Back in October 2017, the concept of an “insect apocalypse” was breaking through into the public consciousness for the first time. A study based on 27 years of data from German nature reserves revealed a dramatic drop of over 75% in flying insects. Although scientists are not yet clear if declines are happening on a global level, studies have been published suggesting similar drops, from Puerto Rico to the UK.

One scientific review, which predicted that all insects could go extinct within a few decades, has been widely questioned (not least because insects are the most diverse set of organisms on the planet) but there seems to be widespread agreement that the numbers we’re now seeing should be a wake-up call.

Dr Lynn Dicks is an ecologist and sustainable agriculture expert at the University of East Anglia. She told Unearthed: “if you have a 75% decline over that period of time, that rate of decline cannot go on. If that is really happening everywhere and is not an anomaly of that particular place, then we really are facing a crisis, and we need to do something about that which is extremely urgent.”

The media and public reacted (albeit briefly) with a similar sense of urgency – and foreboding. The media reported prospects of “ecological Armageddon” and “the collapse of nature”. Readers commented that if insects vanish, “presumably humans will follow shortly after”. Even Barbra Streisand got involved, calling it “a potentially catastrophic event for all life on this planet”.

Talk of the absolute extinction of the human species can seem hyperbolic but when it comes to climate change, environmental campaigners have long spoken about it in existential terms. Could the same be said of species extinction? Could it lead to our own?

Leading insect experts, like Dr Alexandra-Maria Klein at the University of Freiburg, aren’t exactly reassuring.

“It’s hard to say because I don’t know what’s happening in the future and how much genome editing we have or how many other solutions we have, but at the moment I would say without insects we will not survive for a very long time.”

She points to the soil crisis as a major threat, which is perhaps not surprising, given that 95% of our food comes from the soil and the UN has warned that the world’s topsoil may vanish within 60 years.

“Don’t think about pollinators, think about soils organisms and all these functions that are in the soil. When we don’t have the insects or the organisms there, then the soils are not functioning anymore. And then we have a really intensive agricultural landscape, without any organisms in the soil, any organisms above soil. It will not function at one point, and then it is not possible to produce any crops.”

This message has even reached a select group of politicians. Speaking in 2017, UK environment secretary Michael Gove warned the UK is 30 to 40 years away from “the fundamental eradication of soil fertility” in parts of the country.

Dr Lauren Holt is an ecological specialist at the University of Cambridge’s Centre for the Study of Existential Risk (CSER).

She told Unearthed: “Ecosystems represent hugely complex structures that interact with others so it’s difficult to predict, but if we lose some key organisms at the bottom of the food chain we could definitely precipitate a major ecosystem collapse, but for it to be global we would probably need multiple runaway situations. All the previous mass extinction events have been associated with changes in the gaseous composition of the planet and the ocean has been the real driver of change.”

Garry Peterson, head of sustainability science at the Stockholm Resilience Centre (SRC) thinks that to focus on whether biodiversity loss would lead to actual extinction of the human species is somewhat missing the point:

“I dont think thats a useful or good way of talking about things – it’s more that the loss of the living world is harming people today, and has been harming people for decades and is unnecessary.  We can create a much better world so could we not worry about hypothetical things? It makes it a bit too science fictiony.”

Ecosystem collapses at local or regional levels seem much more likely. In fact, they are already happening.

Peterson’s research identifies three characteristics of such collapses: abrupt decline of a species, persistence, and a mechanism to keep the population low.  

He points to the recent degradation of the world’s tropical coral reefs as one example, a third of which are believed to have been bleached to death – including half of the Great Barrier Reef – within the space of three years, from 2014 to 2017.

In other ecosystems, sudden events are occuring that are degrading ecosystems and impacting people, but it’s too soon to know if they will recover or trigger a collapse.

Take the mass starfish deaths along the Pacific coast for example, which are leading to an increase in sea urchins (which starfish feed on). The sea urchins are eating the kelp forests, which shelter many types of fish, such as crabs, and which lock away carbon.

So how about the penguins, I ask? Could the recent announcement of the death in 2016 of almost all the chicks in the world’s second largest emperor penguin colony be a sign of ecosystem collapse? It’s too soon to know, says Peterson. It’s certainly an example of an abrupt decline, but it’s too soon to know if that will persist.

“A lot of this biodiversity loss is slow, until it’s not slow….What most people would expect is that you would have positive feedbacks where unravelling of the planet leads to more unravelling,” says Peterson.

These abrupt events can lead to the extinction of a species, and so preventing the absolute loss of rare species is where conservation efforts often focus. But these events don’t only matter because they could lead to numerical extinction, but because they could trigger functional extinction – when numbers drop to a level that means a species is no longer able to perform its roles in an ecosystem. This is particularly relevant when it comes to keystone species, which may not on be an IUCN endangered species list, but which perform unique or essential roles in an ecosystem. Without them, the ecosystem could eventually trigger its collapse.

This is why insect declines are so alarming. It’s not because of (highly questionable) claims that insects could disappear altogether by the end of the century, but because they perform fundamental roles that enable the rest of the ecosystem – including us – to function.

Pollination is often the first such function that springs to mind. Indeed, the most up-to-date assessment of the dependency of our global food system on insect and animal pollination – authored by Dr Klein – suggests that around three quarters of global food crop types rely on them to some degree. These make up about a third of our food, including most of the food from which we get our vitamins and minerals.

But bugs perform other functions too: spiders, ladybirds and wasps (to name a few) act as pest controllers, preventing the populations of insects such as aphids or mites from destroying crops. It’s thought that the job these tiny predators do protects at least 10% of all food production.  

And that’s not all. Insects are fundamental to the food web, providing food for birds and animals. They also play an essential role in recycling nutrients. For example, when a mammal dies, flies and wasps quickly arrive. They eat its flesh and feed it to their larvae or when their eggs hatch, they turn into maggots which eat the meat. The protein in the meat gets broken down and returns to the soil, where it can be taken up by plants.

Everything is connected.

“There’s a whole complex chemical process of recycling,” says Dr Dicks. “It’s very quick. If we didn’t have insects, we’d basically have mouse carcasses everywhere.”

As the loss of functions provided by one species starts to affect others, an ecosystem can start to lose the things that would enable it to recover. And the larger the area that is lost, the less the remaining ecosystem can draw on to come back.

Peterson says: “You lose one coral reef and it takes a long time for that to come back if you try to fix it, but if you lose a big area of coral reefs you don’t have anything to help you come back.”

“You need to have coral for your coral reef, so where do you start to grow from? You need little fish to eat the algae off the coral and to make new habitat for coral. You also need to have big fish, that make places that can be colonised by coral, by scraping the coral and the limestone. So they need to be able to live for a while, to not be caught by fishermen or killed by something else. You need to have support areas and ways they can move there and in these areas you need a minimal amount of functional diversity, of these different types of roles. ”

Thanks to trade, species are moving around the world in a way never seen before. Ecosystems are mixing, and the problems that lead to degradation are passing from one to the next – think of the frogs for example. This is creating a more homogenised and simplified world. This, in turn, creates instability.

“People expect the world to be one way and it changes to another without them expecting that to happen,” says Peterson.

“A simplified world is maybe producing stuff that some people want like food, but it’s very unstable so it’s not reliable in anything it’s doing – and that’s a very hard world for people to live in. So for example one year you manage to grow a whole bunch of weed, and the next year it’s all eaten by some pest you’ve never heard of…Having a destabilised world makes it difficult to keep what you have and plan for the future.”

In spite of that, Peterson still doesn’t like the existential question.

“Existential for who?”, he asks.

It’s a good question, and one that people of colour campaigning in the climate movement have pointed out.

It’s particularly relevant to the work of Prof Harindra Fernando, a scientist at the University of Notre Dame. For 22 years, he lived in Sri Lanka, one of the countries worst affected by the 2004 Boxing day tsunami. His family still live there, on the beach front.

For him, this disaster was not only an illustration of nature’s power to destroy, but of its power to protect.

Prof. Fernando specialises in science concerning the movement of water so after the tsunami happened, he returned to Sri Lanka to see if he could be of any professional use. He heard about how communities along the coastline had seen huge discrepancies in the impact of the wave, from town to town.

Near a town called Peraliya, approximately 1,700 people died when a 10m high wave tore inland for a kilometre and a half and swept a train off its tracks. Yet just 3km south at a town called Hikkaduwa, the wave was a quarter of the height and flooded inland for only 50m. Here nobody died.

So why the difference? Local people suggested that it could be down to coral mining.

Fernando’s investigation concluded there was a “striking correlation” between the extent and strength of the wave and the extent of coral and rock reef cover.

So did the coral reefs save lives in the tsunami?

“Oh yes, definitely. It is very clear,” Fernando told Unearthed.

“Coral reefs and other natural barriers can make a big role in the reduction of tsunamis, storm surges and other natural disasters related to oceans,” he says.

For Fernando’s family, who live on the beach front around 25km north of the coral reefs, it was the sand dunes that mattered, because here there weren’t any reefs.

“The area my folks live the beach slope is much higher, so they did get water – three or four feet – but not to the extent of destroying everything…The beach slopes certainly saved their lives.”

People living on others parts of the coast were not so lucky. Six months before the tsunami, Fernando had stayed in a hotel in a holiday resort called Yala on the south coast, where the sand dunes had been removed. He spoke to the hotelier:

“He told me they opened it up so the people in the hotel could look at the ocean better. So they opened up this region and this was where the water jetted through….Within minutes [the hotel] perished”.

Around the world, people living by the coasts are increasingly at risk from extreme flooding events, because the ecosystems that protect them are being destroyed – from mangroves, to wetlands to seagrass meadows. This degradation is particularly a problem for small island states that are already at most risk from climate change and which depend on them for food, tourism and medicine.

But while mining, pollution and fishing pose local threats, they are also up against an overwhelming global threat: climate change.

According to the IPCC, if global temperatures increase by 2 degrees celsius by the end of the century, virtually all tropical coral reefs could be severely degraded within 30 years.

These ecosystems are not only protecting communities – to some degree – from extreme weather events,  they are also protecting us from climate change itself. Mangroves and marshes can take up carbon up to 40 times faster than tropical forests.

So as climate change is degrading these ecosystems, it is degrading their ability to protect us against it. This feedback loop between biodiversity loss and climate change can be seen across ecosystems on land and at sea; they soak up 5.6 gigatons of carbon every year, equivalent to 60% of the world’s human-induced emissions.

Species help to keep ecosystems healthy and able to retain carbon, from tapirs in the Amazon rainforest that disperse seeds in their dung, to reindeer in the Arctic that trample snow thus protecting its role as a carbon sink, to krill in the Antarctic that transfer carbon to the deep ocean, locking it away for centuries or millennia.

The deep-rooted connections between these two environmental crises and the need to address them in parallel is the philosophy behind calls for a Global Deal for Nature (GDN), equivalent to the Paris accord for climate change.

Two weeks ago, an international group of scientists set out their manifesto for change in a paper published in the journal Science Advances. It lays out two objectives: to slow climate change in order to protect nature, and to conserve nature in order to protect the climate.

It argues that the two crises are similarly urgent, with many ecosystems and species likely to reach “points of no return” if land conversion rates are not dramatically reduced or halted within a decade.

“[The biodiversity crisis] is at least as frightening in terms of what people are going to lose – we are losing the web of life and species,” co-author Dr Carly Vynne Baker says.

“We used a decade in the GDN to tie in with the climate crisis, as models are showing that in order to use land based solutions, which are the most available and likely scenario for mitigating climate change…We need to have a moratorium on new land clearing in the next ten years and be working on a lot of restoration in the meantime. In terms of the biodiversity and extinction crisis it feels like we are there. If you look at the trends – we are at 30% risk of species extinction – when are you going to call an emergency?”  

The concept of a global deal for nature is not a new one. In fact, that’s exactly how some are describing COP15, the UN’s Convention on Biological Diversity (CBD). World leaders will meet at this global summit in China at the end of 2020 where they will face pressure to agree new targets to slow the destruction of habitats. It’s most likely that this will be through the mechanism of protected areas: some have called for 50% of the Earth’s surface to be protected; others say 30% is more realistic.

Before then, campaigners hope governments will agree a new global treaty on the high seas, the two thirds of the oceans that are outside of national laws, which provide 95% of the habitat occupied by all life on Earth.

While Vynne Baker’s paper calls for high levels of protected areas, she also says that the deal in China will not be enough.

“We probably need something bigger and new….There is a lot of work that’s outside the protected area framework that needs to be done, whether it’s connectivity, ocean pollution and plastics, or maintaining freshwater sources.

Even Watson – the chair of IPBES – agrees that the CBD will not be adequate:

“Protected areas are not the answer to the loss of biodiversity. They can play a role – don’t misunderstand me – they can play an important role. But we have to integrate biodiversity concerns into everything we do in agriculture, everything we do in water, everything we do in energy.”

The scientists at IPBES are certainly not the first to issue a warning about the consequences of humanity’s increasing destruction of wildlife.

Half a century ago, the conservationist Rachel Carson published her seminal book Silent Spring, a brazen warning about the consequences of destroying habitats and spraying the living world with chemicals specifically designed to kill plants, insects and other animals in order to boost food production.

“Clean cultivation and the chemical destruction of hedgerows and weeds are eliminating the last sanctuaries of these pollinating insects and breaking the threads that bind life to life,” it warned.

But alarm about the consequences seems to have hardly registered outside of scientific and conservation circles.

Dr Daniel Pauly, arguably the world’s leading fisheries scientist, has been witnessing such changes in the ocean for close to half a century, in which time the populations of fish and marine mammals, birds and reptiles are estimated to have halved, according to one study.

“We do know the direct role of fishing is to remove life from the ocean, so if we remove life from the ocean then that we should not be surprised when they are not there,” he says.

And yet while international biodiversity summits have been established even longer than those for climate change – both known as the Conference of the Parties – they barely get reported and it seems neither does the issue more broadly. As a result, public understanding has surely suffered.

“We’re all very good at deferring and delaying and denying the extent of what faces us,” says George Monbiot, who has been an environmental journalist for 33 years.

“We become so much better at it if we’re saturated in a media environment that tells us there’s nothing to worry about or at the very least doesn’t highlight the things we should be worrying about so it stays at the back of the mind, as a background worry.”

Data suggests that the media has neglected biodiversity in particular.

At the time of the Rio Earth summit in 1992, media interest in biodiversity was equal to climate change, according to a study published in Frontiers. But by 2016 – the year after the Paris climate change deal – newspapers were 8 times more likely to publish a story about climate change than about biodiversity. Over the full 15 years of the analysis, they were 3.3 times more likely.

“The science, the challenges and the problems associated with biodiversity issues are not likely reaching the public,” the researchers concluded.

They suggest there could be several reasons for this, including the localised nature of the biodiversity crisis and a lack of public understanding about its impact on human society. They also point to differences between IPBES and IPCC, their roles being to bridge the gap between science, policy and the public. IPBES was created a full 20 years after the IPCC and has suffered from a cash crunch in recent years.

Monbiot thinks language is also to blame.

“One part of the problem – and it is only one part but I think an important part – is that we use the most alienating terms possible for the things that we’re trying to talk about. ‘Biodiversity’ – who knows what biodiversity is? It doesn’t create any pictures in people’s minds. ‘Wildlife’ creates pictures in people’s minds. ‘The living planet’, ‘the natural world’ creates pictures in people’s minds but not ‘biodiversity’. ‘The environment’. How cold an alienating can you get? You talk about the environment, have you ever seen the environment? Have you ever touched it? What is it? Where is it?”

A concept that Pauly has popularised might also point to the lack of public recognition of the issue: shifting baseline syndrome. This is the idea that each generation takes its memory of the state of ecosystems at the start of its conscious lives as the bar for what is normal, and thus acceptable. Anything lost before that, we don’t perceive as a loss.

“The modification of the habitat that has occurred in Europe – for example around the UK – is tremendous and most people don’t believe it because they are not familiar with this older literature of 120 years ago,” says Pauly.

“When a young fisheries or marine biologist starts his or her study they look at data from 20 years ago, not from 120 years ago so because of that they cannot imagine the amount of fish that was there.”

If we are becoming disconnected from nature over time, then we are also becoming disconnected through geography.

Since 1992, the world’s urban area has doubled – largely at the expense of tropical forests, wetlands and grasslands – a process that is decoupling our consumption habits from the means of production, and severing our understanding of our dependency on the natural world.

“There are people that really understand the linkage, although they don’t live it,” says Sebsebe Demissew, professor of plant systematics and biodiversity at Addis Ababa university. He has spent decades collecting and documenting plants across Africa, often working with Indigenous and traditional peoples.

“But there are other people that don’t even think that nature’s contribution to people is so important, because sometimes if you are in town what you are really concerned about is what bread or something would cost, rather than its effect on a poor farmer.”

Demissew believes that the knowledge of these communities needs to be included alongside that of scientists.

“Humans beings have lived on this planet for a long time. And scientists now sometimes think we really know best. No, it’s the traditional people that know best – they really think nature.  If you have people that live in the forest, they can’t distinguish between themselves because they are part of that environment. They live there, they eat there, they farm there – where would they go? How do they really see it differently?”

This year, IPBES have responded to such calls by making the knowledge of local communities and social science part of their global assessment at a level not seen before.

Given that the biodiversity crisis plays out very differently in different parts of the world, the need for local knowledge is significant, not least because many scientists seem palpably aware of how much we have yet to learn.

“It is our scientific ignorance that is the greatest source of our existential risk,” reads a paper on ecosystem collapse and existential risk published last year in the journal Futures. It points in particular to unknowns surrounding climate change, environmental feedback loops and the way ecosystems connect to each other.

Peterson talks about the ingenuity gap, a concept popularised by the political scientist Thomas Homer-Dixon. Homer-Dixon’s hypothesis is that we may be reaching a point where the world is now changing so fast that we are creating problems faster than our capacity to analyse, understand and solve them.

“That’s a lot of the concern with biodiversity,” says Peterson.

“You can’t just measure it like carbon dioxide, in concentrations. It’s very hard to say what’s going on with the world’s biodiversity. We can only estimate on partial looks from all sorts of places in the world – trying to assemble a global picture is a huge amount of work.”

The complexity of the crisis is a problem that’s also been raised by those calling for action.

“Climate change has always had one advantage over the issue of biodiversity: we’ve got a single metric, we’ve got to stop the world warming more than 2C, or we’ve got to stop it warming more than 1.5C. The problem with biodiversity: there’s no simple number,” says Watson.

The inability for knowledge to keep up with our discovery of problems has been highlighted by recent reports on insect decline, where scientists have pointed out that studies are piecemeal and because insect numbers can vary wildly from one year to the next, reliable data takes many years to collect.

Dr Dicks says that in order to have a good sense of trends in insect numbers, you need about two decades of data. In the case of the landmark German study, it took almost three.

Does that mean we have to wait decades before we have enough evidence to act? Dicks says no.

“We don’t wait for 30 years. We have to act now. We need to transform how we do agriculture, look carefully at the use of chemicals and the planning of agricultural land. We need to make sure farmers everywhere around the world are taking account of the insects in their landscapes and looking after them”

Existential ecologist Holt agrees: “Sometimes we focus too long on quantifying something and waiting for our knowledge to be better. Sometimes all we can do is step back and although it’s very complex, we know enough to say we must act. The hour is very, very late.”

A correction was made to this story on 7 May 2019. It previously said that a third of global food crops depend on insect and animal pollination. In fact, around three quarters of global food crops depend on pollination and these crops provide about a third of our food.