## 1 Introduction
Their investigation revealed that by the conclusion of the 21 st century, the anticipated alterations in the hydrological cycle demonstrated resemblances under the high-emission scenarios of both CMIP5 and CMIP6. Furthermore, the researchers indicated that when considering two scenarios from CMIP5 and CMIP6, the evolving patterns in the daily biomass and leaf area index of winter wheat and summer maize during their respective growing seasons exhibited parallel trends. [PERSON] and [PERSON] [10] carried out an extensive analysis comparing the spatio-temporal variability of long-term flood susceptibility between CMIP5 and CMIP6 models. The researchers determined that the computed flow discharge distributions from both CMIP5 and CMIP6 models were nearly indistinguishable, showing insignificant variations for monthly and seasonal peak discharges. While the provided maps highlight notable disparities in monthly and seasonality peak discharge across various stations, it remains challenging to definitively conclude which model offers a more pronounced monthly peak discharge across all scenarios (stations and months). Therefore, considering the differing model outputs in various regions, it is advisable to examine both CMIP5 and CMIP6 models when conducting studies to capture a comprehensive view of climate impacts [27]. The persistence of CMIP5 models despite the advancements in CMIP6 can be attributed to several reasons. Firstly, the gradual transition between CMIP phases necessitates time due to ongoing CMIP6 development [28], while CMIP5 models are widely accepted. Research projects and evaluations are based on CMIP5, demanding the shift. Secondly, CMIP5 models serve as a baseline for historical climate comparisons, offering reliable data for past climate assessments. For long-term research requiring consistent data, CMIP5's adoption is favored to avoid mid-project inconsistencies [29]. Comparative analysis across CMIP phases aids model comprehension. Researchers may opt for CMIP5 due to specific research inquiries or historical data compatibility. Resource constraints and ongoing CMIP6 evaluation further influence the choice, emphasizing the nuanced decision-making process between CMIP5 and CMIP6 models. The main objective of this study was to examine how projected changes in temperature and precipitation, based on the CMIP5 and CMIP6 models using CanESM2 and CanESM5 climate simulations, will influence pesticide usage on Quebec's golf courses. The actual active ingredient rate (AAIR) (kg/100 m\({}^{2}\)) was projected using three different climate change scenarios based on both CanESM2 and CanESM5 models across three distinct projected periods. Using the calculated AAIR, total pesticide use was calculated (kg). The present study aimed to (1) compare the projected climate variables (temperature and precipitation) between CanESM2 (CMIP5) and CanESM5 (CMIP6) models; (2) quantify the impact of these projected climate changes on pesticide application rates, particularly in terms of the active actual ingredient rate (AAIR) across three projected periods (2023-2048, 2049-2074, and 2075-2100); and (3) investigate differences in pesticide use projections under different climate change scenarios (RCP and SSP pathways) from both CanESM2 and CanESM5. The tested hypothesis was that the climate projections from the CanESM5 model (CMIP6) would lead to significantly higher pesticide usage on Quebec's golf courses than the CanESM2 model (CMIP5) due to increased temperatures and reduced precipitation. Additionally, it was expected that the projected increases in pesticide use would be particularly pronounced for certain pesticide categories (such as fungicides and herbicides) and during the later projected periods (2075-2100). The study also hypothesized that CanESM5 would project a more intense impact on pesticide use than CanESM2 due to its higher projected temperature increases and more moderate precipitation decline.