This study investigates the relationships between climate changes and growth in semi-arid forests located in the Kurdistan Region of northern Iraq by utilizing tree-ring Blue Intensity (BI) parameters alongside stable carbon isotopes (δ¹³C). The sensitivity of detrended tree-ring width (TRW), earlywood blue intensity (EWBI), latewood blue intensity (LWBI), and delta blue intensity ΔBI to temperature, precipitation, and physiological responses are measured on three species of tree <em>Quercus aegilops, Juglans regia</em> and <em>Fraxinus</em>. Tree-ring Blue Intensity chronologies for 100 years, are used to look at climate-growth interactions over time for all three species. Results show a dominant temperature control on wood formation. EWBI is correlates with temperature (r ≈ 0.37, p < 0.001) and with precipitation in <em>Quercus aegilops</em>, whereas ΔBI is a positive temperature proxy (r ≈ 0.37, p < 0.001), this shows that when years are warmer, the density contrast of earlywood and latewood is increased. In <em>Juglans regia</em>, the strongest temperature sensitivity in TRW is found in LWBI (r ≈ -0.45, p < 0.001). The positive correlation of ΔBI with δ¹³C (r ≈ 0.30, p < 0.01) indicates a positive structural and physiological response to drought stress. The TRW sensitivities of <em>Fraxinus</em> are weaker (r = 0.128 in Erbil, r = 0.122 in Duhok), and the temperature BI(EW-LW) relationships are negative and significant (r ≈ -0.340, p < 0.01) (r ≈ -0.280, p < 0.01). Wavelet coherence analysis indicates a shift in the growth trend from precipitation-driven growth prior to ~1980 to the temperature-related growth thereafter, with increasing non-stationarity and episodic drought signatures. The integrated BI-δ¹³C approach captures anatomical and physiological adjustment, revealing that recent warming led to a decrease in radial growth, less earlywood development and changed wood density structure across species. The results show the potential of BI as an effective indicator of detecting climate-driven ecosystem shifts and temperature variability.