The Times Australia
The Times World News

.
The Times Real Estate

.

Here's why climate change isn't always to blame for extreme rainfall

  • Written by Andrew King, Senior Lecturer in Climate Science, The University of Melbourne
Here's why climate change isn't always to blame for extreme rainfall

Extreme rain and floods can trigger claims[1] climate change is to blame. But these claims are not always well founded.

In our new paper[2] in Nature Geoscience, we discuss what can and can’t be attributed to climate change straight after extreme rain events. We use the floods of early 2022 in eastern Australia as a case study.

We know a warmer atmosphere can hold more moisture, so it would seem reasonable to say climate change makes extreme rain events worse. But this really only applies to short, heavy downpours. For longer duration events, the climate change signal tends to be weaker and more variable.

We hope our suggestions will improve the quality of scientific statements in the media and, ultimately, increase public understanding of climate change effects on extreme weather.

Read more: On our wettest days, stormclouds can dump 30 trillion litres of water across Australia[3]

The early 2022 Australian floods

In late February and early March 2022, persistent extreme rainfall caused severe floods across much of the east coast of Australia. Many new rainfall records[4] were set.

Brisbane recorded three consecutive days of over 200mm for the first time and Sydney experienced 16 wet days in a row, tying with a previous record. Much of southeast Queensland and northeast New South Wales had the wettest week since at least 1900.

The floods came towards the end of a third consecutive La Niña[5] summer. Persistent heavy rainfall, associated with large-scale moisture transport in the atmosphere interacting with a trough, caused the flooding.

A blocking high pressure pattern in the Tasman Sea prevented the weather system from moving to the east. This caused the rain to continue and supported the formation of an east coast low, which brought rainfall to the greater Sydney region in early March.

The rain fell on already soaked surfaces, which worsened these floods and also set up the conditions for subsequent floods in Lismore and other parts of the east coast.

The heavy rainfall that led to floods in February and March 2022 was caused by different weather and climate influences coming together. Author provided

These floods occurred not long before the Australian election and led to a renewed focus on climate change action.

While we need to rapidly reduce greenhouse gas emissions to limit the damages caused by climate change[6], the role of climate change in this extreme rain event is unclear.

Rainfall in a warming world

There are two necessary ingredients for extreme rainfall to occur – an abundant supply of moisture and ascending air. Heavy rain can occur when moist air rises, cools and condenses. Air can be forced upwards by obstacles such as mountains and by low pressure systems.

As the atmosphere warms it can hold more moisture – about 7% more for every 1℃ of warming. This means climate change has increased the moisture-holding capacity of the atmosphere.

But the climate change effect on low pressure systems that cause air to rise varies across the planet. In some places these are becoming more common and intense. In other places they’re occurring less often.

In the prolonged heavy rainfall of February-March 2022, the duration of the weather patterns was a major factor in the flood impacts. It’s unclear how big a role climate change played.

Flooding at Murwillumbah, NSW, February-March 2022. A short film by Josh Northeast.

Short downpours or longer drenching rains?

Heavy rain events that cause flash flooding and pass in minutes or hours are often limited by how much moisture is available to fall as rain. A warmer atmosphere can hold more moisture, so these short duration rain events are intensified in a warming world. Recent research[7] shows that in Sydney there has been an increase in sub-hourly heavy rain intensity of about 40% over the last 20 years.

For persistent heavy rain that tends to cause river flooding, the limiting factor is more the positioning of weather systems and whether they stall. As a result, the climate change signal in these events tends to be weaker and more variable across the world.

What can we say after extreme events?

In the emotionally charged time following extreme events, it is important that commentators – whether they are scientists or journalists, politicians or advocates – make scientifically accurate statements on the role of climate change.

In our paper, we recommend scientists consider different lines of evidence before making statements on the role of climate change in extreme rainfall. These include examining observational trends and relevant peer-reviewed research on the climate of the area where the extreme event occurred.

Different lines of evidence should be considered when thinking about the climate change role in extreme rain events. For the multi-day east Australian heavy rainfall in early 2022, these lines of evidence point in different directions. Author provided. Modified from King et al. (2023)

Robust statements on the effects of climate change on extreme events improve the public discourse and are crucial to planning for weather and climate extremes in a warming world.

The impacts of climate change are drastic enough. We don’t need to sensationalise them.

Read more: Global warming to bring record hot year by 2028 – probably our first above 1.5°C limit[8]

Read more https://theconversation.com/heres-why-climate-change-isnt-always-to-blame-for-extreme-rainfall-206958

The Times Features

Why Regional Small Businesses in Bendigo Deserve Better Access to Finance in 2025

In the heart of regional Victoria, Bendigo has long stood as a beacon of innovation, resilience and community spirit. As we step further into 2025, the importance of nurturing sm...

Is It Time for a Deep Cleaning? Signs You Shouldn’t Ignore

Most people know they should visit the dentist for a regular check-up and cleaning every six months. But sometimes, a standard cleaning isn’t enough. When plaque and tartar build...

The Hidden Meaning Behind Popular Engagement Ring Cuts

When it comes to engagement rings, the cut of the diamond is not just about aesthetics. Each shape carries its own symbolism and significance, making it an important decision for...

Annual Health Exams in the Office: How They Can Reduce Sick Days and Healthcare Costs

Regular health check-ups, especially annual health exams in the office, can significantly impact the overall well-being of your workforce. A proactive approach to employee health...

Best Deals on Home Furniture Online

Key Highlights Discover the best deals on high-quality outdoor furniture online. Transform your outdoor space into a stylish and comfortable oasis. Explore a wide range of d...

Discover the Best Women's Jumpers for Every Season

Key Highlights Explore lightweight jumpers for spring and summer, ensuring breathability and ease. Wrap up warm with cozy wool jumpers for the chilly autumn and winter season...

Times Magazine

The Essential Guide to Transforming Office Spaces for Maximum Efficiency

Why Office Fitouts MatterA well-designed office can make all the difference in productivity, employee satisfaction, and client impressions. Businesses of all sizes are investing in updated office spaces to create environments that foster collaborat...

The A/B Testing Revolution: How AI Optimized Landing Pages Without Human Input

A/B testing was always integral to the web-based marketing world. Was there a button that converted better? Marketing could pit one against the other and see which option worked better. This was always through human observation, and over time, as d...

Using Countdown Timers in Email: Do They Really Increase Conversions?

In a world that's always on, where marketers are attempting to entice a subscriber and get them to convert on the same screen with one email, the power of urgency is sometimes the essential element needed. One of the most popular ways to create urg...

Types of Software Consultants

In today's technology-driven world, businesses often seek the expertise of software consultants to navigate complex software needs. There are several types of software consultants, including solution architects, project managers, and user experienc...

CWU Assistive Tech Hub is Changing Lives: Win a Free Rollator Walker This Easter!

🌟 Mobility. Independence. Community. All in One. This Easter, the CWU Assistive Tech Hub is pleased to support the Banyule community by giving away a rollator walker. The giveaway will take place during the Macleod Village Easter Egg Hunt & Ma...

"Eternal Nurture" by Cara Barilla: A Timeless Collection of Wisdom and Healing

Renowned Sydney-born author and educator Cara Barilla has released her latest book, Eternal Nurture, a profound collection of inspirational quotes designed to support mindfulness, emotional healing, and personal growth. With a deep commitment to ...

LayBy Shopping