Climate Science: Understanding Earth's Changing Climate

The Greenhouse Effect

Earth receives 340 W/m² solar radiation. Without greenhouse effect, surface temperature would be -18°C instead of +15°C. Greenhouse gases absorb and re-emit infrared radiation: CO₂ (66% of forcing), CH₄ (16%), N₂O (6%), halocarbons (12%). CO₂ concentration: 280 ppm (pre-industrial) → 424 ppm (2024) — highest in 800,000 years (ice cores). CO₂ lifetime: centuries to millennia. Methane: 80× more potent than CO₂ over 20 years, but shorter lifetime (~12 years). Sources: fossil fuels (73%), deforestation (11%), agriculture (12%), industrial processes (4%). Radiative forcing: +2.72 W/m² (2019) relative to 1750.

Climate Models

General Circulation Models (GCMs): discretized atmosphere/ocean on 50-100 km grid, solving Navier-Stokes equations with thermodynamics. Earth System Models (ESMs): add carbon cycle, vegetation, ice sheets, biogeochemistry. CMIP6: Coupled Model Intercomparison Project — 100+ models from 50+ institutions. SSP scenarios: SSP1-1.9 (best case, 1.5°C), SSP2-4.5 (middle), SSP5-8.5 (worst case, 4-5°C). Equilibrium Climate Sensitivity (ECS): warming from doubling CO₂ — likely range 2.5-4.0°C (IPCC AR6). Transient Climate Response (TCR): 1.4-2.2°C. Model limitations: cloud feedback (largest uncertainty), convection parameterization, tipping point dynamics.

Observed Changes

Global mean temperature: +1.1°C since pre-industrial (2011-2020 average). Rate: +0.2°C/decade (2010-2023). Arctic warming: 2-3× global average (Arctic amplification). Sea level rise: +3.7 mm/year (2006-2018), accelerating. Ice loss: Greenland losing 270 Gt/year, Antarctica 150 Gt/year. Arctic sea ice: -13% per decade (September minimum). Ocean heat content: 90% of excess heat absorbed by oceans, +0.88 W/m² (0-2000m). Extreme events: heat waves 2.8× more likely, heavy precipitation +7%/°C warming. Ocean acidification: pH decreased by 0.1 (26% increase in acidity). Permafrost thawing: 10% loss since 1980s.

Impacts

Agriculture: yield reductions in tropics (maize -7%/°C, wheat -6%/°C). Water: increased drought in subtropics, flooding in high latitudes. Biodiversity: 1 million species at extinction risk (IPBES). Coral reefs: 70-90% lost at +1.5°C, >99% at +2°C. Health: heat stress mortality, vector-borne disease expansion, air pollution. Sea level rise: 1 billion people in low-elevation coastal zones at risk. Climate migration: World Bank estimates 216 million internal climate migrants by 2050. Economic costs: 2-3% global GDP loss per degree of warming. Feedback loops: permafrost methane, ice albedo, Amazon dieback.

Mitigation and Adaptation

Net zero by 2050 required for 1.5°C target (IPCC AR6 WGIII). Energy transition: renewable electricity (solar LCOE: $0.049/kWh in 2023), wind, nuclear, storage. Electrification: EVs, heat pumps, industrial processes. Carbon capture: point-source CCS, direct air capture (Climeworks, 4000 tCO₂/year). Nature-based solutions: reforestation (0.9 Gha potential), peatland restoration, blue carbon. Methane reduction: oil/gas leak detection, enteric fermentation reduction, rice paddy management. Green hydrogen: electrolysis using renewable electricity — steel, shipping, ammonia. Carbon pricing: EU ETS (€80-100/tCO₂), carbon border adjustment mechanism. Adaptation: drought-resistant crops, flood infrastructure, early warning systems, climate-resilient cities.

Try it live

Everything above runs in your browser — open Climate-Ecology Biome Shift Model and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.