Bureau of Meteorology

We need urban trees more than ever – here's how to save them from extreme heat

Retrieved on:

Monday, September 25, 2023

And we’ve just watched the Northern Hemisphere swelter through their summer, making July 2023 Earth’s hottest month on record.

Key Points:

And we’ve just watched the Northern Hemisphere swelter through their summer, making July 2023 Earth’s hottest month on record.
We studied the effects of extreme heat on urban trees in Western Sydney during Australia’s record-breaking summer of 2019–20.
So we hold grave concerns for the survival of both native Australian and exotic species in our urban forest.
Read more:
Climate change threatens up to 100% of trees in Australian cities, and most urban species worldwide

Trees during heatwaves in Sydney

Those most vulnerable to heatwaves included both native Australian and exotic species.
Some trees died, including red maple (Acer rubrum), tulip poplar (Liriodendron tulipifera), coast banksia (Banksia integrifolia) and water gum (Tristaniopsis laurina).
Read more:
Without urgent action, these are the street trees unlikely to survive climate change

Why are some species more vulnerable?

For example, species with large, thin leaves are particularly vulnerable.
Thin leaves are less able to buffer against overheating on hot, sunny days when the wind lulls.
Our research found most urban tree species –- even those under drought stress –- opened their pores to cool leaves on hot summer days.
This results in rapid water loss but may help prevent tree leaves from scorching.

Why is water so important during heatwaves?

We found water loss was higher than predicted during heatwaves for all plants.
In urban trees, leaves reached lethal temperatures of 49–50℃ for species with the lowest rates of water loss.
But when species with low rates of water loss had access to water, there was little heat damage or scorched leaves.

Preserving our natural air conditioners

That means urban greening programs need to find ways to provide trees with enough water when rainfall is unreliable.
Cities need trees now more than ever, as these natural air conditioners take the edge off the extremes.
David S Ellsworth receives funding from the Australian Research Council, the New South Wales Government, Hort Innovation, and the Herman Slade Foundation.

Canada's Online News Act may let Meta and Google decide the winners and losers in the media industry

Retrieved on:

Monday, June 26, 2023

The act is meant to change the way journalism in Canada is funded by requiring tech giants like Meta and Google to bargain with Canadian media businesses for using news content on their platforms.

Key Points:

The act is meant to change the way journalism in Canada is funded by requiring tech giants like Meta and Google to bargain with Canadian media businesses for using news content on their platforms.
The Parliamentary Budget Office has estimated news organizations could share a total compensation of $329 million annually.
The Online News act was modelled on Australia’s News Media Bargaining Code (NMBC), legislation that was the first to compel Meta and Google to pay for third-party news content on their sites.

Meta’s predictable response

For Australians watching the legislation proceed through the Canadian Parliament, Meta’s actions seem to signal a case of history repeating.
Meta acted in much the same way while the NMBC was being debated, blocking Australians from accessing or posting news content.

The Australian NMBC one year on

Late last year, the Australian Federal Treasury completed the first review of the NMBC and positioned the legislation as a success.
There was, however, a significant difference between Google and Meta when it came to the deals made.
I was part of an Australian research team that wanted to understand how Google and Meta were able to have such different responses to the code.

Lack of transparency under the NMBC

Some of the news executives of smaller organizations said lack of transparency around the funding led to an unintended shift.
The market imbalance between media organizations and platforms was now felt much more among the media organizations themselves.
Misha Ketchell, editor of The Conversation Australia, said more transparency might have improved the “information asymmetry” between larger corporations and smaller independent organizations.

Platforms opting out of NMBC negotiation

As Nick Shelton, publisher of lifestyle-focused Broadsheet Media, argued:
“The platforms are the ones who are in a position to determine who they deal with … .
Lastly, our interviews also showed that platforms were also able to push for individual deals that aligned with their own business priorities for news on the platform.
This impacted the kinds of journalism being invested in, and reliance on particular forms of funding to pay for it.

What does this mean for Canadians?

There are valuable lessons to be learned from the framing of the Australian code.
Canadians should consider how much influence platforms already have and how much they might seek to gain once the Online News Act comes into effect.

An El Niño looms over Australia's stressed electricity system – and we must plan for the worst

Retrieved on:

Saturday, June 10, 2023

The Bureau of Meteorology this week declared a 70% chance of an El Niño developing this year.

Key Points:

The Bureau of Meteorology this week declared a 70% chance of an El Niño developing this year.
It’s bad timing for the electricity sector, and means Australians may face supply disruptions and more volatile energy prices.
And unfortunately, the likely El Niño comes as the electricity sector grapples with other significant headwinds.

How does hot weather affect energy supplies?

At the same time, electricity generators – including coal, gas, solar and wind – can become less efficient in hot temperatures, and so provide less energy to the system.
This lowers their capacity to transport energy.
This occurred in Tasmania in 2016, and contributed to an energy crisis in that state.

Other headwinds are blowing

The market operator pointed to delays to the Snowy 2.0 hydro project and the gas-fired Kurri Kurri Power Station, both in New South Wales.
It was scheduled to begin operating in December this year – in time for the first summer since the Liddell coal-fired power station closed.
But the operator also said delays to the Kurri Kurri project posed risks to reliability in NSW this summer.
Combine all this with a likely El Niño, and the electricity sector may be facing a challenging summer.

El Niño years are not normal

However, the way the assessment is derived may mask the real risk during El Niño periods.
But if an El Niño arrives, this summer will not be average.
So the grid may be deemed reliable even though electricity supplies are under immense pressure.

What can be done?

A mechanism exists that allows the market operator to secure emergency energy reserves.
It could mean, for example, calling on a large industrial plant to pause operations to reduce its electricity use, or starting up a standby diesel generator.
The operator can start procuring this months ahead of time, and will no doubt be monitoring the situation closely.
Several federal funding measures – the Capacity Investment Scheme and Rewiring the Nation – might help realise these projects.

Humanity's tipping point? How the Queen's death stole a climate warning's thunder

Retrieved on:

Friday, May 5, 2023

On September 8, 2022, at 6.30pm in Britain, Buckingham Palace announced the death of Queen Elizabeth II.

Key Points:

On September 8, 2022, at 6.30pm in Britain, Buckingham Palace announced the death of Queen Elizabeth II.
The news broke just 30 minutes before the press embargo lifted on a major review of climate change tipping points in the journal Science.
Read more:
Climate tipping points could lock in unstoppable changes to the planet – how close are they?

Grappling with tipping points

And tipping points once thought to be far off in the distance have come into sharp relief.
It asks when melting of ice sheets on Greenland and West Antarctica would become irreversible, ultimately contributing many metres to sea level.
The pivotal paper in Science reviewed more than 220 papers published since 2008 to estimate what level of global temperature rise (relative to pre-industrial levels) would trigger each of the global and regional climate tipping points.
Disturbingly, the threshold for this tipping point may have already been crossed.
But the combination of some of those other tipping points might get us there, setting off a further cascade of tipping points.

Can we avoid disaster?

But, clearly, this research shows that limiting warming to 2℃ will not keep us safe.
The focus on “net zero by 2050” has in fact done us a disservice.
We need to act quickly and at least halve current emissions by 2030 on the way to net zero before 2050.
Where will hundreds of millions of people go after being displaced by extreme wet bulb temperature, crop failure, fire, flooding and sea level rise?

How did we get here?

A failure of leadership, of decision making, of information dissemination through media, and perhaps our priorities, has left us in this extremely challenging position.
These include fossil fuel companies funding misinformation and climate-related “green washing” – exaggerating or misrepresenting their climate credentials.
Earlier low-resolution climate models failing to capture local scale processes, and therefore underestimating climate system sensitivity.

A turning point

Humanity faces a choice between retreat into fear and war, or cooperation and collaboration.
There is much already happening and a lot we can do, as individuals and communities.
We can restore landscapes, reward sustainability, create a circular economy and electrify everything.

Want to see a total solar eclipse? Here's how to plan for it – and how to set your expectations in case of clouds

Retrieved on:

Monday, April 17, 2023

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Weather permitting, they are coming to see one of nature’s greatest sights – a total eclipse of the Sun on Thursday April 20.

Key Points:

Weather permitting, they are coming to see one of nature’s greatest sights – a total eclipse of the Sun on Thursday April 20.
Whether staying at hotels, resorts or camping sites, many would have made travel arrangements a year or more in advance.

A fully immersive experience

The bright disc of the Sun is entirely hidden for a short period – seconds or minutes.
They are not only treated to the magnificent sight of the corona, but get a fully immersive experience.
The gathered observers, whether from your own group or from distant countries, are united in the experience.

An addictive hobby

One is that chasing them is addictive.
Often people who have seen their first eclipse immediately want to start planning to see their second.
Seeing the corona surrounding the dark Sun come into view was an awe-inspiring experience, heightened by the fascinating location and the elation of fellow observers.
But if it’s your first time, it’s probably better to just watch and absorb the event, rather than try photographing it.

Plan ahead and stay mobile

After passing through Mexico, the path of totality sweeps across the United States from Texas to Maine, before moving to parts of Canada.
However, before picking a site, it’s important to study the “climate report” for the eclipse.
This grants the best chance of avoiding the eclipse watcher’s greatest enemy – clouds.
Seasoned observers try to stay mobile, so that if the weather forecast is bad for their location, they can move to another location to avoid the clouds.

Cyclone Ilsa just broke an Australian wind speed record. An expert explains why the science behind this is so complex

Retrieved on:

Saturday, April 15, 2023

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Tropical cyclone Ilsa has been downgraded to a category-three cyclone as it moves southeast through Western Australia.

Key Points:

Tropical cyclone Ilsa has been downgraded to a category-three cyclone as it moves southeast through Western Australia.
It has delivered Australia’s highest ten-minute sustained wind speed record at landfall: about 218 kilometres per hour.
The science of reporting on cyclone wind speeds is highly complex – and it can be easy to misconstrue the figures without some context.

Record-breaking sustained wind speeds

Apart from the ten-minute sustained record mentioned above, Ilsa had a one-minute sustained record of 240km per hour, and a three-second sustained record of 295km per hour.
When it comes to making potential damage assessment for insurance purposes, firms will often model damage associated with a three-second sustained wind speed.
But there are several challenges that come with recording and making predictions about cyclone wind speeds.

How are tropical cyclone winds recorded?

These measure wind speeds at locations across the country, and are often placed in flat areas, such as near airports.
Their specific placement is very important, because wind can change form as it moves over and through certain types of terrain.
However, wind passing closer to the ground, where the topography varies, will often be higher than winds passing directly above.
Accurate and consistent data points are crucial if we want to record and predict the kinds of extreme winds we might experience during future tropical cyclones.

Cyclone intensity will increase

It’s worth mentioning Ilsa formed pretty late in the cyclone season.
This has been consistent with real-world data, and puts Australia at odds with other regions of the world, where cyclone frequency is increasing.
Read more:
Anatomy of monster storm: how Cyclone Ilsa is shaping up to devastate the WA coast