Climate Index shows mild temperatures, yet extreme rainfall

Climate Index shows mild temperatures, yet extreme rainfall

By August 4, 2021Climate Risk, News

The latest Australian Actuaries Climate Index has reported an extreme autumn for 2021.

Despite milder temperatures, extreme rainfall early in the season and high sea-levels resulted in remarkable flooding with devastating impacts.

The Finity climate team, who compile the index, noted the fourth highest extreme rainfall index for Eastern NSW in the Climate Index, as shown below in red.

Heavy rainfall between the 16 - 23 of March in NSW caused significant flooding which resulted in the deaths of 5 people and damage costing approximately $1 billion.

Rade Musulin, Finity’s climate leader, said “The impact of the rainfall was extensive. Thankfully, we saw La Nina come to an end in Australia at the end of March, and we should see less rainfall going forward. Our research also showed that extreme low temperature for Australia was also below the reference period average for only the third time since 2012. This indicates that the minimum temperatures have been higher than in the base period of 1981-2010 for some time, but have now dipped just below that average.

Read more about the Australian Actuaries Climate Index and the latest analysis here.

Recent wild weather globally

The extreme flood event in NSW as reflected in the AACI is part of a pattern of extreme weather globally. In recent months, parts of North America have been struck by extreme drought, heatwaves, and wildfires, while Germany and China have been tormented by record rainfall and floods. In Zhengzhou, China, a years’ worth of rainfall fell within 3 days, breaking hourly and daily records of data collected over the last 70 years.1 In western Canada, temperatures soared to 46 degrees, the highest ever recorded. The impact of these events has caused significant disruption across communities with multiple lives lost, infrastructure damage, and an economic and environmental cost that is yet to be recognized.

The events unfolding around the world are just an example of many to have occurred globally in recent years. Climate scientists have found human induced climate change to have raised the severity of historic drought and extreme rainfall experienced around the world23. For example, the Cape Town ‘Day Zero’ meteorological drought in 2018 was found to have been 5 to 6 times more likely to occur due to anthropogenic climate change4. Higher temperatures intensify evaporation from soils and water bodies and reduce snowmelt volumes5. This in turn has significant implications on the rainfall-runoff volumes as dry soils absorb any available water. At the same time, higher temperatures mean the air can hold more moisture resulting in more intense precipitation events as that seen in China. With some climate models projecting a decrease in moderate rainfall, an increase in prolonged dry periods are likely to offset any increase in precipitations during extreme rainfall events, resulting in strains in available water supplies6.

As climate scientists warn us to prepare for higher global temperatures, it becomes critical that communities begin to prepare for more wild weather, beyond what is known to have occurred historically. Emergency response plans and infrastructure standards need to reviewed for their adequacy to deal with unprecedented events. For drought events, a growing demand for water enforces the need for sectors and communities to start identifying and optimising their reliance on water to prepare for prolonged dry periods. This can include the uptake of strategies such as water recycling, crop modification to include drought resilient strains, and water management policies.

As we noted in a prior blog on the NSW Floods, a complicating factor in planning protection against drought and flood is that often the same infrastructure is used for multiple purposes, such as water management, irrigation, flood protection, hydroelectric power generation, and so forth. More extreme weather will make it increasingly important to harden such infrastructure to flexibly address additional stresses.

For more information please contact our Climate Risk team.


Rade Musulin

Ph +61 2 8252 3444
rade.musulin@finity.com.au

 

Sharanjit Paddam

Ph +61 2 8252 3300
sharanjit.paddam@finity.com.au

[1] https://www.theguardian.com/world/2021/jul/22/china-floods-military-blasts-dam-release-water-as-floods-death-toll-climbs
[2] https://www.nature.com/articles/s41467-021-24262-x
[3] https://www.nature.com/articles/s41467-021-22314-w
[4] https://www.pnas.org/content/117/47/29495
[5] https://www.carbonbrief.org/explainer-what-climate-models-tell-us-about-future-rainfall
[6] https://www.c2es.org/content/extreme-precipitation-and-climate-change/