While accelerating sea level rise will result in widespread intermittent flooding and long-term inundation in many coastal communities, the paper, recently published in Nature Communications, showed that when these levels increase above 4 feet, minority populations will be disproportionately at risk of isolation.

Rising sea levels could lead to isolation by disrupting transportation networks and roads, meaning that those affected lose access to essential locations such as critical emergency services and schools.

The study further exposed that renters and older adults face a greater risk of isolation, highlighting the growing connection between historical drivers of existing social inequality and the groups that incur the most risk of climate change.

According to Kelsea Best, lead author of the study and an assistant professor of civil, environmental and geodetic engineering at The Ohio State University, the first step in better characterizing these threats is changing how researchers assess community risk, as most studies measure this by exclusively determining impacts via direct flooding. But concentrating on this sole measurement neglects more complex aftereffects of sea level rise, such as isolation, and reinforces inequality in coastal areas, Best said.

“We need to re-conceptualize how we measure who is burdened by sea level rise because there are so many ways that people might be burdened before their home is flooded,” she said.

Current reports estimate that around 20 million coastal residents in the U.S. will be affected by rising sea levels by 2030, but the paper notes that this number doesn’t include the whole impact global warming will have on certain communities and demographics.

Notably, because people need access to essential places like grocery stores, public schools, hospitals and fire stations, Best and her colleagues argue that an inability to reach these places impacts individuals just as negatively as if they were living in inundated homes themselves, and should be documented as such.

Most importantly, their results expose one of the main reasons for these vast differences in risk: A group’s risk of isolation is intimately entwined with specific road networks and where vital services are located in relation to where affected individuals reside.

They identified these disparities in risk by overlaying OpenStreetMap (OSM) road network data with National Oceanographic and Atmospheric Administration (NOAA) mean higher high water (MHHW) scenarios. These projections were then combined with recent census data to estimate the percentage of a population that would be left out or missed in estimates of who would be impacted by sea level rise if researchers only counted those who suffered direct inundation.

“If we take a one-size-fits-all approach, or a seemingly ‘neutral’ approach to understanding who gets access to safe, affordable housing and community in a world with climate change, then we’re really just exacerbating these inequities and it’s not good enough,” said Best. “We have to deliberately seek to provide access to adaptation resources to groups of people who have historically been left out and therefore have fewer resources to respond in the first place.”

The researchers showed that Hispanic populations are often overrepresented in the total citizenry for being at risk of isolation beginning at 4 feet of sea level rise, and Black populations are overrepresented after 6 feet. Alternatively, white populations are underrepresented after 5 feet of sea level rise.

But to determine when these disparities will begin to develop, Best’s team compared two long-term sea level rise scenarios: an intermediate scenario in which global sea level rise increased by a meter by 2100, and a high scenario in which that number increased to 2 meters by the same year.

Alarmingly, the study found strong evidence that these isolation effects would set in by 2120 in the intermediate scenario and as early as 2090 in the high scenario. “This timeline matters from a planning and adaptation perspective,” said Best. “Part of why we included the temporal piece is to say this issue would not be as much of a problem if we had urgent, aggressive mitigation.

“The effects of climate change are going to be further reaching and more cascading than might be directly obvious, and those effects are not going to be felt equitably,” said Best. “So we need to be thinking about those populations most at risk from the beginning and develop policies to support them.”

The work was supported by the Clark Distinguished Chair Endowment (given to study co-author Deb. A. Neimeier of the University of Maryland) and the National Science Foundation. Other co-authors were Qian He from Rowan University, Allison C. Reilly from the University of Maryland, and Mitchell Anderson and Tom Logan from the University of Canterbury.

The researchers propose that if a terrestrial planet has substantially less carbon dioxide in its atmosphere compared to other planets in the same system, it could be a sign of liquid water — and possibly life — on that planet’s surface.

What’s more, this new signature is within the sights of NASA’s James Webb Space Telescope (JWST). While scientists have proposed other signs of habitability, those features are challenging if not impossible to measure with current technologies. The team says this new signature, of relatively depleted carbon dioxide, is the only sign of habitability that is detectable now.

“The Holy Grail in exoplanet science is to look for habitable worlds, and the presence of life, but all the features that have been talked about so far have been beyond the reach of the newest observatories,” says Julien de Wit, assistant professor of planetary sciences at MIT. “Now we have a way to find out if there’s liquid water on another planet. And it’s something we can get to in the next few years.”

The team’s findings will appear in Nature Astronomy. De Wit co-led the study with Amaury Triaud of the University of Birmingham in the UK. Their MIT co-authors include Benjamin Rackham, Prajwal Niraula, Ana Glidden Oliver Jagoutz, Matej Peč, Janusz Petkowski, and Sara Seager, along with Frieder Klein at the Woods Hole Oceanographic Institution (WHOI), Martin Turbet of Ècole Polytechnique in France, and Franck Selsis of the Laboratoire d’astrophysique de Bordeaux.

Beyond a glimmer

Astronomers have so far detected more than 5,200 worlds beyond our solar system. With current telescopes, astronomers can directly measure a planet’s distance to its star and the time it takes it to complete an orbit. Those measurements can help scientists infer whether a planet is within a habitable zone. But there’s been no way to directly confirm whether a planet is indeed habitable, meaning that liquid water exists on its surface.

Across our own solar system, scientists can detect the presence of liquid oceans by observing “glints” — flashes of sunlight that reflect off liquid surfaces. These glints, or specular reflections, have been observed, for instance, on Saturn’s largest moon, Titan, which helped to confirm the moon’s large lakes.

Detecting a similar glimmer in far-off planets, however, is out of reach with current technologies. But de Wit and his colleagues realized there’s another habitable feature close to home that could be detectable in distant worlds.

“An idea came to us, by looking at what’s going on with the terrestrial planets in our own system,” Triaud says.

Venus, Earth, and Mars share similarities, in that all three are rocky and inhabit a relatively temperate region with respect to the sun. Earth is the only planet among the trio that currently hosts liquid water. And the team noted another obvious distinction: Earth has significantly less carbon dioxide in its atmosphere.

“We assume that these planets were created in a similar fashion, and if we see one planet with much less carbon now, it must have gone somewhere,” Triaud says. “The only process that could remove that much carbon from an atmosphere is a strong water cycle involving oceans of liquid water.”

Indeed, the Earth’s oceans have played a major and sustained role in absorbing carbon dioxide. Over hundreds of millions of years, the oceans have taken up a huge amount of carbon dioxide, nearly equal to the amount that persists in Venus’ atmosphere today. This planetary-scale effect has left Earth’s atmosphere significantly depleted of carbon dioxide compared to its planetary neighbors.

“On Earth, much of the atmospheric carbon dioxide has been sequestered in seawater and solid rock over geological timescales, which has helped to regulate climate and habitability for billions of years,” says study co-author Frieder Klein.

The team reasoned that if a similar depletion of carbon dioxide were detected in a far-off planet, relative to its neighbors, this would be a reliable signal of liquid oceans and life on its surface.

“After reviewing extensively the literature of many fields from biology, to chemistry, and even carbon sequestration in the context of climate change, we believe that indeed if we detect carbon depletion, it has a good chance of being a strong sign of liquid water and/or life,” de Wit says.

A roadmap to life

In their study, the team lays out a strategy for detecting habitable planets by searching for a signature of depleted carbon dioxide. Such a search would work best for “peas-in-a-pod” systems, in which multiple terrestrial planets, all about the same size, orbit relatively close to each other, similar to our own solar system. The first step the team proposes is to confirm that the planets have atmospheres, by simply looking for the presence of carbon dioxide, which is expected to dominate most planetary atmospheres.

“Carbon dioxide is a very strong absorber in the infrared, and can be easily detected in the atmospheres of exoplanets,” de Wit explains. “A signal of carbon dioxide can then reveal the presence of exoplanet atmospheres.”

Once astronomers determine that multiple planets in a system host atmospheres, they can move on to measure their carbon dioxide content, to see whether one planet has significantly less than the others. If so, the planet is likely habitable, meaning that it hosts significant bodies of liquid water on its surface.

But habitable conditions doesn’t necessarily mean that a planet is inhabited. To see whether life might actually exist, the team proposes that astronomers look for another feature in a planet’s atmosphere: ozone.

On Earth, the researchers note that plants and some microbes contribute to drawing carbon dioxide, although not nearly as much as the oceans. Nevertheless, as part of this process, the lifeforms emit oxygen, which reacts with the sun’s photons to transform into ozone — a molecule that is far easier to detect than oxygen itself.

The researchers say that if a planet’s atmosphere shows signs of both ozone and depleted carbon dioxide, it likely is a habitable, and inhabited world.

“If we see ozone, chances are pretty high that it’s connected to carbon dioxide being consumed by life,” Triaud says. “And if it’s life, it’s glorious life. It would not be just a few bacteria. It would be a planetary-scale biomass that’s able to process a huge amount of carbon, and interact with it.”

The team estimates that NASA’s James Webb Space Telescope would be able to measure carbon dioxide, and possibly ozone, in nearby, multiplanet systems such as TRAPPIST-1 — a seven-planet system that orbits a bright star, just 40 light years from Earth.

“TRAPPIST-1 is one of only a handful of systems where we could do terrestrial atmospheric studies with JWST,” de Wit says. “Now we have a roadmap for finding habitable planets. If we all work together, paradigm-shifting discoveries could be done within the next few years.”

“From 2009 to 2022, we conducted a series of field surveys in South China and collected a number of specimens of the Calotes versicolor species complex, and found that the population of what we thought was Calotes versicolor in South China and Northern Vietnam was a new undescribed species and two subspecies,” says Yong Huang, whose team described the new species.

Wang’s garden lizard (Calotes wangi) is less than 9 cm long, and one of its distinguishing features is its orange tongue.

“Calotes wangi is found in subtropical evergreen broad-leaved forests and tropical monsoon forests in southern China and northern Vietnam, mostly in mountainous areas, hills and plains on forest edges, arable land, shrub lands, and even urban green belts. It is active at the edge of the forest, and when it is in danger, it rushes into bushes or climbs tree trunks to hide. Investigations found that the lizards lie on sloping shrub branches at night, sleeping close to the branches,” says Yong Huang.

It is active from April to October every year, while in the tropics it is active from March to November or even longer, and eats a variety of insects, spiders, and other arthropods.

For now, the researchers estimate that the new species is not threatened, but they do note that in some areas its habitat is fragmented.

“In addition, their bodies are used medicinally and the lizards are also eaten,” they write in their research paper.

This is why they suggest that the local government strengthen the protection of their ecological environment and pay close attention to the population dynamics.