diff --git a/.github/workflows/spack-ci.yml b/.github/workflows/spack-ci.yml
new file mode 100644
index 000000000..760ca18e1
--- /dev/null
+++ b/.github/workflows/spack-ci.yml
@@ -0,0 +1,122 @@
+name: Spack CI GCC Build
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+    # Do not run if the only files changed cannot affect the build
+    paths-ignore:
+      - "**.md"
+      - "**.pro"
+      - "**.sh"
+      - "**.perl"
+      - ".github/CODEOWNERS"
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}
+
+jobs:
+  build_gcm:
+    name: Spack CI GCC Build
+    runs-on: ubuntu-24.04
+    steps:
+
+      - name: Checkout GCM
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 1
+          filter: blob:none
+          repository: GEOS-ESM/GEOSgcm
+
+      - name: Set all directories as git safe
+        run: |
+          git config --global --add safe.directory '*'
+
+      - name: Setup Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.13'
+
+      - name: Pip install mepo
+        run: |
+          python -m pip install --upgrade pip
+          pip install mepo
+          mepo --version
+
+      - name: Mepo clone external repos
+        run: |
+          ls
+          mepo clone --partial blobless
+          mepo status
+
+      - name: Mepo develop usual suspects
+        run: |
+          ls
+          mepo develop GEOSgcm_GridComp GEOSgcm_App GMAO_Shared GEOS_Util
+          mepo status
+
+      - name: Update other branches
+        if:
+          "!contains('refs/heads/main,refs/heads/develop', github.ref)"
+        run: |
+          mepo checkout-if-exists ${GITHUB_HEAD_REF}
+          mepo status
+
+      - name: Set up Spack
+        uses: spack/setup-spack@v2
+        with:
+          ref: develop      # Spack version (examples: develop, releases/v0.21)
+          color: true       # Force color output (SPACK_COLOR=always)
+          path: spack       # Where to clone Spack
+          buildcache: false # Do not use the spack buildcache
+
+      - name: Find compilers
+        shell: spack-bash {0}
+        run: |
+          spack compiler find
+
+      - name: Set default compiler and target
+        shell: spack-bash {0}
+        run: |
+          spack config add 'packages:all:compiler:[gcc@14.2.0]'
+          spack config add 'packages:all:require:target=x86_64_v3'
+
+      - name: Create Spack environment
+        shell: spack-bash {0}
+        run: |
+          spack env create spack-env
+          spack env activate spack-env
+
+      - name: Login
+        shell: spack-bash {0}
+        run: |
+          spack -e spack-env mirror add geos-buildcache oci://ghcr.io/GEOS-ESM/geos-buildcache
+          spack -e spack-env mirror set --oci-username ${{ github.actor }} --oci-password "${{ secrets.BUILDCACHE_TOKEN }}" geos-buildcache
+          spack -e spack-env mirror list
+          spack -e spack-env buildcache update-index geos-buildcache
+          spack -e spack-env buildcache list --allarch
+
+      - name: Concretize
+        shell: spack-bash {0}
+        run: |
+          spack -e spack-env concretize
+
+      - name: Install
+        shell: spack-bash {0}
+        run: |
+          spack -e spack-env install --add --no-check-signature --use-buildcache only \
+            esmf gftl gftl-shared fargparse pflogger pfunit yafyaml ecbuild udunits openblas
+
+      - name: Build with Cmake
+        shell: spack-bash {0}
+        run: |
+          spack env activate spack-env
+          spack load \
+            esmf gftl gftl-shared fargparse pflogger pfunit yafyaml ecbuild udunits openblas
+          spack find --loaded
+          FC=gfortran-14 CC=gcc-14 CXX=g++-14
+          cmake -B build -S . -DCMAKE_INSTALL_PREFIX=$PWD/install -DCMAKE_BUILD_TYPE=Debug -DUSE_F2PY=OFF -DCMAKE_Fortran_COMPILER=${FC} -DCMAKE_C_COMPILER=${CC} -DCMAKE_CXX_COMPILER=${CXX}
+          cmake --build build -j 4
+          cmake --install build
+
diff --git a/.github/workflows/workflow.yml b/.github/workflows/workflow.yml
new file mode 100644
index 000000000..71302eac4
--- /dev/null
+++ b/.github/workflows/workflow.yml
@@ -0,0 +1,83 @@
+name: Build Tests
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+    # Do not run if the only files changed cannot affect the build
+    paths-ignore:
+      - "**.md"
+      - "**.pro"
+      - "**.sh"
+      - "**.perl"
+      - ".github/CODEOWNERS"
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.ref != 'refs/heads/main' }}
+
+jobs:
+  build_gcm:
+    name: Build GEOSgcm
+    if: "!contains(github.event.pull_request.labels.*.name, '0 diff trivial')"
+    runs-on: ubuntu-24.04
+    container:
+      image: gmao/ubuntu24-geos-env:v7.32.0-intelmpi_2021.13-ifort_2021.13
+      # Per https://github.com/actions/virtual-environments/issues/1445#issuecomment-713861495
+      # It seems like we might not need secrets on GitHub Actions which is good for forked
+      # pull requests
+      #credentials:
+        #username: ${{ secrets.DOCKERHUB_USERNAME }}
+        #password: ${{ secrets.DOCKERHUB_TOKEN }}
+
+    env:
+      OMPI_ALLOW_RUN_AS_ROOT: 1
+      OMPI_ALLOW_RUN_AS_ROOT_CONFIRM: 1
+      OMPI_MCA_btl_vader_single_copy_mechanism: none
+
+    steps:
+      # https://github.com/orgs/community/discussions/25678#discussioncomment-5242449
+      - name: Delete huge unnecessary tools folder
+        run: rm -rf /opt/hostedtoolcache
+
+      - name: Checkout GCM
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 1
+          filter: blob:none
+          repository: GEOS-ESM/GEOSgcm
+
+      - name: Set all directories as git safe
+        run: |
+          git config --global --add safe.directory '*'
+
+      - name: Versions etc.
+        run: |
+          ifort --version
+          mpirun --version
+          echo $BASEDIR
+
+      - name: Mepo clone external repos
+        run: |
+          mepo clone --partial blobless
+          mepo status
+
+      - name: Mepo develop usual suspects
+        run: |
+          mepo develop GEOSgcm_GridComp GEOSgcm_App GMAO_Shared GEOS_Util
+          mepo status
+
+      - name: Update other branches
+        if:
+          "!contains('refs/heads/main,refs/heads/develop', github.ref)"
+        run: |
+          mepo checkout-if-exists ${GITHUB_HEAD_REF}
+          mepo status
+
+      - name: CMake
+        run: |
+          cmake -B build -S . --install-prefix=${pwd}/install -DCMAKE_Fortran_COMPILER=ifort -DCMAKE_BUILD_TYPE=Debug -DMPIEXEC_PREFLAGS='--oversubscribe' -DUSE_F2PY=OFF
+
+      - name: Build
+        run: |
+          cmake --build build -j 4
+          cmake --install build