It’s winter in Australia, but as you’ve probably noticed, the weather is unusually warm. The top temperatures over large parts of the country this weekend were well above average for this time of year.
Almost 35 years have passed since the Intergovernmental Panel on Climate Change released its first assessment report. It found human activities were substantially increasing concentrations of carbon dioxide (CO?) and other gases ion the atmosphere, which was warming the global climate.
Since then, countries around the world have introduced a slew of policies designed to reduce greenhouse gas emissions. But what actually worked?
This question is at the heart of a landmark new paper by German researchers. They analysed 1,500 climate policies implemented around the world over the past two decades, and found only a small fraction were effective.
Importantly, they found most emissions reduction relied on a mix of policies. The results point to a way forward for Australia, where an economy-wide carbon price is currently politically impossible.
At a global level, emissions-reduction policies have yet to produce the sustained reduction in CO? emissions needed to hold global heating below 2°C.
So it’s important to understand how well, or badly, emissions-reduction policies in various countries have worked.
A few ad hoc observations can be made. For example, Australia’s carbon emissions fell during the brief period of the Gillard Labor government’s carbon price, then rose when the Abbott government removed the policy. It is not hard to identify causality here.
Rarely is the cause for success or failure so clear-cut. Globally, in the past few decades, various policies have been introduced, modified, and in some cases, abandoned. It can be seemingly impossible to disentangle their effects.
But a new paper attempts this task.
The research was led by Annika Stechemesser from Germany’s Potsdam Institute for Climate Impact Research. It employs a standard technique for determining the effects of a policy intervention, known as the “differences in differences” approach.
This approach compares changes in outcomes over time between two groups. If a policy was ineffective, the differences between the groups should stay the same over time. If the gap changes in the expected direction, the policy is assumed to be effective.
The method was applied most famously in a 1994 study in the United States by economists David Card and Alan Kreuger. They compared fast-food restaurants in New Jersey, where minimum wages were increased, with those in Pennsylvania, where wages were unchanged.
They found the rise in the minimum wage had no effect on the number of people employed by restaurants. The analysis led to a radical change in thinking about minimum wages.
But that analysis involved a single change. The Potsdam team sought to distinguish the effects of more than 1,500 climate policy interventions, implemented across 41 countries over two decades.
It required sorting through a huge volume of data, while applying the “differences in differences” approach. The researchers did this using artificial intelligence.
They analysed four sectors: buildings, electricity, industry and transport. They examined eight kinds of policy interventions, primarily focused on:
pricing policies, such as carbon taxes and permits that can be bought and sold
regulation, such as bans, building codes and energy efficiency rules
applying or removing subsidies, such as governments paying property owners to install rooftop solar, or removing tax breaks for the fossil fuel industry.
The researchers identified 63 cases where climate policies had led to large emissions reduction.
Unsurprisingly, though a little disappointingly, no “silver bullet” policy emerged. Rather, most successful cases – at least in developed economies – were the result of two or more policies working together.
This might mean, for example, a fuel efficiency mandate for vehicles, combined with subsidies to help develop a network of charging stations for electric vehicles.
The study also found successful policy mixes vary across sectors. For example in developed countries, pricing was particularly effective policy in sectors dominated by profit-oriented companies, such as electricity and industry. But a mix of incentives and regulations worked best in the buildings and transport sectors.
And countries have different needs, depending on income. In developing countries, for example, pricing interventions did not lead to large emission reductions in the electricity sector. This may change, however, as China gradually develops carbon markets.
The researchers have made the data available to the public in a handy tool. It is easily searchable by sector and country.
The strength of this approach is the ability to integrate analysis across many different countries. However, this global approach precludes a fine-grained analysis for each country.
For example, because Australia’s carbon pricing scheme was so short-lived, and its effects rapidly reversed, the differences-in-differences analysis did not capture its significance.
The research is an impressive effort to distil lessons from the mass of confusing data surrounding climate policy.
The findings would once have been unwelcome news to the economics profession, which in the past has largely advocated for one stand-alone policy applied across the economy – most commonly, putting a price on carbon.
Carbon prices are not a complete solution, but they are important. Research in 2020 showed countries with carbon prices, on average, had annual carbon emissions growth rates two percentage points lower than countries without a carbon price.
Unfortunately in Australia, the federal Coalition is resolutely opposed to any kind of price-based measure to cut emissions. And following the Gillard government’s politically bruising experience over the carbon price, the Albanese government is allergic to any mention of such policies.
So while price-based mechanisms are, theoretically, the ideal way to cut emissions, most economists now accept there’s no point holding out for it. If a combination of measures in different parts of the economy is the best we can do, it’s better than nothing. The important task is to reduce emissions.
The political constraints on price-based policy mean Australia must push harder on other policy approaches – namely regulations and subsidies – to reach net-zero by 2050.
John Quiggin is a former member of the Climate Change Authority
Most fungi need only wind or water to disperse their spores. But some, including truffles, need a little help from animals.
Usually, truffles and truffle-like fungi (which don’t belong to the truffle genus, but are otherwise similar) are dull-coloured and grow underground.
They use scent to attract mammals, which eat them and disperse the spores across the landscape in their dung. This ancient truffle-mammal relationship is why truffle pigs and truffle dogs (and many humans) love eating these fungi.
But Aotearoa New Zealand had no native land mammals to disperse truffles. Our new study resolves a 30-year mystery about whether fruit-eating birds might instead have taken this role.
In most ecosystems, truffles are eaten by small mammals, especially rodents and marsupials, which are critical for fungal dispersal and forest health.
In the 1990s, mycologist Ross Beever noticed something odd about truffle-like fungi growing in New Zealand.
Many had brightly coloured fruiting bodies which emerged above the forest floor, essentially mimicking fallen fruit. Because of New Zealand’s lack of mammals (with the exception of bats), Beever hypothesised that these characteristics had evolved to attract birds as spore dispersers because they rely more on vision than scent to find food.
Beever and his colleague Teresa Lebel detailed this fascinating hypothesis elegantly in 2014, but it remained untested for three decades.
In our research, we asked whether New Zealand really has more brightly coloured truffle-like fungi or whether we are simply paying more attention to them and under-appreciating the dull ones. And we investigated if there was a link between their distribution and fruit-eating birds.
First, we gathered information about the colour and habit (above or below ground) of 479 truffle-like fungus species from around the world. We then obtained more than 24,000 locations for these species from the Global Biodiversity Information Facility database.
These data were analysed alongside environmental factors (such as precipitation and temperature) and biological aspects (such as forest cover and the presence of fruit-eating birds) that might help explain any spatial patterns.
While colourful truffle-like fungi are also found in South and Central America and Australia, our results confirmed New Zealand has a much greater proportion compared to other landmasses. This is especially true for red and blue coloured species.
We also found that, across the world, regions with more fruit-eating birds also had more colourful truffle-like fungi.
Until recently, birds were thought to have a limited role in dispersing truffle-like fungi.
But this changed in 2021, when a study of faecal samples from two fruit-eating bird species from Patagonia (Chucao tapaculo and Black-throated huet-huet) found DNA and spores from a wide range of fungi, including truffle-like fungi.
The research team also observed both bird species uncovering truffles on the forest floor, thereby demonstrating the important role birds could have in fungal dispersal.
A further finding of the Patagonian study was that many of the truffle-like fungi detected in the faecal samples are part of the underground network of fungi-plant root interactions known as mycorrhiza.
In New Zealand, most colourful truffle-like fungi are also mycorrhizal with locally dominant forest trees such as beeches and podocarps. These fungi make it easier for the trees to access water and mineral nutrients from the soil. Therefore, birds that eat truffle-like fungi may not only be important for the fungi themselves, but for entire forest ecosystems.
The results of our study support the idea that colourful truffle-like fungi are adapted for bird dispersal, and that they are more common in New Zealand than elsewhere in the world.
Yet, paradoxically, the number of observed instances of local birds eating truffle-like fungi can be counted on one hand. Why is this? The answer may lie in New Zealand’s legacy of extinction.
Around one third of all bird species on the mainland and offshore islands have become extinct since the first human settlers arrived during the 13th century. Many more have had their populations reduced to the point of functional extinction. Among these are many large birds known to have eaten fruit, including nine species of moa and k?k?p?.
In 2018, a study of DNA from ancient dung of moa and k?k?p? found evidence these birds once ate mycorrhizal truffle-like fungi. The loss of such birds from New Zealand’s forests represents the end of millions of years of co-evolution with fungi.
These bird-adapted fungi may now remain as ghosts of past mutualisms – the association between organisms of two different species in which each benefits – much like the large tropical fruit once eaten by gomphotheres, an extinct group related to modern elephants.
How will our forest trees cope with the loss of these bird-fungus interactions, which help facilitate plant growth on bare soils? Can introduced animal species act as surrogate dispersers for native fungi?
The implications for forests, haunted by species loss, remain unknown. With continued research and conservation efforts, however, we can better understand and support the balance of our forest ecosystems to ensure the rich and unique biodiversity of New Zealand’s forests endures for generations to come.
This study received funding from Royal Society of New Zealand Marsden Fund.
Greenpeace among 150 groups expressing outrage after preemptive arrests led to cancellation of protest camp
Greenpeace and Friends of the Earth have accused police of acting as “private security” for the UK’s biggest carbon emitter after dozens of pre-emptive arrests forced the cancellation of a climate protest camp near Drax power station.
In a statement signed by almost 150 groups, they called the operation against activists who had spent months planning the camp near the wood-burning power station “an unreasonable restriction of free speech”.
Dion George says avoiding extinction of African penguin is his objective, and settling case aimed at stopping fishing around major colonies will help
South Africa’s new environment minister has said he wants to stop African penguins from going extinct by taking measures including settling a case brought by two environmental charities to stop fishing around the birds’ major colonies.
BirdLife South Africa and the Southern African Foundation for the Conservation of Coastal Birds (SANCOB) said they want an extension of no-fishing zones around six beaches and islands where the penguins breed, after failing to reach an agreement with fishing industry groups demanded by the previous minister.