The series of heatwaves we are currently experiencing in western Europe is a clear sign of human-induced global warming. ESA’s Clement Albergel explains how we monitor these events using satellites such as the Copernicus Sentinel-3 mission and puts them in the context of the long-term climate data record generated via ESA’s Climate Change Initiative.
The series of heatwaves we have been experiencing in Western Europe are the clearest sign of global warming caused by human activities, our emission of greenhouse gas in the atmosphere.
To better understand the variability of our climate system, we need observations. Satellite earth observations such as those operated by the European Space Agency in collaboration with the European Commission in the context of the Copernicus Program are particularly useful as they provide global coverage, uniformity, rapid measurement, and continuity.
Copernicus is powered by a dedicated family of satellites, the Sentinels.
Sentinel 3 is an instrument a radiometer that measures land surface temperature. In the last two weeks of July, it has measured record-breaking land surface temperature. More than 45 degrees celsius in the UK, more than 50 degrees celsius in France, and more than 60 in Spain.
We can also combine land surface temperature from Sentinel 3 with those from previous satellites in order to develop long time series. And that’s what we do in the context of ESA’s climate program, the climate change initiative.
We put together data from different satellites in order to develop global scale long-term satellite-derived time series of key components of the climate system, also known as essential climate variables. Land surface temperature is one of them.
We have recently released a 25 years climate data record of land surface temperature and the data indicate a stable increase of about 0.2 degrees celsius per decade on average at a global scale with strong regional variability.
Heat waves can also be followed by wildfire. Extremely high temperatures combined with low air humidity and dry vegetation increase the risk of wildfire in case there is a source of ignition.
Satellites are very useful as they permit the monitoring of different fire characteristics. From a risk assessment point of view, we can detect areas that are dry and prone to wildfire outbreaks, we can monitor actively flaming fires, smoldering fire, as well as burn area, the scar let on the ground by fire. We can monitor smoke plumes as well as trace gas in the atmosphere.
Another consequence of prolonged heat waves when combined to extremely low level of precipitation is droughts. Soils are getting drier and many rivers in Europe have now reached level low record.
Images acquired by Sentinel-2 show part of the Po Valley near Piacenza in Italy and revealed how the river has shrunk between June 2020 and June 2022. This is partially due to the lack of precipitation Northern Italy usually receives with extremely high temperatures and the lack of snow in the mountain that usually feeds the river.