Carbon Cycle and Climate Impact

Overview

This lecture covers the carbon cycle, its connection to climate change, and the environmental impacts of processes like combustion, photosynthesis, and the greenhouse effect.

Carbon Sinks and Carbon Movement

• Four carbon sinks: atmosphere, oceans, biosphere (living things), and geosphere (rocks/soil).
• Carbon enters sinks via processes like photosynthesis (biosphere), dissolution (oceans), and deposition (geosphere).
• Carbon leaves sinks through respiration (biosphere to atmosphere), combustion (geosphere to atmosphere), and outgassing (oceans to atmosphere).

Carbon as the Element of Life

• Carbon is the element of life because it forms the backbone of organic molecules essential for organisms.

Ocean Acidification and Ecosystem Impact

• Ocean acidification is the decrease in ocean pH due to increased CO₂ absorption.
• It harms marine life by affecting shell formation and disrupting food webs.

Combustion vs Cellular Respiration

• Both combustion and cellular respiration convert carbon-based molecules and O₂ into CO₂ and energy.
• Both release energy but combustion is faster and uncontrolled.

Photosynthesis and Gas Exchange

• Photosynthesis and gas exchange both involve the movement of CO₂ and O₂ between organisms and their environment.
• Both regulate atmospheric gases essential for life.

The Greenhouse Effect (Diagram not drawn)

• Solar energy enters Earth's atmosphere, some is absorbed (warming Earth), and some is re-radiated as heat.
• Greenhouse gases trap this re-radiated heat, warming the atmosphere.

Carbon Pathways: Atmosphere and Biosphere

• Carbon enters the atmosphere via respiration, combustion, and volcanic eruptions.
• Carbon enters the biosphere through photosynthesis.

Carbon Leaving the Atmosphere and Biosphere

• Carbon leaves the atmosphere through photosynthesis and absorption by oceans.
• Carbon leaves the biosphere via respiration, decay, and fossilization.

Fossil Fuel Combustion and the Greenhouse Effect

• Burning fossil fuels increases atmospheric CO₂, enhancing the greenhouse effect and causing global warming.

Global Warming vs Climate Change

• Global warming refers specifically to rising average global temperatures.
• Climate change includes global warming plus broader changes in weather patterns.

Effects of Climate Change

• Sea level rise leads to flooding of coastal areas.
• More extreme weather events damage ecosystems and communities.
• Ocean acidification harms marine biodiversity.

Greenhouse Effect: Positive and Negative Impacts

• Positive: Greenhouse effect keeps Earth warm enough to sustain life.
• Negative: Excess greenhouse gases cause overheating and climate disruptions.

Graph Trends and Natural Factors

• General trend: long-term increase in global temperatures.
• Three natural factors: volcanic activity, solar radiation, and ocean circulation.
• Natural factors cause short-term variations but do not explain the long-term warming trend.

Key Terms & Definitions

• Carbon Sink — a reservoir that stores carbon.
• Ocean Acidification — the lowering of ocean pH due to CO₂ absorption.
• Greenhouse Effect — trapping of heat in Earth’s atmosphere by greenhouse gases.
• Biosphere — all living things on Earth.
• Geosphere — Earth's solid rocks and soils.

Action Items / Next Steps

• Review assigned textbook sections on the carbon cycle and climate change.
• Practice drawing and labeling the greenhouse effect diagram.
• Analyze provided climate graphs for trends and factor impacts.