A study from Princeton University has found that, based on data dating back to 1991, the oceans have absorbed an level of heat energy which is 150 times the energy humans produce as electricity. This level of heat has been consistently absorbed each year. The research sends a strong warning about the extent of ocean warming and it signals that the Earth is even more sensitive to fossil-fuel emissions than earlier research has indicated. This comes at the same time as the WWF reports how populations of mammals, birds, fish, reptiles, and amphibians have, on average, declined in size by 60 percent in just over 40 years.
Earlier estimates of the heating of the oceans have been drawn from hydrographic temperature measurements and data taken from the Argo float program. Argo is an international program that uses profiling floats to observe temperature, salinity, currents, and, recently, bio-optical properties in the Earth’s oceans.
The new research has found that Argo is based on an imperfect ocean dataset and there are further uncertainties due to a relatively sparse coverage in terms of the location of the data capturing floats. Instead the researchers have used an alternative measure based on atmospheric oxygen and carbon dioxide. These levels increase as the ocean warms and releases gases. The researchers state they have generated a whole-ocean thermometer.
The research is important because the ocean takes up around 90 percent of all the excess energy produced as the Earth warms. This means understanding fluctuations with the ocean temperature allows for estimations to be made about surface warming. Given the rate is faster than previously seen, the researchers contend that tighter measures must be taken to lower emissions of carbon dioxide globally.
The research has been published in the journal Nature. The research paper is titled “Quantification of ocean heat uptake from changes in atmospheric O2 and CO2 composition”. The research was funded by the U.S. Climate Program Office of the National Oceanic and Atmospheric Administration.
