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Overfishing can teach us valuable lessons about ecosystem resilience. Andreas Altenberger/Shutterstock.com

As we head into the Anthropocene epoch, the era in which humankind has become the prevailing influence on our planet, we often stand accused of inadvertently running “global experiments” through our effects on wildlife, food chains, landscapes and the climate.

But what if these experiments are exactly the kind of science we need?

Of course, we’re not suggesting we deliberately trash the planet in the name of science. But if these phenomena are happening anyway, the least we can do is learn something along the way. That’s what experiments are for, right?

With science budgets shrivelling, the apparent alternative is to channel funding into ever smaller, shorter and cheaper experiments. But good luck recreating the complex tapestry of life in a coral reef, say, when all you have is a 10-cubic-metre tank.

Our research, published in the journal Ecosystems, argues that one of the only feasible solutions to the current intellectual and financial crisis lies in “large-scale, unreplicated natural experiments”, or LUNEs. These “off-the-shelf”, expansive experiments have inadvertently been created by humanity and nature.

Think tsunamis, deep earthquakes, oil spills, shark finning, alien invasions (yellow crazy ants, not Martians), and the construction of the Suez Canal.

Together, these rare but powerful manipulations of the environment can be tapped by scientists to test important hypotheses about how the world works.

Letting nature and human activity do the “dirty work” when it comes to experimental design has its advantages: it’s cheap, it’s realistic, and in many cases it’s the only ethical or logical way to study a particular question. In cases of human activity, it also allows us to understand the ecosystem response to these “interventions”.

There is also a growing consensus that no matter how many small-scale or theoretical studies we churn out, things often play out alarmingly differently when we examine ecological processes at large scales.

For example, you might be forgiven for thinking that an invasion of poisonous cane toads would be bad news for the snakes that eat them (and that’s what most studies have suggested). But a recent large-scale analysis found not just that many snake species were unperturbed by invasive toads, but that some lucky groups even increased in abundance.

Why else should we give LUNEs a chance? For statistical reasons, they are a particularly powerful tool when they operate across an ecological gradient, potentially allowing us, for example, to identify “tipping points” within ecosystem function.

In addition, gradual accumulations of LUNEs can ultimately power meta-analyses that can be used to draft robust “rules of thumb” about how ecological processes work.

For example, you might think that marine protected areas (MPAs) are a no-brainer when it comes to generating environmental and economic benefits. But this has been surprisingly difficult to prove scientifically. However, a 2014 meta-analysis of 87 MPAs showed conclusively that they help fish grow bigger and more abundant, particularly when these marine reserves are old, large, well-enforced, and have no-take fishing rules.

Deliberate oil spills?!

But LUNEs constitute a Faustian bargain, damaging the natural world in return for more knowledge. That also means they’re generally impossible to replicate, because it’s hard to run the experiment for a second time, even if you were mad enough to want to.

The US government is unlikely to green-light a second Deepwater Horizon oil spill, earthquakes are unpredictable and different each time, and we’re (hopefully) unlikely to experience another Big Bang any time in our near future.

An important question LUNEs raise is whether the conventional scientific need for experimental replication surpasses the urgent need to understand humanity’s effects on the planet.

We argue that the “conceptual” replications LUNEs offer are far more valuable than exact, controlled scientific replications, which when carried out on small scales can be highly misleading anyway.

Here’s an example. Water quality declined in many North American rivers and lakes in the 1960s, turning them green with nutrient-driven algal blooms. Small-scale experiments pointed the finger at nitrogen and carbon, but when researcher David Schindler began deliberately injecting whole lakes in western Ontario with different nutrients, he realised that phosphorus was the crucial factor.

His research didn’t use traditional scientific replication. But the results were eventually enough to persuade the Canadian government and several US states to ban phosphorus, which is now recognised as the major culprit.

In other cases, LUNEs have not overturned scientific consensus, but have proved crucial in highlighting the seriousness of the issues. There was 20 years' worth of evidence from small-scale lab experiments and modelling studies about the dangers of chlorofluorocarbons used as refrigerants and aerosol propellants. But the world only moved to ban them after the discovery that these chemicals had punched a large hole in the ozone layer over Antarctica.

Together, these examples suggest that LUNEs and other large-scale studies can play a crucial role in galvanising the policy changes that avert environmental crises.

Homo sapiens derives from the Latin sapientia, meaning “wisdom”. But our ongoing failure to use our planet’s resources sustainably suggests that we are still a long way from living up to our name.

Fast-tracking LUNES and other large-scale studies, and placing value on their findings, may help us develop the far-sightedness we’ll need to survive the Anthropocene epoch.

The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond the academic appointment above.

Alinta Energy says distributed geothermal could provide heating and cooling needs for new housing estates, and combined with solar need not be connected to grid.

MPs warn that the uptake of ultra-low emission vehicles is too low to meet national climate change targets

The government is falling behind on its commitments to switch a proportion of Britain’s car fleet to electric vehicles, an influential committee of MPs said on Thursday.

Take-up of electric vehicles has been slower than hoped in the UK, but the technology is essential to reducing greenhouse gas emissions from transport, and tackling the air pollution produced by the increased number of diesel cars on the road.

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There’s plenty of early adopters out there who will buy battery storage regardless of the return on investment, because early adopters like the technology and the independence it offers.

Online energy retailer Click Energy has launched an electricity plan targeting electric vehicle owners, offering lower electricity rates or higher solar feed-in tariff.

A reconstituted Climate Change Authority has delivered its long-awaited, long-delayed report on Australia's climate policy options. And it looks remarkably like something that the Coalition could have written itself, and is too little, too late.

Australia the only country to receive a rating of ‘very poor’ in a majority of categories in Climate Transparency scorecard

Australia is the worst country among the G20 when it comes to action on climate change, according to a comprehensive assessment before the G20 summit in China.

Under China’s leadership, this weekend’s G20 in the eastern city of Hangzhou has had a strong focus on climate-related issues.

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Hill End, Weardale Turf starved of nutrients creates a doll’s house lawn, a tapestry of fescues and eyebright

From the fell where we stood, knee-deep in purple heather, the old limestone quarry in the valley seemed just another scar on the landscape, a great bite of mineral wealth torn from the hillside leaving a bare cliff face, rushy pools and broken rock.

It was only when we got close, really close, that it revealed another legacy, one that lasts for just a few weeks in late summer.

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Gutted by Malclm Turnbull, its latest report a cop out, the Climate Change Authority has become yet another impediment to climate action in Australia.

Defeat of remaining legal challenge to Carmichael coal mine means it is finally time for Adani to put its money where its mouth has been.

ACT names 8 winners of $2m funding to roll-out 2MW solar-integrated battery storage across 600+ homes and businesses.

A startling number of solar households think the best use of their investment is to feed power to the grid. Education is needed.

Coalition and Labor fudge on commitments to ARENA, with vote on funding cuts looming next week.

Slash subsidies or back 100% renewables? Australia's Coalition parties at odds over whether to support or oppose wind and solar.

Free movement between the US and Mexico - the hottest of topics in the 2016 US presidential campaign - is not just a human issue.

HUGE FIND: The oldest fossils known to date have been discovered in 3.7 billion-year-old rocks in Greenland by an Australian-led team of researchers.

A look at Kenya's fast-growing crocodile farm industry, which is enjoying a big rise in demand for the animal's meat, led by China.

Of the many devastating pictures to come out of central Italy after last week’s deadly earthquake, the clock tower of Amatrice standing defiantly amid the rubble of the town has become an iconic image.

The clock tower was reportedly built in the 13th century and its solid stance defies us to understand how this remarkable structure has evaded destruction at least twice in the past 800 years.

But perhaps surprisingly, it’s not unusual for tall, ancient structures to survive earthquakes.

Unlikely survivors Nepal’s Dharawara tower in 2013, before it was destroyed in the 2015 earthquake. KATHMANDU NEPAL FEB 2013, CC BY-SA

Similar towers are relatively commonplace in Italy and part of the country’s charm. The town of San Gimignano, about 200km from the centre of the Amatrice earthquake, has 14 towers that date as far back as the 12th century – and have consequently survived many earthquakes big and small. Other towers can be seen in Alba in northern Italy.

Further afield, a memorable image of the Izmit earthquake in Turkey in 1999 was of the tower of the Golcuk Mosque standing forlornly among the ruins.

Photos from the 1906 San Francisco earthquake show a slender tower and an array of chimneys standing in the rubble of the city.

In many instances, however, the towers fall, as happened to the Dharahara tower during the magnitude-7.8 Nepal earthquake in April 2015.

Why do some of these slender icons survive repeated earthquakes and others fall? An article in The Economist suggested that the clock tower was better constructed than the surrounding buildings, pointing out that it even survived better than a modern school and hospital. The L'Aquila experience suggests that this is probably one part of the story.

However, the reality is more complex. Other factors can and do contribute to the resilience of buildings.

On shaky ground

It is very likely that the clock tower’s survival was influenced by the relationship between the frequency of the earthquake waves and the natural resonance of the building. To understand why, we have to consider how earthquakes interact with buildings.

Earthquakes generate seismic waves that pass through the ground. Like ocean waves, they have peaks and troughs. The frequency of the wave is related to its “period” – the time taken for one complete waveform (including a peak and a trough) to pass.

A building has a natural period that causes it to vibrate back and forth. Think of a child on a swing – a swing with short ropes will complete a full cycle much more quickly than a long swing.

The same is true of buildings with different heights. A building is effectively an upside-down pendulum and taller buildings have longer natural periods of oscillation (swinging back and forth).

The ground also has a preferred period at which it oscillates. Soft sediment in a river valley will oscillate over longer periods, and hard bedrock over shorter ones.

High-frequency (short period) earthquake waves are therefore amplified in bedrock, such as the site of Amatrice, and are the dominant frequency radiated by small to moderate and shallow earthquakes such as last week’s.

Low-frequency (long period) earthquake waves are amplified in sediment and form a greater part of the seismic energy radiated by larger earthquakes, such as the Tohuku earthquake in Japan and the Nepal quake that felled the Dharahara tower.

When the resonant frequency of the ground coincides with the resonant frequency of the building, the structure will undergo its largest possible oscillations and suffer the greatest damage. The rigidity and distribution of mass along the height of a building also have a big effect on the likely damage sustained in a given earthquake, as this governs the way the induced forces are distributed.

You can try this for yourself by experimenting with a broom handle and a 30cm ruler. Held vertically, the top of the broom handle will do little if you vigorously shake its base with small movements, whereas the ruler will oscillate under the same shaking.

Slow the shaking down and the handle will begin to whip back and forth while the ruler settles down. Place a large mass on the end of either the ruler or the broom handle and the characteristics will change.

The concept is beautifully demonstrated in a video by Robert Butler of the University of Oregon.

A resonant problem

Of course, real structures and real earthquakes are far more complex. Real structures have many natural frequencies, and earthquakes vibrate across a spread (or spectrum) of frequencies.

Destruction occurs when any of a buildings’s natural frequencies coincide with any of the dominant frequencies of the earthquake. In some situations, there may be just a few structures that avoid this dangerous combination, such as the clock tower at Amatrice, or the chimneys of San Francisco.

The characteristics of shaking at Amatrice have not yet been published, but it is highly likely that the tower is standing not only because it was built well in the first instance, but also because it is just the right size and shape to survive the frequency of shaking that occurs during Italy’s moderate-magnitude earthquakes.

This process is equally important in other regions. The magnitude-6.8 Myanmar earthquake on August 24 damaged many historic temples in the Irrawaddy Valley, but none appears to have collapsed. These high-but-squat structures are susceptible to high-frequency shaking, whereas the passage of earthquake waves through alluvium is likely to have amplified mainly low-frequency earthquake waves.

Notably, much of the damage to the temples seems to have occurred as a result of the collapse of recent cheap “restorations”.

Building practices are extremely important in mitigating the effect of shaking on buildings. Modern buildings are commonly fitted with devices to reduce the effects of resonance. Engineered solutions are available to retrospectively enhance the performance of unreinforced masonry buildings, with little impact on their aesthetics.

In Italy, this retrofitting needs to be done as quickly as possible before the next earthquake. This will be a costly exercise. Even apparently resilient medieval towers may require retrofits, because they have commonly accumulated a degree of damage.

However, Italy is a globally important cultural and tourism hub, and her earthquake-prone buildings, like those in Myanmar, are part of our collective heritage. Italy should not be left to struggle alone with the management of earthquake-prone building hazards.

The authors do not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and have disclosed no relevant affiliations beyond the academic appointment above.

Most scientific experts agree that data from the initial trial badger culling areas in Gloucestershire, Somerset and Dorset do not justify further extension of culling (Scientists criticise badger cull extension, 31 August). In ignoring this advice, and extending culling to five new areas, the government risks not only wasting much money but also giving farmers false hope that the approach will contribute to reducing TB in cattle. The initial trial areas were set up to test whether free-range shooting could be done humanely and at the same time reduce badger populations by at least 70% – the figure previously established as the level needed to achieve a significant reduction in TB in cattle.

The government was able to announce last year that it had achieved its culling targets, but only because they were based on unrealistically low badger population estimates – not on the central or best estimate value, but on the lowest bound value of the statistical margin of error around this estimate. This was simply a fudge. In none of these exercises did it achieve a 70% reduction based on the most likely population estimate.

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A drug that destroys the characteristic protein plaques that build up in the brains of patients with Alzheimer's is showing "tantalising" promise, scientists say.