GEO4990/9990 The Earth System - Course Notes

Course Goals

  1. Understand dynamics and interactions of Earth System spheres and their impact on climate.

  2. Assess human influence on the Earth Climate System.

  3. Explore methods in climate sciences for assessing changes.

Key Course Materials

  • IPCC Report: 6th Assessment Report (2021), selected chapters on Canvas.

  • Lectures Include: Contributions from special guests (e.g., Jan Fuglestvedt, Heiko Goelzer).

Core Concepts of Earth Climate System

  • Interconnected Spheres: Atmosphere, hydrosphere, cryosphere, geosphere, biosphere interact dynamically.

  • Energy Balance: Solar energy drives climate; energy input/output affects global temperatures (radiative equilibrium).

Climate Feedback Mechanisms

  • Positive Feedback: Self-reinforcing processes (e.g., water vapor feedback).

  • Negative Feedback: Self-diminishing processes.

Climate Change Drivers

  • Radiative Imbalance: Caused by factors like greenhouse gases, land use changes, and solar variances affecting energy budget.

Methods of Study

  • Earth System Models: Discretization, parametrization, model comparison.

  • Ensemble Simulations: Multi-model, initial condition, and perturbed parameter ensembles used to assess uncertainties.

Assessment and Confidence in Climate Science

  • Evidence Evaluation: Analyzing data from observations, experiments, and models.

  • Terms of Likelihood: Ranges from "extremely unlikely" to "virtually certain."

Further Study Questions

  • Distinguish between weather and climate.

  • Identify positive and negative climate feedbacks.

  • Explore Shared Socioeconomic Pathways (SSPs) and climate forcing mechanisms.