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Reefs of Time: What Fossils Reveal about Coral Survival
How fossilized reefs hold clues to the survival of corals in the Anthropocene
With rising global temperatures, pollution, overfishing, ocean acidification, and other problems caused by humans, there’s no question that today’s coral reefs are in trouble. As predictions about the future of these ecosystems grow increasingly dire, scientists are looking in an unlikely place for new ways to save the past. The reefs of yesteryear faced challenges too, from changing sea level to temperature shifts, and understanding how they survived and when they faltered can help guide our efforts to help ensure a future for reefs.
Lisa Gardiner weaves together the latest cutting-edge science with stories of her expeditions to tropical locales to show how fossils and other reef remains offer tantalizing glimpses of how corals persisted through time, and how this knowledge can guide our efforts to ensure a future for these remarkable organisms. Gardiner takes readers on an excursion into “the shallow end of deep time”—when marine life was much like today’s yet unaffected by human influence—to explore the cities of fossilized limestone left behind by corals and other reef life millennia ago. The changes in reefs today are unlike anything ever seen before, but the fossil record offers hope that the coral reefs of tomorrow can weather the environmental challenges that lie ahead.
A breathtaking journey of scientific discovery, Reefs of Time reveals how lessons from the past can help us to chart a path forward for coral reefs struggling for survival in an age of climate crisis and mass extinction.
With rising global temperatures, pollution, overfishing, ocean acidification, and other problems caused by humans, there’s no question that today’s coral reefs are in trouble. As predictions about the future of these ecosystems grow increasingly dire, scientists are looking in an unlikely place for new ways to save the past. The reefs of yesteryear faced challenges too, from changing sea level to temperature shifts, and understanding how they survived and when they faltered can help guide our efforts to help ensure a future for reefs.
Lisa Gardiner weaves together the latest cutting-edge science with stories of her expeditions to tropical locales to show how fossils and other reef remains offer tantalizing glimpses of how corals persisted through time, and how this knowledge can guide our efforts to ensure a future for these remarkable organisms. Gardiner takes readers on an excursion into “the shallow end of deep time”—when marine life was much like today’s yet unaffected by human influence—to explore the cities of fossilized limestone left behind by corals and other reef life millennia ago. The changes in reefs today are unlike anything ever seen before, but the fossil record offers hope that the coral reefs of tomorrow can weather the environmental challenges that lie ahead.
A breathtaking journey of scientific discovery, Reefs of Time reveals how lessons from the past can help us to chart a path forward for coral reefs struggling for survival in an age of climate crisis and mass extinction.
288 pages, Hardcover
Published June 10, 2025
7 people are currently reading
186 people want to read
About the author
Lisa S. Gardiner
1 book1 followerDr. Lisa S. Gardiner is a science writer, geoscientist, and educator. She is the author of Reefs of Time: What Fossils Reveal About Coral Survival (Princeton, 2025) and Tales from an Uncertain World: What Other Assorted Disasters Can Teach Us about Climate Change (Iowa, 2018). Her writing has appeared in the Atlantic, Hakai Magazine, The Guardian, Nautilus Magazine, Scientific American, and other publications.
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Displaying 1 - 4 of 4 reviews
June 10, 2025
"Don't get too comfortable. Resilience has its limits"
Through this book I learned that coral are some of the most resilient animals, but even coral have limits to their resilience.
In REEFS OF TIME, Lisa Gardiner weaves together her personal experience studying coral reef (as a paleoecologist), the ecology and geology of coral, and the history of the field of paleoecology.
This book was a fascinating deep dive (no pun intended) on the science of coral.
I learned so much about fossils and coral through reading this book. I had no idea that the majority of limestone (calcium carbonate) in tropical oceans was made by living organisms. It totally makes sense, because so many creatures like clams and mussels and coral remove calcium and carbon from the ocean to build their shells and then fish contribute to the calcium carbonate with their lime-y poop.
The biggest surprise for me was learning all of the many threats that coral face: the ever-increasing temperatures of the ocean (and extreme heat waves), the changing microbiome, overfishing, and also sometimes too many harmful fish. Gardiner writes about the Crown of Thorns starfish that acts like a "reef Roomba" gobbling up all of the coral. Apparently the Crown of Thorns Starfish was a major reason for the devastation that has taken place in the Great Barrier Reef.
I also hadn't thought about how rising sea levels will actually be harmful for Coral because their Algal symbionts won't be able to photosynthesize. That blew my mind!
Chapter 7, which focused on coral's ability to lay low during extreme weather, was fascinating. This concept is called refugia, and it is coral (and other species) ability to shelter until environmental conditions have improved. For example, during the glacial period when sea levels dipped, the coral would grow on the sides of limestone platforms instead of the top.
One of the most heartbreaking stories was the coral in Belize that were able to recover after a major death event only to be wiped out by a heat wave in 2023. This story really demonstrated the limits of coral's resilience.
Some of my favorite parts of this book were the times when Gardiner wove in her own personal experiences diving to study coral. I want to know way more about this underwater paper they are using! What is it made out of? I also loved the moment where she is diving to collect death assemblage of coral and some tourists are trying to wave her down because they don't know she is a scientist.
The personal accounts really enhance this book for me. I love narrative nonfiction that is written by the actual expert!
I was absolutely charmed by the many images created by Gardiner. The smiling parrotfish, the diver collecting dead coral, and the many images showing how coral form.
Highly recommend reading this book if you are someone who is interested fossils, coral, marine life and the impact of climate change on coral. I really appreciated that this book went a bit deeper on the science but still kept it incredibly accessible!
Thank you to the author for providing me with an advanced copy of this book!
Through this book I learned that coral are some of the most resilient animals, but even coral have limits to their resilience.
In REEFS OF TIME, Lisa Gardiner weaves together her personal experience studying coral reef (as a paleoecologist), the ecology and geology of coral, and the history of the field of paleoecology.
This book was a fascinating deep dive (no pun intended) on the science of coral.
I learned so much about fossils and coral through reading this book. I had no idea that the majority of limestone (calcium carbonate) in tropical oceans was made by living organisms. It totally makes sense, because so many creatures like clams and mussels and coral remove calcium and carbon from the ocean to build their shells and then fish contribute to the calcium carbonate with their lime-y poop.
The biggest surprise for me was learning all of the many threats that coral face: the ever-increasing temperatures of the ocean (and extreme heat waves), the changing microbiome, overfishing, and also sometimes too many harmful fish. Gardiner writes about the Crown of Thorns starfish that acts like a "reef Roomba" gobbling up all of the coral. Apparently the Crown of Thorns Starfish was a major reason for the devastation that has taken place in the Great Barrier Reef.
I also hadn't thought about how rising sea levels will actually be harmful for Coral because their Algal symbionts won't be able to photosynthesize. That blew my mind!
Chapter 7, which focused on coral's ability to lay low during extreme weather, was fascinating. This concept is called refugia, and it is coral (and other species) ability to shelter until environmental conditions have improved. For example, during the glacial period when sea levels dipped, the coral would grow on the sides of limestone platforms instead of the top.
One of the most heartbreaking stories was the coral in Belize that were able to recover after a major death event only to be wiped out by a heat wave in 2023. This story really demonstrated the limits of coral's resilience.
Some of my favorite parts of this book were the times when Gardiner wove in her own personal experiences diving to study coral. I want to know way more about this underwater paper they are using! What is it made out of? I also loved the moment where she is diving to collect death assemblage of coral and some tourists are trying to wave her down because they don't know she is a scientist.
The personal accounts really enhance this book for me. I love narrative nonfiction that is written by the actual expert!
I was absolutely charmed by the many images created by Gardiner. The smiling parrotfish, the diver collecting dead coral, and the many images showing how coral form.
Highly recommend reading this book if you are someone who is interested fossils, coral, marine life and the impact of climate change on coral. I really appreciated that this book went a bit deeper on the science but still kept it incredibly accessible!
Thank you to the author for providing me with an advanced copy of this book!
January 12, 2026
Reefs of Time by Lisa S. Gardiner, was a fascinating deep dive into coral reefs and their resilience, or fragility, in the face of ocean warming and acidification.
Coral reefs act as living archives, recording ocean
temperatures, chemistry, and human impact over centuries. Modern science only started systematically recording nature and understanding climate change relatively recently. By the time we started measuring, we may already have been observing a significantly reduced baseline.
My favourite chapter was Chapter 5 When Reefs Fall Apart.
QUOTES
p. 100: “When you see a new place, a coral reef for example, it forms an as pression. And that impression serves as your baseline for what reels a like. It defines what is normal. Your baseline doesn't take into accoat what happened in a coral reef before you saw it. Any future change would be compared to how reefs appeared when you first got to lon them, which is why I was so sad to revisit Florida reefs in 202) and se them looking terribly degraded compared with the reefs I had m nearly three decades before while collecting the death assemble Those who arrive to see reefs in the future would likely form there derstanding of what's normal at that point, which may be algae cores reefs with weedy corals.” (shifting baseline syndrome)
“I had been thinking about myself as an Anthropocene tourist with an itch to see places before they’er gone.” p. 159
Coral reefs act as living archives, recording ocean
temperatures, chemistry, and human impact over centuries. Modern science only started systematically recording nature and understanding climate change relatively recently. By the time we started measuring, we may already have been observing a significantly reduced baseline.
My favourite chapter was Chapter 5 When Reefs Fall Apart.
QUOTES
p. 100: “When you see a new place, a coral reef for example, it forms an as pression. And that impression serves as your baseline for what reels a like. It defines what is normal. Your baseline doesn't take into accoat what happened in a coral reef before you saw it. Any future change would be compared to how reefs appeared when you first got to lon them, which is why I was so sad to revisit Florida reefs in 202) and se them looking terribly degraded compared with the reefs I had m nearly three decades before while collecting the death assemble Those who arrive to see reefs in the future would likely form there derstanding of what's normal at that point, which may be algae cores reefs with weedy corals.” (shifting baseline syndrome)
“I had been thinking about myself as an Anthropocene tourist with an itch to see places before they’er gone.” p. 159
July 30, 2025
Coral Reefs of the past, the present,
and the future. Very interesting.
and the future. Very interesting.
November 28, 2025
As the author, I know I'm biased, but I think this book is wonderful and I hope you do too!
Displaying 1 - 4 of 4 reviews