Cienciaes.com: The oceans in a changing climate. We speak with Denis Gilbert.

2019-11-23 11:58:45

Lately we have heard disturbing news very frequently about the evolution of the climate on Earth: elevation of the average temperature of the atmosphere due to the greenhouse effect, rise in the level of oceanic waters, increase in violent atmospheric phenomena, melting of polar ice, etc. . These news are not random, they are conclusions that are drawn from the analysis of data on terrestrial parameters obtained by thousands of expert scientists in the most disparate disciplines. A good example of this is that in the preparation of the last Special report on the ocean and cryosphere in a changing climate of the IPCC, the efforts of 100 specialists from 36 countries have been needed to analyze more than 7,000 specialized scientific publications. Among those researchers is our guest on Talking to Scientists, Denis Gilberta Canadian researcher who studies climate, physics and oceanography at the Department of Fisheries and Oceans Canada

Denis Gilbert has been participating in the project ARGO, a research effort that has deployed more than 3,800 buoys, loaded with sensors, throughout the terrestrial oceans, which obtain continuous information on changes that occur in the waters. These buoys have been designed to withstand the enormous pressures that occur in the depths, they are equipped with an automatic system that allows them to submerge up to 2,000 meters below the surface of the waters and, once there, begin to rise taking data from the temperature, salinity, acidity changes and, in ten percent of them, the oxygen concentration of the waters it crosses. When one of these buoys reaches the surface, it connects with the constellation of satellites Iridium to transmit the exact data of your position by means of GPS and all the measures it has carried out. The buoys work autonomously and are dragged by the currents so that information on the movement of the waters around the globe is added to the data obtained.

All these data are analyzed and studied by a large scientific community spread across universities, government laboratories, and meteorological and climate forecasting centers. The results of the investigations carried out from the analysis of the data provided by the project ARGO, together with many other observations made by stations, oceanographic ships and satellites, allow scientists to validate climate models and extract information about the evolution of climate and oceans. The analysis of more than 7,000 of these publications has allowed the elaboration of the Special report on the ocean and cryosphere in a changing climate approved by the IPCC.

The report makes clear the fundamental role of the oceans in the Earth’s climate. Its waters have absorbed more than 90% of the excess heat that the climate system has accumulated since 1970, due to the increase in greenhouse gases, and models predict that if current warming is limited to a rise of 2ºC, for By 2100, the oceans will have absorbed between two and four times more heat than in the last 50 years. The oceans play a very important role as a moderator of the level of greenhouse gases, the measurements reveal that they have absorbed between 20 and 30% of the carbon dioxide released by humans, but it has its negative side, the absorption has produced a increase in the acidity of the water. The changes detected in ocean currents, the loss of sea ice in the Arctic and the melting of permafrost or the rise in the level of the oceans are some of the points analyzed in the report.

Another aspect mentioned in the report is the deoxygenation of ocean waters, a field that Denis Gilbert has spent many years analyzing and researching, especially in North Atlantic waters. The concentration of oxygen in the waters is vital for the respiration of the higher organisms that inhabit them. Virtually all multicellular living things that live in the oceans need oxygen to extract energy from nutrients because, with oxygen, an organism can obtain 19 times more energy from each glucose molecule in the form of ATP that without him But the oxygen concentration is changing. Global observations show that the ocean lost approximately 2% of its amount of oxygen in the last five decades, something that obviously can have important implications for marine ecosystems.

The change varies from place to place, Gilbert explains, but a higher than average rate of deoxygenation has been detected in coastal areas of the North Atlantic. Changes in ocean currents bathing the region, that is, the Gulf Stream, which carries warm, oxygen-poor waters to the north, and the Labrador Current, which carries cold, oxygenated waters to the south, appear to be the cause. Specifically, a decrease in the volume of water carried by the Labrador Current has been detected and this influences the average oxygen concentration of the waters in the area.

I invite you to listen to Denis GilbertClimate, Physics and Oceanography researcher at the Department of Fisheries and Oceans Canada and participate in the elaboration of the last Special report on the ocean and cryosphere in a changing climate of the IPCC.