface have been since 2010.
High sea surface temperatures also lead to ‘marine heatwaves’ which threaten marine ecosystems and the diversity of sea life.
The Great Barrier Reef has experienced five mass coral bleaching events in the past decade.
Continual bleaching means reefs don’t have enough time to recover between events, impacting their resilience.
Sea levels
The average sea level has increased by 22cm, globally, since 1900. Half of this growth has occurred in the past 54 years.
Rising sea levels place particular stress on coastal communities. South-eastern parts of Australia have seen some of the largest sea level growth.
The report found an “abrupt decrease” in Antarctic ice from 2015, as warming ocean temperatures lead to melting ice sheets. Melting ice across Antarctica and Greenland are also contributors to rising sea levels.
Greenhouse gas
The current level of greenhouse gases is at a two million year high.
Processes like mining, livestock farming, and landfill create around 65% of the world’s methane emissions.
Measured over the span of two decades, the “State of the Climate” report said the impact of methane on global warming is 80 times greater than carbon dioxide.
The report says reducing the amount these greenhouse gases in the atmosphere is a key “pathway to manage climate change.”
In the coming decades…
- More extreme warming
- Less extreme cooling
- More dry weather and drought
- Longer bushfire seasons
- More heavy rainfall in short periods
- Less tropical cyclones
- More intense tropical cyclones
- Increasing sea levels
- More ocean warming
- More marine heatwaves
Comments
While Australia’s emissions have declined in the past two decades, continued extreme heat is expected. The report says Australia “will need to accelerate” its emissions reduction in order to meet its 2030 targets.
CSIRO research manager Dr Jaci Brown said: “Rising sea levels [put] coastal infrastructure and communities” at an increased risk of flooding.
BOM climate services manager Dr Karl Braganza said Australia’s warming “has led to an increase in extreme fire weather and longer fire seasons”.
