Vision for 2022: Looking Back To Move Forward.

As 2021 comes to an end and a new year approaches, we look back at all the important Earth science that has been revealed. This is a good opportunity to reflect on all we’ve learned so far and apply what we’ve learned to better understand and forecast the numerous ways our planet will change in the future decades. Every new discovery leads to new understandings and areas of investigation on our planet, which is an interconnected system. Our climate is changing, and NASA satellites and research have been studying it from a variety of viewpoints and views over the last decade. The highlights of the science satellites have enabled during the last decade, as well as crucial issues to research in the decades ahead, are listed in this article.

In 2012, the Arctic sea ice cover shrank to its tiniest point ever measured from a satellite and scientists have watched it decline much further in the years afterwards. The study of sea ice melting has revealed fresh information on the feedback loops that climate change has triggered. In the past, the Arctic sea ice cover insulated that region of the world from global warming. Ice reflects more light and heat than black water because it is a much brighter surface. Because of the melting ice, the ocean now absorbs the heat, hastening warming in the Arctic.

The average age of sea ice has been shown to be affected by sea ice loss, with less and less of the seasonal cover surviving many years. Because the bulk of the sea ice is now seasonal, melting with the summer, additional changes in ice thickness and age will occur more slowly now that most of the multiyear ice has been gone. Monitoring the Arctic sea ice from airborne and spaceborne platforms will be essential in understanding the consequences of climate change in that region in the coming years.

The average worldwide CO2 concentration surpassed 400 parts per million (ppm) in May 2013 and has continued to grow since then. The annual low CO2 concentration also hit 400 parts per million in 2017, emphasising the need of monitoring carbon dioxide levels in our environment. Satellite missions like the Orbiting Carbon Observatory 2 (OCO-2) have provided space-based global CO2 observations with the precision, resolution, and coverage required to define CO2 sources and sinks (fluxes) on regional scales. In 2019, the Orbiting Carbon Observatory 3 (OCO-3) was launched to broaden the horizons of the Orbiting Carbon Observatory 2 (OCO-2) by concentrating its instrument on metropolitan cities.

When they’re not analysing carbon dioxide, OCO-2 and OCO-3 are busy monitoring plant growth. The OCO-2 scientific team discovered that their sensor could be used to detect the little amount of glow that plants emit when they photosynthesise, and they’ve been investigating plant health and stress alongside the project’s other science goals.

Since it was originally found, NASA has been investigating the ozone hole, and 2019 has shown the tiniest hole yet. It usually reaches a maximum size of 8 million square miles, but this year it reached 6.3 million miles. While this is encouraging news for the ozone hole, it is not completely due to the repair efforts that began with the signing of the Montreal Protocol on Substances that Deplete the Ozone Layer. In the absence of additional factors, a decrease in the number of chlorofluorocarbons (CFCs) in the atmosphere after they were outlawed in 1987 would result in the ozone hole returning to its previous levels around 2070.

The Antarctic ozone hole arises in late winter in the Southern Hemisphere, when the Sun’s rays return and begin ozone-depleting processes. Chemically active versions of chlorine and bromine produced from man-made chemicals are used in these processes. Chemical interactions on the surfaces of cloud particles that originate in cold stratospheric layers lead to runaway reactions that destroy ozone molecules, which is the chemistry that leads to their production. Warmer temperatures cause polar stratospheric clouds to develop less often and for a shorter period of time, slowing the ozone depletion process.

The smaller hole is due in part to a reduction in CFCs in the atmosphere, but it is also due to rising temperatures. Warmer temperatures cause fewer polar stratospheric clouds to develop, and they last less time, decreasing ozone depletion.

NASA and the National Oceanic and Atmospheric Administration (NOAA) use different approaches to research the ozone hole. Aura’s Microwave Limb Sounder sensor measures amounts of chlorine in the atmosphere, while three NASA satellites detect ozone from orbit. Meanwhile, NOAA personnel deploy weather balloons with ozone-measuring sensors from the ground, giving the second set of data to complement the space-based record.

The Earth Science programme at NASA is constantly evolving, and numerous missions are now in development. The Surface Water and Topography (SWOT) and NASA-ISRO Synthetic Aperture Radar (NISAR) Missions, both of which will launch in the next several years, are two to keep an eye on among the many in development. Each new mission in development will bring a fresh perspective to Earth science, allowing us to gain a greater understanding of the complex and interconnected processes that control our world.

-Amrit Agarwal.