The UCI School of Physical Sciences offers the following undergraduate degrees:

Chemistry, B.S.
Earth System Science, B.S.
Environmental Science and Policy, B.A.
Mathematics, B.S.
Physics, B.S.

The distinction of B.S. versus B.A. is one of focus versus flexibility.

Comparison of B.S. and B.A. Degree Programs in the Department of Earth System Science

B.S. Program (Earth System Science)
        http://www.ess.uci.edu/undergrad/bs

B.A. Program (Environmental Science and Policy)
       https://www.ess.uci.edu/ensp