Climate Models: Tools for Predicting Global Climate Changes

Climate model: A set of thousands of equations for all processes that affect climate and move heat energy around the world. Can be used to predict climate.

Energy Balance Model Equation: Stefan-Boltzmann Equation - amount of radiation by a body depends on its temperature. Warmer temps means higher radiation

Climate Model Development and Tuning → done through grids, compare predictions to observations and adjust as needed. Grid is necessary to show regional differences.

Major types of climate models:

Atmosphere-Ocean General Circulation Model (AOGCM) are older, used where biogeochemical feedbacks aren’t critical.

Earth System Models (ESM) include various biogeochemical cycles (carbon, sulfur, ozone). Best for simulating past and future responses of the climate system to external forcings. State of the art.

Earth System Models of Intermediate Complexity (EMIC) are simplified ESMs used to understand climate feedbacks over time scales of thousands of years.

Climate Model Intercomparison Project (CMIP5): Over 100 models have been developed, run the same experiments through each model and compare the results. Average these results over time and it becomes a multimodel ensemble. Used for hurricane prediction.
After 1960, Model results close to observations only when human impacts on climate are included. Models show that without human impact earth would be cooler. 

Causes of Variability in Climate Record: Sunspots, Volcanic components, El Nino/La Nina, etc.

Description of Future Scenarios for Modeling: Models cannot predict future temps due to uncertainty about GHG production. Instead, they use scenarios with specific amounts of gases and emissions in the atmosphere.

Socioeconomic Scenarios: Related emissions to socioeconomic development, energy production/use, tech, forestry, ag, and land use.

Representative Concentration Pathways (RCP): Specify concentrations and emissions of gases, including short lived gases, and land use changes that produce a given radiative forcing by 22100. Covers range found in literature. RCP 8.5 is worst-case scenario, RCP 2.6 is like what we have now.