What has been the dominant gas in Earth’s atmosphere from 4.6 to 2.7 billion years ago?
Carbon dioxide (CO₂)
Released by volcanic activity, along with nitrogen (N₂) and water vapor (H₂O).
What process significantly reduced carbon dioxide levels in the atmosphere from 2.7 billion to 200 million years ago?
Photosynthesis by algae and later plants
The equation is 6CO₂ + 6H₂O + light → C₆H₁₂O₆ + 6O₂.
What gases are considered greenhouse gases?
- Carbon dioxide (CO₂)
- Methane (CH₄)
- Water vapor (H₂O)
These gases absorb and re-emit radiation, trapping heat in the atmosphere.
What is the primary consequence of increased greenhouse gases in the atmosphere?
Global warming
This leads to an increase in Earth’s average temperature.
What are some effects of global climate change?
- Sea level rise
- Extreme weather events
- Changes in rainfall patterns
- Impacts on ecosystems
- Melting of polar ice caps
These changes are driven by global warming.
What is a carbon footprint?
The amount of carbon dioxide and methane released into the atmosphere by a product, person, or process
Important for understanding individual and collective environmental impact.
True or False: The Earth’s atmosphere currently consists of approximately 80% nitrogen.
True
Current composition includes ~20% oxygen, ~0.04% carbon dioxide, and very little water vapor.
What pollutants are released from the incomplete combustion of fuels?
- Carbon monoxide (CO)
- Particulates (soot and unburnt hydrocarbons)
- Sulfur dioxide (SO₂)
- Oxides of nitrogen (NOx)
Each has detrimental effects on health and the environment.
Fill in the blank: The process by which plants and algae use sunlight, water, and carbon dioxide to create energy is called _______.
Photosynthesis
What is the role of volcanoes in the early Earth’s atmosphere?
They released gases and ash, contributing to the composition of the early atmosphere
Important for understanding atmospheric evolution.
What is acid rain?
Rain that is acidic due to atmospheric pollution
Caused by pollutants like sulfur dioxide and nitrogen oxides.
What is the significance of studying ice cores in climate science?
They provide evidence of atmospheric composition over millions of years
Useful for understanding historical climate conditions.
What challenges exist in predicting climate change?
The atmosphere is a complex system
This complexity can lead to skepticism about climate models.
What are some sources of methane emissions?
- Rice cultivation
- Cattle farming
Significant contributors to greenhouse gas concentrations.
What does the term ‘combustion’ refer to?
The process of burning something
Often associated with the release of pollutants.
What is the current percentage of carbon dioxide in the Earth’s atmosphere?
~0.04%
This is a critical factor in understanding greenhouse gas concentrations.
