diff --git a/esmvalcore/cmor/tables/custom/CMOR_gtfgco2.dat b/esmvalcore/cmor/tables/custom/CMOR_gtfgco2.dat
deleted file mode 100644
index dba2aa00c6..0000000000
--- a/esmvalcore/cmor/tables/custom/CMOR_gtfgco2.dat
+++ /dev/null
@@ -1,21 +0,0 @@
-SOURCE: CMIP5
-!============
-variable_entry:    gtfgco2
-!============
-modeling_realm:    ocnBgchem
-!----------------------------------
-! Variable attributes:
-!----------------------------------
-standard_name:     
-units:             kg s-1
-cell_methods:      time: mean area: where sea
-cell_measures:     area: areacello
-long_name:         Global Total Surface Downward CO2 Flux
-comment:           Gas exchange flux of CO2 (positive into ocean)
-!----------------------------------
-! Additional variable information:
-!----------------------------------
-dimensions:        time
-type:              real
-!----------------------------------
-!
diff --git a/esmvalcore/preprocessor/_derive/gtfgco2.py b/esmvalcore/preprocessor/_derive/gtfgco2.py
deleted file mode 100644
index 64efd558b1..0000000000
--- a/esmvalcore/preprocessor/_derive/gtfgco2.py
+++ /dev/null
@@ -1,96 +0,0 @@
-"""Derivation of variable `gtfgco2`."""
-import iris
-import numpy as np
-
-from ._baseclass import DerivedVariableBase
-
-
-def calculate_total_flux(fgco2_cube, cube_area):
-    """
-    Calculate the area of unmasked cube cells.
-
-    Requires a cube with two spacial dimensions. (no depth coordinate).
-
-    Parameters
-    ----------
-    cube: iris.cube.Cube
-        Data Cube
-    cube_area: iris.cube.Cube
-        Cell area Cube
-
-    Returns
-    -------
-    numpy.array:
-        An numpy array containing the total flux of CO2.
-
-    """
-    data = []
-    times = fgco2_cube.coord('time')
-
-    fgco2_cube.data = np.ma.array(fgco2_cube.data)
-    for time_itr in np.arange(len(times.points)):
-
-        total_flux = fgco2_cube[time_itr].data * cube_area.data
-
-        total_flux = np.ma.masked_where(fgco2_cube[time_itr].data.mask,
-                                        total_flux)
-        data.append(total_flux.sum())
-
-    ######
-    # Create a small dummy output array
-    data = np.array(data)
-    return data
-
-
-class DerivedVariable(DerivedVariableBase):
-    """Derivation of variable `gtfgco2`."""
-
-    @staticmethod
-    def required(project):
-        """Declare the variables needed for derivation."""
-        required = [
-            {
-                'short_name': 'fgco2',
-                'mip': 'Omon'
-            },
-            {
-                'short_name': 'areacello',
-                'mip': 'fx'
-            },
-        ]
-        if project == 'CMIP6':
-            required = [
-                {
-                    'short_name': 'fgco2',
-                    'mip': 'Omon'
-                },
-                {
-                    'short_name': 'areacello',
-                    'mip': 'Ofx'
-                },
-            ]
-        return required
-
-    @staticmethod
-    def calculate(cubes):
-        """Compute longwave cloud radiative effect."""
-        fgco2_cube = cubes.extract_strict(
-            iris.Constraint(name='surface_downward_mass_flux_of_carbon_dioxide'
-                            '_expressed_as_carbon'))
-
-        try:
-            cube_area = cubes.extract_strict(iris.Constraint(name='cell_area'))
-        except iris.exceptions.ConstraintMismatchError:
-            pass
-
-        total_flux = calculate_total_flux(fgco2_cube, cube_area)
-
-        # Dummy result cube
-        result = fgco2_cube.collapsed(
-            ['latitude', 'longitude'],
-            iris.analysis.MEAN,
-        )
-        result.units = fgco2_cube.units * cube_area.units
-
-        result.data = total_flux
-        return result