GCOS Implementation Plan - WMO

Implementation Plan for the Global Observing System for Climate in Support of the UNFCCC
(2010 Update)
• Global monitoring of the composition and distribution of aerosols and their precursors, and linked
observation of aerosol and cloud for study of their interactions;
• Global monitoring of water vapour especially at the surface and in the upper troposphere and
lower stratosphere, and linked observation of water vapour and cloud, especially for deep
convection;
• Unbiased estimation of high temporal resolution precipitation amount and type, especially over
the oceans, over high latitudes and over areas of complex orography;
• Combination of in situ and space-based measurements of greenhouse gases in reanalysis and
inverse modelling; e.g., development of active (lidar) and passive sensors for the estimation of
column CO 2 from satellites;
• Development of consistent climate-quality reanalysis products for all ECVs.
5. OCEANIC CLIMATE OBSERVING SYSTEM
Role of the Oceans in the Climate System
The oceans play critical, but generally not obvious, roles in the fundamentally coupled oceanatmosphere-land
Earth climate system. Perhaps the most obvious role is through sea level, which
directly affects society at the coasts by displacement of human populations and by stressing coastal
ecosystems. Less obviously, but very importantly, transport of heat from the Tropics toward the poles
is a major factor in determining the surface temperature of many nations; east-west transport of water
in the tropical Pacific controls the onset and evolution of El Nino events; transport along and under ice
shelves may determine how rapidly they separate from land. The oceans hold about 50 times more
carbon than the atmosphere, and their sediments thousands of times more.
The oceans also vary on decadal time scales and will experience greater changes than will result from
climate change over the same period. The upwelling zones of the oceans provide nutrients that
support some of the most biologically productive zones of the planet, and there is growing evidence
that oceanic physical and chemical changes strongly control ocean ecosystems and may affect them
more in the decades ahead. Tracking the heat and carbon stored and the exchanges of heat,
moisture, momentum and greenhouse gases with the atmosphere are vital for understanding and
forecasting the evolution of climate variability and change. Observing changes in the biogeochemical
system and in marine ecosystems is critical to projecting their future states, as well as the oceans’
ability to continue to provide food to vulnerable societies.
Sea level is a critical variable for low-lying regions, and globally is driven by volume expansion or
contraction due to changes in sub-surface ocean density, and by exchange of water between the
oceans and other reservoirs, such as land-based ice and the atmosphere. Local sea-level changes
can also be strongly influenced by regional and local circulation changes, by isostatic rebound from
the last glaciation period, and by land-use changes. Sea-surface temperature is a critical variable for
the coupled atmosphere-ocean system. In addition to the surface atmospheric variables, others of
note include sea ice, sea-surface salinity, and partial pressure of carbon dioxide (pCO 2 ). Ocean colour
is used to indicate biological activity in particular. Ocean life is dependent on the biogeochemical
status of the ocean, which is affected by changes in its physical state and circulation. Sea ice is
important as an indicator of climate change as well as through its albedo feedback and its impact on
polar ecosystems. Melting or forming sea ice affects salinity and hence density and ocean currents.
Technology is developing rapidly to permit additional observations in coastal regions and for boundary
currents, narrow straits and shallow regions (choke points where flow is limited), biogeochemical
variables, primary productivity, and other ecosystem variables.
Observing the Oceans
The composite surface and sub-surface ocean observing networks, as described in the IP-04, include
global monitoring of certain ECVs where this is feasible. Monitoring of other ECVs depends on
observations from reference stations or sites, or, in the case of sub-surface ocean carbon, nutrients
and tracers, repeat ship-based surveys. Very recently, there have been significant contributions to
sub-surface ocean measurements, particularly in data-sparse areas near ice margins from animalmounted
conductivity, temperature and depth (CTD) devices. The global ocean observing system put
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