The sun is setting on the most recent geological epoch, the Holocene, with its astonishing multitude of species and breathtakingly beautiful wild landscapes. Fuelled by an enormous spending spree which turns resources into waste at an alarming rate, we are entering the Anthropocene, an epoch marked, among others, by the fact that humanity's impact on planetwide natural processes is starting to exceed the regeneration ability of those processes.
For all the endangered species and all the species that are already lost this is truly the time of “Apocalypse Now”.
We have created a planetwide mass extinction event of species and are currently tinkering with the planet's climate control system. All the CO2-exhaust of all the coal, oil and gas that was burned since circa 1832 has permanently accumulated in the atmosphere. Some studies even fear that we might tip the scales towards a runaway climate change scenario.
There is so much information available about climate change today (which should rather be called climate destabilisation) that many can’t see the wood for the trees. So, let´s get back to basics. Just pretend with me that you are a future scientist and you are conducting experiments with planets.
|1.||First you take a planet like earth and remove the atmosphere, the water and everything else except for the stones on the surface. Now measure the temperature. Rays of sunlight that reach the ground are transformed into heat. This heat is reflected back into space. At noon, your experimental planet will therefore show a temperature of approximately +130°C on the surface because of direct sunlight exposure and at night just before sunrise you will measure a temperature of approximately –160°C because almost all heat has escaped into space, which has a temperature of –270°C. These are temperatures you currently find on the moon. On your experimental planet, you will get a calculated average temperature of minus 15°C, daily alternating between –160° and +130°C.|
|2.||Next you add an atmosphere of 78% nitrogen, 21% oxygen and 1% inert gases (similar to that on earth). Now the temperature is spread around the globe by this moving gas. The extreme temperatures of direct sunlight and frosty space are mixed but the result is still an average temperature of –15°C.|
|3.||Now you add a tiny amount of a so-called greenhouse gas to your atmosphere: for example carbon dioxide. It lets sunlight through but prevents the heat from radiating back into space by reflecting it back to earth (the greenhouse effect). It thereby creates a moderate and cosy planetwide temperature rise of +30°C. The surface temperature of your planet rises from –15°C to +15°C on average and you have created a more or less pleasant climate on your planet. Hurray!|
|4.||Instead of carbon dioxide you could also use water as a natural greenhouse gas on your experimental planet. But if you add water to your planet everything gets really complicated: the icecaps reflect sunlight like giant mirrors and clouds shield the surface from sunlight. Moreover, you get local weather patterns and now everything becomes really hard to predict. You need giant computer models to calculate what is happening with the temperatures all over the place. In the table below you can see the differences between your experimental planet with carbon dioxide as the sole greenhouse gas and earth with both, carbon dioxide and water vapor as greenhouse gases (plus a tiny amount of methane and traces of others just to make things a bit more complicated). Looking at the table you should by now understand the workings of a “greenhouse gas” per se and can see that even the extremely complicated predictions of computer models for the development of our earth’s climate have a simple basis.|
Your very simple experimental planet
| Extremely complex |
atmospheric computer model(s) for earth
|Average temperature without natural greenhouse gases||–15°C||–18°C|
| Temperature effect of |
natural greenhouse gases
| Type of natural greenhouse |
gases and their part of the
|Carbon dioxide|| Water vapor (36%-72%)|
carbon dioxide (9-26%)
traces of others (3-7%)
| Average temperature with|
natural greenhouse gases
On a blue planet that consists mainly of oceans, the amount of vapor in the air is directly related to the air temperature and cannot be controlled. This leaves just one main switch for the planetary heating system: carbon dioxide.
Between 1832 and 2016 we have turned the heat switch up from 284 parts per million (ppm) to 409 ppm by burning fossil fuels and converting them into carbon dioxide. This is an increase to 144% (409 ppm) in 2017 compared to 100% (284 ppm) in 1832.
It is very easy to trace the increase in carbon dioxide back to human industrial activities: Radiocarbon (the instable isotope 14C) is produced naturally in the atmosphere. Fossil fuels, which have been underground for millions of years, are devoid of 14C. First observed by Hans Suess in 1955 the dilution of atmospheric 14CO2 by fossil carbon provided one of the first indications that human industrial activities were strongly affecting the global carbon cycle.
We start a second experiment: This time we put a kettle on and watch the water while it heats up. While we are watching, the water starts to move around faster and faster until it finally starts to boil. The same principle applies to the atmosphere (although gas is not as heavy as water and therefore moves more easily). If it gets warmer, it moves faster. Top wind speeds increase. Faster winds can carry more weight, thereby increasing the size of hail before gravitation kicks in. If the air moves faster there will also be more clashes of very warm and very cold air with violent interchanges resulting in an increase in storms. Warmer air can soak up more water. This water will come down eventually, so we will see more flooding.
If water gets warmer it expands, so the sea levels rise as the oceans expand. Even the crust of the earth will expand resulting in increased pressure on tectonic plates which might generate more earthquakes. Do we really want all that? Can we afford to pay both the economic and the human costs?
In general terms, the direction of human-made climate change is not very difficult to understand. By burning fossil fuels since the start of the industrial revolution we have pretty much been conducting an experiment on our planet which is the basis of our very own lives. Increasingly, it looks like our real-life experiment is not going to turn out very well for us – unless we put a stop to it soon.
The English “List of periods and events in climate history” with its sub-links is very good, although a bit overwhelming: List of periods and events in climate history
Global Temperature Change 1850 to 2016
https://www.climate-lab- book.ac.uk/2016/spiralling-global- temperatures/
|Paläo-Temperature of the last 500 000 000 years, |
complied from different proxy-data batches
Paläo-Temperaturkurve der letzten 500 Millionen Jahre,
erstellt aus einer Reihe verschiedener Proxy-Daten
(Zero ist the average temperature 1960 to 1990)
|CC BY-SA 3.0|
File: All palaeotemps G2.svg
Erstellt: 8. August 2014
Here is a graph from Wikipedia showing the state of the art on the entire earth's climate history. Despite the small number, a plus of 2.5°C looks quite scary on this scale. Moreover, you can see quite severe climate fluctuations showing that there are some kind of tipping points involved that we do not completely understand yet. What you cannot see on this scale is the fact that former climate changes usually took several thousand to 100,000 years instead of the current change that is taking only 100 to 150 years. Animals and plants can hardly adapt to evolutionary changes that are this fast. They need to move away from their habitat. If they are "trapped" on a mountain, on an island, in a lake, on a reef or near the coast where they are surrounded by "hostile" environment, they will soon need relocation or they will die out. Whether human agriculture can adapt remains to be seen.
Glaciers and the polar ice caps reflect sunlight like gigantic mirrors. In contrast to when sunlight hits the ground, this sunlight is not converted into heat but is instead reflected back into space. When glaciers and polar ice caps melt, the size of these reflecting mirrors shrinks and the new ice-free ground turns sunlight into heat. This heat is then captured in the lower atmosphere by carbon dioxide. The planet is getting warmer. In addition, the melting of ice absorbs a lot of energy. What will happen to this energy when all ice is gone?
The great currents of the oceans depend on differences in water temperature and salinity. The Gulf Stream, for example, transports vast amounts of energy from the tropics to the North Pole thereby warming Western Europe. Then it transports cool water back down south. If you change the salinity of the seawater by adding large amounts of meltwater from melting polar ice caps and in addition change the water temperature, the currents might slow down and stop eventually. A collapse could produce severe cooling in Europe and North America even while global warming is still in progress. The changes could be quite sudden, like a five degree drop in average temperature in a single decade. Research shows that it might lead to harsher winters in Europe and North America and severe drought in Australia, South America and southern Africa. That global warming can lead to cooler local climate is confusing for some people but it is all part of the same climate change pattern.
The meltdown of the polar ice caps and the expansion of warmer water in the oceans leads to a measurable rise in sea level (approximately 20 cm so far). While a few are still discussing whether climate change really exists, The Netherlands have already started a program to increase the height of all their dams and are spending two billion Euros annually to protect their land from the rising sea.
The permafrost belt currently covers 20% to 25% of the land area of the earth, mainly in Canada and Russia. The moors of the permafrost belt contain huge amounts of frozen methane (swamp gas). Methane captures heat 25 times better than carbon dioxide. Melting permafrost soil might release large amounts of the greenhouse gas methane into the atmosphere, leading to an acceleration in global warming. In recent decades, the Siberian swamps, for example, have started to thaw.
Under certain conditions of cold water temperature and pressure, methane forms ice. The oceans contain enormous amounts of this so-called shelf ice or methane clathrates. A change in water temperature could lead to a massive release of vast amounts of additional methane into the atmosphere. Then the heat really will be on.
For further information search the net with keywords like `methane plume´, `clathrate gun hypothesis´ or `Palaeocene–Eocene Thermal Maximum (PETM)´.
The global increase in population has called for a global increase in food production. The use of mineral fertilizers and pesticides has led to an unprecedented rise in food production all across the planet. But this so called “Green Revolution” has many unwanted by-products. For example, massive cattle herds lead to massive release of methane (the greenhouse gas 25 times as potent as carbon dioxide) and massive use of mineral fertilizer releases large amounts of nitrous oxide N2O (a greenhouse gas 298 times as potent as carbon dioxide). Cutting down forests to produce pasture land or forage crops is another part of the climate change programme.
You can buy carbonized “sparkling” water at your local shop. It is acidic, it burns in your mouth. The same happens to the oceans. The oceans have absorbed much of the carbon dioxide that was released from fossil fuels since 1830 as carbonic acid and will continue to absorb more. This is called acidification of the oceans. They turn into sparkling water. The acid dissolves the calcium skeletons of some plankton and corals, thereby killing them. But plankton is one of the major recyclers of carbon dioxide to oxygen – whoops – and of course major part of the food chain in the oceans.
As the water in the oceans becomes warmer than ever, corals can´t stand the heat and die off. Coral bleaching is the result. Coral reefs are the kindergarten of life in the oceans.
Giant amounts of carbon dioxide are recycled from the atmosphere by plants. Forests contain large amounts of stored carbon from carbon dioxide. Unfortunately, humans have been cutting and burning them down at an astonishing rate, releasing the formerly stored carbon dioxide.
On top of climate change and its worldwide effects on animals and plants the overpopulation of the earth leads to a fierce competition for available space between humanity and all the other plant and animal species. This is called habitat loss. It occurs due to development: housing projects, farming projects, street and transportation projects and industrial projects. Further habitat loss occurs through waste and pollution like mine effluents or oil spills. Finally, some species are wanted for food (overfishing of the oceans), health issues, recreational issues or status issues (poaching, hunting) and some species are undesirable because they threaten food production or health (many insects and weeds, hence the overall use of pesticides). Insect die-off leads to a loss of insect-eating animals (many birds, some mammals) and the breakdown of certain food chains. Some species are threatened by accident or as a by-product of development. Many night insects are irritated by street lights and have been vastly diminished due to so called light pollution. Insects, birds and other animals are also prone to frequent road kill.
All these effects together have led to a loss in species today that equal a planetwide sixth mass extinction event. We are losing the diversity, resilience and beauty of our home planet at an astonishing speed. Butterflies, bumblebees, birds, mammals, amphibians, reptiles and orchids are all tumbling into the abyss of extinction. Welcome to the Anthropocene.
A graph published recently in Yuval Noah Harari’s bestselling book Homo Deus (Penguin Random House UK 2015, page 72) states that today’s biomass of large animals worldwide can be divided as follows: