During the Carboniferous period, plant growth was extensive but rates of decomposition slowed (probably due to the formation of vast, oxygen-poor swamp habitats). As a result, large amounts of biomass accumulated in terrestrial environments (much of this biomass is now coal). The fossil record indicates that atmospheric oxygen increased, atmospheric carbon dioxide decreased, and global temperatures dropped. Explain why.

Verified step by step guidance

1. Step 1: Understand the Carboniferous period. During this time, plant growth was extensive due to the warm, humid climate. The plants absorbed carbon dioxide (CO2) from the atmosphere for photosynthesis, a process that also releases oxygen (O2) into the atmosphere.
2. Step 2: Understand the role of decomposition. Decomposition is a process where dead organic material is broken down into simpler forms. This process is usually carried out by decomposers like bacteria and fungi, and it requires oxygen. In the oxygen-poor swamp habitats of the Carboniferous period, decomposition slowed down, leading to the accumulation of large amounts of biomass.
3. Step 3: Connect the accumulation of biomass to the formation of coal. Over millions of years, the accumulated biomass was buried and subjected to heat and pressure, transforming it into coal. This process effectively sequestered the carbon in the biomass, preventing it from being released back into the atmosphere as CO2.
4. Step 4: Understand the effect on atmospheric gases. The extensive plant growth and slowed decomposition led to a decrease in atmospheric CO2 (as it was absorbed by plants and sequestered in coal) and an increase in atmospheric O2 (as it was released by photosynthesis).
5. Step 5: Connect the changes in atmospheric gases to global temperatures. CO2 is a greenhouse gas, meaning it traps heat in the atmosphere. Therefore, a decrease in atmospheric CO2 would lead to a drop in global temperatures.

Key Concepts

Carbon Cycle

The carbon cycle is the process through which carbon is exchanged between the atmosphere, land, water, and living organisms. During the Carboniferous period, extensive plant growth led to increased carbon fixation through photosynthesis, which reduced atmospheric carbon dioxide levels. This process is crucial for understanding how biomass accumulation can influence global carbon levels and climate.

Decomposition and Biomass Accumulation

Decomposition is the breakdown of organic matter by microorganisms, which releases carbon back into the atmosphere. In the Carboniferous period, slower decomposition rates due to oxygen-poor swamp habitats allowed for the accumulation of biomass, which eventually transformed into coal. This accumulation is significant as it represents a long-term storage of carbon that affects atmospheric composition.

Atmospheric Changes and Climate Impact

Changes in atmospheric composition, such as increased oxygen and decreased carbon dioxide, can significantly impact global temperatures and climate. The rise in oxygen levels during the Carboniferous likely contributed to cooler global temperatures, as higher oxygen concentrations can enhance the efficiency of photosynthesis, further reducing carbon dioxide levels and influencing climate patterns.