The Anthropocene
It is claimed that we are now entering a new era with the transition from the previous geological epoch, the Holocene, which began some 10,000 years ago with the retreat of the ice age and the development of human civilizations, to the Anthropocene which is characterised by the increasing influence human activities are having on the planet; this began, possibly with the Industrial Revolution in the late 18th century, but accelerated with the start of the atomic age in the 1950’s. Since that time there has been a remarkable increase in world population which has now doubled and is still increasing and, as we become wealthier, there has been a tenfold increase in the use of the world’s resources to the point that this now threatens climate stability, a loss of biodiversity, a healthy water cycle and oceans, sustainable nitrogen and phosphorus use, clean air and sustainable material use.
A publication by the IGBP (International Geosphere-Biosphere Programme) “Global Change and the Earth System – A planet a under pressure” (www. igbp. kve.se) contends that “A profound transformation of Earth’s environment is now apparent, owing not to the great forces of nature or to extra territorial sources but to the numbers and activities of people – the phenomenon of global change”.
It points out that phenomenon of global change has undergone a profound acceleration during the second half of the 20th century. Half of Earth’s land surface has been domesticated for direct human use. Most of the world’s fisheries are fully or over-exploited. More than half of all accessible freshwater is appropriated for human purposes, and under- ground water resources are being depleted rapidly in many areas. The composition of the atmosphere – greenhouse gases, reactive gases, aerosol particles – is now significantly different to what it was a century ago. The evidence that these changes are affecting the basic functioning of the Earth System, particularly the climate, grows stronger every year. The magnitude and rates of human- driven changes to the global environment are in many cases unprecedented for at least the last half-million years.
While the global population more than doubled in the second half of the last century, grain production tripled, energy consumption quadrupled, and economic activity quintupled. Although much of this accelerating economic activity and energy consumption occurred in developed countries, the developing world is beginning to play a larger role in the global economy and is having increasing impacts on resources and environment. Many human activities reached take-off points sometime in the 20th century and have accelerated sharply towards the end of the century. The last 50 years have without doubt seen the most rapid transformation of the human relationship with the natural world in the history of humankind.
Global change is real, it is happening now, and in many ways it is accelerating. Global change is more than, but includes climate change where a common factor enabling these changes is the increasing consumption of energy and in particular of fossil fuels, coal, gas and oil.
The extreme weather conditions with heavy rainfall and high winds and flooding now experienced in many areas in the UK are now being attributed to climate change; a warmer world will lead to more intense daily and hourly rain events. Attention in this country is understandably focused on our own climate but we are not alone; Australia has experienced its hottest year on record, there are heat waves in Argentina, tropical cyclones which killed more than 5,700 people in the Philippines, arctic weather in the US, but melting ice caps at the North Pole. Climate change is a global phenomenon.
The debate is now turning to the measures that should be taken to minimise the damage and costs – adaptation or mitigation – as if these were alternatives. The answer should surely be we must do both although they are fundamentally different.
Adaptation is essentially a response to effects of climate change – both anticipating, and dealing with events as they occur. Despite efforts to limit the man-made causes of climate change it is increasingly being accepted that some change in our climate is unavoidable. It is then clearly wise to increase flood prevention and response measures to cope with heavy and prolonged winter rainfall. But we may also have to consider the possibility of severe droughts and high temperatures in the summer. The need for adaptation is obvious; the only controversy is on the amount of money to be spent and the measures to be taken.
All this has been well known and debated for many years with reports and assessments from the Government, Met Office, Scientific Institutions etc dating from 1999 or earlier. But not enough has been done and the money spent on adaptation measures has been reduced. It seems that now, alarmed by the likely political fallout from the flooding, the Government may be ready to take some action; but to repeat, adaptation is only a short term but necessary response – a quick fix that all can agree with.
In New York for instance the electrical utility ConEd is now to spend $1 billion by 2016 to protect its most critical equipment from storms. This is a response to hurricane Sandy — 44 dead, billions of dollars in damage, a flooded subway system and ConEd’s largest ever power outage. It is now accepted that the New York City area is highly exposed to the threat of sea level rise and extreme weather in a changing climate. That includes increasing risks of worsening heat waves and damaging storm surge during hurricanes because of rising sea levels. It is estimated that another Sandy-like storm could cost the city $90 billion if it were to hit mid-century. Adaptation is a sensible response.
Mitigation – actions to reduce net carbon emissions and limit long-term climate change must first identify and limit the causes of the problem; a complex and controversial problem – who or what is to blame. If, as seems increasingly probable, climate change is associated with the continuing growth in emissions of carbon dioxide, methane and other greenhouse gases, the necessary measures to reduce them will immediately impact on, and be opposed by, the fossil fuel industries.
For every 12 tonnes of carbon burnt 44 tonnes of carbon dioxide are released into the atmosphere. The carbon content of coal can range from 45% to up to 85% or even 90%. In 2012 the UK consumed 64.1 million tones of coal of which 70 % was imported and of this 54.9 million tonnes (85% of the total) was burnt to generate electricity. Assuming 75% for the carbon content of this coal the carbon dioxide emissions from UK power stations in 2012 would amount to 150 million tonnes.
The UK however is only a minor player. The emissions from countries such as China and India, or of Poland, and now increasingly from Germany, within the EU, will be much larger. Even though the manmade combustion discharges are only a small addition (5%) to the natural cycle between photosynthesis and plant respiration and decay, the concentration of carbon dioxide in the atmosphere has risen continuously and is still rising. World consumption of coal still increasing; it is becoming increasingly difficult not to believe that the 34 billion tones of carbon dioxide discharged in 2012 must be a driver in the increase in global temperature, and other climate changes.
The increase in atmospheric carbon dioxide concentration provides a useful measure with which to evaluate the rate and magnitude of human- driven change compared to natural variability. Measurements from the Mauna Loa Observatory of atmospheric CO2 show that concentrations have been rising from about 300 ppmV in 1960 at an accelerating rate and now stand at 400 ppmV; and this has been reached at a rate at least 10 and possibly 100 times faster than increases of CO2 concentration at any other time during the previous 420 000 years. These human-driven changes are well outside the range of natural variability exhibited by the Earth System for at least the last half-million years.
With increasing carbon dioxide emissions as the principal driver of climate change, mitigation must attempt to reduce them. This meets severe problems. Many countries, particularly China, India, Mexico and most of the developing countries now depend on coal as a vital energy source. Carbon capture and storage is quite impractical at the level of billions of tonnes per year on grounds of cost and indeed safety. With energy as the driver of economic growth the problems of replacing coal, – political and technical and economic – are daunting. It is for instance not surprising that Australia, despite experiencing record high summer temperatures and bush fires, does not, officially, accept that climate change could be caused by carbon emissions; it is both a major consumer and exporter of coal. But Australia at least has an alternative in its large uranium resources.
The other fossil fuel is gas. When burnt in a power plant the emissions from gas at about 270 kg/MWh are almost half those from coal at 480/MWh. But there are now reports suggesting that the leakage of methane during the production and transport of gas should also be taken into account.
No alternative
It is now possible to understand the differences between climate change sceptics, who argue that the changes we now experience are due to the natural variations of the climate, and the scientists who are convinced that they are the consequence of human activities. Both are to some extent right. There are and always have been natural variations in the climate, and it will always be possible to point to some past extreme event. But the world has moved on. We are in a period of continuing growth – in population, in human activities and consequently in energy consumption. Natural variations in the climate will be enhanced, and their effects magnified by human activity that is continually increasing, so that even lesser natural variations which in the past would have been almost unnoticed, now have a major effect and will occur at an ever- increasing frequency.
Water vapour also has a strong greenhouse warming effect, but unlike carbon dioxide that can remain in the atmosphere for centuries extra water vapor will only remain a few days before falling as rain. The concentration of water vapor in the atmosphere is in equilibrium. The atmosphere can only hold more water vapour if overall temperatures increase. So a warming effect caused by human CO2 emissions will increase the amount of water vapour in the atmosphere. The added water vapour leads to even more warming, thus amplifying the CO2 warming effect. Water vapour follows temperature changes, it doesn’t drive them; it amplifies already occurring warming.
World carbon emissions from burning fossil fuels and cement production have increased steadily since the time of the Industrial Revolution and now amount to almost 40 billion tons per year of carbon dioxide, a greenhouse gas. The concentration of carbon dioxide in the atmosphere has now reached 400 ppm. Although, if expressed as a percentage this might seem almost negligible, the atmospheric concentration of other greenhouse gases – methane, CFC’s etc – is also increasing. It is difficult to believe that this will be without effect on the climate.
Climate change is real, it is happening now and will continue to pose an increasing threat unless we can reduce the burning of fossil fuels. It is dangerous to pretend otherwise. There are in addition the present, immediate threats of deaths and disease by the air pollution from the combustion gases that can be spread by the wind the to neighbouring countries. It is then astonishing, indeed regrettable, that those countries that are now increasing their emissions, notably Germany and now to a lesser extent the UK, are not penalised by the EU. More effort must now be devoted to replace the burning of coal and lignite by other energy sources. In this respect methane gas, although still producing carbon dioxide is less dangerous in that it does not discharge solid carbon particles that can penetrate into the lung.
There is also the problem that there can be significant leakages of methane, particularly in the production of shale gas, as well as leakage from pipelines; methane is a powerful greenhouse gas. Hydropower is limited by a shortage of suitable sites, while the so-called “green energies” wind and solar are both expensive and intermittent; they will require back up from fossil fuels if they are to make any serious contribution to the electricity supply.
The dangerous consequences of the continued discharge of combustion gases are now being more widely appreciated and understood. It is reported by Reuters that “some 200 countries have agreed to try to limit global warming to less than 2.0 degrees Celsius above pre-industrial times, largely by cutting emissions from burning fossil fuels like coal, oil and gas”. But so far there seems a reluctance to accept that this must leave nuclear power as the only source that can safely and securely meet the ever-increasing energy demands of a growing world economy without endangering public health and the climate. There is no alternative.
Global Change and the Earth System: A Planet Under Pressure. Executive summary www.igbp.kva.se
Figures 8 (page 7) and 9 (page 8) from this paper show the rapid increase over
the last 50 years in all the human activities examined.
All of these depend on and will require an increase in energy consumption. Quite clearly the world has entered a new era in which we can no longer rely on fossil fuels.
Of the non-carbon energy sources, hydropower is limited by the number of suitable sites, while of the Renewables, wind and solar, are too intermittent to provide a reliable source of energy to fuel the expected growth.
This leaves nuclear power as the principal source to fuel the ever-increasing energy consumption of the Anthropocene.