Projected changes of temperature and precipitation in Texas from downscaled global climate models

Climate change projections, in particular precipitation and temperature under different IPCC future emissions scenarios in Texas, were based on statistically downscaled multi-model ensembles. A comparison of downscaled model results with observations and reanalysis data for the present-day climate shows that all models simulate monthly variations in surface air temperature well (correlation coefficient: 0.98), while precipitation correlation coefficients vary widely across different models (from 0.79 to 0.92). We performed a detailed analysis for the Texas region with an emphasis on 5 sub-regions. Our probability analysis shows an overall increase in surface air temperature towards the end of the 21st century of 4.8, 3.6, and 2.2 degrees C for A2, A1B, and B1 emission scenarios, respectively, relative to the mean of 1971-2000. Surface air temperatures in northwestern Texas increase more under various scenarios, while they are projected to increase steadily in southeastern Texas in response to the large thermal capacity of the Gulf of Mexico. The trends in precipitation are not as clear as those in temperature, suggesting more complicated mechanisms. Precipitation and surface air temperature changes are negatively correlated on an annual basis. This indicates that, as surface air temperature increases in Texas, most regions are projected to become drier. Precipitation changes correlate negatively with surface air temperature changes in summer, while no correlation appears between them for the winter season.