A simple object-oriented and open-source model for scientific and policy analyses of the global climate system – Hector v1.0

Abstract

Abstract. Simple climate models play an integral role in the policy and scientific communities. They are used for climate mitigation scenarios within integrated assessment models, complex climate model emulation, and uncertainty analyses. Here we describe Hector v1.0, an open source, objectoriented, simple global climate carbon-cycle model. This model runs essentially instantaneously while still representing the most critical global-scale earth system processes. Hector has a three-part main carbon cycle: a one-pool atmosphere, land, and ocean. The model's terrestrial carbon cycle includes primary production and respiration fluxes, accommodating arbitrary geographic divisions into, e.g., ecological biomes or political units. Hector actively solves the inorganic carbon system in the surface ocean, directly calculating airsea fluxes of carbon and ocean pH. Hector reproduces the global historical trends of atmospheric [CO 2 ], radiative forcing, and surface temperatures. The model simulates all four Representative Concentration Pathways (RCPs) with equivalent rates of change of key variables over time compared to current observations, MAGICC (a well-known simple climate model), and models from the 5th Coupled Model Intercomparison Project. Hector's flexibility, open-source nature, and modular design will facilitate a broad range of research in various areas.

Ocean acidification over the next three centuries using a simple global climate carbon-cycle model: projections and sensitivities

“…3). There is a low bias in Hector compared to CMIP5 models after 2100, due to the low bias in projected atmospheric [CO 2 ] within Hector over the same time period (Hartin et al, 2015). We find Hector to be in closer agreement with the observation record.…”

“…In this study we use Hector v1.1, with an updated ocean temperature algorithm, to better match the CMIP5 mean. For a detailed description of the land and atmospheric components of Hector, please refer to Appendix A and Hartin et al (2015).…”

“…The terrestrial component consists of user defined biomes or regions for vegetation, detritus, and soil. The earth pool is continually debited to act as a mass-balance check on the carbon cycle (Hartin et al, 2015). The ocean consists of four boxes, with advection (represented by straight arrows) and water mass exchange (represented by curved arrows) simulating thermohaline circulation.…”

“…Hector is run to equilibrium in a perturbation-free mode, prior to running the historical period, ensuring that it is in steady state (Hartin et al, 2015;Pietsch and Hasenauer, 2006). DIC (µmol kg −1 ) in the surface boxes is a function of the total carbon (Pg C) and the volume of the box.…”

BRICK v0.2, a simple, accessible, and transparent model framework for climate and regional sea-level projections

“…For example, they are used for uncertainty quantification (Bakker et al, 2017;Grinsted et al, 2010;Urban et al, 2014;Urban and Keller, 2010) and complex model emulation (Applegate et al, 2012;Bakker et al, 2016;Hartin et al, 2015;Meinshausen et al, 2011a), and are incorporated into integrated assessment models (Hartin et al, 2015;Meinshausen et al, 2011a).…”