BY BRYN GLOVER
During the first decade of this century, a number of separate specialist scientific groups, with members from around the globe, met independently, but with similar purposes. Their common objective was to attempt to quantify the precise mess that we had got ourselves into, with respect to our one-and-only planet. The outcome of these meetings was universal agreement that there were nine areas of significant concern where the actions of humanity were impacting on the natural world, and where immediate action was imperative.
The various conclusions of the groups indicated that urgent steps needed to be taken to avoid tipping points beyond which changes would be inevitable and unstoppable, but that in some cases, they believed that such points had already been exceeded, and that only ‘firefighting’ could now prevent severe disasters. The groups sought to analyse the extent of the various impacts, to produce precise and stark warnings about limits, and to define in specific mathematical terms what they referred to as ‘Sustainable Planetary Boundaries’, or SPBs.
The nine areas of concern were as follows: climate change, ocean acidification, stratospheric ozone depletion, biochemical flow boundaries (the nitrogen and phosphorus cycles), global freshwater use, change in land usage, biodiversity loss, atmospheric aerosol loading and chemical pollution & novel entities.
The original sustainable boundaries were agreed in around 2010, but already in 2025, those that were defined for six of the systems – climate change, chemical pollution, biodiversity, land usage, freshwater usage and the nitrogen & phosphorus cycles – have been crossed. Ocean acidification and atmospheric aerosols remain within limits, but with the caveat described below. Action to halt ozone depletion has been largely successful, and the ozone layer is on track to full restoration by the end of the century, barring any further human misbehaviour. So we can make a difference if we really try.
Though the nine areas were separately defined and each was assigned its own sustainable boundaries, it will be clear that there is considerable interaction between several of the groups. The availability of freshwater is, obviously, crucially dependent upon rainfall etc. Also the occurrence of atmospheric aerosols and other pollutants both adds to warming and is made much worse by that warming in a positive-feedback cycle.
Each of the planetary boundaries will now be considered individually in more detail.
Climate Change
This basic heading includes such primary features as the rise in atmospheric CO2 levels (and other greenhouse gases), the rise in average global air temperatures, the rise in oceanic temperatures, the rise in ocean levels and atmospheric pollution. However, there are numerous secondary features that must also be considered.
A person would need to be perversely obstinate to deny the changes we have all seen in the last few decades. Stories of wildfires and destructive floodings have dominated our news media and the root cause of both is the same. As the atmosphere and the oceans have both warmed, even very slightly, so the climate consequences have followed. Warmer air can hold more water vapour; more vapour and warmer air lead to lower pressures, and these in turn create more violent storms. The El Niño/La Niña cycles are disrupted and oceanic mixing currents have become unpredictable. The very latest data indicate that the oceans have, in fact warmed significantly more than we feared, and of course, warmer waters occupy greater volumes, and so sea levels inexorably rise.
Ocean acidification
This has been called the ‘evil twin’ of climate change, since it too is caused mainly by the increase in atmospheric CO2 levels. The gas dissolves in water where it undergoes a slight chemical transformation, producing carbonic acid, H2CO3. This is a weak acid, in the chemical sense, but its presence lowers the pH value of sea water. The drop is quite small numerically, but it has been causing significant changes in the ability of shell-forming creatures to deposit the calcium carbonate that largely makes up their shells; without shells, they simply cannot survive, and food chains collapse.
Ozone depletion
This area can largely be seen as a success story in that world-wide efforts have now outlawed the production of the chemicals which caused it, and we can look forward to the possibility of a complete recovery of the ozone layer by the end of this century.
Nitrogen and phosphorus
Both Nitrogen (N) and Phosphorus (P) have been cycling and recycling through living organisms for as long as there has been life on Earth: they are essential components of that life, and especially of the proteins that constitute life. Phosphorus is present in minute quantities in some of Earth’s rocks, but minute quantities are all that are needed for life. Nitrogen is the principal component of the atmosphere, and is mostly converted into solid chemical form through being absorbed by a number of species of bacteria which can be found, for example, living in nodules on the roots of leguminous plants. Both elements are incorporated into plant tissue, they transfer to animals when the plants are eaten, or they are released into the soil when the plants die and rot, and thus the two elements recycle continuously.
Early human farmers would have soon realised that to collect animal (and human) waste and to spread it over their fields would have the beneficial effect of increasing the next year’s crop yield. There was nothing wrong with that; it merely concentrated a process that would have occurred naturally anyway. Problems began to arise once the massive social changes of the late 18th century began to bite, and millions of country dwellers were driven into the new burgeoning industrial centres. All these people needed food, and this was brought in from the countryside. They also needed to dispose of all their wastes, and instead of this being returned to the land, it was seen as a problem to be solved by the building of sewers and by dumping the waste into our rivers and seas.
Alongside this waste, there arose a serious and dire need to find artificial sources for the N and P we dumped. The current global usage of artificial nitrates is in excess of 120 million tonnes, whereas the planetary boundary committee felt that the maximum should be 35 million tonnes; thus the ‘safe’ limit has been exceeded by nearly four-fold. The story for phosphorus is not quite so dire, in that the current (rapidly rising) usage is somewhat under 10 million tonnes, compared with a boundary limit of 11 million tonnes.
Global freshwater use
The world’s glaciers act, in many places, as summer reservoirs of fresh water. Snow adds to their bulk in winter, and their slow melting in summer allows continuous supplies along the length of their rivers. However, rapid melting has already produced uncontrollable flooding, but perhaps more significantly, the much-reduced sources are now unable to meet traditional needs. This is seen acutely in the Andes and the Himalayas; in the latter case presenting the people of Bangladesh who are at the end of the rivers in question with a monstrous challenge to their existence. Humans have merely added to this problem by building dams upstream to harvest the scarcer supplies, but to exacerbate the crisis for those downstream.
A second natural source of fresh water lies in underground aquifers. These are generally vast tracts of porous rocks which together, on a global basis, may carry billions of tonnes of fresh water. But this is water which is replaced naturally on an extremely long time scale of centuries or even millennia. Farmers who are desperate to irrigate their crops in times of drought will readily drill down into the aquifers and take what they need, usually at rates far in excess of the replacement rates from natural rainfall. The result is dramatic depletion which often affects the very structure of the underlying layers. Earth tremors, landslides and land collapses result with dire consequences for humanity and often a permanent loss of the resource.
Soil degradation
The assessment of soil degradation is the subject of a number of recent global studies that highlight the deterioration of our planet by the action of humanity. In 2016, the Intergovernmental Science Policy Platform on Biodiversity and Ecosystem Services (IPBES) released a global biodiversity study that warned that the human destruction of nature is rapidly eroding the provision of food and water, and the security of billions of people.
Species loss and shift
Species have always ‘gone extinct’. However, the rate of extinction of species has rapidly increased over recent decades, and this increase is purely due to the rapacious invasion by humans into ever more natural, previously untouched, environments.
Before the industrialisation cut-off date of 1750, the natural rate of species loss was in the range of 0.1 to 1.0 species per million per annum. The committee of scientists which considered this matter suggested that an SPB for this should be 10 per million per annum. It is a shocking fact that the current rate is actually ten times that at around 100 species lost every year per million species on Earth, or one thousand times the natural rate.
Atmospheric aerosols
Because of the extreme complexity of this topic and because of the difficulty in making reliable measurements of parameters which are constantly changing, the committees on planetary boundaries did not define any ‘safe’ limits. This is not to say that great concern has not been expressed about the current levels of pollution in general, nor that strenuous efforts need still to be made to reduce aerosol loading. Paradoxically, some solutions to global heating actually propose releasing thousands of tonnes of certain specific aerosols, such as silver salts, into the upper layers of the atmosphere. Here, it is hoped, they would reflect the sun’s light and heat back into space, and thus cause a small degree of planetary cooling. The problems with such a plan, however, would include the need to continue the process indefinitely – perhaps even to ramp up the process, as artificial cooling would do nothing to assist the urgency of the need to stop releasing carbon dioxide. As we relax that need, so the reliance on aerosols would grow, and any unforeseen side-effects would then simply and suddenly release all the disastrous effects of the increasing CO2 levels.
Chemical pollution
This is another field in which precise planetary boundaries were not originally set, and for broadly the same reasons as just described. Nonetheless, the rough limits that were described have now been exceeded. The number of synthetic chemicals produced by humanity numbers in the tens of thousands, which does not include all the bizarre and largely unquantified chemical entities which arise as these compounds interact with themselves and with atmospheric gases high up in the energy-rich stratosphere.
Even so, there can be no doubt that the spread of chemical pollution in the form of heavy metals, radioactivity and organic molecules represent one of the most serious threats to life on Earth, whether that be human life or the entire range of animal and plant life. Chemical pollution is one of the factors causing the much-increased loss of biodiversity, which was described above.
It is under this heading that the scourge of plastics must be included. The word itself can include anything from the large scale such as plastic bags to the microscopic scale which are readily ingested by the smallest of oceanic creatures, thereby becoming incorporated into every food chain. The dramatic reduction of the use of such materials in every walk of life is now a vital necessity.
Other forms of chemical pollutant would include the surplus pesticides which drain into our watercourses and the spent drugs which we metabolise and excrete, and which find themselves in ever increasing concentrations in our water sources and therefore in our drinking water. These compounds all have in common the potential to cause illness and damage, not only to ourselves, but also to the rest of life on Earth. Many of these substances can cause cancer or loss of fertility; in humans, we have ways of compensating for such loss, but in the wild, the inevitable result would be to increase the rate of extinction of species.
What is to be done?
Climate change and changes in other systems do not happen in gradual, predictable steps, but rather take the form of sudden tipping points fed by positive feed-back mechanisms. Positive feed-backs are also known as ‘amplifying mechanisms’ and the one which should concern us most is that of polar ice. As the ice disappears and is replaced by dark water, so the poles heat up much more rapidly than the rest of the Earth, and whether or not this will cause the great ice sheets to disappear completely is currently unknown. But if such a catastrophe should occur, it is likely that it will happen very fast, and ocean levels will rise too fast for humanity to do anything about it.
The warmer poles are also causing the wholesale melting of vast areas of what has hitherto been permafrost. Some welcome this as the release of more usable land, but under the permafrost lie possibly billions of tonnes of so-called ‘methyl-clathrates’, which can be described as ice-cages containing methane. The loss by melting of these will cause another disastrous tipping point as more methane than we can imagine will be released into the atmosphere; the volumes involved will make the belching of cattle seem like a trivial problem.
The now yearly COP climate conferences have so far produced much in the way of long-term promises but little in the way of immediate deeds. Many climate commentators have identified the 2020s as the most significant decade for action; what happens in the next ten years will affect humanity for the long-term foreseeable future to extents greater than in any preceding decade.
For this reason, the Glasgow and subsequent COP meetings needed radical re-thinking from all our leaders, who so far, have merely demonstrated that they do not fully grasp what is at stake, nor how painful and difficult are to be the decisions they must make. The anodyne promises and pious commitments of the past are no longer sufficient, and a sustained, committed outcome which will change traditional thinking and traditional practices is more vital than ever.
We simply cannot negotiate with the planet. We cannot bargain with nature.
We cannot do deals to lessen changes or lengthen timescales. We have no choice but to act as our world tells us.
Bryn Glover is a member of the AGS national committee
Alliance for Green Socialism 