by Bruno David
President of the French National History Museum
Evoking universality immediately projects our planet as an emblem of this asset shared by all. Faced with the upheavals we are seeing, Bruno David, Palaeontologist and President of the French Natural History Museum, shares with us his thoughts on the changes affecting the biodiversity and the associated risks, as well as actions to preserve a living and liveable planet for all.
Biodiversity: An asset shared by all mankind
The living fabric of our planet, etymologically “diversity of the living”, biodiversity is intrinsically an asset shared by all mankind. This diversity of living things on our planet is highly structured for ecological reasons — some species prefer heat, others cold, some are aquatic, others airborne — and also for historical reasons, as the configuration of continents and oceans has caused them to evolve in this or that place. Thus, there are no polar bears at the South Pole and no penguins at the North Pole, separated as they are by history. Ecological barriers also prevent polar bears from crossing the Equator and Tropics to reach the South Pole and vice versa for the penguins. These historical and ecological constraints have fashioned the biodiversity and sketched out our lives and landscapes.
Biodiversity: "our life insurance"
From breathing to contemplating landscapes, via what is on our plates and the purification of water and medicines, biodiversity renders us countless “services”. Our atmosphere with its 21% oxygen is created thanks to lifeforms having released the oxygen for hundreds of millions of years for subsequent use by other organisms to breathe, whilst protecting themselves against its oxidising properties. Plants renew this oxygen unceasingly thanks to photosynthesis. Say plants, and we initially conjure up large forest trees. But something is even more effective than trees — given that they only produce oxygen through their leaves, thereby restricting production to seasons with trees in leaf —; marine plankton encloses a whole host of single-cell algae that are essential “oxygen factories” in this function. Endangering the plankton could thus endanger mankind.
Diversity of cultures is a way of protecting against plant or animal parasite species (fungus, insects, etc.) that can easily proliferate in intensive monocropping, without using large amounts of pesticides and fungicides. Our pharmacopoeia also comes from the biodiversity to a very large extent. Ancient remedies, of course, but also a very large portion of our current therapeutic arsenal with, for example, recent antibiotics or cancer treatments that are the fruit of biodiversity in its wealth and surprises. Take Bryostatin, for example, a cancer treatment extracted from bryozoans, small marine animals that look like moss. These animals go through a larva phase and the larvae are protected from predators by bacteria living in their folds. These bacteria manufacture the anti-cancer agent. The discovery can seem unlikely, but it underlines how much the presence of between two and twenty million species on our planet provides life insurance, a universal shared asset that deserves our attention as a whole. We cannot choose to eliminate or protect one particular element. We do not have the ability to sort through what might be essential, useful or superfluous in well-informed fashion. The complexity of interrelations forces us to maintain complex balances, save for running the risk of getting rid of an essential element whose disappearance would lead to the collapse of an ecosystem and the services it renders to us.
We are all linked together in a complex chain
We have seen the importance of ocean plankton in producing oxygen. It also plays a major role in forming many clouds made up of droplets of water. These droplets are caused by the condensation of the water vapour from oceans evaporating in a fixing point, dimethyl sulphide (DMS), produced by the plankton. Thus, the quantity of plankton acts on the nebulosity, which can itself act on the plankton, and so on. Similarly, the CO2 from the atmosphere incorporated into the ocean can alter its pH and act on the reproduction of organisms. This can ultimately influence the overall climate of the planet, far away from the CO2 emission source . This “delocalised” effect was noted with the CFC, gases used in the 20th century in aerosols and refrigerators found in huge quantities in the Northern Hemisphere, that caused a hole in the ozone layer at the other end of the planet and thus increased the risk of skin cancer for the populations of Australia and South America.
Soon there will be eight billion inhabitants on Earth and the impact of industrial, political or agricultural actions or decisions is becoming massive. Greeks in ancient times already had an influence on the Mediterranean forest that was far more dense than now and home to a wealth of fauna, including lions, for example. Its balance was unstable and its destruction, even though limited by the means and population density at the time, saw it diminish. Today’s issues are global. The Amazon forest services itself through evapotranspiration of the vegetation that produces clouds and rain and keeps the forest alive. The daily destruction of hundreds of hectares of forest is rupturing this cycle, that could ultimately see it replaced by savannah and even desert, with a global ecological impact. These balanced virtuous cycles are fragile and subject to threshold effects with an oft-unknown limit and therefore time when an irreversible problem may appear. The complexity and inter-dependence of systems can only be an incentive to respect them.
Biodiversity in danger: disappearing universal heritage
The large African mammals are on the path to extinction and with them a universally-shared heritage. Elephants and rhinoceros, all these animals are part of our history and although their disappearance would arguably have little ecological impact, the symbolic impact is potentially huge. And why are they disappearing? Possibly through hunting, but more likely anthropic pressure combined with climate change, a set of causes that are also acting in the most insidious, less visible and yet most worrying way. Concern is greatest for the decline in the abundance of common species: birds, insects and micro-organisms in the soil whose extremely rapid disappearance must make us sit up and take notice. The Museum sounded the alarm on 22 March 2018 with CNRS (National Centre for Scientific Research) for precisely that reason: “Silent Spring”, repeating the expression coined by Rachel Carlson who as early as 1962 alerted the USA to the disappearance of birds due to the use of pesticides. Very strict observation protocols in the Val de Sèvres have reported birds disappearing from the countryside at a staggering rate — a two-thirds drop in their populations on average in fifteen years.
A pace of change never before seen
The biodiversity landscape has changed constantly since the origin of life on Earth, but at a rate in step with biological evolution. Today, anthropic pressure is accelerating things at a speed faster than what life can accept, thereby endangering the biodiversity.
Our planet has experienced major biodiversity crises: in the last five hundred million years, five major and fifty minor crises have rocked our planet under the influence of huge volcanic eruptions, continental plate movements, meteorites and significant climate oscillations. Today, natural climate oscillations play an infinitesimal role and global warming is more than 90% due to human activity. CO2 was merely 280 ppm before the industrial era; today it has reached 405 ppm.
The warming phenomenon is global, despite paradoxically causing local cooling by cold air from the poles, fuelling the arguments of climate change sceptics. The reality is that the average increase in temperature of the Earth’s atmosphere is clear. Warming like this would not be a problem if it was produced at a pace compatible with biological evolution — life would find a way to adapt. But we are forcing a pace of change on life on Earth that is a hundred to a thousand times faster than the fastest rates in the past. We are currently in time steps in the order of a century or two centuries, which is nothing. It is this speed that represents the more significant risk factor.
Act: Anthropisation that respects the factors weighing on the biodiversity
Influencing the climate equates to influencing the CO2 emissions, for example by controlling our heating methods, means of transport, anything that should help the situation to improve. The problem for the biodiversity is more complex, for there many contexts as well as causes. The best way is therefore to act on the stressors weighing on the biodiversity: limit our environmental footprints (concreting, car parks, etc.), restrict over-exploitation of resources, control pollution, limit the transport of species, use fewer herbicides and pesticides and review monocropping systems. We must agree to change systems willingly or by force to return to a responsible and moderate degree of human intervention, like the one that fashioned the balanced landscapes that give our countryside its aesthetic appeal, the beauty and wealth of the landscapes we love.