The five-year moving average of the Actuaries Climate Index (ACI), which tracks changes in climate extremes and sea level conditions, has been updated to reflect data from fall 2024. The index shows an increase compared to the summer 2024 period.
The updated moving average now stands at 1.35, compared to the baseline average of zero calculated over the reference period from 1961 to 1990.
In the previous seasonal update, published in February and based on summer 2024 data, the ACI was recorded at 1.31.
“The increase is primarily due to shifts in the frequency of temperatures below the 10th percentile (T10) and above the 90th percentile (T90),” the May 27 release stated.
Comparison with fall 2019
With the addition of fall 2024 data, the five-year moving average of the ACI for Canada and the United States has reached 2.07. Since the index is updated quarterly and based on a rolling five-year period, the new figure replaces the data from fall 2019, which had stood at 1.22.
When ACI values rise above the reference average of zero, it signals that extreme climate events are occurring more frequently and that sea levels continue to rise.
Index based on combined climate data
The ACI is based on several quarterly seasonal data points, capturing variables with the greatest impact on populations and economies. These include extreme high and low temperatures, heavy precipitation, droughts, high winds, and sea level changes.
For the sea level sub-index covering Canada and the United States, the value rose to 4.51 in fall 2024, compared to 3.15 in the previous quarter. The five-year moving average of this sub-index reached 2.96 in the fall of 2024, compared to 2.45 in the fall of 2019.
