The world is creeping closer to the extinction of the northern white rhino, with the death of Nola, a 41-year-old female that had been living at the San Diego Safari Park since 1989.

Nola was euthanised due to diminishing health, and her death leaves just three northern white rhinos (Ceratotherium simum cottoni) on Earth, all living at the Ol Pejeta Conservancy in Kenya.

Nola had undergone a recent surgery to drain an infected abscess on her pelvis, and while the procedure was was successful, over the past couple of days, she’d stopped eating and her energy levels had dropped.

The San Diego Zoo announced her death earlier today in a Facebook post, and asked people to share their memories of her on the hashtag #Nola4Ever.

It is with heavy hearts that we announce the death of Nola, a critically endangered northern white rhino who lived at... Posted by San Diego Zoo on Sunday, November 22, 2015

This means there are now just three northern white rhinos left in the world. The last remaining male, named Sudan, is being protected 24/7 by armed guards in Kenya, and has had his horn removed to dissuade poachers from targeting him.

Unfortunately, the two remaining females are infertile, which makes the outlook for the species pretty bleak. But the San Diego Zoo has recently offered US$2 million to prevent its extinction.

This involves sequencing the species' genome to find clues to its survival in its genetic code, and researchers are also going to try and use IVF to produce offspring using the limited amount of sperm available from Sudan.

They’ll use this sperm in an attempt to fertilise preserved eggs taken from female northern white rhinos that have passed away, including Nabire who died in July this year.

If fertilisation is successful, they’ll transplant the embryo into the closely related southern white rhino in the hopes of carrying a baby to birth.

The northern white rhino has been pushed to extinction as a result of extensive habitat loss and poaching over the past two decades.

Researchers are hoping they can prevent the same thing from happening to the black rhino by using drone surveillance, spy cameras, and alarms to help protect rhinos and their horns.

Let’s hope humanity can avoid making the same mistakes twice.