Global Warming, As Seen from Space

Humanity must prepare for a different world, lulled by a warmer climate. Data transmitted by satellites plays a vital role in the scientific study of global warming: the quality and the quantity of data produced from space keeps going up. Today, the debate revolves around the extent to which human activities are responsible for climate change, because this point is hardly in doubt anymore, and may be worse than predicted. To discuss the matter further, the CNES has invited the climatologist Jean Jouzel and Yann Kerr, director of the Center for the Study of the Biosphere from Space Centre d’Études Spatiales de la Biosphère to join us tonight, May 20^th at 7:30pm, at the Café du Pont-Neuf in Paris.

Cet article existe également en français : Le réchauffement climatique vu de l'espace. Il a été traduit vers l'anglais par Abby Tabor.

The SMOS satellite plays a role in cyclone prevention.
(Image: CESBIO)

Global warming is no longer in doubt. Questioning its early effects would prove difficult. For Jean Jouzel, a climatologist with France’s CEA and member of the IPCC, “We’ve had the same scientific diagnosis for 25 years. Today, the warming is more concrete: we used to talk about what was going to happen, now we see the effects.” The analysis of data coming from satellites allows scientists to confirm and to clarify the details of global warming. According to Yann Kerr, director of CESBIO (the Center for the Study of the Biosphere from Space), “What satellites are measuring today is worse than the most alarmist predictions of the IPCC.” The key signs of this diagnosis are the melting of ice, the level and temp”erature of the oceans, and the humidity of the soil.

Among the numerous projects underway, the Meteostat program, managed by the European Space Agency and whose second generation is now active, brings together five geostationary satellites. One of their missions is to measure the temperature of the seas, thanks to infrared radiation. This is also the job of its American equivalent, the GOES program (Geostationary Operational Environmental Satellite), another network of meteorological satellites. The temperature of the seas and the oceans is a vital piece of data, as it has a direct impact on the formation of hurricanes and cyclones. One of the active roles for satellite data is, thus, to help predict natural risks, in order to adapt in real time to the consequences of climatic change. Similarly, the SMOS satellite (Soil Moisture and Ocean Salinity), launched in 2009 and developed following the recommendations of CESBIO, contributes to the prevention of cyclones by measuring the humidity of the soil and the salinity of the ocean surface. The data transmitted by satellite are accessible faster than before (from 3 to 24 hours after acquisition, at the latest) and are more and more reliable and precise, thanks to improvements to the devices onboard.

Space observation in the service of climate change is also the business of transatlantic partnerships. The fruits of a joint effort of the CNES and NASA, the satellites Jason-1 and Jason-2 are able to analyze the topography of the sea floor and the height of the oceans with the help of radar: using satellite altimetry, it is possible to demonstrate the rise in sea levels linked to the warming climate. As Jean Jouzel reminds us, “The real problems linked to global warming will happen in the second part of the 21^st century. Events like rising sea levels will have serious consequences.”

These two satellites are the successors of TOPEX/Poseidon, whose launch aboard an Ariane rocket in 1992 revolutionized oceanography, allowing scientists to map the tides and to validate models of ocean circulation. The history and the growth of measurements taken from space give researchers a certain distance from which to analyze the evolution of the climate. Climate change is recognized, but as Yann Kerr points out, “Now it’s about knowing how much of global warming is due to a natural evolution, and how much to human activity.” For several years, the emphasis has now been on standardization of the data, as well as making it available to the scientific community on open servers. That, in particular, is the ambition of programs like the Climate Change Initiative of the European Space Agency, or the Copernicus project of the European Union. It’s not only about collecting more Earth-observation data, but also about making better use of it, with better processing of the information and accessibility for the greatest number. This policy was born of an alarming conclusion shared by the majority of the scientific community, including the members of the IPCC. “Over the last ten years, greenhouse gas emissions have continued to rise more significantly than in the ten preceding years; nothing has been done right. Consequently, we may no longer be able to limit global warming to 2°C by the end of the century,” Jean Jouzel remarks. The latest volume of the Fifth Assessment Report of the IPCC, published at the end of March, is titled Impacts, Adaptation and Vulnerability and lays out the first repercussions of climate change. The objective is, thus, no longer just to slow down the phenomenon, but to prepare ourselves for its direct consequences.

For such a subject that concerns us all, we need to rise above it, all the while remaining down-to-earth. Worried citizens, or the simply curious, readers involved in the debate or neophytes: the CNES, the Bar des sciences and MyScienceWork invite you into the heart of the debate, tonight, May 20^th at the Café du Pont Neuf, or online via the hashtag #CNEStweetup.