diff --git a/.github/workflows/CI.yml b/.github/workflows/CI.yml
index a71a236..25ab893 100644
--- a/.github/workflows/CI.yml
+++ b/.github/workflows/CI.yml
@@ -69,6 +69,7 @@ jobs:
       VER_ECCODES: 2.40.0
       VER_OASIS: tsmp-patches-v0.1
       VER_ICON_UPSTREAM: release-2026.04-public
+      MAKE_JOBS: 4
 
     steps:
       - uses: actions/checkout@v4
@@ -131,7 +132,7 @@ jobs:
           export CPPFLAGS=-I/usr/include/hdf5/openmpi
           export LDFLAGS=-L/usr/lib/x86_64-linux-gnu/hdf5/openmpi
           ./configure --prefix=${DEPENDENCIES_ROOT}/netcdf-c-${VER_NETCDF_C}
-          make -j4 install
+          make -j${MAKE_JOBS} install
 
           # Verify
           tree -L 2 ${DEPENDENCIES_ROOT}/netcdf-c-${VER_NETCDF_C}
@@ -166,7 +167,7 @@ jobs:
           export CPPFLAGS=-I${DEPENDENCIES_ROOT}/netcdf-c-${VER_NETCDF_C}/include
           export LDFLAGS=-L${DEPENDENCIES_ROOT}/netcdf-c-${VER_NETCDF_C}/lib
           ./configure --prefix=${DEPENDENCIES_ROOT}/netcdf-f90-${VER_NETCDF_F90}
-          make -j4 install
+          make -j${MAKE_JOBS} install
 
           # Verify
           tree -L 2 ${DEPENDENCIES_ROOT}/netcdf-f90-${VER_NETCDF_F90}
@@ -204,7 +205,7 @@ jobs:
                 -DCMAKE_INSTALL_PREFIX="${INSTALL_DIR}"  \
                 -DMPI_INCLUDE_DIR="${MPI_HOME}/include"  \
                 -DHYPRE_ENABLE_OPENMP="ON"
-          cmake --build bld --parallel 4
+          cmake --build bld --parallel ${MAKE_JOBS} 
           cmake --install bld
 
           # Verify
@@ -243,7 +244,7 @@ jobs:
                 -DCMAKE_INSTALL_PREFIX="${INSTALL_DIR}"  \
                 -DMPI_INCLUDE_DIR="${MPI_HOME}/include"  \
                 -DHYPRE_ENABLE_CUDA="ON"
-          cmake --build bld --parallel 4
+          cmake --build bld --parallel ${MAKE_JOBS} 
           cmake --install bld
 
           # Verify
@@ -278,7 +279,7 @@ jobs:
 
           # Install
           cmake -S . -B bld -DCMAKE_INSTALL_PREFIX=${DEPENDENCIES_ROOT}/eccodes-${VER_ECCODES}
-          cmake --build bld --parallel 4
+          cmake --build bld --parallel ${MAKE_JOBS}
           cmake --install bld
 
           # Verify
@@ -471,7 +472,7 @@ jobs:
           if [[ "${{ matrix.config.name }}" == "ICON standalone" ]]; then
             MODEL_OPTS="${MODEL_OPTS} --ICON_SRC ${TSMP2_ROOT}/models/icon-model"
           fi
-          BUILD_TSMP2_CMD="./build_tsmp2.sh ${MODEL_OPTS} --no_update"
+          BUILD_TSMP2_CMD="./build_tsmp2.sh ${MODEL_OPTS} --no_update --parallel ${MAKE_JOBS}"
           echo $BUILD_TSMP2_CMD && echo ""
           eval $BUILD_TSMP2_CMD
 
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 90ad5fe..601cab6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-cmake_minimum_required (VERSION 3.21.1)
+cmake_minimum_required (VERSION 3.29.3)
 project(TSMP2 LANGUAGES C CXX Fortran)
 include(ExternalProject)
 
@@ -24,6 +24,10 @@ if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
   set_property(CACHE CMAKE_BUILD_TYPE PROPERTY STRINGS "DEBUG" "RELEASE")
 endif()
 
+if(NOT DEFINED PARALLEL_JOBS)
+  set(PARALLEL_JOBS "1" CACHE STRING "Number of parallel make jobs for building model components." FORCE)
+endif()
+
 # init CMAKE internal variables
 string(TOUPPER $ENV{SYSTEMNAME} SYSTEMNAME)
 set(MODEL_ID "")
@@ -144,5 +148,3 @@ if(CMAKE_INSTALL_PREFIX_INITIALIZED_TO_DEFAULT)
 endif()
 
 print_model_versions("${COMPONENT_MODELS}" "${TSMP2_MODEL_VERSIONS}")
-
-#message(FATAL_ERROR "at the end of script")
diff --git a/build_tsmp2.sh b/build_tsmp2.sh
index 9d07bc3..023fd2c 100755
--- a/build_tsmp2.sh
+++ b/build_tsmp2.sh
@@ -41,17 +41,7 @@ function help_tsmp2() {
   echo "  --install_dir    Set install dir cmake, if not set bin/<SYSTEMNAME>_<model-id> is used. Model executables and libraries will be installed here"
   echo "  --clean_first    Delete build_dir if it already exists"
   echo "  --env            Set model environment."
-  echo "  --version        Print $0 scipt version"
-  echo "  -q, --quiet      Write less output during shell execution"
-  echo "  -v, --verbose    Enable verbose output from Makefile builds using CMAKE_VERBOSE_MAKEFILE"
-  echo ""
-  echo "Examples:"
-  echo ""
-  echo "  ./build_tsmp2.sh icon eclm parflow"
-  echo "  ./build_tsmp2.sh eclm parflowGPU"
-  echo "  ./build_tsmp2.sh iconGPU"
-  echo "  ./build_tsmp2.sh icon eclm"
-  echo "  ./build_tsmp2.sh eclm pdaf"
+  echo "  --parallel, -j   Set the maximum number of jobs to build the code, if not set compilation is serial."
   echo ""
   exit 1
 }
@@ -144,6 +134,7 @@ while [[ "$#" -gt 0 ]]; do
     --build_dir) build_dir="$2"; shift ;;
     --install_dir) install_dir="$2"; shift ;;
     --env) env="$2"; shift ;;
+    -j|--parallel) parallel_jobs="$2"; shift ;;
     *) echo "Unknown parameter passed: $1"; exit 1 ;;
   esac
   shift
@@ -319,6 +310,15 @@ else
 fi
 mkdir -p "${cmake_install_dir}"
 
+if [[ -z "${parallel_jobs}" ]]; then
+  if [[ ! -z "${TSMP2_PARALLEL_JOBS}" ]]; then
+    parallel_jobs=${TSMP2_PARALLEL_JOBS}
+  else
+    parallel_jobs=1
+  fi
+fi
+message "Parallel make jobs set to ${parallel_jobs}"
+
 #
 # 5. CMake configure
 #
@@ -336,6 +336,7 @@ cmake_conf="-S ${cmake_tsmp2_dir} -B ${cmake_build_dir}"
 cmake_conf+=" -DCMAKE_BUILD_TYPE=${cmake_build_type}"
 cmake_conf+=" -DCMAKE_INSTALL_PREFIX=${cmake_install_dir}"
 cmake_conf+=" -DCMAKE_VERBOSE_MAKEFILE=${cmake_verbose_makefile}"
+cmake_conf+=" -DPARALLEL_JOBS=${parallel_jobs}"
 cmake_conf+=" ${cmake_comp_str}"
 cmake_conf+=" ${cmake_compsrc_str}"
 message "cmake ${cmake_conf}" |& tee "${build_log}"
diff --git a/cmake/BuildICON.cmake b/cmake/BuildICON.cmake
index 12867db..adea7ba 100644
--- a/cmake/BuildICON.cmake
+++ b/cmake/BuildICON.cmake
@@ -144,7 +144,7 @@ ExternalProject_Add(ICON
                       MPI_LAUNCH=${MPIEXEC_EXECUTABLE}
                       --prefix=${CMAKE_INSTALL_PREFIX}
                       ${EXTRA_CONFIG_ARGS}
-    BUILD_COMMAND     make -j8 install
+    BUILD_COMMAND     make -j ${PARALLEL_JOBS} install
     INSTALL_COMMAND   ""
     BUILD_ALWAYS      YES
     DEPENDS           ${MODEL_DEPENDENCIES}
diff --git a/cmake/BuildOASIS3MCT.cmake b/cmake/BuildOASIS3MCT.cmake
index c66840f..7ad86c9 100644
--- a/cmake/BuildOASIS3MCT.cmake
+++ b/cmake/BuildOASIS3MCT.cmake
@@ -24,7 +24,7 @@ file(APPEND  ${OASIS_MAKE_INC} "ARCHDIR         = ${OASIS_INSTALL_PREFIX}\n")
 file(APPEND  ${OASIS_MAKE_INC} "NETCDF_INCLUDE  = ${NetCDF_F90_ROOT}/include\n")
 file(APPEND  ${OASIS_MAKE_INC} "NETCDF_LIBRARY  = ${NetCDF_LIBRARIES}\n")
 file(APPEND  ${OASIS_MAKE_INC} "MPI_INCLUDE     = ${MPI_Fortran_INCLUDE_DIRS}\n")
-file(APPEND  ${OASIS_MAKE_INC} "MAKE            = make\n")
+file(APPEND  ${OASIS_MAKE_INC} "MAKE            = make -j ${PARALLEL_JOBS}\n")
 file(APPEND  ${OASIS_MAKE_INC} "F90             = ${CMAKE_Fortran_COMPILER}\n")
 file(APPEND  ${OASIS_MAKE_INC} "F               = $(F90)\n")
 file(APPEND  ${OASIS_MAKE_INC} "f90             = $(F90)\n")
diff --git a/cmake/BuildPDAF.cmake b/cmake/BuildPDAF.cmake
index a653e44..7d39088 100644
--- a/cmake/BuildPDAF.cmake
+++ b/cmake/BuildPDAF.cmake
@@ -279,7 +279,7 @@ ExternalProject_Add(PDAF
   SOURCE_DIR        ${PDAF_SRC}
   BUILD_IN_SOURCE   TRUE
   CONFIGURE_COMMAND ""
-  BUILD_COMMAND     make ${PDAF_ENV_VARS} clean directories libpdaf
+  BUILD_COMMAND     make ${PDAF_ENV_VARS} clean directories libpdaf -j ${PARALLEL_JOBS}
   INSTALL_COMMAND   ""
   DEPENDS           ${PDAF_DEPENDENCIES}
 )
diff --git a/cmake/BuildPDAFFRAMEWORK.cmake b/cmake/BuildPDAFFRAMEWORK.cmake
index 81652f8..a76202d 100644
--- a/cmake/BuildPDAFFRAMEWORK.cmake
+++ b/cmake/BuildPDAFFRAMEWORK.cmake
@@ -34,7 +34,7 @@ ExternalProject_Add(PDAF-Framework
   SOURCE_DIR        ${PDAF_SRC}/interface/framework
   BUILD_IN_SOURCE   TRUE
   CONFIGURE_COMMAND ""
-  BUILD_COMMAND     make ${PDAFFRAMEWORK_ENV_VARS} clean all
+  BUILD_COMMAND     make ${PDAFFRAMEWORK_ENV_VARS} clean all -j ${PARALLEL_JOBS}
   INSTALL_COMMAND   ""
   DEPENDS           PDAF-Model
 )
diff --git a/cmake/BuildPDAFMODEL.cmake b/cmake/BuildPDAFMODEL.cmake
index 49345e6..f92fafa 100644
--- a/cmake/BuildPDAFMODEL.cmake
+++ b/cmake/BuildPDAFMODEL.cmake
@@ -214,7 +214,7 @@ ExternalProject_Add(PDAF-Model
   SOURCE_DIR        ${PDAF_SRC}/interface/model
   BUILD_IN_SOURCE   TRUE
   CONFIGURE_COMMAND ""
-  BUILD_COMMAND     make ${PDAFMODEL_ENV_VARS} clean all
+  BUILD_COMMAND     make ${PDAFMODEL_ENV_VARS} clean all -j ${PARALLEL_JOBS}
   INSTALL_COMMAND   ""
   DEPENDS           PDAF
 )
diff --git a/cmake/BuildParFlow.cmake b/cmake/BuildParFlow.cmake
index 8171145..4f5531d 100644
--- a/cmake/BuildParFlow.cmake
+++ b/cmake/BuildParFlow.cmake
@@ -77,27 +77,29 @@ endif()
 
 # Pass options to ParFlow CMake
 ExternalProject_Add(ParFlow
-    PREFIX      ParFlow
-    SOURCE_DIR  ${PARFLOW_SRC}
-    CMAKE_ARGS  -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
-                -DCMAKE_C_FLAGS=${PF_CFLAGS}
-                -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
-                -DCMAKE_Fortran_COMPILER=${CMAKE_Fortran_COMPILER}
-                -DCMAKE_Fortran_FLAGS=${PF_FFLAGS}
-                -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
-                -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}
-                -DPARFLOW_ENABLE_HYPRE=ON
-                -DPARFLOW_ENABLE_NETCDF=ON
-                -DPARFLOW_AMPS_SEQUENTIAL_IO=ON
-                -DPARFLOW_ENABLE_TIMING=TRUE
-                -DPARFLOW_ACCELERATOR_BACKEND=${PF_ACC_BACKEND}
-                -DMPIEXEC_EXECUTABLE=${MPIEXEC_EXECUTABLE}
-                -DMPIEXEC_NUMPROC_FLAG=${MPIEXEC_NUMPROC_FLAG}
-                -DPARFLOW_ENABLE_SLURM=${ENABLE_SLURM}
-                ${PF_UMPIRE_FLAG}
-                ${PF_SUNDIALS_FLAG}
-                ${PF_CLM_FLAGS}
-    DEPENDS     ${MODEL_DEPENDENCIES}
+    PREFIX           ParFlow
+    SOURCE_DIR       ${PARFLOW_SRC}
+    CMAKE_ARGS       -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
+                     -DCMAKE_C_FLAGS=${PF_CFLAGS}
+                     -DCMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER}
+                     -DCMAKE_Fortran_COMPILER=${CMAKE_Fortran_COMPILER}
+                     -DCMAKE_Fortran_FLAGS=${PF_FFLAGS}
+                     -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
+                     -DCMAKE_INSTALL_PREFIX=${CMAKE_INSTALL_PREFIX}
+                     -DPARFLOW_ENABLE_HYPRE=ON
+                     -DPARFLOW_ENABLE_NETCDF=ON
+                     -DPARFLOW_AMPS_SEQUENTIAL_IO=ON
+                     -DPARFLOW_ENABLE_TIMING=TRUE
+                     -DPARFLOW_ACCELERATOR_BACKEND=${PF_ACC_BACKEND}
+                     -DMPIEXEC_EXECUTABLE=${MPIEXEC_EXECUTABLE}
+                     -DMPIEXEC_NUMPROC_FLAG=${MPIEXEC_NUMPROC_FLAG}
+                     -DPARFLOW_ENABLE_SLURM=${ENABLE_SLURM}
+                     ${PF_UMPIRE_FLAG}
+                     ${PF_SUNDIALS_FLAG}
+                     ${PF_CLM_FLAGS}
+    BUILD_COMMAND    make -j ${PARALLEL_JOBS} install
+    INSTALL_COMMAND  ""
+    DEPENDS          ${MODEL_DEPENDENCIES}
 )
 
 get_model_version(${PARFLOW_SRC} PARFLOW_VERSION)
diff --git a/cmake/BuildeCLM.cmake b/cmake/BuildeCLM.cmake
index 42f0f64..28ca83e 100644
--- a/cmake/BuildeCLM.cmake
+++ b/cmake/BuildeCLM.cmake
@@ -26,9 +26,7 @@ ExternalProject_Add(eCLM
                       ${COUP_OAS_FLAGS}
 		              ${PDAF_FLAGS}
     BUILD_ALWAYS      YES
-    BUILD_COMMAND     ""   # This needs to be empty to avoid building eCLM twice.
-                           # This happens because INSTALL_COMMAND triggers rebuild
-                           # which is abnormal. This is a problem in eCLM and should be fixed.
+    BUILD_COMMAND     make -j ${PARALLEL_JOBS} install 
     DEPENDS           ${MODEL_DEPENDENCIES}
 )
 
diff --git a/env/jsc.2025.gnu.openmpi b/env/jsc.2025.gnu.openmpi
index b74707e..a3e705f 100644
--- a/env/jsc.2025.gnu.openmpi
+++ b/env/jsc.2025.gnu.openmpi
@@ -61,6 +61,7 @@ export FC=mpif90
 export CXX=mpicxx
 export MPI_HOME=$EBROOTOPENMPI
 export MPIEXEC_EXECUTABLE=$(which srun)
+export TSMP2_PARALLEL_JOBS=16
 
 # Display compiler settings
 module list
diff --git a/env/jsc.2025.gnu.psmpi b/env/jsc.2025.gnu.psmpi
index 2776ccf..fc7c8ba 100644
--- a/env/jsc.2025.gnu.psmpi
+++ b/env/jsc.2025.gnu.psmpi
@@ -57,6 +57,7 @@ export CC=mpicc
 export FC=mpif90
 export CXX=mpicxx
 export MPI_HOME=$EBROOTPSMPI
+export TSMP2_PARALLEL_JOBS=16
 
 # Display compiler settings
 module list
diff --git a/env/jsc.2025.intel.psmpi b/env/jsc.2025.intel.psmpi
index 710f41f..ec424cd 100644
--- a/env/jsc.2025.intel.psmpi
+++ b/env/jsc.2025.intel.psmpi
@@ -67,6 +67,7 @@ export FC=mpif90
 export CXX=mpicxx
 export MPI_HOME=$EBROOTPSMPI
 export MPIEXEC_EXECUTABLE=$(which srun)
+export TSMP2_PARALLEL_JOBS=16
 
 # Display compiler settings
 module list
diff --git a/env/jsc.2026.gnu.openmpi b/env/jsc.2026.gnu.openmpi
index d006c93..c09c171 100644
--- a/env/jsc.2026.gnu.openmpi
+++ b/env/jsc.2026.gnu.openmpi
@@ -60,6 +60,7 @@ export CXX=mpicxx
 export MPI_HOME=$EBROOTOPENMPI
 export UMPIRE_ROOT=$EBROOTUMPIRE
 export SUNDIALS_ROOT=$EBROOTSUNDIALS
+export TSMP2_PARALLEL_JOBS=16
 
 # Display compiler settings
 module list
diff --git a/env/jsc.2026.nvhpc.openmpi b/env/jsc.2026.nvhpc.openmpi
index 8196102..0606c81 100644
--- a/env/jsc.2026.nvhpc.openmpi
+++ b/env/jsc.2026.nvhpc.openmpi
@@ -53,6 +53,7 @@ export CUDACXX=nvcc
 export MPI_HOME=$EBROOTOPENMPI
 export UMPIRE_ROOT=$EBROOTUMPIRE
 export SUNDIALS_ROOT=$EBROOTSUNDIALS
+export TSMP2_PARALLEL_JOBS=16
 
 # Display compiler settings
 module list
diff --git a/env/ubuntu.gnu.openmpi b/env/ubuntu.gnu.openmpi
index 4875ecf..16fcda7 100644
--- a/env/ubuntu.gnu.openmpi
+++ b/env/ubuntu.gnu.openmpi
@@ -13,6 +13,7 @@ export MPI_HOME=/usr/lib/x86_64-linux-gnu/openmpi
 export MPIEXEC_EXECUTABLE=$(which srun)
 export SYSTEMNAME="UBUNTU"
 export STAGE=$(lsb_release -sr)
+export TSMP2_PARALLEL_JOBS=8
 
 # ParFlow additional libraries
 if [[ "$1" == "--parflowgpu" ]]; then
diff --git a/env/uni-bonn.gnu.openmpi b/env/uni-bonn.gnu.openmpi
index a3be772..47e6895 100644
--- a/env/uni-bonn.gnu.openmpi
+++ b/env/uni-bonn.gnu.openmpi
@@ -42,6 +42,7 @@ export FC=mpif90
 export CXX=mpicxx
 export MPI_HOME=$EBROOTOPENMPI
 export MPIEXEC_EXECUTABLE=$(which mpirun)
+export TSMP2_PARALLEL_JOBS=8
 
 # Display compiler settings
 module list