A B757-200 Flight Attendant reported a strong cooking smell in the aft cabin up to about row 20 during climb out. An emergency was declared and the aircraft returned to land. The smell dissipated after the recirculation fan was turned off.

Narrative

During climbout at 13;000 Flight Attendant from rear station called cockpit. Pilot not flying (Captain) took call while I flew and covered ATC. Pilot not flying ended call with Flight Attendant and said they smell a strange odor that was consistent with a burnt cooking smell in the rear cabin. Pilot not flying reached up and turned right recirculation fan off and said we have to return to our departure airport and we will declare an emergency. He notified ATC of this and we were given a lower altitude and a left turn back direct the airport. Several minutes later; upon completing 180 degree turn; Flight Attendant called back. Said smell seemed to be dissipating and wasn't as bad. We discussed it for a minute; and both determined that the safest course of action would be to continue the return - especially since the origin of the smell was unknown and it had a burnt type of odor to it. Never was there any hint of an odor or any smell in the cockpit to the two of us or the jumpseater also in the cockpit. Pilot not flying notified Dispatch on local VHF frequency and made Company aware of return. Normal approach and landing was made to Runway 10. We taxied clear of the runway; rescue vehicles circled aircraft and said nothing unusual was apparent. We told Ground we were safe to taxi to gate and deplaned aircraft. Departed approximately 2 hours later in another aircraft. Upon talking to flight attendant crew after deplaning; odor was quite strong to them and passengers from the rear of the aircraft up to about row 20 (Midcabin). No one in the forward part of the cabin reported any odor whatsoever.