There are strong indications that there was only one ice age.
This is a flat out lie.
The article briefly addresses cores from the Ocean Drilling Program but in no way falsifies the data (and even neglects most of it). The reason the data conflicts with the four-ice-age model is because that model is no longer tenable nor is it held in the realm of geology anymore.
Not only are there isotopic variations for Oxygen, but there is also evidence from biogenic sediment production and its flux to the seafloor for components like opal and calcium carbonate. Productivity of organisms producing these sediments depends STRONGLY on climate variability. Not only do these fluctuations correspond to short term orbital variations but also climatic variations corresponding to glacial advances and retreats. Furthermore we have evidence from eolian dust contained in those cores indicative of changing wind strengths based upon the particles contained in the cores. These fluctuations also correspond to climatic variations if a spectral analysis is done (and was done by David Rea I think).