One glance skywards and the evidence is all too clear with no vapour trails being made by airplanes.

Data by Flightradar24.com shows there are 70% less plane journeys nationwide, and even less over the Shotley peninsula, which sits in the Stansted flight path.

Anecdotally, there has been an increase in bird sighings and being able to hear the dawn chorus more clearly.

As the Covid-19 pandemic response decimates air traffic, it provides a unique opportunity for scientists to study how planes' contrails trap heat in the atmosphere.

It is the chance to study how much aviation increases global warming. The dramatic fall in air traffic is the largest since the 9/11 attacks in 2001.

Scientists with Nasa and European research groups hope to use clear skies to narrow down massive uncertainties about the warming effect of condensation trails.

The science of how much added warming is caused by the contrails (and other non-CO2 impacts of aviation) is complex and more research is needed. But it is likely that the overall impact of aviation on climate is about double that of the CO2 alone. It is perhaps 4-5% of the global total of human climate impact.

Researchers will use satellites and measurements by planes to study how clouds form naturally when thousands of flights are grounded in the absence of aircraft.

Would clouds have formed anyway, in the absence of planes? However, there are problems with Covid-19 social distancing, in assembling teams of technicians to install sensors on planes and find pilots to fly them.

It is understood an initial report will be made by the end of this year.