Technical Abstract: Animal waste storage facilities are important point sources of greenhouse gas emissions to the atmosphere. Being point sources, containment of gaseous emissions via improved storage conditions may be possible using surface covers. Permeable surface covers (natural crusts and artificial covers) are becoming more popular due to their capacity to reduce various gaseous emissions from the manure storage facility. Microbial transformations in permeable surface covers include bacterial methane oxidation, but this interface between nitrogen-rich liquid waste and the atmosphere is also an environment with intense nitrogen turnover that can lead to nitrous oxide emissions. Strategies to reduce environmental impact must consider the total greenhouse gas balance. In the following review, greenhouse gas mitigation options for manure storages are discussed with reference mainly to practical storage conditions in Europe and North America.