Hydrology, Carbon dioxide, Peat, Methane and Atmospheric sciences are his primary areas of study. His Hydrology research includes themes of Boreal, Ecosystem respiration, Atmospheric methane and Vegetation. Patrick M. Crill combines subjects such as Organic matter, Eddy covariance and Growing season with his study of Carbon dioxide. His studies in Peat integrate themes in fields like Permafrost, Dissolved organic carbon, Mineralogy and Wetland. His Methane research incorporates elements of Sediment and Water content. His research integrates issues of Climate change, Ecosystem and Greenhouse gas in his study of Atmospheric sciences.