Climate Change Modeling

Historical temperature trends, CO₂ correlation, and future projections

Ice-core records (Vostok, EPICA) show atmospheric CO₂ and temperature have been tightly coupled for 800,000 years, cycling between ~180 ppm (glacials) and ~280 ppm (interglacials). Since industrialization, CO₂ has risen to 420+ ppm — 50% above the highest natural level — driven by fossil fuel combustion and deforestation. The IPCC uses Shared Socioeconomic Pathways (SSPs) to project future warming: SSP1-2.6 (sustainable, ~1.8°C by 2100), SSP2-4.5 (middle of the road, ~2.7°C), SSP3-7.0 (regional rivalry, ~3.6°C), SSP5-8.5 (fossil-fueled, ~4.4°C). Key feedback loops include water vapor (amplifies warming), ice-albedo (less ice → more absorption), and permafrost methane release. The 'carbon budget' for 1.5°C is approximately 500 Gt CO₂ remaining.