Observing the oceans for signs of climate change
2007/11/01 Fischer, Albert - UNESCO--IOC Programako aditua eta ozeanografia-ikertzailea Iturria: Elhuyar aldizkaria
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It is not long before the observations of the subsurface ocean began to take place seriously: They began after World War II and concentrated in areas with heavy maritime traffic such as the North Atlantic. However, this story is long enough to calculate the trends of subsurface temperatures with a reasonable degree of scientific certainty.
In fact, the subsurface ocean is the ideal place to seek clear evidence of man-made climate change. In fact, a change in the climate system, such as the one caused by greenhouse gases, forces the entire climate system to find a new balance: As the earth is warmer, it emits more heat to the space to compensate. This extra heat is mainly absorbed by the oceans. On the other hand, the subsurface oceans are less noisy than the superficial ones -- which are influenced by time and time seasons -- so they are the clearest signs of long-term climate change.
An indisputable proof of the oceans
In an article published in the journal Science in July 2005, Tim Barnett and his colleagues demonstrated that the warming trend observed in the oceans over the past 40 years cannot be explained through natural variability, but that this trend was clearly associated with climate predictions that take into account man's influence on climate. However, this discovery did not correspond to measurements made elsewhere.
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In any case, the study has provided reliability to models regarding the climate change simulation capacity of climate models including land, ocean and atmosphere. To a large extent, it is no longer questioned that human activity has caused climate change. However, it remains to clarify exactly how it will change.
The World Climate Research Program (WCRP) tries to answer these questions. This program is sponsored by the Intergovernmental Oceanography Commission (IOC) of UNESCO, the World Meteorological Organization (WMO) and the International Council of Science (ICSU). Its main objective is to determine the limits of the predictability of the climate system and of the human influence on the climate.
It is still difficult for scientists to distinguish between man-made climate change and natural climate variability. Climate variability itself seems to be changing: The extremes of incidents outside the "normal" time field are further separated from each other. It is an indicator of climate change. In this context, the WCRP's climate variability and predictability project helps to better predict extreme weather situations and model -- on a temporary scale of better days, months and years.
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Observing the oceans to understand them
The UNESCO Intergovernmental Oceanography Commission (IOC) and its cutting-edge programme, GOOS, are responsible for the continued observation of the oceans within the United Nations. A team of IOC experts (OOPC) collaborates in defining the standards and objectives of the GOOS “global climate” concept and in defining system control and evaluation tools.
In parallel, with the participation of the World Meteorological Organization in a technical committee of oceanography and marine meteorology (JCOMM), IOC is actively working on the coordination of global networks through an on-site platform management center (waters) located in Toulouse (France) (JCOMMOPS). This center permanently controls thousands of beacons, boats and buoys, both fixed and drifting, providing oceanographic data.
Among these networks in situ, Argo's network of buoys is the fastest growing. Argo buoys are a robotic and automatic tool to measure the ocean that is applied to 2 km deep in the ocean. Every ten days, pumping oil to an outer tank, they rise to the surface. At the ascension, they collect information about temperature and salinity (some also measure oxygen) and, when on the surface, transmit that information via satellite.
At the end of 2005, over a four-year period, the Argo project had more than 2,000 scattered buoys, two-thirds of the initial target (3,000 buoys), almost a 100,000 km 2 buoy, with a four-year survival. When batteries run out at age four, buoys cannot rise to the surface and many sink.) The Argo buoys have been dispersed across the world's oceans thanks to the efforts of more than 20 participating countries. And in some places, the buoys provide more information about the subsurface ocean for a year than in the entire history prior to Argo's setting.
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On the other hand, the buoys that are adrift on the surface give way to the currents of the world surface, providing data on the surface: temperature, fast and often barometric pressure. These buoys provide real data to check satellite calculations on sea surface temperature, being the best witnesses of ocean surface currents, which are guided by wind and ocean eddies. They also improve weather forecasts by reporting surface pressure.
The objective of the OOPC (expert group of the UNESCO Intergovernmental Oceanography Commission) was to have a buoy of 300,000 km 2, representing a total of 1,250 drifting buoys. Objective met in September 2005: 1.250. The Global Drifter buoy was launched at a special event in Halifax, Canada. He was the first of the networks established for on-site observation of the ocean that fulfilled its goal, a truly memorable fact.
However, scientists cannot proclaim victory and simply go home. The network of drifting buoys must be continuously renewed, as buoys fail and quickly move away from areas of divergence. In addition, only 55% of the planning of the global in situ ocean observation network (composed of buoys, receivers, prospectors, seafarers and voluntary and research ships) has been completed.
Scientists walking the oceans
In addition to the buoys, ships also participate in research. The merchant ship Skogafoss, container cargo of 100 meters in length, sets sail monthly from the port of Reykjavik (Iceland). Transports frozen fish containers to North America. Back at two weeks, he makes the same trip, year and year. In the North Atlantic it takes the northernmost boat route and, despite being in the middle of spring, it must avoid the icebergs that the Labrador Current leads to the south.
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This is a gift for scientists, as modern research packages are often very expensive. Fuel, maintenance and equipment of 3-8 people (official media team, engineers and sailors) pay between 20,000 and 50,000 dollars a day. These voluntary packages are, in turn, one of the main engines of expansion of the drifting surface buoys and Argo buoys, which fill the gaps of the observation network as they appear.
Global information for local decisions
The global component of GOOS was designed to monitor, predict and investigate climate, but it also contributes to improving weather and marine prediction. It manages and disseminates ocean data (currently supplied by about 70 countries) in a coordinated manner, from which they create oceanic and climatic models and other products. For example, IOC plays an important role in coordinating global natural hazard alerts, especially regarding tsunamis. In fact, many times the observation platforms that feed the warning systems are the same: associated buoys and marographs are used, both in climate observation systems and in tsunami observation systems.
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However, the commitment of States is not sufficient. The oceans of the world that cover so much of the Earth are the heritage of all nations. Almost all countries, rich and poor, have a national meteorological agency that makes atmospheric predictions, but very few have an oceanographic agency for observing the oceans and even less an order of observation of the world's oceans.
Ocean observation networks were built thanks to the constant work of oceanographic researchers. However, the existence of the network itself poses problems, as is the case with the instruments of measurement of subsurface currents that have been controlling thermohaline circulation in the Atlantic for more than ten years, but some of them will not be renewed, since national research agencies prefer to create something new. Once this surveillance is over, there will be nothing else to supply that absence.
Poor long-term forecast
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World governments do not commit to permanent observation because they have a short-term vision. Politicians are very weak at the human-caused greenhouse gas problem, but it is clear that the climate continues to change and that this change can accelerate.
Scientific observation and research are critical to help understand how climate will change, improve predictions about short-term changes in local climates, improve our limited knowledge of ocean chemistry and how to change ecosystems, and provide better knowledge to global governments and citizens to make future decisions.
Earth's climate has been altered unprecedented by man. Addressing the conclusions will require collecting as much information as possible.
For more information:
http://ioc.unesco.org/iocweb/climate-change
Source: UNESCO. "Watching the oceans for signs of climate change", A World of Science, 4. vol. No. 1, January-March 2006 (http://www.unesco.org/science/)
Article translated and adapted by Elhuyar with the authorization of UNESCO.
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