Climate Exchange

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cosystems

using more than 50 million measurements of varia-

tions in gravitational attraction. For the first time, its

measurements also allow global currents to be extracted

directly from satellite altimetry data: ocean currents are

understood as a major engine of our global climate.

The ESA Soil Moisture and Ocean Salinity (SMOS)

mission followed in November 2009. SMOS provides

the first global measurements of two key variables in

the water cycle – soil moisture and ocean salinity. Thus,

scientists are able to trace the inter-annual variation of

water available in soils and produce accurate ocean

surface salinity maps around Earth.

Only five months after the launch of SMOS, the third

Earth Explorer – ESA’s Ice mission Cryosat – was deliv-

ered into orbit inApril 2010. TheCryoSatmissionmeasures

ice sheet thickness and volume in the Arctic and Antarctic

for the first time ever. This allows a new understanding of

the complex relationship between ice and climate. In April

2012, scientists published the first Cryosat seasonal cycle

of arctic ice thickness (October 2010 to April 2011). A

few months later, satellites witnessed an alarming record:

the lowest Arctic sea ice extension since the beginning of

systematic measurements.

The next mission, ready for launch, is ESA’s magnetic

field mission Swarm, which will provide the best ever

survey of the Earth’s geomagnetic field and its varia-

tion in time while enabling new insights into the Earth’s

interior and climate. Further Explorers are under

development or selection. Each mission uses the most

political action upon climate-related data. Satellites deliver such data

in a reliable way.

The European Space Agency (ESA) is a pioneer in terms of Earth

observation satellites. It has been instrumental in making meteorol-

ogy one of the first sustainable and operational space applications

in Europe, having put efforts into the development of the Meteosat

missions since the 1970s. The long-lasting ERS-1 and ERS-2

missions, as well as Envisat, the world’s largest Earth observa-

tion satellite ever, have provided an immense amount of valuable

research data to more than 4,000 scientific projects worldwide and,

routinely, to service providers every day. The data collected by

sophisticated sensors over decades form a vast archive that is still

far from being completely exploited.

One of the most urgent topics is the understanding of the under-

lying mechanisms of climatic change, and the contribution of

humankind to it. In order to arrive to useful findings it is indispen-

sable to look at the state of and, more importantly, the changes in

the Earth’s climate which come about as the result of the interaction

between components such as the atmosphere, cryosphere, hydro-

sphere, land masses and not least the human sphere of influence.

ESA is developing a veritable fleet of Earth Explorer missions that

shed light on open questions regarding these Earth systems. Three

Earth Explorers are already in space.

Gravity field and steady-state Ocean Circulation Explorer

(GOCE), a mission to map the Earth’s gravity field with unprece-

dented accuracy, was launched in March 2009. GOCE has produced

the most accurate model of the geoid ever produced. In doing so,

the satellite carries the first gradiometer in space at one of the lowest

satellite orbits ever (about 255 km). GOCE’s geoid has been created

A scientific novelty – the first Arctic seasonal ice volume change data delivered by Cryosat

Source: ESA 2012