Challenge: Monitor greenhouse gas (GHG) emissions every day at every location on earth
Why: To measure the movement of carbon from activities on Earth's surface, anthropogenic and otherwise, to the atmosphere because GHGs have caused warming of ~1°C around the world
Solution: Satellites and remote sensing
Since the 1990s negotiators have been coming to the COP to address key issues related to "dangerous anthropogenic interference with the climate system", what that means is an entirely different blog post. However, due to the burning of fossil fuels, humans have increased the concentration of carbon dioxide (CO2) in the atmosphere to over 400 parts per million (ppm). This has caused substantial warming around the world, and continued carbon emissions have the world concerned about future warming and impacts from a changing climate system.
Since the first measurements of atmospheric CO2 concentrations by Charles Keeling in 1958, we have come a long way in measuring the quantity of carbon in the atmosphere. In 2002 the Europeans launched the first satellite to measure atmospheric CO2 from space, called SCIAMACHY. This satellite used differential optical absorption spectroscopy, basically a fancy way of saying it measured light at various wavelengths, to quantity the concentration of CO2 in the atmosphere. This gave the scientific community a proof of concept that we could indeed measure CO2 concentrations from space.
In 2009, the Japanese Space Agency (JAXA) launched the first dedicated satellite to measure carbon in the atmosphere called GOSAT. This satellite revolutionized the way we view carbon emissions as this mission allowed scientists to see the impact of individual cities, or even singular power plants, on the global atmospheric carbon reservoir. Needless to say, it revolutionized the way we measure anthropogenic carbon emissions.
The Paris Agreement calls on every country to report their GHG emissions to the global community and then make efforts to reduce those emissions. In this way, GOSAT is playing a crucial role for the global community in allowing countries to measure their emissions. While there are many ground stations around the world, it is impossible to cover the entire globe with in situ atmospheric carbon measurements. Satellites solve this problem by monitoring the atmosphere from space and collecting data for every location on Earth.
And no, it is not just the Japanese. NASA tried to get in the game too in 2009. They were actually coordinating with the Japanese and their GOSAT mission with planned joint cooperation on ground validations for the space measurements. Unfortunately, NASA's OCO-1 did not succesfully launch in 2009 due to some technical issues (sorry, no spectacular explosions). It was not until 2014 with the launch of OCO-2 (Orbiting Carbon Observatory) that a second dedicated satellite was launched into space to monitor atmospheric carbon.
Since that time, the Chinese have launch their own satellite for carbon observations, TanSAT (2016). The Europeans launched Sentinel 5p, which is focused on methane emissions just last month, on October 13, 2017. More are coming in the near future too.
The global space agencies have additional plans to launch even more satellites with GOSAT-2 coming from JAXA in 2018, OCO-3 coming from NASA in 2018, MicroCarb coming from the French and UK agencies in 2020, Merlin coming from the French and German space agencies in 2021, GeoCarb from NASA in 2022, GOSAT-3 coming from JAXA in 2023, another satellite in the Sentinel series coming from the European Space Agency coming in 2025, and ASCENDS coming sometime in the late 2020s from NASA. Soon enough, space will be crowded and we will have daily or hourly(?) measurements of atmospheric carbon around the world.
Some of these missions deserve to highlighted further:
Merlin is an effort from the French and Germans based in active remote sensing. This means that they are including an energy source on the satellite in the form of a LiDAR system to monitor GHGs, mostly methane. This will allow for observations at night, something that is not possible right now. This is particularly important in polar regions where the winter passes without any sunlight. This will allow for greater understanding of permafrost thaw among other processes.
GeoCarb is also special because NASA is using this mission to dedicate a geostationary satellite above North America to monitoring GHGs in the atmosphere. This satellite will always be located above North America and will continuously monitor GHG emissions from the region. This will illuminate a much greater understanding of small scale carbon fluxes and provide unprecedented insight into anthropogenic and background carbon emissions.
The best part about all of this, all the data is free and open to everyone around the world from all the space agencies.
Will is a US National Science Foundation Graduate Research Fellow at the University of Maine where he is pursuing a masters degree in the School of Earth and Climate Science. Will is interested in glaciers around the world and works with remotely sensed and in situ data to answer questions about glacier dynamics and mass balance.