Protecting the Planet
A WEA Course
Week 8: Loss of biodiversity, and species extinction (not just due to climate change) – of animals, insects, plants:
Introduction – why the sixth extinction? #introduction
Why is the loss of species important? #importance
Factors contributing #factors
The Scale of the problem #scale
An overview #overview
In the UK #UK
Conclusion and discussion of causes #conclusions: human population, growth of the economy, tragedy of the commons
Solutions:#conservation, (2) #resurrection‘ (genetic engineering), (3) #sea - marine parks, (4) #rivers - protection for rivers, (5) #ring-fence - ring-fencing habitats from farmland, (6) #re-wilding, (7) #garden solutions.
We could be on the edge of the sixth mass extinction.
May 2015: a ‘meta-study’ of 131 studies of the impact of climate change on biodiversity loss concludes that one in six species face extinction if nothing is done about global warming and the temperature rises by 4 degrees. If the rise in global temperature is kept back to 2 degrees then one in twenty species still face extinction. Most endangered: those that depend on Arctic ice.
Why the sixth?
There have been five major extinctions in earth’s history
(from Tori Blakeman, Imperial College, Observer 10th Sep 2017):
Ordovician-Silurian: 443 million years ago. Really two events, separated by hundreds of thousands of years – most life was in the sea at this stage, and 85% of it was wiped out.
Late Devonian: 359 million years ago. Scientists believe that the seas became devoid of oxygen, and shallow seas and reefs were worst affected. It took more than 100 million years for reefs to recover.
Permian-Triassic: 252 million years ago. 96% of marine species and 70% of land species were wiped out. Possible causes are massive volcanic eruptions in Siberia causing global warming.
Triassic-Jurassic: 200 million years ago. Roughly half of all species were lost, allowing dinosaurs to flourish, but plants were not affected.
Cretaceous-Tertiary: 65 million years ago. A giant asteroid caused dinosaurs and many other organisms to perish. Mammals then evolved.
Importance of biodiversity – rich biodiversity means more stability (see notes on ecology Week 1, chances of survival better for all in the system.
Biodiversity is a crucial resource: for food, medicine, fuel, economic benefit etc. Another way of looking at this is to say that biodiversity serves 5 ‘functions’: pollination, pest control, decomposition, carbon sequestration, cultural value.
Climate change, and habitat loss – also pesticides (and maybe pollution: plastics have been found in sea creatures, and microplastics which are likely to be poisoning them. There is an extraordinary amount of plastic in the oceans... See Updates)
We noted last week one aspect of this: as Al Gore points out (p 152 ff), if the seasons change, then food (plants or insects) will not necessarily be available for creatures when they hatch – since hatching has been ‘timed’ for the point in the year when food is available.
See Al Gore (2006) p 163: the rate of loss is now 1,000 times higher than the normal background rate.
(15th June 2016, Michael Slezak): the first recorded extinction of a mammal anywhere in the world thought to be primarily due to anthropogenic climate change – the Bramble Cay melomys, a small rodent from an island (Bramble Cay) in the eastern Torres Strait, that is part of the Great Barrier Reef. The island is off the north coast of Queensland, Australia (340metres long and 150 metres wide) which sits three metres above sea level at most. It was first recorded by Europeans in 1845 – sailors shot the ‘large rats’ with bows and arrows. In 1978 it was estimated there were a few hundred. It hasn’t been seen since 2009. The sea has risen on a number of occasions and inundated the animals’ habitats. The area of the island above sea level has been shrinking and vegetation cover has been declining. It lost 97% of its habitat in 10 years.
The island is also a breeding ground for green turtles and a number of seabirds.
One other mammal has been driven to extinction recently, but it was wiped out by cats.
Barnes writes that he saw a slender-billed curlew 20 years ago – unlikely anyone has seen another, as it is at least ‘critically endangered’ according to the Red Data Book, compiled by the IUCN (International Union for the Conservation of Nature). ‘So I’ve seen an extinct bird. A rum feeling.’
The Yangtze dolphin (or baiji) was declared ‘functionally extinct’ in 2006. It lived in the dark depths of the river Yangtse, and moved around by sonar. It was the victim of ‘chemical pollution, noise pollution, propeller strikes’ etc – i.e. living among so many people.
According to the Living Planet index, compiled by the WWF and the Zoological Society the world’s wild animals will decline in number by two-thirds by 2020. Of the 85,000 species listed by the IUCN, more than 24,000 are in danger, including lions, rhinos and giraffes. Numbers have fallen by 40% since 1985. Among primates, three-quarters have falling numbers, with 60% threatened with extinction, including gorillas and chimpanzees.
But the crucial point Simon Barnes makes is that domesticated animals are not declining – and nor are humans (themselves animals!). The balance is changing: whereas 10,000 years ago humans and their domestic animals made up 0.4% of the total, now it’s 96% and rising.
Palaeontologists agree that there have been 5 major extinctions in the history of the earth. The most recent saw the dinosaurs killed off 65 million years ago. We are now going through the sixth extinction. We are losing both biodiversity and bio-abundance. What will the world look like?
John Burton of the World Land Trust says: ‘We’ll always have rats and cockroaches and their like for company. Which is not inappropriate.’ It is ironic that the species that will survive are those we have always despised. They will survive because they have adapted to live with humans... Meanwhile we are killing off numbers of species because we think of ourselves as superior. Peter Singer, the ethical philosopher, says we suffer from ‘speciesism’ – we have evolved from only caring about our immediate family, to the tribe, the nation, and now to all humanity (perhaps!). But now we need to extend our ‘circles of concern’ to include animals.
There will be no wild fisheries – after decades of over-fishing, and the creation of ‘dead zones’ – there are now 405 dead zones in coastal waters across the world, including an area of 6,500 square miles in the Gulf of Mexico (as mentioned before).
There will be very few flowering plants – because of the lack of insects to pollinate them. Dandelions will survive because they don’t need insects to pollinate them. In some places, e.g. Sichuan in China, pollination of fruit is done by humans with paintbrushes... Lynn Dicks of Cambridge University’s zoology department, estimates that loss of wild pollinators will reduce global production by 5 to 8 per cent. But the human population is continuing to grow, so we need more food to be produced.
A report from Biodiversity International (26th Sep 2017, Damian Carrington reports) stresses the importance of preserving food crops. Three-quarters of the world’s food today comes from just 12 crops and 5 animal species. Reliance on a few strains is risky (see below on biodiversity, and remember the Irish potato famine). At least 1,000 cultivated species are already endangered, but there are many thousands of wild crops that could provide food, or give more resistance to disease, and be better able to cope with the changing environment. (DC 10th May 2016) 2,000 new species of plant are discovered each year. Kew identify 200-300 new species a year, e.g. last year five new species of onion. There are still large areas of the world where we do not know what is growing there.
(Biodiversity International): an additional advantage of finding out what else is growing, is that more diversity in people’s diets would make them healthier – so we need to work on agro-biodiversity. New valuable foods include quinoa, and a red fruit from Vietnam called the gac, and the Asupina banana, both of which are rich in beta-carotene (for vitamin A).
Other kinds of loss can be identified: bird song? Flowering plants? Simon Barnes points out that losing these could lead to psychological damage for us. It’s not just that we would suffer emotionally from this loss, but experiments have shown that when we have contact with nature we are nicer, more moral, towards each other.
A book that is very readable, and that sets out how extinctions occur, is by Elizabeth Kolbert: The Sixth Extinction. As well as tracing how individual species have become extinct, she makes a number of interesting points.
First: what helps a species to survive is adaptability – but what helps it adapt varies according to its environment. At one time, being large and strong was valuable in fighting off predators, acquiring food etc. Now it is precisely these ‘megafauna’ that have become the most vulnerable: this is because they have not been able to combat humans, who are quicker and smarter.
Second, even if only a small number of a large species of large mammal is killed, they could die out over time when another factor is taken into account: their reproductive rate. Thus an elephant’s gestation period is 22 months, and they only have pone offspring at a time (no twins!). Thus even if only a small number of mammoths, for example, or great sloths, were killed – over several centuries the species would decline and then disappear, as it could not replace the population quickly enough.
Third, extinctions can happen gradually, as humans are not likely to notice what is happening over such a long period of time – especially if they could find alternative sources of food. In North America, while mammoth numbers dropped, the white-tailed deer (which has a relatively high reproductive rate) survived to feed the population. ‘Mammoth became a luxury food, something you could enjoy once in a while, like a large truffle’!
Being able to change what you eat is therefore an advantage when it comes to surviving the present crisis (specialising in your diet makes an animal more vulnerable).
In the current global warming scenario, those creatures that can adapt to the increasing heat – or move! – will be most likely to survive, as will those creatures that have already learned to live with humans, such as rats! And of while we are the most numerous big animal on earth... the next in line are the animals we have created through breeding to feed and serve us’ (quote from Gaia Vince reviewing the book cited next).
Expressing a different point of view to Elizabeth Kolbert, and in fact it seems to me running against the dominant view, Chris D Thomas of York University has written a book: Inheritors of the Earth: How Nature is Thriving in an Age of Extinction... he points out that while everyone has focussed on the widespread extinctions (which he does not deny are happening), we find: immigrant species (adding to the biodiversity of a location – provided they do not destroy native species), newly emerging hybrids and subspecies exhibiting freshly evolved adaptations. He says that humans have increased the number of species existing everywhere by taking them with us, and the vast majority of introduced species do no harm. Controversially, he warns us that ‘conservation’ may be misguided (e.g. the sparrow is not ‘native’ to this country but came from the Asian Steppes – it was a pest in Tudor times, but now is protected even though there are millions of them!). Re-wilding may also be the wrong approach if it is guided simply by nostalgia: everything has changed over time, so which ‘past’ do we want to return to? Or should we welcome the changes that are happening, since – as Thomas argues – there could be even greater biodiversity in future.
I would, however, agree with the reviewer I have quoted (Gaia Vince, 2nd Sep 2017) – there doesn’t seem to be much point in speculating about very distant futures: ‘Come back in a million years [says Thomas] and we might be looking at several million new species whose existence can be attributed to humans.’
Secondly, the extinctions we are faced with are happening over a very rapid time-scale, compared to ‘normal’ evolutionary change. As with climate change itself, we should be concerned about this – and about ‘tipping points’, beyond which change is not only undesirable but irreversible.
Finally, as Elizabeth Kolbert points out, there are reasons why some species and not others are surviving, (rats and not the great apes): and I don’t feel that Thomas has thought about this argument or the implications of it.
Sep 2017 (Simon Barnes, NS – see above): In the UK we have lost 8% of our butterfly species (see above), 3% of our beetles, and the hen harrier is close to extinction. Between 1,200 and 3,180 species will have become nationally extinct in the past couple of centuries.
30th April 2017 (Alys Fowler) RHS: Gardening in a Changing Climate:
In the south – prolonged periods without rain, in the north – wetter winters. More extremes, wetter and windier storms and more flooding and water-logging. Hence a longer growing season for some plants, but poor for those that need a cold spell in winter. Earlier flowering will stress pollinating insects (out of sinc!) – and some new pests are likely (rosemary beetles are a recent introduction).
Plants remove CO2 from the atmosphere and lock carbon in the soil, Garden soils store almost 25% more carbon than arable soils. Gardens make up 25% of all urban areas and account for around 25,000 sq km of our land.
9th Dec 2015 (Emma Howard)
Biggest analysis of British wildlife ever conducted, with researchers from Reading University, and the Centre for Ecology and Hydrology (led by Dr Tom Oliver).
The study builds on the 2013 State of nature report.
It looked at records covering 4,424 species, over the period 1970-2009, and was based on observations by thousands of trained volunteers.
It analysed species according to the functions they performed in the ecosystem:
pollination, pest control, decomposition, carbon sequestration, cultural value.
28% of pollinators (bees, moths, hoverflies) à rise in price of food, some crops unavailable
16% of natural pest controllers (ants, ground beetles, hedgehogs)
8% of those supporting decomposition
10% of those helping carbon sequestration
14% of those with cultural value (lesser horseshoe bat, dark green fritillary butterfly, pasque flower)
At risk of extinction: one in ten species.
There will be new fish in our waters as the temperature rises – some will be harmful to other species, others may become new items in our diet, according to a report in Aquatic Conservation: Marine and Freshwater Ecosystems.
Slipper limpits could destroy mussel and oyster beds, but the American razor clam and the Pacific oyster could be valuable for fishermen.
Haddock is being forced north – but sole and plaice have nowhere to go. Cod may be more resilient, but it is being caught more round Iceland. Cuttlefish and sardines are rising in numbers, and red mullet and john dory will become more common.
A study by Butterfly Conservation and the Centre for Ecology and Hydrology – ‘The State of the UK’s Butterflies 2015’ - reports: more than three-quarters of Britain’s 59 butterfly species have declined over the past 40 years.
Chris Packham says: this is the final warning bell – if butterflies are going downhill like this, what’s happening to our grasshoppers, our beetles, our solitary bees?
The decline of some rarer butterflies (e.g. Duke of Burgundy and pearl-bordered fritillary) has been arrested by conservation efforts. But:
The high brown fritillary has declined 96% (in occurrence, i.e. on sites at which it is present) since 1976, the wood white is down 88% in abundance, the white admiral down 59% in abundance.
The causes for ‘habitat specialist’ butterflies are clear, but why have once more common species declined? The wall butterfly is now down in both occurrence and abundance (in lower numbers and in fewer locations) – climate change and pesticides seem to be playing a bigger part than previously thought. Packham says we need more funding to find out the causes, though he thinks it is broad-spectrum insecticides and neonicotinoids.
Some species have moved further north, and Scotland sees more common butterflies than England does. The same is true of moths. However, they do not always score highly on both occurrence and abundance.
Climate change means more migratory butterflies have been arriving – clouded yellow, red admiral and painted lady have all increased.
The hedgehog is vanishing from Britain. There were approximately 1.55 million in 1995 – since then they have declined by a third in urban areas and by 75% in the countryside. They are declining by 3% a year. Modern life seems to threaten them (dogs, cats, machines to cut grass, bonfires, slug pellets, road traffic etc).
Main cause is habitat fragmentation. Females travel an average of 1km every night in search of insects and earthworms, and males 2km. They need good patches/stretches of good land connected to each other. Hugh Warwick has written a book: Linescapes showing how roads etc cut land up. They have been around for 15m years, mostly living near hedges. The enclosures of the 18th and 19th centuries actually helped, and peak time was around the second world war. The industrialisation of agriculture changed it all.
Also a small dose of chemicals and pesticides can do serious harm, but banning slug pellets is not as important as providing the right landscape. But they are declining more in the countryside – badgers are seen as the problem. The badger population is growing – the number of active setts in England has doubled since the late 1980s. They share the same diet (earthworms, grubs, beetles) – but if that food becomes scarce, or the badger population becomes more dense, then the badgers prey on hedgehogs. But the changing environment we have created leads to this situation – we need smaller fields and thicker hedges. Between 1984 and 1990, 121,000km of British hedges were destroyed – 22% of the total.
Unusually warm spells in winter can make the hedgehog come out of hibernation when there isn’t food around. Milder winters also lead to more parasites.
Good news: people are aware and rescue hedgehogs. We can check before strimming long grass or starting a bonfire, leave patches of dead leaves, long grass or log piles. Best of all, make a CD-sized hole in your fence to let them travel through. NB the hedgehog is a generalist, but it is still disappearing (it is easier to understand when a specialist has lost its food source). They may not die out completely though.
We notice hedgehogs and then do something about them – what about the creatures we are not aware of?
A report, by the British Trust for Ornithology, RSPB and the Wildfowl and Wetlands Trust and others, says more than a quarter of our birds need urgent conservation efforts to ensure their survival. 15 more birds have been put on the ‘red list’ since the last report in 2009 (meaning they are in danger of extinction or experienced significant decline). The total on the red list is now 67 out of 247.
8 species are in risk of global extinction (Balearic shearwater, aquatic warbler, common pochard, long-tailed duck, velvet scooter, Slavonian grebe, puffin and turtle dove).
Causes: land use change (afforestation, drainage of fields for farmland) – also an increase of predators (crows, foxes), and global climate change that affects migration.
The curlew has declined by 64% from 1970 to 2014 due to habitat loss. The UK supports up to 27% of the global curlew population.
Some species have increased: bittern and nightjar have moved from red to amber, and 22 species have moved from amber to green. The golden eagle has increased by 15% since 2003, and the red kite has been reintroduced, and is now on the green list. These had been threatened by people protecting grouse moors, and others taking eggs.
Our populations of arctic skuas, arctic terns and kittiwakes are in free fall. Colonies are withering away, especially in northern Scotland. On St Kilda: a 99% reduction in kittiwake numbers since 1990. Marwick Head on Orkney – once a home to thousands of kittiwakes - is deserted. Fair Isle puffins are down from 20,000 to 10,000 over the past 30 years. On Orkney and Shetland guillemots have halved in number... in the past 25 years Scotland may have lost half its breeding bird population.
The UK is home to most of the world’s population of some of these birds. The government carries out a census every 15 years but has not taken any action.
The main cause is the 1C rise in sea temperature – this has led to a loss of zooplankton, and sand eels have disappeared from many parts of the Atlantic and North Sea. The birds which only eat sand eels are declining more rapidly.
One in five of the world’s plant species are threatened with extinction, putting food and medicines at risk, according to The State of the World’s Plants, a report produced by Kew Gardens. There are 390,000 species of plants, and more than 31,000 are used by people. Of the latter, 57% are used to derive drugs. More than 5,500 are human foods and 1,400 have ‘social uses’ viz. Tobacco and cannabis.
- destruction of habitats for farming – 31% (e.g. palm oil production and cattle ranching),
- deforestation for timber – 21%
- deforestation for buildings and infrastructure – 13%
- climate change – 4% (but this is likely to grow).
Note also that breeding crops over a long time to produce high yields means that other genes are lost, such as those that help fight pests and cope with changes in climate. Bananas, sorghum and aubergines now have very little genetic diversity and are therefore vulnerable to new threats. Finding wild relatives is the way to get genetic diversity back.
Moreover, more than 5,000 species have invaded foreign countries, causing billions of dollars of damage each year. Japanese knotweed costs UK £165m a year to control.
Growth rates of some fauna such as bryozoans moss and a marine worm have been increasing. The moss then pushes out other species and reduces overall biodiversity levels. The area usually has a very rich biodiversity – like coral reefs. We had been more concerned about the Arctic than the far bigger southern ice cap – but temperatures have been rising there, and a one-trillion-tonne block of the Larsen C ice shelf has collapsed into the sea.
As argued earlier, the point about biodiversity is that ecosystems have more components than they ‘need’ to make the system function – they have a ‘redundancy’. Dicks says: ‘The argument in ecology is that the redundancy is needed for the long-term resilience of the system.’ So it’s possible that the whole system will collapse even if only a proportion of the existing species goes extinct.
Barnes says that this demonstrates the ‘tragedy of the commons’: ‘if I don’t grab it someone else will’. But a more important cause, surely, is that we have been encouraged to only value individual property? We have polluted the air, and the rivers and the sea because we don’t see them as ‘ours’.
Barnes ends his piece by talking about how it all comes back to population: since 1950 the world’s population has tripled; in 2016 we reached 7.4 billion. As Lynn Dicks says, world population is increasing by 75 million a year... Barnes points out that energy and water use have both increased by five times. ‘Human population growth is the principal driver of the extinction crisis. There are not separate crises going on: it’s all linked. The loss of biodiversity and bio-abundance inevitably ensues.’
Tony Juniper says: ‘solutions are linked. It’s about sustainable economies – if we continue with economic growth, we will trash ecosystems and the soil. We need to end the extinction, reduce CO2 emissions and protect soils.’
What is most important as a cause of declining biodiversity – human population growth, unsustainable economies, or ‘the tragedy of the commons’?
(1) – conservation: 15th Feb 2017: a group of 14 scimitar-horned oryx (type of antelope) reintroduced to a nature reserve in Chad (the size of Scotland!), by the Sahara desert where they used to live. (Driven to extinction during civil unrest 1980s and 1990s). Bred in captivity in zoos including Whipsnade. Zoological Society of London announced.
(2) 17th Feb 2017: scientists are trying to
‘resurrect’ the woolly mammoth (by splicing mammoth
(3) – protection of the sea: ocean ecologists want 30% of Britain’s seas protected – we have achieved on 0.01% (off Lundy Island in the Bristol Channel, Lamlash Bay off the Isle of Arran, Flamborough Head in East Yorkshire). ‘When you establish reserves in which fish and shellfish can breed and grow to large sizes, [you get a] ‘spillover effect’ – fish migrating to the surrounding waters’ – so the policy actually helps the fishing industry.
‘Declaring areas of sea off-limits to the fishing industry would also revitalise other coastal industries [attracting] divers, whale watchers and sport fishers – all of whom tend to bring in more income and jobs than commercial fishing.’
A rich ecosystem includes many different species of fish, tuna, ‘blue, porbeagle, thresher, mako and occasional great white sharks’, and behind, within sight of the shore, fin whales and sperm whales...’ As described by Oliver Goldsmith in the late 18th century ‘[fish] in distinct columns of five and six miles in length and three or four broad.’ George Monbiot on re-wilding the seas, 4th Feb 2017.
- the world’s largest marine park has been created in the Ross Sea off Antarctica – widely seen as Earth’s last intact marine ecosystem. (29th Oct 2016 Michael Slezak)
(4) – protection of rivers: payments in lieu of fines: businesses are paying ‘enforcement undertakings’ as an alternative to prosecutions – Environment Agency says the money will go to charities and projects to clean up rivers etc and for community groups to invest in public parkland. Northumbrian Water has paid £375,000 for pumping sewage into a river, and Anglian water has paid £100,000 twice for 2 pollution incidents which killed fish. 31st Jan 2017 Press Association
(5) Paul Wilkinson of the Wildlife Trust which helped write the 2013 State of nature report: we need a/the? 25-year Plan for Nature, to stop the loss of wildlife and secure its recovery within a generation. The government should introduce regulation to ring-fence habitats from farming, and to prevent the use of the most harmful pesticides. But recent cuts to the budget for the environment have not helped.
(6) – rewilding: Lynx UK hopes to introduce six Eurasian lynxes, imported from Sweden, into Kielder Forest (a nature reserve in Northumberland). Lynx was last seen across Britain in AD700. They would reinvigorate the biggest forested area in Britain and control its herbivore population – their main food is roe deer, which is damaging the growth of wild flowers and plants, and preventing the regeneration of trees. They have been successfully re-introduced in northern Germany. Dr Ian Convery (Univ of Cumbria) says we have lost significantly more nature over the long term than the global average and we are amongst the most nature-depleted countries in the world. Three benefits: restoring ecosystems, controlling deer, attracting tourists (as happened in Germany).
Other re-wilding initiatives: (Observer 13th May 2015, p 31 Tracy McVeigh): attempts are being made to return wild animals (and plants etc) to areas from which they have died out. Examples: reindeer (extinct since the 12th century, reintroduced 1952, especially in Cairngorms) black Grouse (reintroduced in Derbyshire in 2003), wild horses, wild boar have been re-establishing themselves for several decades (but these have escaped from farms?).
(Observer 26th June2016 Jessica Aldred): dormice being reintroduced to Yorkshire Dales National Park. They need managed (coppiced) woodland and hedgerows – England lost 50% of its hedgerows between 1946 and 1993 from an estimated 500,000 miles to 236,000. Dormice need to be off the ground, so drystone walls and woods are essential.
This community it is hoped will link up with another released three miles away. A good species to get people involved with conservation, and what’s good for them is also good for birds, bats and butterflies.
Beavers have improved water (flood management etc) and biodiversity in Devon. Wolves could manage deer. Sea eagles were returned to the Inner Hebrides (but endangered sheep...).
Avoid using peat
Grow a diverse range of pollinator-friendly plants - Bee-friendly flowers have less petals
Compost kitchen and garden waste
Make spaces for wildlife
Love your soil: don’t mess with it too much, add organic matter (preferably compost)
Create a variety of trees, shrubs, perennials, annuals, ground cover, something in flower for most of the year
Use a water butt.