For me, our earth is a fascinating and mysterious place. Already the existence of a planet with liquid water and life is an absolute miracle and can put everything else into perspective when you think about it. It is also a pleasure to explore how everything on our planet is working and to explore its secrets, which are of infinite number.

To better understand the complexity of earth, I find it easier to regard it as a unity consisting of different parts, meaning the earth’s four spheres: the lithosphere, the atmosphere, the hydrosphere, and the biosphere. The lithosphere consists of all the rocks of the earth crust and the upper part of the earth mantle. The atmosphere includes all the air from just below the surface until up to 10 000 m above the earth surface. The hydrosphere is composed of all the earth’s water, mainly oceans, lakes, and rivers, as well as groundwater, ice, and water vapor. And the biosphere consists of all living organisms.

Every sphere on its own is already fascinating to study. The fields of biology and geology cover the biosphere and lithosphere, respectively. The atmosphere is studied by different fields, like meteorology and atmospheric sciences. The hydrosphere is also covered by different fields, like hydrology, limnology, meaning the study of inland waters, or oceanography. For all of the four spheres, physics and chemistry are essential to understand underlying processes. In all of these fields researchers accomplished already great achievements in describing and understanding the four individual spheres.

In the Environmental Sciences, a great focus lies on the interactions between these four spheres. Everything on this planet is connected in many ways! And that is what fascinates me the most about the environment.

I just want to give some examples of how everything is connected. Live has conquered many habitats, there are not only plants and animals living on land and in water and birds flying in the air. Especially microorganisms are incredibly adaptive to many sorts of hostile conditions. They live in hot water with temperatures over 100 °C and inside frozen water. They live in the most toxic environments, where nothing else can survive. They live in the air and they live deep under to earth’s surface, inside the rocks. This is super cool if you ask me 🙂 Not only has life conquered the other three spheres, it also depends on them. Every living cell needs water and many essential nutrients, which come from minerals of the lithosphere. And not all, but many organisms like plants and humans depend on gas exchange with the atmosphere, especially of oxygen and carbon dioxide. The atmosphere is also exchanging gases with the hydrosphere. Many gases dissolve in water, meaning in the oceans and inland waters. Water vapor, as part of the hydrosphere, is anyway located in the atmosphere. The atmosphere is also shaping the lithosphere by wind erosion and oxidation of the earth’s surface. Volcanos release gases to the air, shaping its composition. Water is also often located in the rocks as groundwater, it is eroding them, and in exchange compounds from the rocks dissolve in water. And there are many, many more interactions, which we know or don’t know yet.

As fascinating and complex all of the connections in the environment are, as many are the influences that humans have on the earth and its spheres. For instance, the burning of fossil fuels, taken from the lithosphere, changes the composition of the atmosphere by increasing the concentration of greenhouse gases, which also alter the chemistry of water as consequence of gas exchanges between water and air. Greenhouse gases absorb energy from the sun, heat the earth, cause ice to melt and increase the ocean’s water level. Forests are burned, natural habitats destroyed, and at the same time biodiversity drops. Life is forced to adapt to a changing environment faster than ever. Agriculture enhances soil erosion and loss of fertile soils. Water of lakes and groundwater are taken and rivers are re-directed for human purposes, what changes the impact the water has on the surrounding rocks. And finally, human made pollution is everywhere and alters the environment, for instance in oceans, in the groundwater, in soils, in the air, and in the food web. The parts of the environment that are influenced by humans, are also called the anthroposphere.

These are just examples of the complexity of nature and the chains of interactions. Eventually, what people do to the earth, is coming back to them, in the form of increasingly scarce resources, health threatening pollutions, and other deteriorations of our living conditions. This is both frightening, as all of us have to suffer the consequences, and motivating to start getting active and to do something to protect our astonishing environment. And to take measures and to protect the earth, it is essential to understand the science of how our environment works and what effects humans have on it.