The news won't please greens, but the number of airliners in the sky is set to soar.

That at least is the forecast from planemaker Airbus.

The European giant updated its annual outlook on Wednesday (September 18).

It now says there will be 47,680 jets in the air by 2038.

That's more than double the current total, but actually slightly down on the firm's forecast last year.

Even so, it's revised higher the demand for new planes.

It says more will be needed as airlines are phasing out older jets faster than expected to make room for more fuel-efficient new models.

Airbus says airlines will take 39,210 planes over the next two decades - almost 2,000 up on its last prediction.

Asia is once again expected to lead growth.

Air passenger traffic there is set to treble over the period.

That will see China's domestic market leapfrog the U.S. and Western Europe as the world's biggest aviation hub.

In a nod to concern about emissions, Airbus says more efficient planes will make all that growth carbon neutral.