 In its periodic assessments, the IPCC has reached increasingly strong conclusions about the detection of climate change in observations. The IPCC’s Fifth Assessment Report concluded that it is “virtually certain” (i.e., probability &gt;0.99) that the increase in global mean surface temperature seen since 1950 is not due to internal variability alone (Bindoff et al. 2013: 885). That is, the probability that the warming is due to internal variability alone was assessed by the scientists, on the basis of available evidence and expert judgment, to be less than  1%.[4]  Indeed, it was noted that, even if internal variability were three times larger than estimates from simulations, a change would still be detected (ibid.: 881, citing Knutson et al. 2013). Changes have been formally detected in many other aspects of the climate system as well, not just in the atmosphere but also in the oceans and the cryosphere.