Earth has a fever, but the heat is sloshing into the oceans
Posted on 3 April 2014 by John Abraham
Much has been made about the Earth's energy imbalance (extra energy absorbed by the Earth). It is clear the Earth is out of balance, in laypersons' terms, it has a "fever". What isn't clear is how bad the fever is. A new study by Dr. Matt Palmer and Dr. Doug McNeall moves us closer to answering this "fever" question.
These scientists used data from the latest group of climate computer models (CMIP5) to look at the relationships between the energy flows at the top of the atmosphere, the surface temperature of the Earth, and changes in ocean energy. They made (in my mind), three important conclusions.
First, there is a lot of variability in the Earth surface temperature. In fact, these natural fluctuations of the Earth surface temperature (0.3 degrees C per decade) can mask much of the underlying global warming. Consequently, you cannot use Earth surface temperatures over 10 years or so as an indicator of the Earth "fever". As we look over longer periods of time, the "masking" of global warming by internal fluctuations gets smaller; however, even for 15 years or so, natural fluctuations and human-caused global warming can be about the same size.
Second, the authors found that an increase in the ocean energy explains almost all (95%) of the variation in the Earth energy balance. This means that more complete measurements of the global oceans would enable us to better measure the "fever." Finally, for time periods longer than a year, the ocean becomes the dominant storage reservoir for heat.
There were some other conclusions that are noteworthy. For instance, we have heard a lot about how things like volcanoes, human particulate emissions, and solar variability can also impact our understanding of the Earth's "fever." The current paper argues that these "external" influences may be smaller than the natural variability of the Earth system itself – the "sloshing" of energy in/out, and within the Earth system. Another phenomenon that has been reported on quite a bit recently, including by me and my colleague in these pages, is the role of energy storage deep in the ocean. The authors confirm that such storage likely plays a contributing factor to the internal variability.
According to one of the authors, Dr. Palmer, who spoke about the importance of ocean and satellite measurements of the Earth's "fever,"