As a professor of physical geology Prof. Dr. Kempe taught -among other topics- “global cycles” and “biogeochemistry” with a strong focus on C,N,P cycles and hydrochemistry of rivers and seas. He conducted large research projects on the North Sea and the Wadden Sea as well as on the Black Sea and particle and carbon fluxes in the open ocean.
As a member of the IGBP SC he was co-responsible for drafting the science plan for LOICZ, wrote its first report on coastal seas and their importance as a CO2 sink and served on the LOICZ Committee. He was also a member of the German Research Council Global Change Committee dealing with the funding of coastal sea projects.