The Biosphere

The biosphere includes all life on our planet. It is not only all the things that are living, but also the remains of organisms that have died and not yet decomposed. It also includes the regions of the other parts of the Earth system (atmosphere, hydrosphere, geosphere) occupied by living organisms. For hundreds of years, people have recognized connections between living things and the climate (for example, cutting down the trees of a forest can change the temperature of the immediate area). Still, although the term “biosphere” was first coined in the 1920s by Russian scientist Vladimir I. Vernadsky, focused studies of the biosphere’s interactions with the rest of the planet were not underway until the 1960s and later decades.
 

photo of avocets in flight over water

The biosphere includes all living things, both plants and animals, as well as their habitats.

National Park Service

 

How the Biosphere Influences the Earth System

 
In the 1960s, scientists began actively exploring how biological processes, both natural and those due to humans, affect Earth’s atmosphere. For instance, in just a short amount of time, the length of a season, plants change the world. When it is spring and summer in the Northern Hemisphere, more plants are around to photosynthesize and extract carbon from the atmosphere, decreasing the amount of carbon dioxide by about 3% by the time fall arrives. When many of the Northern Hemisphere plants drop leaves and become dormant in the autumn and winter, there is less photosynthesis occurring, leading to more carbon dioxide in the atmosphere in late winter and early spring.
 

animation of global vegetation cycle over one year

Every year, vegetation in Earth’s biosphere changes dramatically with the seasons.

NASA

Dr. Charles Keeling began making his now-famous measurements of carbon dioxide in the atmosphere in 1958 from the top of Mauna Loa in Hawaii. The graph of Keeling's data captures this natural fluctuation, visible as yearly wobbles in the carbon dioxide values linked to photosynthesis. Keeling’s graph of atmospheric carbon dioxide concentrations became known as the "Keeling Curve" and helps illustrate the impact of the biosphere on the atmosphere.
 

carbon dioxide measurements from Hawaii by scientist Charles Keeling

Since 1958, scientist Charles Keeling and others have measured the amount of carbon dioxide in Hawaii's atmosphere. The yearly fluctuations in carbon dioxide are due to seasonal plant growth, while the overall rise in carbon dioxide over many years is due to a combination of fossil fuel burning, deforestation, and cement production. 

L.S. Gardiner/UCAR

 
Keeling’s data tell another story too. At the close of each year, the carbon dioxide levels are a bit higher than they were the year before. The values  look like they are heading uphill on the graph because of an increase in carbon dioxide over several decades. These data were the first concrete evidence that the amount of carbon dioxide in our atmosphere has been increasing over time, and viewing Earth as a system can help us understand why.
 
As part of the biosphere, humans account for just 0.01% of Earth’s biomass. Even at that small scale, our impacts on the overall Earth system can be quite large, whether or not we expect them to be.  For example, since 1750, the amount of carbon dioxide in the atmosphere has increased from a relatively stable 280 parts per million to over 420 parts per million in 2022. That’s an increase of nearly 50%, which seems dramatic. But it didn’t happen all at once. As humans began extracting and using more and more fossil fuels, carbon dioxide amounts in the atmosphere began to slowly increase, causing the uphill appearance of the Keeling Curve. Each year, the extra carbon dioxide added into the atmosphere accumulates, so that for every year and every decade, the total amount continues to rise.  

Gaia: Balance in the Earth System

view of Earth from space showing clouds, continents, and ocean

Earth behaves as a single system where all of the individual components, including atmosphere, oceans, land, and life, are interconnected.

The Gaia hypothesis, developed by James Lovelock in the 1970s, proposed that living organisms interact with their surroundings as part of a complex but self-regulating system to maintain and perpetuate the conditions allowing life to thrive. The main tenet of the Gaia hypothesis is that our planet is analogous to a single cell — everything it has or could need is contained within the cell, aside from energy that comes in from the Sun.  On some levels, this is a challenging concept, and the ability of the Earth system to “self-regulate” in the face of multiple changes and stressors has not been unequivocally proven. However, the general idea of Earth as a contained system, balanced by the interactions between its components, is now widely accepted. Lovelock’s hypothesis links well with the concept of Earth as a system, which illustrates that the parts of our planet are interconnected in a multitude of ways.

Today, interdisciplinary research combining biochemistry, geochemistry, biology, hydrology, and atmospheric science helps us to better understand the biosphere’s role in the Earth system and, in particular, how biogeochemical cycles affect the Earth system. This understanding of the biosphere forms part of the framework utilized by supercomputer models, which describe and predict Earth’s climate.

 

 

Learn More