Climate change:
Up to 95% of ocean surface climates may disappear by 2100
Between 35.6% and 95% of 20th century ocean surface climates — defined by surface water temperature, pH and the concentration of the mineral aragonite — may disappear by 2100, depending on how greenhouse gas emissions develop in the first half of the 21st century, according to a study published in Scientific Reports. The findings also suggest that between 10.3% and 82% of the global ocean may experience surface climates that have not existed before.
Katie Lotterhos and colleagues modelled ocean climates globally for three time periods: the early 19th century (1795–1834), the late 20th century (1965–2004) and the late 21st century (2065–2104). The authors compared these modelled climates across various locations using two emission scenarios, RCP 4.5 and RCP 8.5. Under these scenarios the volume of greenhouse gases emitted during the 21st century either peaks in 2050 followed by a slowed increase, or peaks in 2100 followed by a slowed increase, respectively.
Through their comparisons, the authors were able to show which ocean climates from the 19th and 20th centuries may no longer be found in the 21st century (disappearance), and climates that may emerge in the 21st century which did not exist in the 18th and 20th centuries (novel climates). The authors showed that while ocean climates did not change significantly between the 19th and 20th centuries, by 2100, 10% to 82% of the ocean surface may experience new climates with higher temperatures, more acidic pH, and lower saturation of aragonite. Aragonite is a mineral which corals and other marine organisms use to form shells. Under the RCP 4.5 scenario, 35.6% of surface ocean climates may disappear by 2100, which rises to up to 95% under the RCP 8.5 scenario.
The authors conclude that while some marine species currently keep pace with changing ocean climates by dispersing to new habitats, this may no longer be possible if existing ocean climates disappear, forcing species to either adapt rapidly to new climates or disappear.
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Article details
Novel and disappearing climates in the global surface ocean from 1800 to 2100
DOI: 10.1038/s41598-021-94872-4
Corresponding Author:
Katie Lotterhos
Northeastern University, Boston, Massachusetts, USA
Email: k.lotterhos@northeastern.edu
Please link to the article in online versions of your report (the URL will go live after the embargo ends): https://www.nature.com/articles/s41598-021-94872-4
JOURNAL
Scientific Reports
DOI
How ocean temperature shapes marine biodiversity over geological time scales
During the Cenozoic era, warmer oceans harbored more species with similar functional roles, according to a new study, which reveals how ocean temperature shapes biodiversity and biogeographic patterns over geological timescales. Studying how biodiversity patterns have changed in the past can be useful for understanding the long-term ecological impacts of current, human-induced climate warming. The spatial and temporal structuring of biodiversity can be measured in terms of species richness (overall number of species) and functional richness (the number of common functional traits shared between species) over time in a given area. While more is known about patterns related to species richness change over time, less is known about patterns related to functional richness. Recent marine ecological research indicates high levels of functional redundancy (duplication of functional roles by multiple species) in tropical-subtropical regions, suggesting that latitudinal gradients of climate or temperature may drive this measure. Understanding this relationship is important because modern ecological studies suggest that functional redundancy may bolster ecosystem resilience to future environmental change. Using the fossil record of shallow-marine mollusks from New Zealand spanning roughly 40 million years, Tom Womack and colleagues illustrate the positive relationship between species richness, functional redundancy, and ocean temperature over geological timescales. Womack et al. found that both richness and redundancy increased in periods with warmer waters, revealing a long-lived and persistent relationship between the spatial and functional structuring of biodiversity and temperature. “Taken at face value, our results suggest that oceanic temperature should increase net species richness and functional redundancy in New Zealand over long timespans, particularly as we shift to a climate more representative of pre-Pleistocene conditions,” write the authors.
JOURNAL
Science
ARTICLE TITLE
A positive relationship between functional redundancy and temperature in Cenozoic marine ecosystems
ARTICLE PUBLICATION DATE
27-Aug-2021
For copepods, there is no free lunch when coping with climate change
Challenges for this small marine animal have ripple
effects through the whole food web and beyond
Peer-Reviewed PublicationThe world’s oceans are becoming increasingly stressful places for marine life, and experts are working to understand what this means for the future. From rising temperatures; to acidification as more carbon enters the waters; to changes in the currents; the challenges are multifaceted, making experiments and projections difficult.
Copepods are small marine animals that are abundant, widely dispersed, and serve as major structural components of the ocean’s food web. A team of scientists from the University of Connecticut, Jinan University in China, and the University of Vermont have found that a species of copepod called Acartia tonsa can cope with climate change, but at a price. Their research was published today in Nature Climate Change.
“We have this problem of climate change and in the ocean, it is a multi-dimensional problem because it’s not just the warming, the ocean is becoming more acidic where pH is going down as we pump more CO2, into the atmosphere. Organisms need to cope, they are under more stress, and things are happening very fast,” says Hans Dam, UConn professor of marine sciences.
Dam explains that previous studies suggest some animals will be more sensitive than others to changes like shifts in pH. Prior studies with copepods showed they are not particularly sensitive to pH changes, but Dam points out those studies were only done with a single generation, or few generations, to a single stressor and shows the ability to acclimate rather than adapt. This new study not only looks at adaptation across 25 generations, it also considered both ocean warming and acidification (OWA), something that few studies have done until now.
“If you want to study the long-term effects, you must consider the fact that animals will adapt to changes or stress in the environment, but to do that you have to do the right experiments. Most people do not do those experiments with animals because it takes a long time to study in multiple generations.”
The researchers looked at fitness, or the ability of a population to reproduce itself in one generation, and how fitness would change through generations in increased OWA conditions. The first generation exposed to new OWA conditions suffered extreme reductions of over 50% of population, says Dam. It was as if OWA was a big hammer that greatly reduced the population fitness. By the third generation, the population seemed to have mostly recovered. However, by the 12th generation, the researchers began to see declines once again.
Though the copepods were able to adapt, the adaptation was limited because fitness was never fully recovered, and the researchers suspect there are some antagonistic interactions at play, leading to a tug of war situation between adaptation to warming and to acidification. These antagonistic interactions complicate predicting what responses can be expected.
James deMayo, co-author and UConn Ph.D. student adds, “Perhaps what’s important to emphasize with this project is that the effects of warming combined with acidification are not the same for every generation or organism that is adapting to that environment. That’s suggested by the data and why the adaptation is limited. While within intermediate generations, organisms might be very well adapted, in later generations, the effects of warming and acidification start to behave differently on the population. That’s one of the exciting parts about the research. It’s not a static, expected result for how organisms or their populations are going to continue to grow or decay.”
For example, deMayo explains, if you took individuals in later generations that had adapted to the experimental OWA conditions and placed them into the conditions of today’s ocean, they would not fare as well.
“That’s one negative consequence, that ability to not tolerate environmental shifts is a cost and an unpredicted consequence for evolutionary adaptation in a lot of systems, not just in copepods,” says deMayo.
The researchers point out that studies looking at single stressors run the risk of making overly simplified inferences about an organism’s ability to adapt, an especially risky proposition when making conclusions about such an integral component of the food web as copepods.
“Particularly when you involve living organisms, there are complexities that you can’t predict,” says Dam. “A priori, you might make the predictions, but you have no certainty that they’re going to unfold that way. In biology these are referred to as ‘emergent properties’ or things that you cannot predict from what you know in advance and this research is a good example.”
In thinking back to the hammer comparison, Dam says impacts in the copepod population have ripple effects through the whole food web and beyond.
“If fitness decreases by say, 10%, down the road we will have a 10% decrease in population size and since these animals are the main food source for fish, a 10% decrease in the world fishery is pretty significant,” says Dam. “And this is really the best-case scenario since in the lab, they’re essentially living in hotel-like conditions so that 10% isn’t taking into consideration other factors like predation or disease. In the real world we could see fitness recovery is actually much worse.”
Additionally, Dam points out another implication is that copepods sequester CO2 and reductions in their numbers reduce the ocean’s carbon sequestration capabilities, bad news at a time when more carbon sequestration is needed.
While the research offers promise for rapid adaptation, it is a reminder that as with many things in nature there’s a catch.
“There is some welcoming news, that yes, there is a recovery of fitness but there is also sobering news that the evolutionary rescue is not complete. There’s no such thing as a free lunch,” says Dam.
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JOURNAL
Nature Climate Change
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Animals
ARTICLE TITLE
Rapid, but limited, zooplankton adaptation to simultaneous warming and acidification
ARTICLE PUBLICATION DATE
26-Aug-2021
Climate change challenge: Terminology used by scientists confounds public
Study participants offered helpful suggestions for
improving climate language
Peer-Reviewed PublicationA new study finds that U.S. residents struggle to understand terms frequently used by scientists to describe climate change. Study participants said some of the terms were too complex to understand. Other terms were misunderstood in the context of climate change. Participants suggested simpler, alternative language.
The study was published in a special edition of Climatic Change titled Climate Change Communication and the IPCC.
The study was spearheaded by the USC Dornsife Public Exchange and included a team of USC researchers and personnel from the United Nations Foundation.
Study participants were asked to rate how easy it was to understand eight terms drawn from publicly available reports written by the Intergovernmental Panel on Climate Change. (The documents used for the study did not include the IPCC’s latest report, which was released to the public on Aug. 9, 2021.) The UN Foundation chose the terms through informal consultation with the IPCC.
The eight terms were “mitigation,” “carbon neutral,” “unprecedented transition,” “tipping point,” “sustainable development,” “carbon dioxide removal,” “adaptation” and “abrupt change.” “Mitigation” was the most difficult term to understand; “abrupt change” was the easiest.
Participants were also asked to provide suggestions for alternative language. In general, they advised using simpler terms and using them in the context of climate change. For example, for the term “unprecedented transition,” which the IPCC defines as “rapid, far-reaching and unprecedented changes in all aspects of society,” participants suggested: “a change not seen before.”
For “tipping point,” which the IPCC defines as “an irreversible change in the climate system,” one respondent offered: “too late to fix anything.”
Previously published research suggests simplifying language to increase comprehension by:
- Limiting sentences to 16-20 words and using words with no more than two syllables, whenever possible (Cutts 2013; Kadayat and Eika 2020; McLaughlin 1969).
- Writing for the public at the level of a reader who is 12 or 13 years old (U.S. grade level 6-7; Wong-Parodi et al. 2013).
Researcher Commentary
Wändi Bruine de Bruin, the study’s lead author and Provost Professor of Public Policy, Psychology, and Behavioral Sciences at the University of Southern California (USC):
“One survey respondent summed it up nicely when saying, ‘It sounds like you’re talking over people.’ Scientists need to replace jargon with everyday language to be understood by a lay audience.”
“In several cases the respondents proposed simple, elegant alternatives to existing language,” Bruine de Bruin said. “It reminded us that, even though climate change may be a complex issue, there is no need to make it even more complex by using complicated words.”
Pete Ogden, vice president for energy, climate, and the environment at the United Nations Foundation:
“We have to get better at communicating the dire threat from climate change if we expect to build support for more forceful action to stop it. We need to start by using language that anyone can understand.”
Study Design
A qualitative researcher from USC Dornsife’s Center for Economic and Social Research posed the terms to 20 participants with a variety of backgrounds and views about climate change. The participants were drawn from USC Dornsife’s Understanding America Study for their varying views about climate change and diversity in terms of age, race, gender and education.
In a qualitative study such as this one, a sample of 20 is large enough to find terms that are likely to be misunderstood (Morgan et al. 2002). Indeed, 88% of the misunderstandings in this study were raised in the first 10 interviews. After 17 interviews, no new misunderstandings were raised. Researchers say a follow-up survey would be needed to examine how often misunderstandings occur or who is most likely to experience them.
About
The USC Dornsife College of Letters, Arts and Sciences is the academic core of the University of California. Its diverse community works across the natural sciences, social sciences and humanities, exploring fundamental questions about who we are, how the world works and what we can do to improve and enrich society.
Public Exchange is an office at the USC Dornsife College of Letters, Arts and Sciences that fast-tracks collaborations between academic researchers and the public and private sectors to define, analyze and solve complex problems together.
The United Nations Foundation is an independent charitable organization created to be a strategic partner for the United Nations to address humanity’s greatest challenges, build initiatives across sectors to solve problems at scale and drive global progress.
Contacts:
Lance Ignon
USC Dornsife College of Letters, Arts and Sciences
Megan Rabbitt
United Nations Foundation
JOURNAL
Climatic Change
METHOD OF RESEARCH
Survey
SUBJECT OF RESEARCH
People
ARTICLE TITLE
Public understanding of climate change terminology
ARTICLE PUBLICATION DATE
12-Aug-2021
COI STATEMENT
N/A
