Overstepping the planetary boundaries

In 2009 a team of 28 scientists lead by Johan Rockström from the Stockholm Resilience Centre and Will Steffen from the Australian National University presented the concept of plane-tary boundaries within which there would be a “safe operating space for humanity” and outside of which there would be an increasing risk of “irreversible and abrupt environmental change“.19 The group identified nine vital categories and were able to propose quantifiable boundaries in seven of these. The scientists found that humanity has already overstepped the boundaries in three categories: climate change, biodiversity loss and interference with the nitrogen and phosphorus cycles. The next critical fields are ocean acidification, change in land use, global fresh water use and stratospheric ozone depletion. For the two remaining categories, chemical pollution and atmospheric aerosol loading, the boundaries have not yet been quantified. For the purpose of this book we will focus on climate change as the most critical challenge at present. But it is important to note that there are at least eight – and probably even more – other areas where humanity is on its way to overstepping the boundaries our planet sets for us.

For more than 100 years we have known that people can change the climate. At the end of the 19th century a Swedish physicist, Svante Arrhenius, developed his ‘greenhouse law’ stating that global temperature rises with the increase of carbon dioxide in the atmosphere. Some years later he pointed out that, by burning coal, mankind was increasing the atmosphere’s CO2 content and thus warming the planet. He was not aware, though, of the dangers that this entailed. On the contrary, he hoped that a warmer climate would improve people’s lives: “We often hear lamentations that the coal stored up in the earth is wasted by the present generation without any thought of the future (…). We may find a kind of consolation in the consideration that here, as in every other case, there is good mixed with the evil. By the influence of the increasing percentage of carbonic acid in the atmosphere, we may hope to enjoy ages with more equable and better climates, especially as regards the colder regions of the earth, ages when the earth will bring forth much more abundant crops than at present, for the benefit of rapidly propagating mankind.”20 Nearly half a century later Harrison Brown, a well renowned geochemist, still believed that increasing the CO2 content of the atmosphere would benefit humanity, helping to feed the world’s fast growing population: “If, in some manner, the carbon-dioxide content of the atmosphere could be increased threefold, world food production might be doubled.”21

Today we are in the midst of a dramatic increase of carbon dioxide – but, sadly, not at all with the positive consequences these scientists expected. During the first 150 years of the industrial revolution, from 1800 to the 1950s, CO2 had grown from 280 to 315 parts per million (ppm), a total of 35 ppm. Over the last 50 years, we have added another 70 ppm, which means twice as much in one third of the time. In 1958 David Keeling started measuring the CO2 content of the atmosphere in Mauna Loa, Hawaii, a location of high altitude in the middle of the pacific, far away from large industrial centres. In March 1958 he measured 315.71 ppm. In October 2014 this figure had gone up to 395.93 ppm.22 On 9 May 2013, Mauna Loa measured for the first time over 400 ppm.[tooltipt t=”Planet Save; http://planetsave.com/2013/05/14/noaas-mauna-loa-observatory-sees-400ppm-carbon-dioxide-levels/ (27 November 2014)”]23[/tooltip] And the increase in CO2 emissions is still accelerating: from 1.1% annually in the 1990s to over 3% a year between 2000 and 2004. “Global CO2 emissions are now growing faster even than the IPCC’s24 worst-case scenario.” And, broadly in line with Arrhenius’ predictions made 100 years ago, temperatures are rising as well. Over the last 100 years the average temperature around the world has increased by 0.6°C. And “even if we were to stop all emissions of carbon dioxide today, the planet would still warm by another 0.6 degree Celsius or so, as the ocean radiated to the atmosphere some of the excess heat it absorbs.”25 Worse still, in some parts of our planet the increases have been much more dramatic: over the last 50 years alone, both the Arctic and the Antarctic have seen temperatures rising by up to 4°C.

As the temperature rises, many scientists expect that we may reach a ‘tipping point’ at which the global climate changes from its present stable state to a new stable state which, in stark contrast to earlier expectations, will most probably be less amenable to human beings. Researchers developed this expectation based on past climate changes. Drilling kilometres deep into the Greenland ice and extracting ice which was several hundred thousand years old and drilling deep into sediments on the Arctic sea floor scientists were able to measure both the CO2 content and the temperature at the time when the ice developed and the sediments built up. They found that temperature changes in our planet’s recent history had been enormous and that these changes, in some cases at least, had happened very fast, sometimes within decades. Wallace Broecker, one of the most eminent climatologists and the first one who, in 1975, spoke of ‘global warming’ refers to these fast and enormous temperature changes when he talks about ‘the angry climate beast’. He wondered how these dramatic changes were triggered and found what he calls ‘a conveyor belt in the ocean’, which links the Atlantic, Pacific and Indian Oceans transporting warm shallow water into the Atlantic and cold, salty, deep water into the Pacific. If this system stops, which it has done before, it may bring quick and dramatic temperature changes.

Meanwhile, practically all serious scientists agree that climate change is happening and we better act fast in order to avoid developments which will threaten human survival in many parts of our planet. If we do not stop releasing CO2 and other greenhouse gases into the atmosphere very soon, we, our children and grandchildren and many generations to come, will have to face a number of scary consequences, the two mostly frequently mentioned ones being sea level rises and severe droughts.

Since the peak of the last ice age, about 20,000 years ago, the sea level has risen by 120 metres – and there is enough ice on our planet to add another 60 to 70 metres. Today, over half of the global population lives within 60 kilometres of the sea. Most of the world’s mega cities, with over 10 million inhabitants, are located close to the sea including London, New York, Tokyo and Shanghai. Even a one metre rise would put these cities in grave danger, especially from storm surges. New York, for example, which experiences a major storm surge about once every 100 years, would have to cope with such a flood on average every three or four years. A disintegration of the West Arctic ice sheet alone would make sea levels rise by about five metres. Cairo and Cape Town, Rome and Rio, Singapore and Sydney and many more of the oldest and most beautiful cities would just disappear. Threats that challenge our imagination. Since the early 1990s, when the use of satellites improved the accuracy of sea level measurements, the sea level has been rising at nearly 3 millimetres a year. If this development continues we would add 30 centimetres over the present century. But many scientists worry that the speed will increase. Estimates on what we might have to face by the end of this century go up to 140 centimetres. The trouble is, we don’t know how fast the sea level will rise and, as the flooding of New Orleans a few years ago has shown, we are not prepared for the worst case scenario.

Scientists have found that the dramatic drought which plagued the Sahel from the late 1960s to the 1980s was probably the first major disaster caused by manmade climate change. About one hundred thousand people and millions of animals died from lack of food and drinking water. Since then the Sahel has seen a lot of rain and the desert is shrinking. But this may not be a long-term trend. Some scientists believe that with a temperature increase of between 3°C and 5°C the climate in the Sahel will reach its ‘tipping point’ leading to permanent drought with even less rain than the drought before. Drought is also becoming a major challenge for the Amazon rainforest. In 2005 there was hardly any rain and deforestation extended rapidly. The danger of bush fires increased enormously and in September 2005 satellites registered up to 73,000 fires burning at the same time. Scientists are seriously worried that the Amazon ecosystem may collapse leading to a dramatic loss of CO2 storage capacity on one side and setting free enormous quantities of additional CO2 on the other.

Looking at climate change from a humanitarian perspective the Global Humanitarian Forum, led by the former UN Secretary-General Kofi Annan, draws a dramatic picture of human suffering: “Every year climate change leaves over 300,000 people dead, 325 million people seriously affected, and economic losses of US $125 billion. Four billion people are vulnerable, and 500 million people are at extreme risk.” And it predicts: “Within the next 20 years, one in ten of the world’s present population could be directly and seriously affected.” The study points to the increasing number of people displaced by climate change: “An estimated 26 million of the 350 million displaced worldwide are considered climate displaced people. Of these, 1 million each year are estimated to be displaced by weather related disasters brought on by climate change.” The Forum expects that “in   the next 20 years the number of climate displaced people could more than triple”.26

Let’s summarise: climate change is happening already; it is too late to worry about avoiding it. We probably have very few years left to start moving away from our carbon based economy and lifestyles in order to limit global warming to a level below 2°C which is generally considered the ‘tipping point’ after which a chain of mutually reinforcing climate events might take developments fully out of our hands. Scientists speak of the most serious challenge humanity has encountered in all of its history. What makes climate change such a special challenge is not only the severity of its consequences; it is also the new quality of the challenge, a quality which humanity never had to face before. Firstly, the damage does not necessarily arise at the place where it was caused. Industrialisation, which has mainly happened in the North, leads to dramatic consequences arising mainly in the South. Secondly, the damage does not necessarily arise at the time when it was caused. Today we know that we have already produced between 1.2°C and 1.4°C of global warming but we can only measure half of that. The other half is stored as heat in the oceans and will be released over the next few decades – even if we would completely stop emitting CO2 today. Similarly the rise of sea levels will take centuries – and similarly it will take a very long time to stop and eventually reverse after we have stopped polluting the atmosphere. Thirdly, the complexity of the challenge is beyond our understanding: We are changing the global climate by accident: we wanted to drive cars, heat our homes and lead ‘modern’ lives but we didn’t want to destroy the climate. This is happening as an unforeseen consequence of industrialisation, and it is happening at a time when we do not (yet?) have sufficient knowledge about the complex interdependencies between the various components of the global climate.

We do not have the space here to review the other eight planetary boundaries we should not overstep. But I believe that with the example we reviewed, the need to change our approach to global development is becoming sufficiently clear. Scientists point to two critical issues which we need to consider when judging our risks: the interdependence between the different categories and the non-linear, often abrupt changes, which can occur once a specific threshold has been passed. This means that we are interfering with a highly complex and closely interrelated set of vital conditions for the future existence of humanity; and we are meddling without sufficient knowledge of the potential damage we may cause and without knowing when and how we may overstep a crucial threshold beyond which there is no way back. Our time, the Holocene, has been a period of exceptionally moderate and stable conditions which were the basis for the rise of human civilisation. But the industrial and agricultural developments of the last 150 years threaten the very foundations which allowed humanity to thrive.