Amsterdam, Netherlands - Airlines are filling the skies over Europe, causing damaging greenhouse gas emissions. But wait a second: There are almost no people on these flights. What's going on?

What's worse than getting ghosted? Ghosting that leads to millions of tons of CO2 emissions.

A huge amount of mostly empty flights are flying to and fro in Europe, just so their airlines can keep the rights to landing slots.

During the pandemic, the EU suspended rules that required airlines to keep planes shuffling around to keep their landing berths at certain airports.

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But according to The Guardian, the ruling has been partially reinstated, so airlines now need to move around at least half of their fleets or again risk losing their rights to landing slots.

In March, the threshold will be upped again to 64% of airlines' planes that need to be in operation to hold the slots, which the industry is actively trying to postpone.

The incredibly wasteful rules mean that some airlines are rolling onto the tarmac without passengers. One of the largest operators, German airline Lufthansa, reported that 55% of its flights were not fully booked.

Lufthansa's CEO Carsten Spohr told FAZ that the airline will have to send 18,000 "extra, unnecessary flights" to follow the updated rules.

Environmental org Greenpeace analyzed the potential European "ghost flights" and found that they will likely emit over two million tons of harmful CO2.

"For us, a ghost flight is a flight that only has a maximum of a couple of passengers and is a flight which the airline would not operate without that slot regulation," Greenpeace's transportation expert Herwig Schuster told the EUobserver.

Millions of tons of CO2 emissions are expected from empty flights in the next few months, doing nothing but fulfilling rules that are far removed from the reality of air travel during a global pandemic. The practice is clearly wasteful, and further damaging to the environment.