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Where do the data on climate change come from?

Photograph of the International Space Station taken from NASA’s SpaceX Crew-2 on November 8, 2021. Courtesy of NASA.

We are starting to get the impression that scientists and governments are announcing new policies and forecasts for our global warming every week. But where do the data come from behind the alarming headlines and future disasters? Much of what we understand about climate change comes from above. Satellites are one of our best tools for detailing the impact of our actions on the planet.

For decades, scientists have placed specialized sensors aboard orbiting spacecraft to better understand the world we live in. About 4000 active satellites currently orbiting the Earth. Most are linked to the military. But there are an estimated 900 Earth Observation Satellites, many of which help us better understand anthropogenic climate change. They were born out of efforts dating back to 1960, when NASA launched its first weather satellite, Infrared Television Observation Satellite-1 (TIROS-1). TIROS housed sensors that tracked the weather, and it was a resounding success. For the first time, scientists were able to see storms in near real time as they developed in the atmosphere.

that of NASA Nimbus program followed in 1964, with sensors that distinguished snow and rain during precipitation events and tracked snow depth and accumulation rates in the Arctic. Nimbus instruments also measured ozone concentrations in the atmosphere, observed plankton in the ocean (to keep an eye on the health of the oceans – as the water warms and acidifies, the plankton dies and produces less oxygen) and monitored sulfur dioxide emissions from volcanic eruptions (to understand when high concentrations of gases can cause respiratory problems and increased temperatures).

Neither TIROS nor Nimbus were designed to track climate change, but they have shown that future satellites could. Over the next half century, nations launched hundreds of Earth observation satellites, each loaded with arrays of instruments that mapped things like CO2 concentrations in the atmosphere and deforestation across the planet. They continue to provide crucial measurements today, using many unique sensors, but with a few of the more common basic types.

At least when it comes to information gathering, international collaboration has created a gigantic global network of satellites that contributes to a more complete understanding of what is happening on the planet.

Synthetic Aperture Radar, or SAR, sensors are also common on Earth observation satellites. These sensors bounce energy pulses off an object and measure the time it takes for the energy to return to determine how far away the object is. Space-based SAR sensors can be used to detect caves and sinkholes, measure glacial movement, determine the extent of forest fire damage, and detect and measure oil spills.

Thermal sensors are designed to detect heat coming from the surface of the planet. They can be used to identify potentially active volcanoes, to measure ocean and land temperatures, and to help detect forest fires.

Beyond collecting observations, there is another way in which satellites advance climate knowledge: by forging collaborations. Slowing global warming will require intense cooperation between agencies and countries, and Earth Sciences is one of the few areas where such teamwork is the norm, rather than the exception, in part because satellites. It takes hundreds or thousands of years of engineers, programmers, and testers to prepare for a launch.

NASA has partnered with what is now the National Oceanic and Atmospheric Administration (NOAA) on TIROS, and the agencies still share responsibility for the program. NASA and the United States Geological Survey are partners in another major program, Landsat, the oldest ongoing Earth mapping satellite project.

The European Space Agency (ESA) – itself an intergovernmental organization of 22 member states – works closely with US agencies, including on ESA’s Sentinel satellites, which are a wealth of information for climate scientists around the world. The most recent launch of the Sentinel mission, the Sentinel 6 Michael Freilich satellite, was a collaboration between NASA, NOAA and ESA.

It is not generally considered a satellite, but the International space station (ISS) is another example of a collaboration that has greatly advanced the observation of Earth from the sky. Working in conjunction with autonomous on-board sensors, the station’s astronauts, from many different countries, use sensors that allow scientists to capture data that can be difficult for remote-controlled satellites to detect. The ISS has proven particularly useful for coastal mapping and imagery of natural disasters.

Going forward, space agencies around the world will continue to partner to measure climate change. A partnership between NASA and the Indian Space Resource Organization, the NASA-ISRO SAR (NISAR) mission, will establish a baseline for large-scale environmental change by imaging large areas of the globe over a three-year period. The platform is expected to launch in 2023. NASA will also maintain its close collaboration with the Japan Aerospace Exploration Agency, sharing data and building sensors for each other’s satellites.

Reading the headlines of the recent Glasgow conference, one can get the impression that the nations of the world are at odds when it comes to climate change. But at least when it comes to collecting information, international collaboration has created a gigantic global network of satellites that contributes to a more complete understanding of what is happening on the planet.

These satellites will continue to evolve and the sensors on board will continue with them. And if we’re smart, we’ll take advantage of the data they provide, take the drastic action needed to reduce the damage we cause, and preserve the planet for future generations.


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