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Report projects by 2050 more than 98% of coral reefs will be afflicted by ‘bleaching-level thermal stress’ each year

The Great Barrier Reef will not survive coral bleaching if current sea temperature trends continue, according to a new report charting increases over the past three decades which blames manmade climate change for the problem.

The study found thermal stress to coral reef areas was three times more likely when its investigation finished in 2012 compared with when it began in 1985, forecasting “more frequent and more severe” bleaching through the middle of this century.

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Langstone Harbour, Hampshire The black swan shrank back as the mute swans stomped up the mud bank towards us and jostled for a handout

The tide was out and as I approached the mill outflow I could see a black swan hunkered down on the exposed shingle. Native to Australia, black swans were introduced to Britain in 1791 as ornamental birds in captive wildfowl collections. Due to inevitable escapees and deliberate releases, sightings in the wild are widespread. Now, the number of breeding sites are increasing at such a rate that Cygnus atratus may be on the brink of establishing a self-sustaining population.

This was the fifth black swan to visit the creek in a fortnight and, as they often pair up during the winter months, it is likely that these birds were roaming in search of a mate. This swan didn’t sport the jet black velvet lustre of mature adult plumage – its sooty feathers had a charcoal grey cast and were fringed with taupe, which gave it an almost scaly appearance.

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Dr Alan Finkel presented the Preliminary Report of the Review to the Council of Australian Governments Leaders’ Meeting on 9 December 2016.

We are only just starting to appreciate the full sexual diversity of animals. What we are learning is helping us understand evolution and how animals will cope with a changing world.

In humans and other mammals, sex chromosomes (the Xs and Ys) determine physical sex. But in reptiles, sometimes sex chromosomes do not match physical sex. We call this “sex reversal”.

Environmental factors such as temperature can trigger sex reversal in reptiles. In our recent study, we investigated how common sex reversal is in reptiles. We concluded that it is widespread and a powerful evolutionary force.

This raises important questions about how reptiles will survive in a warming world.

Xs and Ys, Ws and Zs

In humans, sex chromosomes determine if an embryo’s physical sex is either male (XY) or female (XX).

Reptile sex determination is more complicated. Some species, including snakes, use sex chromosomes like humans do. But in other species, such as crocodiles and marine turtles, sex is determined by the temperature the eggs are raised in.

We’ve recently come to realise that many species use a combination of both. When the temperature sends opposite signals to the embryo’s sex chromosomes, sex reversal is the result. For these lizards, the sex chromosomes don’t match their physical appearance and reproductive function.

The central bearded dragon (Pogona vitticeps) is probably the best-known example of reptile sex reversal. Its sex chromosomes are named Z and W.

Male dragons have two Z chromosomes and females have a Z and W. Female dragons normally produce roughly equal numbers of male (ZZ) and female (ZW) offspring. But when the eggs are incubated in a hot environment (greater than 32℃), more females than males hatch. Some of these females from hot nests are sex-reversed.

Sex-reversed females are fully functional. In fact they produce twice as many eggs as females with female sex chromosomes. This suggests that sex reversal might actually be an advantage in this species.

Another fairly well-understood example from Australia is the eastern three-lined skink (Bassiana duperreyi).

In this species males are XY and females are XX. Although these chromosomes share the same name, they aren’t the same as those found in humans. They have arisen independently and use different genes to trigger male and female development.

In this skink, females (XX) can reverse to males, but at cool incubation temperatures, a phenomenon we’ve observed both in the lab and in a wild alpine population.

In both species, the sex with matching sex chromosomes (ZZ males in the dragon and XX females in the skink) is the one that reverses. In dragons it happens at high temperatures, and in the skink at low temperatures.

Why reverse sex?

Sex reversal can have major effects on the behaviour of an individual. Male-to-female central bearded dragons are bolder than males and females with matching sex chromosomes. This may help them find food and mates, but at the same time exposes them to predators.

Not all lizards lay eggs. Sex reversal caused by temperature is also thought to occur in species that give birth to live young, such as Tasmania’s snow skink (Niveoscincus ocellatus). In live bearers, sex reversal is caused by the environmental temperatures that a mother experiences during pregnancy.

We believe that sex reversal is widespread in reptiles. Emerging evidence suggests that environmentally induced sex reversal may also be common in fish and amphibians, playing a role in evolution of new species and having serious implications in rapidly changing environments.

We suspect the reason no one has yet fully appreciated the role of sex reversal in reptiles is because much research has focused on mammals and birds, where sex reversal is usually caused by mutations that affect gene expression during embryonic development. This has created the false impression that sex reversal is harmful to an individual.

Another reason is that many reptile species have sex chromosomes that are very difficult to tell apart. That makes instances of sex reversal very difficult to spot.

An obvious question of deep concern is whether climate change could cause extinction by reversing the sex of entire populations. For temperature-sensitive species like the bearded dragon, crocodiles and marine turtles, is the future a warmer world without males?

The answer will be different for each species. Reptile survival under climate change depends on the answer to several questions.

Can the species control when and where they nest? How quickly are environmental conditions changing? Can the temperature at which sex reversal occurs change?

Each species will face a unique path as we experience an uncertain and changing environment. Some paths will undoubtedly lead to extinction, but others may utilise flexibility in sex-determination strategies to survive.

This research was conducted at the Australian National Wildlife Collection CSIRO, in partnership with the Institute for Applied Ecology at the University of Canberra and the University of the Sunshine Coast.

Clare Holleley receives funding from the Australian Research Council and the Commonwealth Scientific and Industrial Research Organisation (CSIRO).

Finkel review says wind farms settings cited in reports on South Australia blackout were known and resolved in Europe a decade ago. Why not Australia?

Victoria hires driving force behind ACT's reverse auction program to help drive the state's 40% renewable energy target by 2025.

Adelaide-made silicon-based thermal energy storage system set to target industry, high renewables grid.

ATA report finds 100% renewable grid would be reliable and stable, with appropriate mix of generation sources, energy storage and upgraded infrastructure.

An emissions intensity trading scheme increases the cost of coal power compared to other electricity sources. Indigo Skies Photography/Flickr, CC BY-NC-ND

The preliminary report from the Finkel Review of electricity market security will be presented to COAG today. Leaked versions indicate that the report notes the urgent need for long-term policy certainty on climate change and that some policies (such as carbon pricing) reduce emissions at lower cost than others (renewable energy targets or regulation).

These are hardly inflammatory observations. Yet they link directly with this week’s furious debate within the Coalition government over the inclusion of a particular form of carbon pricing, an emissions intensity scheme, and whether it, and all of its relatives, should be excluded from next year’s climate policy review.

How does it work?

An emissions intensity scheme sets an intensity baseline – effectively a limit on how much carbon dioxide the generators can emit for each unit of electricity they produce.

Power stations can produce electricity above the baseline, but they would have to buy permits for the extra CO₂. Power stations that have lower emissions intensity create permits, which they can then sell.

For example, the intensity baseline might be set at one tonne of CO₂ for every megawatt hour (MWh) of electricity. A brown coal generator produces electricity at 1.3 tonnes CO₂ per MWh.

For every MWh the generator produces, it therefore has to purchase 0.3 permits. Alternatively, a wind farm that emits no CO₂ will create 1 permit for every MWh of electricity generated.

An emissions intensity scheme increases the cost of producing electricity from high-emitting generation, while reducing the relative cost of low-emitting generation. It thus drives emissions down in the electricity sector, because the cost difference favours a switch from high- to low-emitting generators.

Why this type of scheme?

Other forms of carbon pricing, such as a cap-and-trade emissions trading scheme, also increase the costs of high-emitting generation relative to low-emitting generation. But there are differences between the two schemes.

The main one is the short-term impact on prices. A cap-and-trade scheme places a price on each tonne of CO₂ emitted, which is paid to the government. Under an emissions intensity scheme, a price is imposed only on the carbon emitted above the intensity baseline.

Under a cap-and-trade scheme, our brown coal generator would have to purchase 1.3 permits for each MWh it produced, as opposed to the 0.3 it purchases under the intensity scheme.

As a result, electricity prices do not increase as much under an emissions intensity scheme as under a cap-and-trade scheme, at least in the short term. But there are drawbacks.

An emissions intensity scheme does not raise any revenue, as permits are purchased from other generators rather than the government. No revenue means no compensation to those impacted by decarbonisation.

Smaller price increases also mean that consumers are less likely to cut back on their own electricity use. This means that overall emissions will not be reduced as much as under a cap-and-trade scheme.

On the plus side, the lower price increase also means that there is less effect on overall economic activity. This can be mitigated under a cap-and-trade scheme, however, if the government uses the revenue wisely.

Bipartisan support at last?

Consulting firm Frontier Economics assisted the New South Wales government with the design of its greenhouse gas abatement scheme, an emissions intensity scheme that ran in that state from 2003 until 2012, with some success.

In 2009, Senator Nick Xenophon championed the emissions intensity approach as a better alternative to then prime minister Kevin Rudd’s proposed Carbon Pollution Reduction Scheme (CPRS). Malcolm Turnbull joined with Xenophon to attempt to persuade Rudd to adopt the scheme as an alternative to the CPRS; that attempt failed.

In the past couple of years, an emissions intensity scheme has again been advocated as a potential circuit-breaker to the climate policy impasse that has been the norm in Australia for the past decade. The electricity market rule-maker, the Australian Energy Market Commission, the Climate Change Authority and we at the Grattan Institute have all advocated for an emissions intensity scheme in the electricity sector.

This position was also reflected in the Labor Party manifesto at the last general election. While ambivalent about what form it takes, the major generation companies and business groups have all been arguing for a form of carbon pricing.

The Coalition government could get to an emissions intensity scheme in the electricity sector from its existing policies. An absolute limit on total emissions for the sector has already been set under the safeguards mechanism. Arithmetic and legislation are required to change the absolute limit to an emissions-intensity limit.

The advantages and disadvantages of an emissions intensity scheme against other forms of carbon pricing have been debated by academics, economists and policy wonks ever since Australia first committed to tackling climate change. But two things are clear.

First, an emissions intensity scheme would provide the stable carbon policy that the electricity sector needs to have investment confidence and contribute to electricity security.

Second, an emissions intensity scheme would, for some time, limit the impact on electricity prices. Apparently, these are matters of importance to both sides of politics.

Tony Wood owns shares in Origin energy and other energy and resources companies through his superannuation fund.

David Blowers 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.

Now that our rooftop solar industry has matured, we need to reconsider the purpose of FiTs and align them with our goals for the electricity system in the future.

Recent weeks have seen unsurpassed dishonesty and irresponsibility from national political leaders on Australian climate and energy policy.

Chief scientist report into Australia electricity market says huge, unstoppable transition being driven by consumers responding to soaring prices and falling costs of technologies like wind and solar. Solutions abound for high renewables penetration, but not supported by policies.

AMBER FOSSIL: The exquisitely preserved bones and feathers of a dinosaur tail have been discovered in a piece of 99-million-year-old amber found by a palaeontologist hunting for fossils in a Myanmar market.

Former astronaut John Glenn, the first American to orbit Earth, dies aged 95. Pallab Ghosh looks back at the day he made history.

Former astronaut John Glenn, the first American to orbit Earth, dies aged 95.

Mikah Meyer is making a record-breaking attempt in a battered Hyundai his father left him when he died, hoping to highlight parks for gays and millennials

There was the night when something big was sloshing around ominously in the river next to his tent and he was too terrified to look out, but knew wolves and moose were at large.

Then there was the sweaty night when he thought he would bake to death in his van but was too scared to open the windows because he was parked in a sketchy neighborhood in Ohio.

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Senate Democrats vow to fight Trump’s nominee to lead the EPA, a climate denier who has sued the agency multiple times as attorney general of Oklahoma

Democrats have promised to stage a last-ditch effort to thwart the appointment of Scott Pruitt as administrator of the Environmental Protection Agency, amid fears within the agency that he will trigger an “unprecedented disaster” for America’s environment and public health.

Donald Trump has nominated Pruitt to lead an agency he has sued multiple times in his role as attorney general of Oklahoma. Pruitt has vowed to dismantle serried environmental rules and is currently involved in a legal effort by 27 states to overturn Barack Obama’s clean power plan, the president’s centerpiece policy to reduce greenhouse gas emissions.

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The Indonesian government has renewed calls for Australia to encourage the company responsible for the 2009 Montara oil spill in the Timor Sea to compensate thousands of fishermen and seaweed growers.

Increasing population | Theresa May’s cliches | Rich and poor | European moths

I have just scoured eight pages of your Climate Change supplement (7 December). I found not a single reference to one of the key drivers of climate change, the relentless increase of population, now scheduled to be 11.5 billion by 2100. Whatever action we take to reduce emissions, those efforts will be negated by the births of 4 billion more people who, even in the old “third world”, will want to be consumers.
Nigel Reynolds
Mirfield, West Yorkshire

• Theresa May is right to dislike acronyms (Report, 8 December) but it’s time she considered her cliches. I suggest she takes a blue pencil to her sentence “I’m talking about ordinary working people for whom life is a bit of struggle …”. There are people who are too old or otherwise unable to work for whom life is a struggle. And who are ordinary people? I would hope they are those who do not have to struggle to make ends meet.
Peter Le Mare
Allithwaite, Cumbria

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A sample of the smallpox virus from a 17th Century victim challenges current thinking.