Environment & Energy

Michael Mann says that he doesn’t see any acceleration of global warming. Some people would say that the acceleration is already apparent, but the level to which global temperature rises by next May and then falls in the next La Nina, will firmly settle that matter.

Mike also says that he doesn’t see an increase in the rate of heat uptake by the ocean. Fig. 4 (by Li et al.) in our prior communication²¹ shows that there is evidence of increased heat uptake even in the long-term in situ ocean data, which have large error bars because of the difficulty in obtaining adequate coverage of the global ocean with consistent instrument calibrations. However, our analysis refers to the changes underway in the 21st century, when we have much more precise data on Earth’s energy imbalance from the combination of in situ Argo ocean data and satellite CERES data (Fig. 7 above). The increase of absorption of solar radiation by Earth and the increase of Earth’s energy imbalance are much larger than the measurement uncertainty. The measurements need to be continued!⁵³

Mike also says that our paper is “wrong” because nations and industries and businesses are promising to go to zero emissions or net zero emissions in the future (sometimes in the far future, when the promiser will be dead or at least out of office). Leaving aside whether the promisers can all be trusted to deliver and whether their concept of “net zero” is really zero (very big assumptions!), the present global warming and planetary energy imbalance assure that we will hit 2°C global warming. Present knowledge of the consequences of ZEC (Zero Emissions Commitment, the change in global mean temperature expected to occur following cessation of net CO2 emissions), MacDougall et al.,⁵⁴ indicates an approximate stabilization of global temperature from the time at which ZEC is achieved. As for the realism of the assumptions of near-term achievement of ZEC, one would be wise to read the opinions of Dyke, Watson and Knorr,⁵⁵ who have had the real-world experiences needed to grasp the nature of the present situation.