The temperature of the Earth’s oceans is increasing. Those are the findings of four separate studies based on heat recordings taken from these bodies of water. The review and analysis, to be published on January 11, 2019, in the journal, Science, show that the oceans are warming up, and will continue to get warmer unless current energy-use and carbon dioxide-producing practices reduce in scale over time.
The authors of this new paper also assert that their findings debunk the notion of a ‘climate change hiatus’ that has been in effect over the last 15 years. Instead, these scientists believe that, as one of the best indicators of global warming, ocean heat content trends may now suggest the opposite.
The researchers have collaborated across institutions such as the US National Center for Atmospheric Research, the Chinese Academy of Sciences and the Energy and Resources Group at the University of California (Berkeley).
How Scientists Calculate Ocean Temperatures Today
Their work is based on the recordings taken from Argo, a fleet of underwater robots that perform regular, globe-round dives to 2000 meters below sea level. The robots, which are just over 4,000 in number, do this in order to take measurements such as ocean pH, salinity and, of course, temperature.
Argo has been in operation since the last decade and has contributed the data (in conjunction with more traditional techniques such as bathythermography) necessary for three of the four studies on ocean heat trends analyzed in the new Science paper.
A vintage bathythermograph. (Source: NOAA Photo Library)
These three studies evaluated ocean temperature trends from 1970 to the 2010s, using up-to-date techniques that corrected for calibration errors and biases in the Argo robots and the bathythermographs. The fourth study, on the other hand, made indirect measurements through the release of oxygen that occurs in warming seas.
Therefore, the analysis of all these studies gave a better picture of actual ocean-temperature trends over the last 40 years.
What Happens to Oceans when Environmental Policy Doesn’t Change?
The authors reached their conclusions after imposing the Coupled Model Intercomparison Project 5 (CMIP5) model on their data. This model was used under the assumption that the rate of emissions from fossil fuel use will continue apace as they do today, without any attempts at reductions in or other alternatives to their use.
Under these conditions, the analysis resulted in the top 2,000 meters of ocean waters worldwide warming up by 0.78 degrees Celsius, by the year 2100.
This increment may sound less than prepossessing; however, it also represents a much higher rate of warming than indicated by previous studies on the subject. In addition, even that much heat is enough to cause sea levels to rise 12 inches higher than they already are today. This increase would be added to the significant surges predicted as a result of sea-ice and glacier losses. Warmer oceans also increase the risk of weather anomalies such as greater rainfall, hurricane formation and increases in the extent of storm strength.
The authors reported that this projected warm-ocean effect is due to the fact that these seas absorb 93% of the solar energy trapped by emissions such as excess carbon dioxide. In addition, ocean temperatures are not modulated by seasonal hurricane patterns or volcanic events, as it is on land. Therefore, it is a crucial marker of climate stability (or rather, the lack thereof).
The authors of the Science paper also noted that their results put ocean-heating trends in line with other prominent findings on global warming.
Could These Findings Change the Future?
This analysis suggests that actions to address climate change are more necessary than ever. Such measures may also help tackle the issues of impending land surface-area loss due to rising sea levels, and of marine life loss due to environmental changes such as rising temperatures.
Furthermore, this new paper also highlights the clear danger sign that 2018 was found to be the fourth-warmest year on the Earth. This discovery applies to temperatures on land.
Now, scientists such as Zeke Hausfather from the Energy and Resources Group (who also contributed to this latest paper on the subject) also believe that 2018 was the warmest year under the waves too.
Top Image: According to the latest analysis, the oceans are steadily getting warmer. (Source: Belinda/Wikimedia Commons)