During the last inter-glacial (LIG), which ended some 120,000 years ago, hippopotami appear to have been abundant in the Thames River basin near what is now London. (Petersen & Lieberman, 2012) It appears that global temperatures were some 2°C warmer (less in the tropics, more in the upper mid-latitudes) during the LIG. The current interglacial bids fair to surpass those temperatures, if NOAA is to be believed: "Astronomical calculations show that 65N summer insolation should increase gradually over the next 25,000 years, . . . http://www.ncdc.noaa.gov/paleo/milankovitch.html And that's not counting the effects of increased CO2 levels (401.58 ppm as of October of 2015).