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Footprints You Leave on the Beach Contain Your DNA

May 21, 2023

Hotter Years We’re Not Used to Are Approaching

A new report shows that we’re getting much closer to living in a world we’re not accustomed to. The World Meteorological Organization (WMO) predicts that there is almost a 100-percent chance—98 percent to be exact—that at least one of the next five years will be the warmest ever recorded, hotter than it was in 2016 when the average global temperature rise was 1.28C, according to the news site

Credit: Sven Lachmann/Pixabay

The WMO adds that within the next four years, the chances are two out of three that, for the first time, the average temperature will breach the 1.5C limit above pre-industrial levels adopted by nations in the Paris Agreement. Crossing the limit will not be permanent; however, it could start to happen more frequently, even if temporarily. This prediction is significant because it was only eight years ago at the signing of the agreement in 2015 when the chances of temporarily exceeding this boundary were practically zero—but now stand at 66 percent in the next five years. Currently, the average global temperature is about 1.15C above what it was at the end of the 1800s.

The naturally occurring warming of the Pacific Ocean called El Niño and climate change will combine to heat the planet into this uncharted territory. The WMO says that for much of the past three years, La Niña conditions had a cooling influence, but that has ended.

Scientists agree that crossing the 1.5C limit risks dangerous and deadly impacts, including more severe droughts, heatwaves, and rainfall. Added to that, the warming causes sea ice and glaciers to melt, sea levels to rise, and ocean acidification. 

World’s Lakes and Reservoirs Are Shrinking

More than half of all the world’s largest lakes, from the Caspian Sea situated between Europe and Asia to Lake Titicaca in South America, have been shrinking. That’s the conclusion of a new study led by the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado, Boulder, which showed that 5.7 trillion gallons were lost in the period from 1992 to 2020. That amount of loss is the equivalent to water held by 17 Lake Meads, America’s largest reservoir, or in other terms, it’s about how much the U.S. used in all of 2015. The authors said the results were staggering. About one-quarter of the world’s population lives in a water basin with a drying lake.

Pink depicts drying reservoirs; dark red, drying natural lakes. Dark blue marks natural lakes increasing in water storage; and light blue for existing reservoirs doing the same. Purple dots indicate new, filling reservoirs. | Credit: Yao et al., Science (2023)

The report concludes that the major causes of the decline are climate change and unsustainable human consumption, with global warming being the larger of the two. Climate change can cause lakes to lose water because hotter air is sucking up more moisture. After evaporating into the atmosphere, it may fall as rain or snow, but that could happen far away from the lake it came from, one of the authors said in an email to the Associated Press.

The team used satellite snapshots during the 28-year period to survey the area of almost 2,000 of Earth’s biggest lakes. They found that lakes in both dry and wet regions are losing volume. Losses in humid tropical lakes and those in the Arctic show more drying than previously understood.

The team concluded that man-made reservoirs were losing water too, with nearly two-thirds having significant losses.  In those cases, sedimentation was the dominant cause of the decline. In older reservoirs, sedimentation was a more important factor than droughts or rainfall. Sedimentation is the process through which reservoirs fill with sand, gravel, and rock that would have been transported down the river, if it had not been dammed. Sedimentation reduces the amount of water that can be held, and over years, deposits can eventually fill a reservoir. Some lakes grew in size, however. About one-quarter of them were in underpopulated regions in the Northern Great Plains of the U.S., the Tibetan Plateau, and other areas with newer reservoirs.

The study was published in the journal Science.

“Human Genetic Bycatch” May Intrude on Privacy

In recent decades, scientists who wanted to monitor wildlife but didn’t have the time to observe behavior or didn’t want to trap animals as too intrusive, have turned to collecting their DNA. Critters passing through an environment shed a treasure trove of information though pieces of skin, hair, or scales that can be genetically sequenced to reveal more about their health and identity.

Scientists now can detect DNA traces from many different environments. | Credit: Liam Whitmore, University of Limerick/Creative Commons

The same goes for us humans. Maybe not scales—but whenever we breathe, sweat, or touch something, a bit of our DNA remains behind—no swab or blood test required. And the information is there for the taking, which was the dilemma a team of researchers at the University of Florida raised in their recent work with sea turtles.

The scientists were using environmental DNA or “eDNA” to study viral tumors in endangered sea turtles by scooping up beach sand that baby hatchlings crawled across as they made their way to the ocean. They expected to see DNA from other animals, and maybe people, but the high quality of what they called “human genetic bycatch” set off alarm bells. Each of us has a unique genetic code, so could researchers be collecting sensitive information?

To answer that question, they took samples from several Florida locations, including ocean rivers, isolated beaches, and a remote island rarely visited by people. In all but the island samples, they found DNA of such high quality it contained markers for diseases and indicated the genetic ancestry of nearby populations. The team could even distinguish part of sex chromosomes from footprints volunteers left in the sand.

No doubt that eDNA has proved useful in everything from conservation to epidemiology, such as recently helping to monitor COVID-19 in wastewater, but it could also infringe on privacy since harvested materials can reveal specifics of our health and ethnicity.

The study’s authors want to continue using eDNA in research but are calling for regulations that ensure collection, analysis, and data storage are carried out ethically and appropriately.

The study was published in the journal Nature Ecology & Evolution.

A House Made from Diapers Can Fight Climate Change

There’s good news about diapers—specifically the disposable ones piling up in landfills. A team of researchers in Japan has found a way to turn the nappy waste into housing—and help combat global warming in the process.

Diapers were mixed into concrete to replace sand in a prototype house in Indonesia. | Credit Anjar Primasetra

In the U.S., about 4.1 million tons of disposable dumpy diapers are dumped into dumps annually, where they don’t break down and emit methane. However, as reported in the journal Nature, because diapers are made of wood pulp, cotton, and super-absorbent polymers, researchers at the University of Kitakyushu found shreds of them could replace sand when making concrete. That would be a win for the environment as sand is dwindling worldwide, destructive to mine, and is the key ingredient in cement production, which is responsible for almost seven percent of global greenhouse-gas emissions.

In their study, the team washed, dried, and shredded diapers and then combined them with cement, sand, gravel, and water. As Gizmodo explains, they tested different ratios of diaper shreds and found that a 40-percent mixture could be used for non-load-bearing walls and up to a 27-percent blend worked for support beams and columns in a single-story house prototype they built in Indonesia.

The idea was born in recognition that in Indonesia and other low- and middle-income countries, populations are growing—leading to more babies, more diapers, and more demand for low-cost housing. By using recycled materials, the cost of construction could be reduced to make homes more affordable. Lead researcher Siswanti Zuraida says that sourcing used diapers from waste streams would be challenging, given how recycling plastic is already inadequate, but plans to press ahead with the concept.

The study was published in the journal Scientific Reports.