What are the advantages of observations of Earth from space?


Observations of the Earth from space provide a unique vantage point for gathering information essential to forecasting the weather, assessing environmental hazards, managing natural resources, and improving our understanding of climate. Since the first satellites carried cameras into orbit in the late 1950s, space observations have added a matchless perspective, which has grown richer as our space-based instruments have evolved in terms of both variety and sophistication.

Ground, sea, and air-based observing systems that contribute to monitoring our planet are also very important. But they have a major limitation — their view is limited. Even though each piece of surface-based data can be combined into large maps, the data represents only the conditions at one location. Beyond that, while surface observations are relatively numerous in many parts of the world, they are sparse in others — much of Africa, parts of South America, and the oceans. From space, by contrast, you can see the full picture.

For example, sensors on Earth observation satellites measure rainfall and cloud cover, the chemistry and temperature of the atmosphere, water levels in lakes and reservoirs, and deforestation around the planet. More importantly, because satellites orbit the planet for years, they can make consistent measurements over long periods of time. That is how we know so confidently that sea level really is rising, that ice shelves keep breaking off Antarctica, that rainforests are disappearing in the Amazon (and just how quickly), and that Greenland is shedding more ice into the sea than it gains in new snowfall (and, once again, how quickly). 

Earth observation satellites also gave us the first global look at the most fundamental climate measurement — how much energy from the Sun hits the Earth and how much energy leaves the Earth. Scientists perform these measurements by pointing a sensor at the Sun to measure incoming solar irradiance and by pointing a sensor at the Earth to measure the energy that is being re-radiated outward. Other sensors measure properties that influence how much solar energy stays in the Earth’s atmosphere as a result of cloud cover (a major influence). They also measure various gases, ocean currents, and wind patterns.

Space is truly an ideal vantage point for monitoring our planet’s climate.