…And wishing you all the best for 2013

xxx

London: I recently recorded a four-part radio series for BBC World Service about the Anthropocene, called The Age We Made. I spoke to lots of great scientists about the incredible changes we’re making to our planet, and how they will be recorded in the geological record for millions of years.

You can listen to the programmes here:

Part 1: 

Part 2: 

Part 3: 

Part 4: 

Only a short section of our conversation made it into the programme, but Ken had some really interesting things to say, so here’s a longer version of the interview.

Amphibians face extinction owing to climate change, disease and hunting

Barnosky studies biodiversity changes and extinction rates that occurred in the deep past, and compares them to trends happening now. Since life first evolved, billions of years ago, flourished, diversified and made our planet truly distinct from any other we’re aware of, there have been five mass extinctions. Each was triggered by a cataclysmic event and resulted in at least 75% of all species going extinct. The last of these occurred 65 million years ago, when a meteorite slammed into Earth, throwing up persistent clouds of debris that darkened the sky for years. The climate change that followed led to the extinction of the dinosaurs and three-quarters of all other animals.

Dinosaurs dominated Earth until they were done for by a comet

Now, Barnosky calculates, humans are creating a mass extinction on the same scale – the planet’s sixth one – through a combination of habitat encroachment and fragmentation, hunting, climate change, pollution, and the spread of disease and introduced species. Some 30% of all species may be lost over the next four decades, conservationists estimate.

Extinction is actually a natural and common phenomenon – of the roughly 4 billion species estimated to have evolved on Earth, some 99% are gone – however, the extinction rate is usually balanced by the evolution of new species. The current, human-caused extinction is happening so fast that evolution cannot keep pace. Barnosky estimates that the current rate is 1000 times the natural rate, putting it easily on a par with the ‘big 5′ mass extinction events.

The Anthropocene, the Age of Man, will be marked by a rapid decline in biodiversity as animals and plants disappear from the planet – and the fossil record – forever. It won’t just be the individual creatures that vanish, but also their descendants on the evolutionary tree – whole lines of phyla will prematurely cease.

And the Anthropocene will also be notable for its homogeneity – what Barnosky describes as the “McDonaldization of nature”. Many animals and plants have evolved to occupy specific geographical niches, such as islands or mountain lakes. As a result, across the planet it is possible to find endemic species that exist nowhere else on Earth, such as the giant tortoises of the Galapagos, the lemurs of Madagascar or the koalas of Australia. Occasionally, during the history of the Earth, shifting tectonic plates have forced land masses together, enabling the separate biodiversity to mix for the first time. This happened when the North and South American continents smacked into each other, around 3 million years ago, for example. In the invasions that followed, South America got its first large carnivore – the jaguar from North America – which proceeded to eat much of the native fauna, resulting in many extinctions.

This jaguar was rescued from the illegal pet trade

Humans have been orchestrating our own tectonic-scale species migrations, either deliberately or accidentally. As a result, some species including rats, goats, rhododendron, wheat and eucalyptus are found around the world. Meanwhile, many others have become rare or vanished. Many of the introduced species are invasive – or ‘weeds’ – which out-compete the natives for food, light and habitat, or simply eat them to extinction.

And we’ve also been spreading pests and diseases from one place or continent to another, often causing local extinctions. Isolated human populations have even been wiped out in this way, when we’ve introduced diseases such as flu, smallpox, HIV or malaria to places where the local people haven’t developed immunity.

Meanwhile, we’ve been artificially boosting the populations of certain select species, such as cows, dogs, rice, maize and chickens – most of which have been bred to new varieties that are radically different from their wild ancestors. The combined weight of humans and the animals we’ve domesticated now outweighs all the wild back-boned creatures on the land surface by 95:5, Barnosky says. Ten thousand years ago, at the beginning of the Holocene geological epoch, that figure was just 0.1%.

Megafauna of the Anthropocene

So we’re leaving a pretty distinctive mark on the living planet. Nowhere on Earth is truly wild or pristine anymore – everywhere has been touched by humans in some way, from the newly polluted atmosphere that contains different concentrations and isotopes of carbon dioxide, to the sugarcane monocultures that lie where primary rainforest ecosystems once thrived.

Since we have become such a dominant force on our planet, going forward into the Anthropocene we have to decide how best to manage the situation we’re creating. Many are calling for a change in the way that conservation has traditionally been practiced. Instead of battling to return ecosystems to a pre-human state, they say we should be realistic and recognise that humans are an integral part of many ecosystems now. This new-guard of conservationists argue that in many cases, we should accept ecosystems that incorporate non-native species, value them and try to conserve them as ‘novel ecosystems’ that are worth protecting.

From Hawaii to the Galapagos, conservationists are switching tack and starting to embrace the introduced species of Anthropocene ecosystems, while focusing their efforts on rooting out the more harmful invasives that out-compete unique flora or fauna. Thus, in the Galapagos, plagues of blackberry bushes originally from the Himalayas are simply being controlled, whereas rats and goats that eat the food of rare tortoises are being eliminated.

In the Galapagos

In other places, such as the vast monocultures we create through agriculture, efforts are already being made to restore native ecosystems, or in some cases plant non-native trees, grasses or introduce animals to restore the functions that the pre-human ecosystem once provided, such as reducing soil erosion, pollinating flowers or controlling wildfires.

There have never been so many areas of conservation – national parks and protected zones – so for some endangered species, humans may be acting in time to save them from extinction. But many of these areas are protected in name only – the parts of the world with the greatest biodiversity are often in the poorest and most troubled regions, such as the Congo and Borneo.

It is fairly certain that the Anthropocene will be a time of much poorer biodiversity in which once-common species will be extinct or exist only in human-made environments like zoos or private breeding colonies far from their natural habitat, such as the lemur sanctuary in the Caribbean that Richard Branson is proposing.

Lemurs are endangered in Madagascar

Paradoxically, just as we approach a tipping point for extinctions, we are beginning to understand how to bring extinct animals back from the dead. Scientists are hopeful of cloning mammoths and even restoring our own extinct cousin, the neanderthal. Sadly, expensive techniques like this, even if successful for individual animals, could not be applied practically to restore the intricate diversity of life that existed before humans took over the planet. Instead, in our human world, we must decide what type of ecosystems we would collectively like, and set about creating and protecting them. In the Anthropocene, we are no longer just another part of the natural world, we are the planet’s gardeners and that requires nurturing skills.

You can hear my conversations with Barnosky and others, discussing our impacts on the planet’s biodiversity and geology, in a four-part series called The Age We Made, broadcast weekly on BBC World Service from Mondays at 19.32 GMT.

Lucy (Australopithecus) lived 3.2 million years ago in Ethiopia

What our planet would look like now, if humans had gone extinct thousands of years ago? Earth would likely still be largely forested and roamed by large creatures, like mammoths and fearsome sabre-toothed tigers, as the planet headed slowly for the next ice age.

Perhaps a better question is: to what degree has the survival and triumph of our species changed our planet? From my desk, I see an entirely human world built of fashioned materials from glass to bricks. But we are not the only species to modify our environment – termites build towering castles in the sand and beavers deforest and divert rivers with their dams, for example. Tiny microorganisms such as bacteria and algae, arguably have the most profound effect on the planet’s environment, through their production of oxygen. So how do humans compare?

Geologist Jan Zalasiewicz shows me a line in the rocks made 180 million years ago, during Leicester’s tropical days

The best people to answer this could well be those with the grandest perspective. Geologists can take a 4.5-billion-year step back and look at the human impact on our planet in the context of Earth’s long history. And they can also look forward to predict what our current times might look like to their future colleagues. Like a time travelling sleuth, I sought out these geologists for a new radio series I’m presenting, which begins next week on BBC World Service.

There have been plenty of dramatic changes to our planet in the past, when this spinning lump of rock has flipped from a ‘Snowball’ Earth to searing temperatures devoid of ice, times when life has flourished and when it has been beset by mass extinctions. Big changes in planetary states show up in the rock record as stripes that reveal the sudden disappearance or appearance of certain fossil species, or climatic changes that reveal changes in past sea level. We can even identify the concentration of certain gases in the atmosphere or oceans by looking at the types of minerals deposited, because some elements, such as carbon, nitrogen and oxygen exist in fractionally heavier or lighter types – isotopes – and the ratio of these isotopes can vary according to the element’s source.

Fossils from extinct sea creatures that I helped dig up from the muddy Midlands

Geologists label these planetary events as they discover them, in order to piece together a detailed history of what our planet looked like long before anything resembling our species even evolved. For example, they have named the relatively warm period during which dinosaurs dominated the land as the Cretaceous (from the Latin ‘creta’, meaning chalk, because the identifying fossils for the period were first found in chalk beds). Around 65 million years ago, a huge meteorite struck Earth, throwing up clouds of dust and rocks that dramatically cooled the climate and lead to the extinction of much of life on Earth, including the dinosaurs. Geologists can identify when this happened because of they see a sudden arrival of the metal iridium in the rock record, which was carried to our planet on the asteroid. It marks the boundary into a new geological time period, the Tertiary or Paleogene, when mammals came into their own.

Jan examines the ancient mud (this is what geologists look like)

Many geologists think that the changes humans are making to our planet now are so significant in scale and lastingness, that they rank up there with past changes made by asteroid impacts and supervolcanoes. Many are saying that we’ve entered a new geological time period called the Anthropocene, the Age of Man.

For geologists, this is no easy decision. To define a new time period, we would have to be making changes to the planet that would show up clearly a million years from now, or 100 million years. It means that our human footprint would need to be preserved in the rock record in the same way as the changes made 65 million years ago by the comet.

The rock record is composed of layers of deposited sediments building up and being compressed over time until they form solid rock. Organic matter – lifeforms like plants or animals – get trapped in the sediment layers and over time their chemistry changes as the original molecules of life get substituted by metals, silicates and salts. The physical form of a creature may be perfectly preserved, but instead of being made of proteins and bone or skin, they will be solid fossils cast in the rocks for perpetuity. Even tiny forms like pollen grains or delicate leaves and insects may be rendered perfectly identifiable through this process millions of years after they landed in the mud.

Fossil insect

But what about the changes we’re making to our planet now? Would they be identifiable as human-caused, would they be significant enough to show up as a clear boundary in the rock record, and would they last over geological distances? In other words, is the term Anthropocene just a handy reference for current scientists, sociologists and politicians, or does it have a more significant geological meaning?

As the painstaking process of deciding whether to formalise the new time period into official geological nomenclature begins, I’ve been talking to geologists, ecologists, biodiversity experts and ice scientists about how humans have changed the planet and which of these changes would be readable in the rocks 10 million years hence.

At a farm in Maryland, ecologist Erle Ellis described how the global-scale conversion of forests to farmland – Ellis calculates that 75% of Earth’s land surface has been modified by humans – would show up in changes to pollen fossils. There would be an obvious increase in the presence of certain grain species, such as wheat, and a decrease in the wild pre-human flora diversity. Our discovery of nitrogen fertilisers would also be clear. Humans have doubled the amount of reactive nitrogen – the type of nitrogen our bodies can use – through fertiliser use and from fossil fuel pollution. And much of the nitrogen newly entering the planet’s cycle is of a different isotope (weight) to that naturally formed by bacterial processes, so it would be identifiable in the rock record using a machine called a mass spectrometer.

Human-made landscape

We’ve also been rapidly altering our atmosphere, changing the climate and ocean chemistry in ways reminiscent to previous planetary state-changes the Earth has experienced. Like those ancient changes, our recent warming will be visible in the rocks millions of years from now. Polar scientists described ice melt that would lead to sea level rise, which would alter sediment patterns. Melting sea ice in the Arctic would increase the amount of plankton living – and dying – there, and hence lead to an accumulation of organic matter in the seabed. And the acidifying oceans, from the greater amount of carbon dioxide being dissolved, would lead to a dying off of corals and shelled creatures, which would leave a mark in ocean sediments.

We are shifting species around the world, spreading some animals and plants everywhere, such as rats, and eliminating others altogether. In California, biologists Anthony Barnosky and Elizabeth Hadly described a mass extinction we are causing, on a par with the one that wiped out the dinosaurs. Like the meteor caused extinction, our human-led one would be clearly visible in the rocks, they say, as fossilised species disappear in higher layers. And the evolutionary legacy of lost lineages would also be apparent in the descendants of survivors.

Not so fierce now…

Our impact is perhaps most obvious in our cities, roads and infrastructure, and in all the materials we have mined, created and spread around. This is where our human mark will be most clearly tattooed into the rocks, according to geologist Jan Zalasiewicz. Outside Leicester, he showed me where a railway cutting had exposed a clear line in the rocks made 180 million years ago at the end of the Triassic extinction and the beginning of the Jurassic, when reptiles took over the world. A similarly clear mark in the rocks would reveal our human geological age, he said. The rocks of the Anthropocene would show an accumulation of novel chemicals, like artificial PCBs and aluminium and steel, which have to be manufactured.

The shapes of our buildings, our manufactured products like phones and drinks bottles, and our underground cables would leave their mark as synthetic fossils, akin to the imprint of a leaf from the Cretaceous, he thinks.

None of the people I spoke to had any doubt that humans were leaving a profound and lasting mark on our planet’s geology. But whether the Anthropocene will be a long-lasting period in Earth’s history, or a geologically short episode depends on us – how long humans survive as a species and how much further we modify our rocky home. The Earth is in it for the long haul.

You can hear my conversations with these scientists and others, discussing our impacts on the planet’s geology, in a new four-part series called The Age We Made, starting weekly from Monday 22 October at 19.32 BST.

London: 2012 has not been a good year for President Mohamed (Anni) Nasheed of the Maldives. Anni took office in 2008, the country’s first democratically elected president, ending Maumoon Gayoom’s 30-year oppressive dictatorship. In a little over three years, Anni had made good on his promise to invest in people, bringing about social change and democratic reforms. He introduced healthcare, pensions and education improvements.

Talking to Nasheed in London this week

Perhaps most famously, Anni became an international champion of the environment, protecting marine species and campaigning for action on climate change. When I visited him at home in the early months of his presidency, he talked about the urgent risks of sea level rise – Maldives is one of the world’s lowest islands – and his plan for a sovereign fund to help nationals migrate elsewhere when their country became inundated. And he discussed his ambition to make the country carbon neutral by 2020.

In February this year, however, he was forced to resign the presidency at gunpoint during a coup arranged by a coalition of his opposers, including Gayoom’s supporters and radical islamist groups. Anni and several members of his party were injured – some seriously – in the attacks that followed, which were led by the 300-strong secret military police force, set up by Gayoom to root out dissidents during his dictatorship. Since then, there have been continual pro-democracy protests on the streets, often dealt with torture and brutally. Journalists have been beaten and arrested, and Anni and his party members are threatened with imprisonment and, he fears, death.

Nevertheless, he looks refreshingly vital, when I meet in him London this week, and in fighting spirit. “The people won’t stand for it,” he tells me with a confident smile. “Democracy will return soon. We kicked them out before, and we’ll do it again.”

But last time, it took 30 years and you were imprisoned 20 times and tortured, I remind him. You’ll be an old man in another 30 years, and besides, Maldives is sinking – you may not have 30 years.

Anni looks serious for a minute. “You are right, of course, we don’t have 30 years. This is an urgent situation. Every day things are getting worse for my country. This month, they banned singing and mixed gender dancing! These are cultural traditions in the Maldives and I don’t want my daughters growing up in such a regime.”

Maldivian youths have been recruited to islamic schools in Pakistan and elsewhere for religious training, returning to the island nation with fundamentalist beliefs. During the brief democracy, such voices were a kept in check by healthy social forces, Anni says, but now, with their politically powerful roles, they are able to exert greater influence.

How do you plan to return to office, I ask him.

New incumbent Mohammed Waheed (widely acknowledged as Gayoom’s puppet), has agreed to hold elections next July. Although, whether they will be free and fair is the big unknown. If they are, then Anni is confident he would “easily win a majority vote”,  but he fears being arrested (along with the 750 already held) and prevented from taking part.

Under international pressure, Waheed agreed to hold an investigation into February’s coup. The report, for which the new government was allowed to choose the judges, except for the appointment of an independent judge, retired Singaporean GP Selvam, who is notorious for stamping down on opposition and dissent in Singapore, concluded that no coup had taken place and that Nasheed had resigned voluntarily. The report has since been widely criticised (and here), and Anni’s Maldives Democratic Party (MDP) commissioned an independent legal analysis of the report, which concluded that it was deeply flawed.

To me, it seems increasingly unlikely that democracy will return to Maldives. But Anni is optimistic. “They cannot run the country – there are nonstop protests. They have no mandate.” He thinks the coalition of groups will implode, allowing Anni to return. Or, more hopefully, that Western democracies will put pressure on the government to bring about change. Before I met up with him, Anni had been in a meeting with the UK Foreign Secretary, William Hague, who had assure him of his support. And what form will that support take, I ask, bearing in mind that large numbers of people are being killed daily in Syria without much intervention from the UK. I think, I say gently, that Maldives is a fairly low priority for the UK.

“We don’t need foot soldiers or guns, we’re not asking for money or military intervention – it wouldn’t cost anything,” Anni says. “We’re just asking for diplomatic pressure.”

Even if he does return to power next year, where does that leave the plans for carbon neutrality? The day of the coup, Anni was poised to sign a massive new clean energy bill. The government had negotiated $60 million in funding from the World Bank, another $60 million from Finnfund and investments from other players including Germany, to install solar powered electricity across the country. Since Maldives imports all its fossil fuels, it actually works out considerably cheaper to use solar power. Since the coup, all such funding has been withdrawn, and Anni thinks it will take time to generate the monies again.

Nevertheless, he is confident that he could still meet the 2020 target of carbon neutrality, if he gets in next year. “It took us 10 months to achieve 12 of our carbon installation plans. There are a total of 176 in all, before we are carbon neutral, and I think it would be possible by 2020.”

there suck I

And you can request copies or commission him there as well: www.nmp-photography.com

Diggers excavate the construction site

These are embryonic stages to what is perhaps humankind’s most ambitious project: to replicate the Sun here on Earth.

When construction is complete, the pit will host a 73-metre-high machine that will attempt to create boundless energy by the atomic fusion of hydrogen nuclei, in much the same way as stars like our Sun do. Fusion is the holy grail of energy sources – physicists have dreamed of being able to produce cheap, safe, plentiful energy in this way since the 1950s. But the dream has always remained “30 years away” from realisation.

The site is well above the flood plain in the hills of Provence

The need for a new energy source has never been more pressing. Global energy demand is expected to double by 2050, while the share coming from fossil fuels – currently 85% – needs to drop dramatically if we are to reduce carbon emissions and limit global warming.

Fusion, many believe, could be the answer. It works by reacting together two types, or isotopes, of hydrogen at such high temperature that the positively charged atoms are able to overcome their mutual repulsion and fuse together. The result of this fusion is an atom of helium plus a highly energetic neutron particle. Physicists aim to capture the energy from the emitted neutrons and use it to drive steam turbines to produce electricity.

When the reaction occurs in the core of the Sun, the giant ball of gas applies a strong gravitational pressure that helps force the hydrogen nuclei together. Nevertheless, the Sun’s core temperature is around 10 million°C. Here on Earth, the fusion reaction will take place at a tiny fraction of the scale of the Sun, without the benefit of its gravity. So the engineers need to build the reactor to withstand temperatures at least ten times that of the Sun – hundreds of millions of degrees.

It’s just one of the huge number of challenges facing the designers of this groundbreaking project. The concept was discussed and argued over for several decades before finally being agreed in 2007 as a multinational cooperation between the European Union, China, India, Japan, South Korea, Russia and the US – in total, 34 countries representing more than half of the world’s population. Since then, the 5 billion euro budget has trebled, the scale of the reactor has been halved, the completion date has been pushed back and the project, called Iter (meaning ‘the way’ in Latin), has somewhat lost its shine.

At the Tore Supra tokamak in the nuclear facility next-door to Iter

But despite the difficulties, progress is being made. The parts are being manufactured and tested by the participating nations, many of whom hope to develop the expertise to compete in the new international fusion energy market, which is anticipated to follow a successful outcome at Iter.

Since they don’t have access to the special conditions available in the Sun, physicists have designed a donut shaped reaction chamber, called a tokamak, in which the high-temperature hydrogen plasma is held in place for fusion but held away from the reactor walls which could not withstand the heat. The tokamak deploys a powerful magnetic field to suspend and compress the hydrogen plasma using an electromagnet made of superconducting coils of a niobium tin alloy.

A cross-section through the niobium superconducting coils that will make up the electromagnet

Once the reaction is initiated, the heat produced by the atomic fusion will contribute to keep the core hot. But unlike a fission reaction that takes place in nuclear power stations and atomic bombs, the fusion reaction is not self perpetuating. It requires a constant input of material or else it quickly fizzles out, making the reaction far safer. And unlike what you might have seen in a recent Batman movie, the chamber cannot be transformed into a nuclear bomb.

The walls of the tokamak will be coated in beryllium to withstand the harsh temperatures, but the divertor, which channels the energetic neutrons out of the reactor, will also be actively cooled using liquid helium and cooling towers.

“Helium availability might turn out to be a limiting factor,” Iter’s deputy director Richard Hawryluk, tells me. “We know there is some in oil wells and natural gas deposit, but no one knows how much, so it will be extremely important to conserve what we have.” Helium will be produced by the fusion reaction, but only in very small quantities.

The Tore Supra is far smaller than Iter will be, and even though it’s in a secure nuclear facility, it only reacts a non-radioactive hydrogen isotope.

Because one of the hydrogen isotopes used, tritium, is radioactive (with a half-life of 12 years), the entire site must conform to France’s strict nuclear safety laws. And to complicate matters further, the site is also moderately seismically active, meaning that the buildings are being supported on rubber pads to protect them from earthquakes.

These issues, and the logistics of dealing with multiple nations with their own fluctuating domestic budget constrains, mean that the site won’t be ready for the first experiments until 2020. Even then, they will just be testing the reactor and its equipment. The first proper fusion tests, reacting deuterium (a hydrogen isotope abundant in sea water) and tritium (which will be made from lithium), won’t take place until 2028.

Those will be the key tests, though. If all goes to plan, the physicists hope to prove that they can produce ten times as much energy as the experiment requires. The plan is to use 50 megawatts (in heating the plasma and cooling the reactor), and get 500 MW out. Larger tokamaks should, theoretically, be able to deliver an even greater input to output power ratio, in the gigawatts.

The hydrogen is piped into the tokamak doughnut.

And that is the big gamble. So far, the world’s best and biggest tokamak, the JET experiment in the UK, hasn’t even managed to break even, energy-wise. Its best ever result, in 1997, achieved a 25 MW output with a 16 MW input. Scale is an extremely important factor for tokamaks, though. Iter will be twice the size of JET, as well as featuring a number of design improvements.

If Iter is successful in its proof of principle mission, the first demonstration fusion plants will be built, capable of actually using and storing the energy generated for electricity production. These plants are slated to begin operation in about 2040 – around 30 years away, in fact…

Despite the seductive promise of finally getting a supply of electricity that’s “too cheap to meter”, the long wait to readiness and the fact that the technology remains unproven, means that many politicians are hesitant or even hostile to the expensive project. Additionally, because fusion energy won’t be ready for decades, even if it works, other low-carbon energy sources must still be pursued in the short-term at least.

But if we do manage to replicate the Sun on Earth, the consequences would be spectacular. An era of genuinely cheap energy – both environmentally and financially, would have far reaching implications for everything from poverty reduction to conflict easement.

The next generation could be fusion powered – perhaps even within the lifetimes of the workman digging below me.

With a giant tortoise on the Santa Cruz highlands

Giant tortoises, like giant birds, giant sloths, giant kangaroos… there used to be such creatures and large numbers of them. Then humans found them and one by one, most of the world’s megafauna has been wiped out. The giant tortoises of the Galapagos are being protected – belatedly. There are breeding programmes and various attempts to repopulate the islands with near-extinct subspecies. They tried to mate George with closely related subspecies of tortoise – for what? To enable part of his DNA to persist, I suppose, in an enclosure or perhaps back on the island of Pinta where his clan once lived. Anyway, it was unsuccessful. George was uninterested, perhaps infertile, perhaps gay? So he died at 100-years-young, middle age for a giant tortoise, and the last of his type. No doubt there will be talk of trying to clone him.

Wallowing: giant tortoises like to take the weight off

Although George was already a living fossil and kept as a museum piece in his enclosure, in walks across the islands I encountered several other giant tortoises roaming free. So, in our changed, human-centric world, we have decided to keep a place for these giants, and it makes me very happy. They are incredible animals: huge, heavy ancient reptiles that wallow in the mud, graze, fart and poo green pats like cows, carry their houses on their backs and regard you with the expression only otherwise seen on very old men. They are also iconic animals, made famous by Charles Darwin, and the focus of a very lucrative tourist industry.

The future: baby tortoises at a breeding centre

So as another species bites the dust – the extinction rate in the Anthropocene is 1000 times the natural rate – there’s an excellent chance that tortoises born on the islands’ breeding centres will still be around in a couple of hundred years.

RIP Lonesome George (here’s a piece by his biographer and my pal Henry Nicholls).

The wealthy part of Rio as seen from a slum (favela)

In the past two decades, almost all environmental problems targeted by the summit have worsened rather than improved. Indeed progress on addressing the most critical global challenges, such as climate change, has reached a farcical level in which time spent arguing over punctuation and grammar of lengthy documents have stymied any real action on greenhouse gas emissions. Meanwhile, global warming has increased, with the concentration of carbon dioxide in the atmosphere already hitting 400 parts per million in the Arctic, and new data show that the rate of climate change could be even faster than thought.

For those attending the second Earth summit – called the United Nations Conference on Sustainable Development but known simply as Rio+20 – the stakes couldn’t be higher, according to scientists around the world. Humans are now the dominant biophysical force across the planet. We’re now in the Anthropocene rather than the Holocene. Humans are pushing global temperatures, land and water use beyond what we’ve experienced before. We’re polluting the biosphere, acidifying the oceans, and reducing biodiversity. At the same time, we are a global population of 7 billion – going on 9 billion – all of whom need food water, clean air and who lead increasingly complex lives requiring more things to be comfortable.

Last week, 22 scientists warned that we are approaching a planetary tipping point beyond which environmental changes will be rapid and unpredictable. We will enter a new state never before experienced by our species and which threatens us all. The scientists based their alarming conclusion on studies of ecological markers from species extinction rates (currently 1000 times the usual rate and comparable to those experienced during the demise of the dinosaurs) to changes in land use (more than 40% of land is dominated by humans and we impact a further 40%). In the past, they point out, planetary state shifts, such as entering or leaving an ice age, have occurred relatively suddenly after a biophysical threshold, or tipping point, was reached.

So what to do?

I have no doubt that no binding global agreement will emerge at Rio to protect our environment. The past few weeks have seen horrendous images of the ongoing slaughter of Syrian children beamed around the world, and yet the international community has failed to agree on any kind of intervention. What hope then for the more nebulous aims of such a vast summit?

As with any political or social movement, the Environmentalists have split into various – often antagonistic – camps with different opinions on how to solve the problem. The two most prominent are what I call the ‘conservative’ (or cautious) camp, and the ‘radical’ (or bold) camp. The conservatives believe the answer is for humans to do less of everything: reduce consumption, waste, population, fertiliser use, pesticides, fishing, etc. And in that way, reduce our species’ influence back to being just another part of the biosphere rather than the driving force it has become. The radicals believe that technology and human ingenuity will prevent catastrophe, that as we run out of things replacements will be found, that anyway, many of our environmental changes have been to the benefit of humans – things have improved: the rate of population growth has diminished and global poverty has reduced, for example.

Environmentalism, again, like other movements, is for many people a belief system. It feels intrinsically wrong that, say, rhinos should go extinct, or lakes become polluted, even if neither has any impact on the health or wellbeing of people. Some of it is to do with taste: nature is considered more beautiful (especially by urbanites) than artificial constructs like highways or factories.  The unprecedented changes we are making to our planet are of concern to many not just because they threaten us or future people, but because they represent human-made alteration of our biosphere – and there is a belief that we have no right to make such changes. It is perhaps this that guides the conservatives’ preference for organic farming over lab-manipulated agriculture, or the more gentle idea of revolving wind turbines than the potential of global radioactive impact from nuclear energy.

The radicals, many of whom started out as ‘treehugger’ conservatives, are, like all converts, scathing of the conservatives, who they claim are ‘unscientific’ (even though many radicals are economists or journalists with no scientific background). The pragmatic response to solving our problems, the radicals argue, is to use the most effective and efficient tools we have at our disposal – which means using nuclear to produce the most energy with the least amount of warming emissions, and feeding the world with the most advanced crop technologies available.

Fundamentalism of either variety, with its blinkered idealism, will not solve the problems. The world is vast and diverse and we will need to tailor each tried and tested method to its situation. Organic methods of farming, such as using neem as a pesticide, have proved very effective, cheap and safe in parts of India, as have intercropping of legumes or tree planting. Likewise, peanuts genetically modified to contain high levels of vitamin A could solve eyesight problems across the developing world, crops modified to grow in semi-arid or saline conditions, to require less fertiliser or pesticide could help feed millions on less land and with fewer polluting impacts. The problem with many technological solutions is that they are either not ready yet for deployment, or they haven’t been proven effective practically or socially – which is at least as important. Solving this last might involve a fundamentalist cheerleading stance, but I suspect it needs some other technique, while trust remains low. Perhaps, a meeting halfway with the other camp – an acknowledgement that there are uncertainties and that proven conservative methods have different societal benefits.

Technology and innovation have already saved us from plagues, low crop yields, water shortages, reliance on fossil fuels and more. But the planet remains finite – there is nowhere else for us to live except Earth and we depend on it for our every need. And we have never before in the history of our species experienced living in some of the conditions we are creating: where average temperatures exceed anything in our history (perhaps as soon as 2070), where nitrates and other pollutants are greater than anything our ecosystems have evolved to function in, and where our own hungry population is above 7 billion, for example.

Heading for Rio, is a new schism among the Environmentalists over the so-called planetary boundaries. I’ve talked about this debate before, but it’s reared its head again this week, prompting vigorous email discussion between earth-system scientists and interested parties.

In 2009, Johan Rockström of the Stockholm Resilience Centre, and colleagues, identified nine ‘planetary boundaries’ – biophysical thresholds – that must be observed if humanity is to remain in the “safe operating space” of Holocene-like conditions. The boundaries include climate change, ocean acidification, ozone depletion, change in land use and freshwater use. The concept was enthusiastically embraced by institutions from the UN to large NGOs like Oxfam, who adapted the idea to include social boundaries. The concept was a brave attempt to quantify the rather vague threats that our many environmental changes pose and will underly much of the discussion at Rio.

However, others argue that these nine are rather arbitrary choices. I would question whether, for example, we can measure a “change in land use” or “biodiversity loss” boundary. Losing rhinos is far less of a problem than losing pollinators like bees, for example. And the spaghetti-like complexity of all these interactive biophysical elements in our chaotic biosystem makes setting individual boundaries impossible even locally let alone globally, I’d have thought.

Others contest that there are either no biophysical thresholds for these nine, or that we are far from reaching them. I would disagree with this – there is a clear threshold for dangerous loss of stratospheric ozone, for example, and I would also say for global temperature – caused by too many greenhouse gas molecules and too few carbon sinks such as forests – although whether that’s a 2, 3, 4 degree threshold, I’m not sure. I wouldn’t like to go above 2.5, but we are already heading beyond that, so what does that mean – are we all doomed? Possibly.

Now, Ruth Defries, Erle Ellis and some of the authors of the Planetary Boundaries paper, including Diana Liverman, have published another paper, describing Planetary Opportunities. “Scientists’ most useful role is not to set doomsday limits and set thresholds, but to provide a more optimistic opportunity for society,” Ellis told me. “There is no hard-line carrying capacity for the planet. Humans are very adaptive.”

Urbanisation is a good example of the human system responding to a planetary opportunity, Ellis says, by living more efficiently in larger populations, while freeing up rural land for ecosystem services or agriculture. We need to apply human ingenuity on a multi-scale approach – from individuals to the global, both in governance and the scale of scientific analyses – in order to find solutions, he says, citing examples of societies successfully adapting to environmental threats in the past. “Planetary boundaries are not a useful concept for society,” Erle says.

Rockström, counters, saying: “We should not frame this crisis as an opportunity. This is not an opportunity. If we destroy the water supply, the air, the climate, humanity will not be safe,” he says, adding that he finds the whole ‘technology-will-solve-all-our-problems camp tiresome. “But, the journey towards something good represents an opportunity. The safe operating space is an opportunity,” he concedes.

We are already in the Anthropocene – in that humans are the largest driver of planetary change – but we have not yet changed state from stable Holocene to another stable state yet, he says. Breaching tipping points could send us into another state of which we have no experience, and which is likely to be dangerous. Exceeding the planetary boundaries, as we already have for three of the nine, he warns, is a very dangerous game.

However, another publication goes even further this week in its criticism, claiming the Planetary Boundaries concept is “scientifically flawed” and shouldn’t be used to guide global environmental policy. Ted Norhaus and Michael Schellenberger of the radical thinktank Breakthrough Institute point out that many of the Anthropocene conditions we’ve brought about have been to the net benefit of humanity.

Ultimately, a scientific argument over the validity of thresholds and their values is a minor sideshow to the real action: people’s environmental belief or desire. If people decide they want to live in a world with clean air, water and soil, with rhinos and forests, then they will vote for it. If they decide that short-term financial gains are more important – or, as is often the case, corrupt individuals or companies take that decision away from them, then we will continue to see environmental degradation.

There will not be any global agreement at Rio, but people are taking action, either as individuals, communities or countries. Mexico has forged ahead with impressive plans, as has China (despite its mounting environmental problems).

For most of our species’ history, we’ve effectively lived among limitless resources. There are many examples of societies exceeding environmental limitations with disastrous consequences, among some encouraging ones of good environmental stewardship. But perhaps we have not got any better at recognising thresholds except with hindsight. Apart from gravity and (effectively) sunlight, everything else we use has its limits. Whether we can identify those ones crucial to our survival – and whether our poorly adapted human brains are unable to act on this message – is another question.