## TL;DR
Environmental science addresses humanity's most pressing challenge: understanding and mitigating anthropocentric changes to Earth's climate, ecosystems, and biogeochemical cycles.

## Core Explanation
Earth's systems: atmosphere (climate regulation), hydrosphere (water cycle), biosphere (living organisms), lithosphere (geological processes). Carbon cycle: photosynthesis fixes CO₂; respiration, combustion, and decomposition release it. Fossil fuel combustion has increased atmospheric CO₂ from 280 ppm (pre-industrial) to 420+ ppm (2024).

## Detailed Analysis
Climate impacts: sea level rise (3.7 mm/year), Arctic amplification (warming 3-4x global average), ocean acidification (pH decreased 0.1 since industrialization). Renewable energy (solar, wind, nuclear) deployment must accelerate 3-5x to meet Paris Agreement targets.

## Further Reading
- NASA Climate Change
- NOAA Climate.gov
- UN Environment Programme