diff --git a/NOTICE.md b/NOTICE.md
index 76723b284..78c4d5d65 100644
--- a/NOTICE.md
+++ b/NOTICE.md
@@ -1,4 +1,4 @@
-   Copyright 2017-2021 IIASA and the pyam developer team
+   Copyright 2017-2022 IIASA and the pyam developer team
 
    The **pyam** package is licensed under
    the Apache License, Version 2.0 (the "License");
diff --git a/README.md b/README.md
index 7b74f9e97..24d98b12d 100644
--- a/README.md
+++ b/README.md
@@ -133,7 +133,7 @@ doi: [10.21105/joss.01095](https://doi.org/10.21105/joss.01095).
 License
 -------
 
-Copyright 2017-2021 IIASA and the pyam developer team
+Copyright 2017-2022 IIASA and the pyam developer team
 
 The **pyam** package is licensed
 under the Apache License, Version 2.0 (the "License");  
diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
index c5e367d2a..126a03ff5 100644
--- a/RELEASE_NOTES.md
+++ b/RELEASE_NOTES.md
@@ -1,4 +1,12 @@
-# Next release
+# Release v1.2.0
+
+## Highlights
+
+- Implement a `compute` module for derived timeseries indicators.
+- Add a `diff()` method similar to the corresponding `pandas.DataFrame.diff()`
+- Improve error reporting on IamDataFrame initialization
+
+## Individual updates
 
 - [#608](https://github.com/IAMconsortium/pyam/pull/608) The method `assert_iamframe_equals()` passes if an all-nan-col is present
 - [#604](https://github.com/IAMconsortium/pyam/pull/604) Add an annualized-growth-rate method
diff --git a/pyam/core.py b/pyam/core.py
index 336f49eba..c1d935c18 100755
--- a/pyam/core.py
+++ b/pyam/core.py
@@ -418,13 +418,6 @@ def dimensions(self):
         """Return the list of `data` columns (index names & data coordinates)"""
         return list(self._data.index.names)
 
-    @property
-    def _LONG_IDX(self):
-        """DEPRECATED - please use `IamDataFrame.dimensions`"""
-        # TODO: deprecated, remove for release >= 1.2
-        deprecation_warning("Use the attribute `dimensions` instead.", "This attribute")
-        return self.dimensions
-
     def copy(self):
         """Make a deepcopy of this object
 
diff --git a/pyam/units.py b/pyam/units.py
index 1dbc07253..3e5ac2ded 100644
--- a/pyam/units.py
+++ b/pyam/units.py
@@ -104,17 +104,8 @@ def extract_species(expr):
     return SPECIES_ALIAS.get(species, species), units
 
 
-def convert_gwp(context, qty, to):
+def convert_gwp(metric, qty, to):
     """Helper for :meth:`convert_unit` to perform GWP conversions."""
-    # Remove a leading 'gwp_' to produce the metric name
-    if context is not None and context.startswith("gwp_"):
-        context = context[len("gwp_") :]
-        deprecation_warning(
-            f"Use context='{context}' instead",
-            type='Prefixing a context with "gwp_"',
-            stacklevel=5,
-        )
-    metric = context
 
     # Extract the species from *qty* and *to*, allowing supported aliases
     species_from, units_from = extract_species(qty[1])
diff --git a/tests/test_core.py b/tests/test_core.py
index 43c99cf88..3182ed863 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -342,7 +342,6 @@ def test_unit_mapping(test_pd_df):
 def test_dimensions(test_df):
     """Assert that the dimensions attribute works as expected"""
     assert test_df.dimensions == IAMC_IDX + [test_df.time_col]
-    assert test_df._LONG_IDX == IAMC_IDX + [test_df.time_col]
 
 
 def test_get_data_column(test_df):