Pearls and Irritations

Invasive species, including pet cats, have been and remain the major cause of extinctions in Australia. ‘Net zero emissions’ sounds good but is it just a greenwashing delaying tactic?

What is killing our native species?

‘Extinctions are holes in the fabric of life, and Australia is ragged from so many species ripped out.’

Central hare-wallaby. Nielsen Park she-oak. Desert bandicoot. Lake Pedder earthworm. Sharp snouted day frog. Christmas Island pipistrelle. Kangaroo River Macquarie perch. White-chested white eye. Wingecarribee gentian. All gone, and many more, since Europeans began to occupy Australia, including a disgraceful 33 mammal species.

But what is it exactly that is rendering so many of our native species of flora and fauna extinct?

A study of 100 of the animal and plant species that have disappeared in the last 230 years demonstrated that the main cause of extinction for 40% of species has been land clearing and livestock grazing. Hunting (including the thylacine of course) and changes to the availability of water each accounted for around 5%.

But the biggest cause, the one mainly responsible for 45% of extinctions, was invasive species. The results were very similar for the 23 animal and 4 plant extinctions (including probable extinctions) that have occurred since 1960, although pathogens such as myrtle rust (arrived in 2010) and the highly destructive chytrid fungus (first seen in the 1970s) in frogs have also played a part.

Within 20 years of its arrival on Christmas Island around 1987, the Wolf snake wiped out a bat and three reptiles unique to Christmas Island (an extinction hotspot).

Mammals have mainly succumbed to introduced predators, plants to habitat loss, frogs to disease and reptiles to the Wolf snake, a ship’s stowaway from Asia. One of the reasons proposed for the heavy toll of mammals taken by introduced predators is that Australia is the only inhabited continent without native foxes and cats and Australian mammals have ‘prey naivety’.

Brown (above) and Rainbow trout, introduced for fishing, are a serious threat to at least 22 native fishes.

Minister Plibersek has declared ‘no more extinctions’ but the old threats are still with us and new ones are emerging: new invasive species, climate change and bushfires for instance. Imminent extinction is looming for many animals and plants and another ten Australian birds and seven mammals are likely to become extinct over the next twenty years.

It’s quite likely that the bell will be tolling soon for the King Island brown thornbill and the Central rock-rat unless urgent action is taken, including better border security, systematic abatement of threats, threatened species recovery programs, and joint programs and funding by all Australian governments. Conservation funding needs to increase by a factor of ten to around $2 billion per year to meet the minister’s goal.

Victorian grassland earless dragon

When I wrote the piece above about a week ago, the Victorian grassland earless dragon (great name) was on the list in the first paragraph because there had been no confirmed sighting since 1969. But, happily, I’ve had to remove it because news of the discovery of a small population has just been released. A management plan that includes a breeding program and conservation reserves is being developed.

However, now that it’s widely known that there are some dragons still breathing fire, it might be prudent to develop plans to stop traders finding and capturing any remaining wild dragons for sale as ‘pets’.

Roaming pet cats

Finally, a reminder that the killers of our native wildlife aren’t themselves all out in the wild. I’ve railed before about roaming pet cats but their murderous ways can’t be overemphasised. Mention the damage done by cats and most people immediately think of feral cats in the bush, and they are major problem. However, because the density of roaming pet cats in the suburbs of our towns and cities is so much greater than the density of feral cats in the bush, and because many jurisdictions do not require 24 hour containment, pet cats hunt down and kill 30-50 times more native animals per square kilometre than feral cats. This adds up to 6,000-11,000 dead natives per square kilometre per year in urban areas, and a total of over 300 million dead native mammals, birds and reptiles per year across Australia – not even including the dead frogs and invertebrates.

If you are a cat owner who still allows Tiddles to roam in the belief that they don’t hunt:

• 85% of animals killed by pet cats are not brought home,
• About 40% of cats whose owners think they are confined at night actually manage to sneak out,
• If you live near bushland, Kitty is particularly adventurous and murderous.

Net Zero emissions

To halt the two hundred year increase in the concentration of greenhouse gases (GHG) in the atmosphere, technically speaking, humans don’t need to completely stop pumping GHGs into the air. We just need to ensure that whatever CO2 we do produce is balanced by an equivalent amount of CO2 being removed from the atmosphere; when it is, that’s net zero. Well, it is provided that we count only the removal that is above and beyond what would be removed naturally by, for instance, photosynthesis and geological processes on land and in the oceans. Humans can increase the amount of CO2 removed from the air by augmenting plants’ natural absorption processes (e.g. planting forests, mangroves and sea grasses) and/or by new technologies that directly remove CO2 from the air, fix it in some way and then store it underground for ever. Preserving existing forests is immensely important for many reasons but does not increase the removal of CO2 from the atmosphere.

The idea of ‘net zero emissions’ seems reasonable, and at a global level it probably is, but whether it is realistic for individual nations to turn the idea into achievable reality is moot. As for individual business entities achieving net zero, that’s a complete joke in my view. Like paying someone else to do the mourning at your mum’s funeral.

Of course, even if net zero was achieved, that would only hold the concentration of GHGs in the atmosphere at the current level. This is already 50% higher than the pre-industrial level and has caused the global mean temperature to increase by 1.2^oC, with already obvious severe consequences for the environment and humans. To start reducing the concentration of GHGs in the atmosphere to the pre-industrial level – the level that brought unprecedented climate stability to Earth and facilitated the development of human civilisations over the last 12,000 years – GHG emissions would need to fall to below net zero (negative emissions). This is nicely illustrated in the figure below taken from a World Resources Institute article, ‘What Does “Net-Zero Emission” Mean? 8 Common Questions, Answered’.

The questions answered by the WRI include:

• How do we get to net zero? Rapid and just transformation of all global systems – power, transport, food, buildings, land and water – is the recommendation. Political and economic systems are not mentioned.
• How many countries have adopted net zero targets? About 100, representing 80% of global emissions.
• Is the world on track to reach net zero emissions to keep warming under 1.5^oC? We’re on track for 2.8^oC.
• Are net zero targets a form of greenwashing? Not necessarily but they can be an excuse for delaying doing what’s necessary. That’s an understatement if ever there was one!

e-bike battery fires

Delivery people and commuters use them. Ones for hire are littering the pavements everywhere. Ageing recreational cyclists use them. e-bikes (and e-scooters whizzing down the pavements) are becoming ubiquitous and I can see their attraction. But their exploding lithium-ion batteries are becoming an increasingly common cause of fires and fatalities.

In New York city, e-bike battery fires are now as common as electrical fires and more common than fires started by cooking and smoking. Lithium battery fires have killed 13 people in NYC so far in 2023. In London, lithium battery fires are the fastest growing fire risk, with 57 e-bike fires and 13 e-scooter fires so far this year.

The problem usually occurs during the use or charging of a battery. One of the cells heats up, sets up a chain reaction in adjacent cells and creates a ‘thermal runaway’ in the battery. This starts a fire and sometimes an explosion. Overcharging, hazardous home charging practices and manufacturing defects are the usual underlying causes, although anecdotally I understand that in Australia it is also not uncommon for owners to disable the mechanism that limits the bike’s battery output so that less peddling is required.

As more people have taken to e-bikes and e-scooters for more purposes, manufacturers have been increasing the power of the batteries. But a lack of regulation and safety testing of these (relatively small) batteries is a major problem in many places. The batteries in electric cars and energy storage systems are more powerful but have fewer fires because the industries are better regulated. Clearly, governments need to ensure that adequate controls are in place for the growing e-bike and e-scooter industries which are no doubt going to be part of the energy transition, albeit perhaps a serendipitous spin off rather than an essential element.

Burmese peacock softshell turtle hatchlings

Skip the article if you wish, just watch the two short videos to put a smile on your face.