In 1990, I was living a conservationist’s dream.

While developing conservation plans along the coast of Oman, I found a place with great reefs and no people. It looked like protecting the reefs was going to be easy… until the waters heated, and heated, and heated.

This year, things are once again heating up, and we fear that we may witness the worst global coral bleaching event since 1998. But back in 1990, temperatures reached 95°F, hovering there for over a month and killing 95% of the corals through a process called bleaching. It raised a worrying question: how could we conserve coral reefs in the face of climate change?

This dilemma challenged me for a decade. I was based in East Africa when the 1997-’98 El Niño—and the following 1998-’99 La Niña—caused the greatest mass coral bleaching in recorded history, killing off 16% of the world’s coral reefs.

When I joined the Conservancy in 1999, I suddenly had access to a new range of project sites where I could study how climate change hastened coral bleaching. And the clear patterns in bleaching resistance and coral mortality in Palau helped me piece together a possible solution that could reduce bleaching caused by the current warming.

Bleaching is a stress response in corals caused by a number of factors, particularly hotter water temperatures and intense sunshine. So, it stands to reason that reducing the heat or light stress on corals will diminish the intensity of bleaching and reduce mortality.

The importance of this conclusion finally struck me when I was snorkeling around Palau’s Rock Islands. As I swam into the shade provided by one of the island’s rocky overhangs, I noticed live corals under my facemask of the same species that were dead under my swim fins. It all fell together: corals were alive and healthy when protected by cooler water or by shade.

Coral reef scientists were at their wits’ end about what to do regarding coral bleaching. But our observations of factors that help corals survive—and our knowledge of how to design networks of marine protected areas (MPAs) to protect and expand natural refuges—resonated with people around the world and prepared us for the impending bleaching event.

We have waited more than 10 years for another mass bleaching event to be able to test and refine the resilience hypotheses and the principles that Stephanie Wear and our Global Marine team have helped popularize. So, we are mobilizing our field teams and partners to track the current bleaching event in Indonesia and Palau as well as the Caribbean. This new information will allow us to better design MPA networks and ensure that they protect the most resilient corals that will repopulate and heal more vulnerable reefs.

While it’s tragic to witness another major bleaching event, this one can help us improve our methods and the prospects for global coral reef survival. Reefs provide fish, diving and coastal protection: hopefully, we can ensure that enough of them remain to fulfill any conservationist’s dream.

Rod Salm is the Conservancy’s director of marine conservation programs in the Asia Pacific.

(Image 1:  Shaded corals with no bleaching. Credit: Rod Salm/TNC. Image 2: Fantasy Reef pale corals with early heat stress. Credit: Rod Salm/TNC.)

If you believe in the work we’re doing, please lend a hand.


  1. Beautiful pictures-Thank you for sharing-I hope everyone will do whatever is possible to conserve such treasures

  2. I really do expect more integrity from things connected with TNC than what is in your blog. I don’t doubt that you are studying relevant issues and generating real and valuable data but you are clearly pandering to destructive political interests that demagogue conservation for selfish interests with your dialogue. Why else would you talk about weakly correlated events as if the corrleation is established fact. Are your motivations selfish? Are you trying to secure research dollars that are tied to supporting certain conclusions? Conservation would be better served if we stay affiliated only to the science. The politicians you are pandering to would eliminate charities like TNC around the world if they could. They are jealous of any monies that they can’t corrupt. TNC has been the only pure conservation organization for years. I hope this has not changed. I remember the US media atacking TNC several years back for using their resources for conservation instead of playing ball with the media and the party like the sierra club does. If the sierra club does any conservation it is purely by accident. No self respecting scientist would politicize his research and no true conservationist would support an org like the sierra club. I hope we have not lost TNC to the dark side.

    1. Hi Mark,
      This is Darci Palmquist with The Nature Conservancy. I forwarded your comment to the post author, Rod Salm, and here’s what he had to say:

      Thanks for writing, Mark.

      We are reprogramming internal funds with the aim of improving the knowledge base needed to do better coral reef conservation the face of climate change.

      Conservation practitioners are pressed to make decisions that affect our programs on a regular basis. We use the best available information, science and practice to support those decisions. In response to the 1998 mass bleaching event which decimated many of the world’s coral reefs, the Conservancy and others around the world have developed tools to attempt to build resilience to climate change ( into marine conservation activities. The current bleaching event has already severely affected some of the richest reefs in the world and offers a great opportunity to test and refine the resilience science that is being applied to coral reef conservation globally. The Conservancy sees this as too good a learning opportunity to pass up that will enable us and others to make necessary corrections to our methods and improve coral reef conservation.

  3. Re-reading Rod’s original entry and his measured response, I must admit that I had responded to his entry after also reading several different TNC blog entries. It does appear that Rod used appropriately cautious language in describing events as climate change – My apologies.

    Certainly over the coming decades and centuries we will see both cooling and warming trends that will be dangerous for some of our more fractured and isolated ecosystems and this issue is worthy of some forethought. Other entries I see use the more charged term global warming with the associated implications. CO2 is rising in our atmosphere and this is reason for concern. For this reason a great deal of money is being spent trying to develop new technologies. There is no conspiracy against these efforts. There are those who use this issue for selfish political agendas. They exaggerate and fabricate correlational data and use it as a tool to force the world into implementing technologies that are not mature. They have conveniently set themselves up to profit from these positions. The fact that these technologies are not mature will mean that they will directly damage the environment by taking a larger toll than that which they replace. This will nurture poverty the real driver of environmental damage.

    TNC should avoid any association with these political players as a true conservation organization needs to work with people, corporations and politicians of all stripes to achieve their ends.

    – Mark

  4. Very nice article. I am no environmental scientist but here is an idea about assisting in in the prevention of coral bleaching. As we all have seen, there are miles of boom laid out during an oil spill. This same boom could be used before an anticipated bleaching event to contain a bio-degradable and environmentally safe dye that could act as a sun shield. Just a thought (and I hope my ignorance is not showing)

Add a Comment