Life on Earth is not just an assembly of all living things, but also an intricate, diverse and complex self-regulating system striving towards a state known as a dynamic equilibrium. This means that when minor disturbances occur within the eco-systems, or because of outside disturbances, the eco-systems react in a manner that restores balance.

Of course, over longer periods of time, species will go extinct or evolve into new species, and environments will change. The system itself, however, tend to favor increased levels of complexity.

On the global level, we can talk about a biosphere, which in itself affects the atmosphere and other systems which it depends on. The biosphere is simply all the life on Earth, excluding isolated eco-systems (like the deep ocean gas vent eco-systems, the eco-systems in Antarctic lakes or those in closed caves like the Movile system near the Black Sea).

Minor disturbances occur on a frequent basis, are natural and serve as an important impetus for the evolutionary process. Even most large disturbances can be absorbed by the system, and hundreds of such events have happened during the existence of this biosphere.

However, some large disturbances have off-set the balance so much that the biosphere itself has collapsed. The biosphere that we human beings currently are a part of is actually the sixth biosphere in the Earth’s history. It is characterized by land-based eco-systems dominated by mammals and avian (bird) dominance of the skies.

These characteristics have existed for 65 million years, following the end of the Mesozoic biosphere, which was dominated by dinosaurs and sea reptiles, an era mostly characterized by a warm climate and more and smaller continents than today. What brought the end of the Mesozoic had been debated since the latter half of the 19th century – most scholars today are agreeing that the Chicxulub asteroid impact hypothesis is the most believable cause for a mass extinction which wiped out around three quarters of life on Earth.

Today, scientists are estimating that we are losing species at a thousand to ten thousand times the normal background rate. This corresponds to the rate experienced by the biospheres during the previous mass extinction events. Moreover, the characteristics of the systems which are affected by and affecting the eco-systems are rapidly changing. These three systems are the atmosphere, the hydrosphere and the lithosphere – which can be called air, water and earth respectively.

The Climate

For the last millions of years, Earth’s climate has been characterized by a flow between warm periods and ice ages when large parts of the northern hemisphere have been covered by large glaciers. The main regulating atmospheric gas which has governed these seasonal climate shifts have been carbon dioxide, a greenhouse gas which heats the Earth by blocking the reflection of sunrays out from the atmosphere, thus trapping heat.

Carbon dioxide is also one of the gasses that is “breathed” by and stored by vegetation – and then especially trees. The relationship between the forests and the atmosphere have until recently determined the shift between warm periods and ice ages.

During ice ages, forests consume and bind carbon dioxide, reducing the amount of greenhouse gasses in the atmosphere – and thus the climate is becoming colder. This leads to glaciers spreading out throughout the northern hemisphere, which are replacing forests and also binding water, creating a more desert-like and drier climate throughout the Earth.

Such a drier climate leads to forest fires, the spreading of grasslands and deserts and the replacement of boreal forests with tundra. All of these processes serve to liberate carbon dioxide, which heats the Earth. When the Earth is warming, glaciers are melting, creating more water that can be released into the hydrological system, increasing annual rainfall, thus allowing forests to spread out and bind carbon – thus the process repeats itself.

From the 13th century, the Earth was actually starting to enter yet another Ice Age, and the world became regressively colder until the 1860’s, when the climate suddenly first began to stagnate, and then to shift towards an increase in average temperatures.

The reason for this is that the Industrial Revolution has relied on the usage of energy stored in coal and oil, which releases additional carbon when burnt. This means that the amount of carbon dioxide in the atmosphere continuously has increased due to human intervention, and the climate is currently increasing at the greatest rate since we first started to measure it back in the 19th century.

Right now, it is estimated that the average temperature of the planet’s surface will increase by more than two degrees this century, which will present an enormous challenge, especially as it will affect global rainfall and drought patterns, transforming the conditions of agriculture and human inhabitation in the most populated regions of Earth. Additionally, it can lead to the partial or complete collapse of the Greenland ice shelf, the largest inland glacier system on the northern hemisphere – and the subsequent rise of sea levels.

Most of the large cities world-wide are coastal, and the situation could produce hundreds of millions of refugees at the end of this century.

The Oceans

Covering two thirds of the Earth’s surface, the Oceans and Seas are extremely important – especially as they play an important role regulating the planet’s weather and climate. Apart from that, the first advanced eco-systems on Earth were oceanic eco-systems. When the surface of continents were nothing but inhospitable deserts, the seas thrived with coral reefs and a complex biosphere containing tens of thousands of species.

The oceans today are still the home of beautiful and diverse eco-systems – home for beings ancient like the jellyfish, or intelligent like whales. Despite their abundance of life, the oceans are very sensitive however, as much of the diversity is bound to just small parts of it.

The coral reefs, the lungs of the oceans, are far more susceptible to pollution damage than previously thought, and many reefs have either collapsed or are in a state of slow dying.

Overfishing has taken its toll on nearly two thirds of assessed fish stocks worldwide, and while demand is creeping up, the reduction of oceanic biomass has made ocean wildlife a shadow of what it was just forty years ago.

The oceanic eco-systems are some of the most sensitive on the planet, and their collapse may happen well in advance of other collapses which we may see occur at a later date.

The Soils

The soils – once nutrient-rich and deep – are the result of millions of years and tens of thousands of generations of beings that have lived, eaten and died on land, as well as the outcome of the grinding, flooding forces of nature that have nagged down rock into grains and freed minerals. Plants and trees have bound the soil and served to create firm ground, and are in their turn dependent on soil for their survival. The lithosphere – the global soil layer – is what makes life on land possible.

That is why soil degradation is a global environmental problem on the same level as climate change. Reduction of organic matter, erosion, structural deterioration and the effects of changed rainfall patterns all contribute to a decline in the quality of soils on a global level.

To a large extent, this is caused by the expansion of pastures and of high-intensity mono-cultures. In traditional eco-systems, hundreds of species of plants co-exist with one another and return nutrients to the earth when they die. In high-intensity industrial agriculture, the goal is to get the produce to the markets as quick as possible, without any regard to the needs of the soil. If the soils are unable to cope, then you can simply use artificial fertilizers to increase the yields.

For the last 150 years, half of the topsoil of the planet has been lost, and a third of the arable land has become unproductive, according to the World Wildlife Fund.

Freshwater Reserves

Only 2,5% of the water on Earth consists of freshwater – which is distributed in lakes, rivers, brooks and aquifers throughout the world. Freshwater is absolutely paramount for the well-being of the world’s eco-systems. Throughout millions of years, rainwater has been stored in the soil through root systems which later decay.

This has built up large aquifers of freshwater underground, that can sustain both eco-systems and human activities. The amount of freshwater has been near constant since the days of the Dinosaurs. That is… until now.

Sadly, water scarcity is on the rise globally, as cities, water-intense industrial and agricultural practices and other forms of activities are leading to us using up more freshwater than rainfall can renew. Moreover, climate change is causing a melting of glaciers which can turn large swathes of the most populous nations on Earth into desert-like regions.

This crisis has today affected one third of Earth’s freshwater systems, and by 2025, two thirds of the global population may face water shortages.

The sixth mass extinction

Currently, species are disappearing at a rate thousands of time exceeding what has been normal for the last 65 million years. Not only large animals are vanishing, but also small animals, plants and insects. Moreover, more and more species are becoming threatened by extinction, as their gene pools collapse and they are isolated into remote pockets – unable to migrate and have access to their living space.

There are many causes, from climate change and regional environmental crises, to poaching, poisons and destruction of habitats. One of the main reasons can be said to be out-crowding. Monocultures, highways, infrastructure projects, urban sprawls and other activities are now more surrounding nature than nature is surrounding it.

That means that eco-systems are physically being pushed aside, and that species are split in isolated pockets that lead to inbreeding and stagnation. Even if species such as the various tigers survive due to conservation, they are today living at the mercy of human intervention, and will do so for a foreseeable future.

Not even seed banks, zoological gardens or genetic samples can salvage threatened species – because a species is not only a collection of individuals, but a product of their particular environment. When that environment is destroyed, there’s often no room for specialized animals to survive.

By mid-century, it is estimated that a third to half of all species on Earth may face extinction, which will make the events which are to unfold the worst disaster for life on Earth for 65 million years.