Oceans cover over two-thirds of Planet Earth, with a 50-meter-deep layer of warm water near the surface, topping deep cold water beneath. Although this layer is relatively shallow, the high specific heat of water—compared to the temperature of the atmosphere above—preserves the stability of water temperature for longer periods. Specific heat is the heat energy needed to raise the temperature of one gram of matter by one degree.
Whereas we witness rapid changes in atmospheric weather, the ocean temperature changes slowly. It is probable that the temperature of ocean water tomorrow will be only slightly different from its value today, thanks to the good memory of the ocean water. This memory is often used to predict the future conditions of the oceans. According to a recent study published in Science Advances, most oceans are losing their memories, year after year, due to global warming and the increasing concentrations of greenhouse gases.
Greenhouse gases exist in the Earth atmosphere and can absorb and preserve the infrared rays reflected from the surface of the Earth, which raises the air temperature and aggregates the greenhouse effect and global warming. Through studying climate models, researchers found that the ocean's memory deteriorates in response to global warming induced by human activity. As the concentrations of greenhouse gases increase, scientists expect that ocean memory loss will become more articulate in the coming decades. Climate models indicate that ocean memory will vanish by the end of this century. Researchers discovered this phenomenon by investigating differences in ocean surface temperature from one year to another, being a simple indicator of ocean memory.
It is worth mentioning that climate models are mathematical representations that predict climate and environmental changes in the coming decades. There are many types of climate models that differ in terms of complexity. They include several variables such as the condition of the atmosphere, oceans, Earth surface, soil changes, vegetation, man-made infrastructure, social and environmental management mechanisms, and environmental policy decisions.
Researchers link ocean memory loss to the regression of the top layer of most oceans, which is becoming shallower due to the continuing climate changes. Changes in ocean currents and in energy exchange between the atmosphere and oceans also affect ocean memory.
These alternations pose a huge challenge for scientists; they have to make fundamental changes to climate system models to be able to predict climate in the future in light of global warming. The challenge is also represented in our decreasing ability to predict weather and prepare for changes that take place in oceans. This includes the marine heatwaves known for causing sudden evident changes in marine ecosystems around the world. Ocean memory loss will not impact oceans only, but also the management of fisheries, or fish-rich areas that are used for commercial purposes.
For example, researchers need to assess the fish stock in these areas. The factors used for this assessment are based on pre-supposedly stable environmental conditions. The deterioration of ocean memory can make these assessments inaccurate, and necessitate a new approach to the management of fisheries.
The impact of ocean memory deterioration could also affect different species in different biological systems, depending on their ability to adapt to the changing environmental conditions. Prediction of temperatures, rainfall, and snowfall might also be affected since it depends on the stability of the ocean surface temperature.
As ocean memory deteriorates, researchers would face the challenge of finding new methods to predict the condition of the oceans. While researchers exert much effort to ensure the accuracy of climate predictions, the information we obtain from climate models is still experimental. No one knows for sure what the future looks like, but these models help us better prepare for what may lie ahead.
References
fisheries.noaa.gov
nature.com
science.org
weather.gov