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Tony Abbott's Green Army scheme is expected to be cut in MYEFO and the government says goodbye to John Key.

Environment Minister Josh Frydenberg announced his department would be conducting a review of Australia's climate change policies.

These red and yellow blobs are yellow lac scale insects that feed crazy ants. A tiny wasp could reduce both populations. Parks Australia

A couple of days ago I published an article with Peter Green about the imminent release of a tiny wasp that will be used for biological control of a bug that feeds the crazy ants that kill red crabs on Christmas Island.

It is understandable that people are nervous about the introduction of exotic species to manage wildlife in a natural setting. It turns out that ecologists are even more nervous than the public about this, so if they have decided to do it anyway, then there is a remarkably good reason.

Parasitoid wasps use scale insects

The release of the wasp has concerned some readers because they imagine swarms of biting insects setting up their nests in the back garden. The truth is that the wasps that will be released are tiny and unlikely to be noticed at all.

First of all, Tachardiaephagus somervillei are only 2 mm long and cannot sting humans or other animals. They do not form colonies, they do not swarm, and they do not build nests. In fact, they won’t be at all interested in hanging around human habitations unless there is a tree nearby containing a colony of the yellow lac scale insect (Tachardina aurantiaca).

This is because these wasps are parasitoids – a type of parasitic organism that kills its host species. They don’t need a nest or a colony because the scale insects they target are both their food source and their home.

The specificity of the wasp for this particular type of scale insect can be seen in the first part of their Latin names: Tachardiaephagus literally means “eater of Tachardina”.

Scale insects use ants

Scale insects are a type of true bug (in the Order Hemiptera) that line up along tree branches like barnacles, sucking sap from the tree and in their mature form, releasing a sweet liquid known as honeydew from their backsides for the benefit of ants. They don’t do this for nothing. Their strategy is to use the ants as body guards.

In a situation where scale insects are relatively rare this increases the number of the ants who will in turn protect the scale insects. On Christmas Island, where the introduced yellow lac scale insects have become common because they do not have any natural predators, the invasive crazy ants have access to large quantities of honeydew. In this case, the crazy ants are using the yellow lac scale insects as a super abundant food source.

The super colonies that have formed as a result have instigated an environmental disaster. The crazy ants kill red crabs and other species mostly due to their extremely high densities driven by the abundance of honeydew.

Any detractors concerned about the dangers of yet another invasive species have not fully grasped the consequences of doing nothing. Chemical baiting of the ants is ongoing but has consequences for other animals and is not environmentally desirable or sustainable.

People using wasps

If the scale insects can use the ants as bodyguards and the ants can use the scale insects as a free food source, why can’t we use a tiny wasp as a biological control?

Unlike birds, lizards or other predators that may be deterred by ants crawling all over the scale insects, the tiny parasitoid wasps can slip through and lay their eggs in a scale insect without being noticed by the ants. Their eggs hatch and develop inside the scale insect, emerging as adult wasps that are ready to lay their eggs in another scale insect nearby.

In essence, the wasp uses the scale insect as a one-stop nursery, food source and conveniently located launching pad for the next generation. Inside a scale insect colony, they are likely to find another scale insect less than a centimetre from where they were born.

Consider how this will allow the wasp population to quickly grow and, perhaps, reduce the scale insect colony density so that the wasps will eventually have to fly further and further to find another scale insect. At some point the effort to find more scale insects will balance the benefit of finding an insect, and the two populations (wasp and scale insect) will reach a new equilibrium at a lower density.

How will the crazy ants respond?

The wasp will not run out of food, nor will the scale insects become extinct, but the ants will find themselves deprived of excess honeydew and will have to adjust their populations accordingly.

How do you empirically test the response of the ants to the removal of excess honeydew from their environment? Well, you can’t remove the scale insects but you can prevent the ants from getting into the trees where the scale insects live, even though it wasn’t easy. Apparently, doing this involves Glad wrap, Mr Sheen furniture polish, and daily vigilance by a research student.

The result was a 95% decrease in crazy ant activity in a few weeks, an outcome that suggests this approach has every chance of reducing the impacts of crazy ants on Christmas Island.

What happens next?

I understand that the team is gathering in Malaysia today to pack up some wasps and fly them to Christmas Island. The release will not happen right away, as the wasps will be acclimatised and grown up in large numbers in a dedicated facility. Monitoring programs are planned to observe the impacts, both short and long term, on the scale insects, the ants, the crabs and the forest structure.

The research to understand the ecology of Christmas Island sufficiently to identify a biological control agent started decades ago, and many scientists were involved along the way. It is not possible to provide links to all the research articles produced thus far, but here is a link to the final risk report.

I am not involved with the research but am familiar with it and in my view there are two things that could happen next. Either the wasp will fail to reduce the scale insect populations and nothing changes, or they will reduce the scale insect populations which could kick start a cascade of beneficial environmental outcomes for Christmas Island.

We are all really hoping that it is the latter.

Disclosure

Susan Lawler has received funding from the Australian Research Council in the past.

Llanberis, Snowdonia In a clearing, a black-headed beast with horns as magnificent as any fairytale faun, is munching grass next to an old red-painted winding house

The glug-glug of bubbles on the surface is a sign of divers in the depths. I watch their dark shapes rippling slowly in the emerald water for a while, before taking a slippery slate staircase winding up through the still autumnal oak woodland surrounding the flooded Vivian quarry.

In a clearing lit briefly by November sun, a brown-coated, blacked-headed beast with horns as magnificent as any fairytale faun, is munching grass next to an old red-painted winding house. It is a scene of storybook strangeness. The horned head turns slowly, fixing me briefly with a pair of yellow eyes, then returns indifferently to its business.

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Environmentalists say mandatory labelling on food would limit demand for palm oil products and reduce destructive impact of plantations

Environmentalists are warning that Australia’s repeated delays on mandatory palm oil labelling are allowing deforestation and the destruction of orangutan habitats to continue unabated.

A proposal requiring palm oils to be specifically listed on food labels has now been under consideration by Australian and New Zealand ministers for more than five years.

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Climate policy review presents clear opportunity to join host of other countries choosing a credible pathway to net zero emissions by mid-century.

Dry period in semi-arid central Australia James Cleverly

Back in 2010-11 Australia “greened”, as record-breaking rains triggered a boom in plant growth that removed huge amounts of carbon dioxide from the atmosphere and stored it as carbon in the landscape.

But what happened after that? Our latest research, published in Scientific Reports, shows that this greening was short-lived and was rapidly dissipated through drought and fire.

Our study also shows that as extreme wet years are getting wetter and more common, Australia’s terrestrial ecosystems will play a larger role in the global carbon cycle.

Carbon, water and climate change

Each year, land plants absorb the equivalent of more than a quarter of the carbon emissions generated by burning fossil fuels and deforestation. This helps to partly offset global increases in atmospheric CO₂ concentration. In 2011, this “land carbon sink” was unusually large, thanks largely to the greening of Australia’s vegetation, which accounted for 60% of the global carbon uptake anomaly that year.

Flux towers for measuring carbon and water fluxes between ecosystem and the atmosphere: (left) Calperum near Adelaide; (right) Alice Springs Mulga woodland in central Australia. Both sites are part of Australia’s Terrestrial Ecosystem Research Network, or TERN. from www.ozflux.org.au

Satellite imaging and ground observations from CO₂ “flux” towers showed that much of the 2011 greening happened in savannas and grasslands, largely in central Australia. New data shows that the return of drought conditions in many of these areas has quickly un-greened them.

Mulga dry tropical forest in central Australia was extraordinarily green and took large amounts of carbon dioxide from the atmosphere. James Cleverly Be resilient, be prepared

To an extent this is no surprise. Australia’s dryland plant species live in the most variable climates in the world. As such these ecosystems can swing rapidly between being highly productive in wet years and becoming nearly dormant to withstand drought during dry ones.

Given that the 2010-11 extreme greening followed on rapidly from the protracted Millennium Drought, it should hardly be surprising that we find the ecosystem has now swung back the other way so promptly.

Australia’s climate is the most variable in the world. (a) shows the variability of rainfall (coefficient of variance or CV) compared with other continents; (b) shows the same in Australia for four periods. Ma et al. (2016) Australia’s unique native hummock grassland (Spinifex) in dry season (left) and wet season (right). James Cleverly Drought and fire count

On a biological level, the reason that plants take up less carbon dioxide during dry periods is because this process costs water. Plants exchange gases with the atmosphere via tiny pores on their leaves called stomata, through which CO₂ diffuses in during the day but through which water also escapes.

When water is scarce it is more important to conserve it. This is why during drought conditions plants tend to reduce their carbon dioxide uptake by closing stomata or even shedding leaves entirely.

Sometimes the combination of heat and drought can be so stressful that plants die, ultimately decomposing or burning and releasing all of their stored carbon back to the atmosphere.

Australia’s ungreening

Our research shows that these processes began to take hold across Australia during the second half of 2012 and into 2013. As the chart below shows, this diminishes Australia’s large net carbon uptake as boosted by the 2010-11 wet year.

Drought rapidly eliminates Australia’s large land carbon uptake. (left) SPEI drought index; (right) satellite measures of ecosystem productivity and water storage across Australia. Ma et al. (2016)

We also found that carbon dioxide emissions from fires increased during this period. This makes sense too, given that the productive wet period spurred more plant growth, which then became fuel for fire during the subsequent drought.

As a result, Australia’s semi-arid landscapes are mostly dry once again, although the speed with which they greened and then ungreened suggests that they will be quickly refreshed when the next big deluge arrives.

Not alone

Australia’s giant green carbon sink was remarkable, but was it unique? There are two ways we can answer this question: we can wait and see if there’s another one, or we can go back and look at the historical record.

Fortunately, with long-term satellite observations, we have measurements of the entire continent back to 2000, and even earlier for some data sets. Our new research shows that the 2010–11 event was not unique. Rather, it was something that tends to happen whenever Australia has a strong wet phase, such as the one in 2000-01.

This means we can expect more large greening events to happen again in the future. One important question is whether these will be as strong as in 2010-11 – or perhaps even stronger?

Wilder, not milder

Interestingly, by looking at continent-wide rainfall records for each significant wet period dating back to 1900, we found that Australia’s wet episodes have become significantly wetter over the past century. Given this trend, we expect that in the near future Australia’s terrestrial ecosystems will come to play a larger role in the global carbon cycle. The intensification of these wet pulses is mostly seen in central and northwestern Australia.

A wilder future with more rain during wet years will have important implications, not only for carbon uptake by plants, but also for many other important issues such as flood risk management, water rights and increased bushfire danger once the landscape dries out again. We had better keep an eye on that.

Intensification of Australia’s wet extremes since 1900s. Most of the intensification is seen in central and northwestern Australia. Ma et al. (2016)

Australian ecosystems are important locally and globally: they absorb carbon, produce food and contain huge species diversity. But these “ecosystem services” are vulnerable to climate change and the increasing frequency of extreme wet and dry events.

Knowing in detail how the landscape is likely to respond to these ever more erratic swings between wet and dry will be a crucial help in learning how we can best respond to drought and deluge in future.

So long, farewell, (for now) Australia’s “great green boom”.

Xuanlong Ma receives an Early Career Research Grant (PRO16-1358) from the University of Technology Sydney.

Alfredo Huete receives funding from The Australian Research Council, NSW-RAAP, NHMRC, TERN, and UTS.

Ben Poulter receives funding from the United States National Science Foundation, the United State Geological Society, and the National Aeronautics and Space Administration.

Derek Eamus receives funding from The Australian Research Council, Google, Hunter Water Corporation, Mid-Coast Water and UTS.

James Cleverly does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond the academic appointment above.

Proposal for 2000km sub-sea cable to export solar power from Pilbara and Kimberley to Indonesia described as financially viable, possible within decade.

The Minister has approved the retention of three species in the same category of threat in the list of threatened species.

The Minister has approved the inclusion of 14 species in various categories.

Spot prices in NSW and QLD are up 70% over a year ago, and gas prices have doubled. The idea that more gas fired generation is going to solve energy security needs in the medium term seems fairly untenable.

The Minister has approved the inclusion of 14 species in various categories.

Malcolm Turnbull joins right wing bloggers in blaming wind energy for last week's blackout. It seems renewable energy will be sacrificed as Coalition admits Direct Action is a farce, prepares the ground for a baseline and credit scheme. And more gas and more coal.

Australia is progressing towards a USstyle of policy development, with states implementing ambitious policy as they seek to reduce emissions and capitalise on investment

Independent investigation into failure of subsea electricity cable linking Tasmania to mainland Australia has returned a verdict of “cause unknown.”

Herbert Smith Freehills has advised the CEFC on its A$110 million equity investment in the Investa Commercial Property Fund.

As prime minister Malcolm Turnbull plans to meet the boss of Indian company Adani in Melbourne, anti-fossil fuel campaigners rally against the federal government proposal to lend $1bn to the company to build a rail line from the planned Carmichael coalmine to the sea

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The construction of a solar road in France is turning numerous heads due to the novelty value of the project. Solar experts have a different view.

Paris, Madrid, Athens, and Mexico City will ban diesel engines by 2025, mayors of the four major world cities announced this week.

Abandoned working dogs and puppies find new homes; solar power runs composting machines; and Matt Wilson is living the dream, opening his own micro brewery in Albany in WA.