Artificial stepwise increases in homogenized surface air temperature data invalidate published climate warming claims for Canada

Update 2025-12-23: This report is now available on Zenodo

CORRELATION has published a new report entitled “Artificial stepwise increases in homogenized surface air temperature data invalidate published climate warming claims for Canada”, authored by Joseph Hickey.

The report shows that there is a large, apparently non-climatic artifact in Environment Canada’s flagship temperature dataset (the “AHCCD”). Environment Canada promotes the AHCCD for use in calculating long-term temperature trends for Canada and it is frequently accepted as verified data in global temperature analyses.

The said artifact could, on its own, be responsible for essentially all of the calculated warming for many Canadian locations over the past six or seven decades.

The report also demonstrates, with Access to Information emails, Environment Canada’s dismissive response to being alerted to the existence of the artifact in the AHCCD.

The Abstract of the report reads as:

Continental-scale multi-decadal temperature climate trend evaluations rely on networks of land-based weather stations. Long-term surface air temperature records from the said stations are affected by many biasing factors, related to changes to instrumentation, observation methods and procedures, and the environment surrounding the instruments. In determining long-term temperature trends, temperature records are adjusted and homogenized in an attempt to correct for gradual biases and sudden discontinuities. The Canadian government (Environment Canada) provides the Adjusted and Homogenized Canadian Climate Data (AHCCD) to the public and research community for use in long-term temperature trend analysis in Canada, which is promoted and accepted as reliable data. In this report, I show that a significant non-climatic artifact exists in the AHCCD, which is a stepwise increase of approximately 1°C in magnitude occurring at 1998 in the annual average temperature records for most AHCCD stations across Canada, and that this 1°C increase occurring at 1998 can, on its own, be responsible for essentially all of the claimed warming (of approximately 1-2°C) calculated for Canada over the past six or seven decades. This is based on the temperature data itself, and the institutional context is revealed through access to information (ATI) documents. The reported climate warming of Canada appears to be entirely from a temperature measurement artifact.

Download a copy of the report below: