# CanESM5 data for CCCma COVID-19 climate scenarios

Introduction
============

This data is associated with the publication:

    Negligible Influence of Covid-19 Emission Reductions on Global Temperature

    John C. Fyfe, Viatcheslav V. Kharin, Neil Swart, Gregory M. Flato, Michael
    Sigmond and Nathan Gillett

    Canadian Centre for Climate Modelling and Analysis, Environment and Climate
    Change Canada, Victoria, British Columbia, V8W 2Y2, Canada.

The data includes the monthly CO2 emissions used to drive CanESM5, and also the
monthly CO2 concentrations, and Global Mean Screen Temperatures resulting from
the model simulations. Using this data, Figure 1 of the paper can be completely
reproduced. The organization of the data is described below

Data organization
=================

Directories
-----------

- co2_em: CO2 emissions, used to drive CanESM5, in NetCDF format (variable:
          CO2). Files are provided for each of the scenarios detailed below.
	  
- f0## :  Model output of CO2 concentrations and Global Mean Screen Temperatures
          in NetCDF format. Files are provided in separate directories for each
          of the scenarios detailed below. The directories are named "f0##",
          where "##" represents a two digit number specific to the scenario
          (e.g. "f000").

Model output files and format
-----------------------------

In each of the "f0##" directories there are 30 files, representing the 30
realizations conducted for each scenario. The files are labelled such as:

    sc_covid19f000-001_201501_203012_rtd074.nc

where "f000" represents the scenario, and the number following the dash
(e.g. "-001") represents the realization.  The example file above (f000-001)
contains the data for the control scenario "f000" (esm-ssp245), and realization
001.

All files contain data for the years 2015m01 to 2030m12. For any given
realization (e.g. "001"), data are identical across all scenarios until 2019m12,
when forcing perturbations are first introduced in the experiments.

Within each file, data are provided for each month in a separate variable. For
example, screen temperature has the variable names:

    SCREEN_TEMPERATURE_GLOBAL__K__________________JAN_00001(time)
    SCREEN_TEMPERATURE_GLOBAL__K__________________FEB_00001(time)
    ...
    SCREEN_TEMPERATURE_GLOBAL__K__________________DEC_00001(time)
	
and CO2 concentrations have the variable names:

    SURFACE_CO2_CONCENTRATION__PPMV_______________JAN_00001
    SURFACE_CO2_CONCENTRATION__PPMV_______________FEB_00001
    ...
    SURFACE_CO2_CONCENTRATION__PPMV_______________DEC_00001

within each files the year is given by the variable name:

    YEAR__________________________________________ANN_00001

Scenarios
=========

Scenarios are listed below using the "f0##" convention used in the directory and
filenames above.  For further description of the scenarios, refer to Fyfe et al.

- Control runs
  - f000 # control run using "esm-ssp245" forcing. CO2 emissions are
           specified. All other GHG are specified as concentrations, as in
           "ssp245". This is analogous to the C4MIP esm-ssp585 experiment,
           except for using SSP2-4.5 scenario forcing.
	   
- COVID19 CO2 emissions perturbation runs	   
  In these runs, CO2 emissions are altered in 2020-2021 relative to esm-ssp245,
  but all other forcing is the same as in the control.
  - f002 #  -10% peak CO2 emissions scenario
  - f001 #  -25% peak CO2 emissions scenario
  - f018 #  -50% peak CO2 emissions scenario
  - f021 # -100% peak CO2 emissions scenario

- COVID19 Aerosol emissions perturbation runs
  In these runs, anthropogenic aerosol emissions are altered in 2020-2021
  relative to esm-ssp245, but all other forcing is the same as in the control.
  - f013 #  -10% peak AER emissions scenario
  - f012 #  -25% peak AER emissions scenario
  - f019 #  -50% peak AER emissions scenario
  - f022 # -100% peak AER emissions scenario

- COVID19 CO2 and Aerosol emissions runs
  In these runs, both CO2 and anthropogenic aerosol emissions are altered in
  2020-20201 relative to esm-ssp245, but all other forcing is the same as in the control.
  - f016 #  -10% peak CO2 & AER emissions scenario
  - f015 #  -25% peak CO2 & AER emissions scenario
  - f020 #  -50% peak CO2 & AER emissions scenario
  - f023 # -100% peak CO2 & AER emissions scenario

- Paris temperature target runs
  In these runs, CO2 emissions are reduced linearly after 2020, to roughly match
  estimated emissions budgets to stabilize climate at 1.5 degrees or 2.0 degrees
  Celsius above pre-industrial (from ref. 8).

  - f024 # linearly scale down CO2 emissions from 2020 levels to zero by year 2060
  - f027 # linearly scale down CO2 emissions from 2020 levels to zero by year 2035
