Table 3 The summarized results of the Mann–Kendall test and the Sen slope method for trend estimation of variables including maximum temperature (Tmax), minimum temperature (Tmin), diurnal temperature range (DTR), precipitation (PT), relative humidity (RH), and carbon dioxide emission (CO₂) in Mississippi from 1970 to 2020.

Series\test	Tmax		Tmin		DTR		PT		RH		CO₂
Series\test	Kendall tau	Sen slope	Kendall tau	Sen slope	Kendall tau	Sen slope	Kendall tau	Sen slope	Kendall tau	Sen slope	Kendall tau	Sen slope
March	0.139	0.032	0.146	0.030	0.012	0.001	− 0.095	− 0.193	0.047	0.021	–	–
April	0.014	0.003	0.101	0.015	− 0.078	− 0.008	0.090	0.194	0.157	0.060	–	–
May	0.103	0.012	0.178	0.022	− 0.092	− 0.009	− 0.087	− 0.183	0.003	0.000	–	–
June	0.051*	0.007*	0.373***	0.035***	− 0.261**	− 0.028**	0.095	0.163	0.125	0.036	–	–
July	− 0.006	− 0.001	0.262**	0.024**	− 0.401***	− 0.031***	0.119	0.147	0.068	0.022	–	–
August	0.066*	0.009*	0.299**	0.027**	− 0.201*	− 0.019*	0.158	0.269	− 0.009	− 0.004	–	–
September	0.143	0.021	0.183	0.027	0.006	0.001	− 0.063	− 0.112	− 0.110	− 0.060	–	–
MGS	0.176*	0.013*	0.422***	0.027***	− 0.252**	− 0.015**	0.057	0.432	0.027	0.011	0.669***	0.514***
Mean	28.56 °C		16.02 °C		12.54 °C		48.49 mm		66.73%		53.58 million metric tons (Mmt)

Kendall tau negative (–) value signifies downward (decreasing) trend, and positive ( +) value indicates upward (increasing) trend with its value ranging between -1 and 1, and its absolute value signifies the strength of the trend. As the absolute value of Kendall tau approach 1, the strength of the trend becomes strong. The Sen slope value represents the rate of change (of variable) per year. Kendall tau is a pure number (unitless) as it is a correlation coefficient and Sen slope units are °C/year (for Tmax, Tmin, and DTR), mm/year (for PT), percentage/year (for RH), and Mmt/year (for CO₂). The negative (–) value of Sen slope means the rate of decrease per year while the positive ( +) value represents the rate of increase per year. Significance: “*” p < 0.05, “**” p < 0.01, and “***” p < 0.001.

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