7.4 Atmospheric CO2 and Particulates

Sources of CO2 and particulates

Carbon dioxide (CO2) enters the atmosphere mainly from burning fossil fuels, deforestation, and respiration. Particulates (soot, dust, ash) come from combustion, volcanic eruptions, agriculture, and industrial processes. Both natural and anthropogenic sources contribute, but human activity has sharply increased CO2 levels since the Industrial Revolution, as shown in ice core and atmospheric records like the Keeling Curve.

Effects on climate and health

CO2 is a major greenhouse gas, trapping heat and driving global warming. Particulates affect climate differently: black carbon (soot) absorbs sunlight and warms the atmosphere, while lighter aerosols like sulfates can reflect sunlight and cause cooling. Fine particulates (PM2.5) also penetrate lungs, worsening respiratory and cardiovascular disease in humans.

Tracking and reducing emissions

Scientists monitor CO2 using stations like Mauna Loa Observatory, revealing a steady rise with seasonal fluctuations from plant growth cycles. Reducing emissions involves carbon capture, switching to renewable energy, reforestation, and pollution controls like scrubbers and filters that trap particulates before they're released.

Key terms

Keeling Curve

A graph showing the continuous rise in atmospheric CO2 concentration with seasonal fluctuations, measured at Mauna Loa Observatory.

PM2.5

Particulate matter smaller than 2.5 micrometers; can penetrate deep into lungs and bloodstream, causing health issues.

Black carbon (soot)

A dark particulate from incomplete combustion that absorbs sunlight and contributes to atmospheric warming.

Sulfate aerosols

Light-colored particulates that reflect sunlight, causing a cooling effect on climate.

Carbon capture and storage

Technology that captures CO2 emissions from sources or the atmosphere and stores it underground to reduce greenhouse gas levels.

Try an AP-style question

Why is PM2.5 especially harmful to human health?

1. It dissolves harmlessly in rain
2. It penetrates deep into the lungs
3. It only affects plants and crops
4. It is too large to be inhaled