Rapid decline of vertebrate populations

Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and decline

Gerardo Ceballos, Paul R. Ehrlich, and Rodolfo Dirzo

Global data from the study of terrestrial species. Species richness (maps on the left) indicates the number of species; number of decreasing species is presented on the middle maps; percentage of decreasing species is presented at right. The top 3 maps are for all vertebrate animals, and the lower maps are separated my the major groups (mammals, birds, reptiles, and amphibians). The cooler the color on the percentage decreasing maps, the more severe the loss of those animals.
Data: The scientists used a large data set of vertebrate populations (27,600 species and a more detailed data set of 177 mammal species from 1900 to 2015) to examine how the ranges of vertebrate animals have become smaller due to growing populations of humans that are pushing the animals out of their natural habitat. A lot of animals that are not considered endangered have experienced a huge decline in their numbers, indicating that animals all over the world are being IUCN Red List of Threatened Species. This data was was superimposed in a 22,000 grid of 10,000 km3 quadrats covering continental lands. A species was considered decreasing if their ranges (where that species lives) shrunk over time, or if there was a reduction in the number of species. This approach was also applied to 177 species of land mammals to see how their populations have changed through time.

Results: The scientists found that even in populations of animals that are not considered threatened, the rate of population loss is extremely high. In this study, 32% of the known vertebrate species are decreasing, meaning they have shrunk in population size and the ranges, or land in which they live. In the more detailed data set of 177 mammals, all of them have lost 30% or more of their ranges, and more than 40% of the mammal species have experienced severe population declines.

This map represents the percent of population extinctions in 177 species of mammals. The maps were made by comparing historic ranges of the animals to the current ranges. Cooler colors indicate areas that are experiencing the most severe population extinctions (for example, the east coast of the US, southern Australia, and northern Africa).

Why is this study important? This study uses a large data set of vertebrates to examine patterns of species through time to specifically assess how humans are impacting the ranges and populations of the animals. The current decline of species on Earth isn’t happening slowly; instead, it is happening at an accelerated rate. This study highlights the idea that Earth and all its creatures may be in the Sixth Mass Extinction, and remediation efforts are necessary and need to be enacted now in order to save animal populations.

The Big Picture: Humans are fundamentally changing the Earth and the animals that live on it. Through habitat destruction and expansion of housing and urban areas, to name just a few causes, we are taking habitats away from animals. Combined with climate change, the Earth’s animals are experiencing a biodiversity decline.

Citation: Ceballos, G., Ehrlich, P. R., and Dirzo, R., 2017. Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines. PNAS. DOI: 10.1073/pnas.1704949114

Fossil Collecting at Westmoreland State Park, Virginia

Adriane here-

An aerial view of Horse Head Cliffs at Westmoreland State Park overlook the Potomac River. The beautiful parallel layers of sediment contain fossils. Image courtesy of the VA Department of Conservation & Recreation.

Every now and then (well, as often as I can to be honest), I go fossil hunting with family, friends, and colleagues just for fun! There’s nothing like finding the remains of extinct animals and plants out in the field yourself. Although there are very few places where fossil collecting is prohibited, there are very few state parks and places in the US where it is encouraged. One of these places is Westmoreland State Park in Montross, Virginia.

This very well may have been the first place I found my very first fossil. I remember my dad had taken my siblings and I to the park one Saturday afternoon to play in the Potomac River and in the creeks and marshes nearby. But, once he told me we could find shark’s teeth on the river banks, my eyes were glued to the sand, systematically sweeping the ground in front of me. Lo and behold, I did find a shark’s tooth! And, it was a tooth that belonged to Carcharodon megalodon (or just Megalodon for short), one of the largest sharks to ever cruise the Earth’s oceans!

Stratigraphy of Westmoreland

Sifting for fossils on the banks of the Potomac River.

Westmoreland State Park is known among locals for its fossils, but any Virginia geologists will tell you the real gem of the park is its stratigraphy (well, OK, the fossils too). The oldest sediment that contain the fossils was laid down in a shallow extension of the Atlantic Ocean about 23-25 million years ago, during the lower Miocene. Younger sediments from the Pliocene (~5.3-2.5 million years ago) and Pleistocene (~2.5-0.01 million years ago) were laid atop the older Miocene deposits. Together, these different rock and sediment layers are called the Chesapeake Group. In the study of rock layers (=stratigraphy), a group includes different rock formations, each with their own name. For example, the Miocene formations in the Chesapeake Group (at least in parts of Virginia) are called the Calvert and Eastover formations.

After these formations were deposited, sea level dropped as glaciers on Greenland continued to grow. This allowed for rivers to flow further out into what was once a sea. Rivers are very powerful eroding mechanisms, as they have the capacity to move large boulders and wear down rocks (think of the Grand Canyon; it was made by the Colorado River cutting through the rock over time!) One of the rivers that now flows into the Atlantic Ocean is the Potomac River. This river is now eroding the Chesapeake Group formations, releasing all the fossils that were once contained in the rocks. Thus, some of these treasures wash ashore at Westmoreland State Park for visitors to find!

Fossils of Westmoreland

A small C. megalodon tooth found at Westmoreland State Park.

Over nearly a decade of visiting Westmoreland State Park, I have accumulated hundreds of shark teeth and found tons of other fossils. Some of these include whale teeth, vertebrae, rib bones and ear bones, dolphin teeth, vertebrae, rib bones and ear bones, fish vertebrae, shark vertebrae, coprolites (fossil poop), an alligator tooth, and mammal teeth. Most of these fossils are Miocene in age, but some are from the Pliocene and Pleistocene.

One of the most famous fossils to come out of the Chesapeake Group are those of the baleen whales. Several new species of whales have been found in Virginia in formations from the Miocene and Pliocene. One of these species, Eobalaeonoptera harrisoni, was found only five minutes down the road from my home in Virginia! E. harrisoni is a beloved icon of the area, in which it was found, so a complete cast of the whale now hangs in the Caroline County, VA visitor’s center.

The cast of Eobalaenoptera harrisoni that can be visited in the Caroline County, VA visitor’s center. Image from the Virginia Museum of Natural History.

Rocky Mountain Field Trip

Megan here-

Image 1. Grand Teton National Park (in the red ellipse) is located in the northwest corner of Wyoming, just south of Yellowstone National Park.

An exciting perk of attending the University of Wyoming for graduate school is the annual Rocky Mountain Field Trip. This year, the geology faculty planned an adventurous trip to Grand Teton National Park and its surrounding areas (Image 1). Over five days, current and new graduate students explored the unique geology of the Tetons by learning about mountain formations, glaciation, and sedimentation in northwest Wyoming. By the end, we were able to develop an understanding of how this stunning area formed, and how it may change in the future.

Image 2. The view from AMK Ranch stretches across Jackson Lake to the Tetons. This photo looks southwest and shows the northern part of the north-south trending range.

For the first few days of the trip, we were lucky enough to stay at the AMK Ranch, which is home to the University of Wyoming-National Park Service Research Station. From here, we had a stunning view of Grand Teton National Park’s most impressive features: the high-standing peaks of the Teton mountain range (Image 2). These mountains are tremendously tall (the Grand Teton’s peak is 13,775 feet in elevation) due to a complex tectonic history of extension and uplift. Essentially, the mountains uplifted while the valley to the east dropped down. The pointed horns of the Tetons are a result of glacial sculpting during the Pleistocene Epoch.

One of the best parts of this trip was the variety of geology and geologists (Image 3). We learned about glacial geology, sedimentology, structural geology, hydrogeology, paleontology, and so much more. The professors and guests who joined us along the trip had a massive breadth of geologic knowledge. Not to mention, we were able to explore a national park with a geologic lens. That’s one of the most exciting things about being a geologist; you can look at landscapes with towering mountains and glacial lakes, or with meandering rivers and rolling hills, and you can envision the multitude of processes that formed that landscape.

Image 3. New and returning graduate students, UW professors, and even the UW provost mimic the pointed peaks of the mountains on a hazy day in Grand Teton National Park. Photo courtesy of Robert Kirkwood.


FossiLab Outreach at the Smithsonian

Andy here-

One of the most enjoyable activities I got involved with while at the Smithsonian Institution – National Museum of Natural History was FossiLab. FossiLab is a windowed room where volunteers and scientists go about doing work that needs to be done in the museum. Some of the volunteers there do is look through sediment samples for tiny fossils. That’s time consuming work, but it can be done, and done well, with a few afternoons of training. Most of what the volunteers engage in re-housing fossils. Besides research and education, the Smithsonian also very importantly stores lots of items. The NMNH stores over 40 million fossils, and the fossils are only one part of what that particular museum has. Some of these fossils need to be put in new boxes, since the old ones aren’t doing a good job storing them anymore. So, they spend hours cutting new styrofoam to cradle to fossils just so, making new custom ‘housing’ that will keep the fossil safe for decades to come. This means I’ve gotten to see many cool fossils, like Miocene aged dolphin ancestors collected by the scientist who found (though didn’t name) the first Triceratops.

The rare view from the other side of the glass in FossiLab with an empty museum.
An example of some of the measurements on a planktic foraminifer (image generated by Melanie Sorman)

I, as a scientist, was doing research while I was in FossiLab. I study planktic foraminifera. In particular I’m interested in how their history is changed by climate. Can we detect how their evolution was altered by changing climates in the past? While upstairs in FossiLab I spent lots of time measuring individual foraminifera to understand their shape. I was doing this with forams which lived about 100 million years ago in a warm interval, trying to understand the evolution of one particular aspect of their shape. Certain species of foraminifera develop a ‘keel’, a build-up of calcite on the outer-edge of the shell. Yes, if you look at it just right, it does look like the keel on a boat. The question that we’re attacking is ‘did the keel develop from one lineage, or did several independent lineages develop keels simultaneously?’. This is important for a few reasons. The keel is a key feature of the test (internal shells), and has been thought for years to indicate that the foram lived deeper (though that’s not always the case). Also, much evolutionary research in forams depends on understanding how different species are related. We know this really well for the Cenozoic (65 Million years ago to the present), but the Cretaceous has several really important ancestor-descendent relationships that we just haven’t figured out yet. This is one of those. There’s a sign in front of the microscope that I used explaining much of this, and a little slideshow that plays with more detail.

FossiLab also has a door that lets the volunteers or scientists walk out and talk to folks. If people watched for a while, then I’d usually get up and go talk to them. I have a little tray filled with objects to talk about what I do. First, I’d hand them a tray of microfossils (which to a naked eye, look like sand) and ask them to make observations about what they saw. Usually I’d get “It’s sand!”. I then put the tray under my WoodenScope and show them that each ‘grain of sand’ they saw was actually tiny shells. We’d talk about what forams are, and how we use a big boat called the R/V JOIDES Resolution with a drill on it to get them. Describing coring goes like this: 

“Have you ever stuck a straw through a cake?”

“Yes!” Oddly, 80% of the groups have somebody that’s done this.

“OK, so what happened? What’s in the straw?”


“But what’s on top?”

“Right, you get the cake layers. There’s icing on top, then cake, then if it’s a really good cake, there’s another layer of icing and more cake. The ocean is just like that, there are layers. The JOIDES is our straw, and we’re using the cores to sample the layers in the bottom of the ocean.”

Then we finish up by talking about what forams can tell us. We count up forams because if we have more of a kind that likes warm water, then we can tell the water was warmer at that time in that location, or more cold loving forams means colder water.

To finish the interaction, I let the kids or adults ask as many questions as they want. Usually it ends with the parents telling them they have to go.

Global risk of deadly heat

Global risk of deadly heat

Camilo Mora, Benedicted Dousset, Iain R. Caldwell, Farrah E. Powell, Rollan C. Geronimo, Coral R. Bielecki, Chelsie W. W. Counsell, Bonnie S. Dietrich, Emily T. Johnson, Leo V. Louis, Matthew P. Lucas, Marie M. McKenzie, Alessandra G. Shea, Han Tseng, Thomas W. Giambelluca, Lisa R. Leon, Ed Hawkins, and Clay Trauernicht

Data: This study was conducted by gathering data from previous studies and looking at the number of lethal heat events that have occurred around the world from 1980 to 2014. The study also estimates the percentage of the population that is at risk from increased air temperatures and humidity due to human-induced climate change in the future.

The number of days per year that different areas are exposed to deadly heat and humidity (‘threshold’). The simulations, a-d, are from models into the year 2100. A) historical data from other published studies; B) RCP 2.6 scenario where nearly all emissions are cut; C) RCP 4.5 is a scenario where most emissions are cut; D) RCP 8.5 is the ‘business as usual’ scenario where emissions are not cut at all.

Methods: The authors used data from 911 previous studies to use in their analysis. They collected information on the place and dates of lethal heat events, or extreme heat events that led to human deaths. The number of days per year that surpassed the heat threshold for which humans can live in was assessed for each year (1980-2014). To determine how much of the population may be at risk of heat-related deaths in the future, the scientists used four different CO2 scenarios to model air temperature and humidity to year 2100.

Results: From the previous studies, the scientists found 783 cases of human mortality linked to excess heat from 164 cities in 36 countries. Cases of heat-related deaths were concentrated to mid-latitude regions, with high occurrences in North America and Europe. Temperature and relative humidity of an area were both found to be factors important to identifying regions where climate conditions may become deadly, as these are related to human’s ability to regulate their body temperature. Currently, around 30% of the Earth’s population is exposed to climate conditions that are considered deadly. By the year 2100, this number is projected to increase to 48% under a CO2 scenario where emissions are drastically cut, and 74% under a CO2 scenario of increased emissions.

Why is this study important? This study highlights the health risks posed to humans due to increased heating of the Earth. Several countries and large cities, mostly concentrated at the mid latitude regions and equator, are at most risk.

The big picture: Under all emissions scenarios, whether we cut emissions drastically or keep emitting CO2 at the same rate, an increased percent of the human population will be at risk of heat-related deaths. This study emphasizes the importance of aggressive mitigation to minimize the human population’s exposure to deadly climates linked to human-induced climate change.

Citation: Mora, C., Dousset, B., Caldwell, I. R., et al., 2017. Global risk of deadly heat. Nature Climate Change, 7, 501-506. DOI: 10.1038/nclimate3322

Raquel Bryant, Mentor/Instructor

Raquel, pictured on the left, with the August 2016 STEM SEAS cohort in Seattle, Washington.

STEM Student Experiences Aboard Ships (STEM SEAS)

Last summer I got the opportunity to sail on two research vessels through the new NSF funded program STEM Student Experiences Aboard Ships or STEM SEAS. I served as a graduate student mentor on the very first transit aboard the R/V Oceanus in May and as an instructor on the August transit aboard the R/V Siquliak. As an aspiring paleoceanographer, I was excited about the opportunity to experience life on a ship as sailing as a biostratigrapher aboard the JR is something I hope to accomplish during my graduate career. As an aspiring teacher and mentor, I was excited about the opportunity to get to know a promising group of undergraduates and share my passion for geoscience.

So, what exactly is STEM SEAS? STEM SEAS is an NSF funded program that takes advantage of empty berths on UNOLS research vessels during transits. UNOLS ships are operated out of universities across the country and sometimes when the ships travel from port to port in between scientific expeditions there is no science party on board. Our program brings undergraduates aboard the ships for a 6-10 day mobile classroom experience. The students received mini-lectures on topics like oceanography, climate change and micropaleontology and were able to participate in shipboard science like coring and the collection of plankton. The program works to address the low retention rates in STEM disciplines, the lack of diversity in the geoscience community, and the predicted workforce shortage in geosciences.

STEM SEAS targeted groups of students in times of transition to address the issue of low retention in STEM fields. Circumstances of transition include declaring or switching a major or advancing from a 2-year college to a 4-year college. At these times students may be without guidance or strong mentorship and are vulnerable to attrition, in other words dropping out of science majors. Aboard the ships we addressed these issues by talking about the best way to find mentors and reflecting on the types of support systems the students already had in place. Not to mention, being on a ship for the first-time fosters quality bonding time and the students made lasting relationships with each other that are sure to help them feel supported through the next phases in their academic careers.

Our program is dedicated to a broad view of diversity to include students with many identities currently underrepresented in STEM including race, gender, geographic location, institution type, ability and veteran/military status. STEM SEAS gives a diverse group of students the opportunity to explore geoscience in a hands-on fashion with close faculty mentors. It is not our hope that every student will switch their major to geoscience (although some do!) but that our students are empowered to see themselves incorporating science into their lives and careers in some way.

It’s unfortunate that while we live in a time where geoscience is in the news daily, in the form of discussions about climate change, sea level rise, floods, or earthquakes, many high school and college students will not take a geoscience class in their academic career. With a looming geoscience workforce shortage and the pressing issue of climate change, it is imperative that we empower our youth to engage with issues of climate and environment. Once our students return home or to their campuses, they must present some aspect of their STEM SEAS experience to their community. This ensures that STEM SEAS is not only introducing the students, but also their communities to geoscience.

What is next for STEM SEAS? After a very successful pilot year, STEM SEAS continued into summer 2017 on a transit down the east coast of the US. This transit will be open to undergraduates from an HBCU (Historically Black Colleges and Universities). Partnering with an HBCU is in line with the mission of STEM SEAS and we are excited to add another cohort of STEM SEAS students to our alumni community. To stay up to date, follow us on Facebook!

To follow Raquel’s updates please check out her Twitter here. Check out the STEM SEAS webpage here, to keep up to date with new projects.

International School on Foraminifera, Urbino, Italy

Raquel here-

Ciao! Greetings from beautiful and sunny Urbino, Italy! For two weeks earlier this summer, I participated in the 10th International School on Foraminifera at ESRU Urbino. This workshop covers all aspects of foraminifera, from their modern ecology to their evolution since the Cambrian. The school is truly international as we not only have expert lecturers from all over the world, but also students representing more than 12 countries.

Raquel (front, 6th from right) and the other students and teachers that ran the 10th International School on Foraminifera in beautiful Urbino, Italy.

I was only 1 of 4 students from the U.S. I have made friends with fellow micropaleontologists from Brazil, Saudi Arabia, the UK, Israel and Russia and have enjoyed getting to hear what life is like as a scientist and micrpaleontologist in other parts of the world. This also means that for the most part, instead of learning any Italian I have been helping other students improve their English, something I am happy to do since English is the most prominent language of science. Each day we have lectures in the morning and in the afternoon, we look at samples and specimens under the microscope. This is great because everything we learn from lecture is reinforced with real forams and slides! As I am a Cretaceous and planktic person, my favorite lecture was biostratigraphy with Maria Rose Petrizzo. During lecture, we went through the important evolutionary changes in the planktic record and in the afternoon for our lab exercises we had just 10 minutes to pick different morphotypes from residue. Instead of speaking in terms of species, for foraminifera we speak in terms of ‘morphotypes’ this simply means we use shape (morphology) to define them. I had a lot of fun with this!

My microscope, notes, and a tray full of slides, each with different species of foraminifera.

I also really enjoyed the lectures on modern planktic forams. The coolest thing I have learned is that although there is a lot we don’t know about forams in the past, biologists studying modern forams are still puzzled by these amazing protists. There are many questions surrounding their reproductive cycle, feeding habits and general ecology that biologists are still working out.

I learned a lot, but I must say the best part of the trip is the other scientists and foram enthusiasts I am meeting and getting to know. We live, work, and eat together and are forming relationships and networks that I’m sure will last through our careers. We already have plans to meet up at the big forams meeting next year in Scotland!

Bye for now!

Shaina Rogstad, Climate Modeler

My PhD work focuses on climate modeling, oceanography, and climate change. However, I have many scientific interests and in the past my research has been in astrophysics, physics, and applied mathematics researching a wide variety of topics including galactic evolution, quantum mechanics, and gravitational waves.

Shaina (fourth from right) after she defended her master’s thesis. Here, she is pictured with her research group as part of the Applied Math program at UMass Amherst. The research she presented was on modeling Solitons and Vorticies in Bose Einstein Condensates (or negative mass).

I use computer simulations to look at ways the global climate might change as Antarctica melts. As the ice sheet melts, water runs off and chunks of ice calve off from the sheet and float out into the ocean. The world’s oceans are all connected and water moves around allowing it to distribute heat, salt, and nutrients around the planet.  All of the water and ice running off changes how salty the water is and that in turn impacts that movement altering aspects of the climate such as global temperatures and precipitation patterns. Every part of the climate system is connected in these really complex but deeply beautiful ways. I study those connections to learn what might happen to the climate in the future.

Currently I am using data from Rob DeConto and Dave Pollard’s (2016) regional ice sheet simulations that they developed to model the Antarctic ice sheets. This data are really cool because their modeling techniques are state of the art. When their results were published in 2016 it made a big splash both in the scientific community and in the media. Now I am using their data, which was modeled just for Antarctica, along with the Intergovernmental Panel on Climate Change’s Representative Concentration Pathways data, which describes how greenhouse gas concentrations in the atmosphere could evolve, and putting it into a global model that ties together land, atmosphere, oceans, and ice to take the research one step forward and see what their predictions for Antarctica might mean for the climate system as a whole.

A model image from Shaina’s current PhD work. On the left is the amount of runoff (melted ice that is flowing into the ocean) around Antarctica in year 2017. On the right is the modeled amount of runoff around Antarctica under increased CO2 scenarios in the year 2117. Runoff is measured in sverdrups (SV), which is a unit of volume transport. 1 SV is equal to 264,000,000 US gallons per second!

Most people are aware that the polar ice caps are melting as the planet heats up from all of our greenhouse gas emissions. This melting has significant impacts for how climate will change. There are a lot of feedbacks in the climate system and so there are these interactions where climate change causes the ice caps to melt and the melting of the ice caps then causes the climate to change in other ways such as altering ocean circulation. My research specifically looks at how the melting of the Antarctic ice sheet might change the climate, with a focus on changes in ocean circulation. Ocean circulation has a large influence on the planet with ramifications for global temperatures, sea ice distributions, and wind patterns. There is a subtle interplay between all of these things and I will be trying to determine what might happen based on what the computer simulations predict. The goal is to shed light on what may happen to our climate as the melting occurs in hopes of furthering our knowledge and spurring action to mitigate the severity of climate change.

One of my favorite parts of being a scientist is learning how our universe works. I used to be an astronomer and studied stars and galaxies, then I worked on gravitational waves and quantum mechanics, and now I study the earth and the oceans. I love learning all I can about how natural systems work because they have a fascinating logic to them all centering on physics and mathematics and it is very beautiful to me.

My advice to young scientists is to find a support group who will encourage you to grow and explore. Being a scientist can be difficult and occasionally a bit lonely. Most of what kept me going throughout undergrad and my masters work were my fellow students in the programs and clubs I was involved in, and my mom who is always a great cheerleader for me. There will be a lot of times along the way that it will be discouraging, especially if you are a member of a group traditionally underrepresented in the sciences. It is really helpful to have people to work with, study with, and talk to through the tough times. In addition to giving you the support to continue with your work you will also gain friends and collaborators that you will have going forward in your career and in your life.

To learn more about Shaina and the research she does, follow her on Twitter here!

Global warming and bleaching of coral reefs

Global warming and recurrent mass bleaching of corals

Terry P. Hughes, James T. Kerry, Mariana Alvarez-Noriega, Jorge G. Alvarez-Romero, Kristen D. Anderson, Andrew H. Baird, Russel C. Babcock, Maria Beger, David R. Bellwood, Ray Berkelmans, Tom C. Bridge, Ian R. Butler, Maria Byrne, Neal E. Cantin, Steeve Comeau, Sean R. Connolly, Graeme S. Cumming, Steven J. Dalton, Guillermo Diaz-Pulido, C. Mark Eakin, Will F. Figueira, James P. Gilmour, Hugo B. Harrison, Scott F. Heron, Andrew S. Hoey, Jean-Paul A. Hobbs, Mia O. Hoogenboom, Emma V. Kennedy, Chao-yang Kuo, Janice M. Lough, Ryan J. Lowe, Gang Liu, Malcolm T. McCulloch, Hamish A. Malcolm, Michael J. McWilliam, John M. Pandolfi, Rachel J. Pears, Morgan S. Pratchett, Verena Schoepf, Tristan Simpson, William J. Skirving, Brigitte Sommer, Gergely Torda, David R. Wachenfeld, Bette L. Willis, and Shaun K. Wilson

Data: The authors surveyed Australian coral reefs around the Australian coast using aerial photographs and underwater images to assess the amount of bleaching experienced by the reefs. They compared these images and data to sea surface temperature data from the area to determine if there was a correlation between sea surface temperature and coral reef bleaching. Learn about what coral bleaching is by clicking here.

Methods: The authors first took aerial photographs of the reefs from an airplane and helicopter, which flew about 150 meters above sea level, for 10 days in 2016. The researchers then ranked the severity of coral bleaching using a scale from 0 to 4, with 4 being the worse bleaching (over 60% of corals). To check that their scale from the aerial images was correct, the scientists also conducted underwater surveys of the same reefs. The same methods were conducted in 1998 and 2002 by other researchers, so the authors of this study compared their data to previous data. In this way, they have 3 years of coral bleaching data from the years 1998, 2002, and 2016 to see if bleaching events are becoming more common and getting worse. The scientists then compared their bleaching scale to observed sea surface temperatures in the area where the surveys were conducted to observe the relationship between temperature and coral bleaching.

A). The severity of bleaching of coral reefs around the northeast coast of Australia from 1998, 2002, and 2016. Dark green areas indicate <1% of corals bleached, light green indicates 1-10% bleaching, yellow indicates 10-30% bleaching, orange areas indicate 30-60% bleaching, and and red areas are where more than 60% of the corals are bleached. B) Patterns of heat stress during mass bleaching events in 1998, 2002, and 2016. Hotter colors indicate maximum heat exposure.

Results: Coral reef bleaching increased significantly from 1998 to 2016. Associated with the bleaching was an increase in the water temperature around the coasts of Australia where the corals are living.

A) Aerial view of a reef that is close to 100% bleached; B) Severe bleaching of an older coral mass on the northern Great Barrier Reef; C) staghorn corals that were killed by the major bleaching event in 1998; D) the same site in C, but 18 years later and the corals have not recovered; E, F) mature staghorn corals that were killed by heat stress and colonized by algae in just a few weeks time in 2016.

Why is this study important? This study is one of the first to examine a huge amount of coral reefs (1,156 in 2016 alone) to assess the effects of increased water temperature on coral bleaching. The researchers indicate that some coral species can grow back in 10-15 years, but some of the corals that are dying in the reefs are slow growers and very old. It will likely take decades for these corals to return to their former glory. This study indicates that we must take action now to save our coral reefs, not just around Australia, but around the world.

The Big Picture: By using large data sets and looking at trends of corals through time, scientists can concretely state that rising sea surface temperatures due to increased CO2 levels are causing mass coral reef bleaching events. When corals are stressed for too long, they die. Coral reefs are considered the rainforests of the sea because they are home to so many species of marine animals. Once the coral reefs begin to die, other animals will lose habitat to live in, and thus their numbers will, and are, declining. This has huge implications on the fishing industry, as people who rely on the ocean to make a living will no longer be able to catch bountiful amounts of fish that live around the reefs. In short, the effects of dying corals has far-reaching implications that will hurt the marine ecosystem, collapse the marine food chain, and affect economies.

Citation: Hughes, T. P., Kerry, J. T., Alvarez-Noriega, M., Alvarez-Romero, J. G., et al., 2016. Global warming and recurrent mass bleaching of corals. Nature, 543 (7645). DOI: 10.1038/nature21707

Ellen Currano, Paleobotanist & Paleoecologist

I study how ancient forests responded to environmental changes. By looking at what has happened in the past (“time traveling with a shovel,” as Kirk Johnson so brilliantly calls it), we can better predict and prepare for what we might be facing in the coming decades. For example, most of my research considers plant fossils from the western US that are 60-50 million years old. During this time, earth was much, much warmer than today: there was no ice at the poles and crocodiles and palm trees lived all the way up in the Arctic Circle. I am interested in how forests work during warm intervals like this, as well as how different forests were across North America. Today, there are huge differences between forests in Wyoming and New Mexico, due predominantly to the very different temperatures. But what about during the Eocene, when Earth was universally warm?

Representative leaf damage on modern and fossil leaves. Galls (a,b), leaf mines (c,d,e), leaf chewing damage (f, g; H=holes, M=margin feeding, S=skeletonization), oviposition (h, i). Scale bar= 1 cm in A-D, F-I. Tick marks in E=1 mm.

Around 56 million years ago, there was an abrupt global warming event caused by massive release of carbon (as CO2 or methane- the jury is still out on this) into the atmosphere. Atmospheric carbon dioxide levels at least doubled, global temperatures warmed between 4 and 8 degrees Celsius, and ocean acidity increased. This event had a huge impact on living things, and I have studied how plants and insects responded to that increased temperature and carbon dioxide levels.  While studying this interval is not a perfect analog for the present (rates of change are probably 100 times slower 56 million years ago than today), it is the best offered by the geologic record.

My favorite parts of being a scientist are exploring, discovering new things, and exercising my imagination. I have traveled to beautiful and rugged places all over the world to collect fossils. I get a rush of excitement every time I split open a rock and discover a beautiful leaf that has not seen the light of day for many millions of years. As I am collecting fossils, I take pauses to close my eyes and envision what that landscape looked like when the fossil were alive, transforming the barren badlands in which I sit into lush tropical forests.

My advice to young scientists is to be yourself and to never let anyone convince you that science isn’t cool. Everyone needs science, and science needs everyone. We are all citizen scientists. We can all be professional scientists, regardless of race, skin color, religion, gender, or sexuality.

Ellen Currano is a professor at the University of Wyoming see her website here, and is a co-creator of The Bearded Lady Project.