Earth Observation is a global endeavour. It is the process of making measurements of the entire planet using satellites.

These measurements enable us to monitor changes to the environment and patterns of land use and can influence environmental policy. Within two years of satellite monitoring showing a hole in the ozone layer, for example, Europe and 24 non-European countries had signed up to The Montreal Protocol on Substances that Deplete the Ozone Layer.

This protocol protects the ozone layer by controlling the production and consumption of harmful chemicals. More than 160 countries have now formally approved the protocol.

Co-ordinating space missions

The UK recognises the importance of Earth Observation satellites and is involved in the following activities and strategies:

BNSC funds GIFTSS (Government Information From The Space Sector). GIFTSS develops partnerships between UK Government departments and agencies. The aim is to investigate and develop the use of satellite-based data to address challenges such as intelligent transport, long-term landuse monitoring and humanitarian aid distribution.

GMES (Global Monitoring for Environment and Security) is a European Union led initiative in partnership with the European Space Agency (ESA). GMES will build a co-ordinated system for Earth observation and monitoring and has a particular emphasis on climate change. With GMES, Europe's politicians will have access to independent environmental data to form and support their policy decisions.

CEOS (Committee on Earth Observation Satellites) provides an international forum in which to discuss international Earth Observation issues. The CEOS ensures that countries work together to get the most from international civil space missions that observe and study planet Earth.

CEOS consists of 23 members (most of which are space agencies) and 21 associates (associated national and international organisations). It is recognised as the major international forum for the co-ordination of Earth observation satellite programs and users of satellite data worldwide.

Envisat

Envisat is the world's largest and most complex environmental satellite. Launched in 2002, it is the size of an articulated lorry and takes many different measurements of the Earth's land, oceans, atmosphere and ice caps at the same time. This is so we can discover how one factor affects the other.

Envisat has already exceeded its original lifetime and remains in good health. The mission is now extended until 2010.

Data from the Envisat mission will build on information obtained from ERS (European Remote Sensing Satellite) 1 and 2. The ERS satellites have been watching over the Earth for more than 16 years, providing scientists with plenty of data about our planet. Already there is enough satellite information to show long-term trends in sea level rise and reduced ice cover in the Arctic.

Examples in the rest of this section show how scientists use satellites to help tackle climate change, pollution and improve land monitoring.