To truly get the most out of life, a person needs to be able to get a good night's sleep. Lack of sleep due to stress or insomnia has led many to seek out natural products, including CBD, to help them fall asleep and stay asleep. Is there anything behind the idea of CBD for sleep improvement? In this article, we will explore the role that CBD for insomnia can play in a healthy sleep cycle and recommend CBD sleep products from brands we trust.
Our Top CBD for Sleep Picks
Each product featured here has been independently selected by the writer. You can learn more about our review methodology here. If you make a purchase using the links included, we may earn commission.
- Best CBD Sleep Gummies - Medterra CBD Sleep Tight Gummies
- Best CBD Sleep Softgels - R+R Medicinals CBD Softgels
- Best CBN + CBD Oil - CBDistillery CBN + CBD Oil
- Best Melatonin-Free Option - Prima Sleep Tight Softgels
- Strongest CBD Oil for Sleep - Spruce Rest Oil
- Best Organic CBD for Sleep - Cornbread Hemp Whole Flower CBD Oil
- Best CBD Bath Bomb for Sleep - Green Roads Peace CBD Bath Bomb
How We Picked the Best CBD for Sleep
We vetted the source and quality of the CBD for insomnia and sleep in this article. All recommended products were derived from industrial hemp grown in the United States and contains under 0.3% THC, which is required by law. Additionally, all products have been tested by third-party labs to ensure their quality and safety.
When reviewing CBD brands and products, we focus on six major factors:
- Value — is the brand's CBD affordable compared to similar products?
- Strength — how much CBD and what type of CBD does their product contain?
- Source — where does the company source their hemp and how is the CBD extracted?
- Flavor — does the product come in any flavors and do they flavor them naturally?
- Transparency — do they offer third-party lab test results and information about each batch of CBD?
- Customer experience — what do customer have to say about the product and purchasing experience?
Using these standards we were able to select the best CBD for insomnia and sleep. Learn more about our choices below.
The Best CBD for Sleep Products
Medterra CBD Sleep Tight Gummies include 25 mg of CBD isolate and 3 mg of melatonin to promote a restful night's sleep. We also like that they are made with calming natural ingredients like chamomile and lemon balm. All of Medterra's CBD comes from Kentucky-grown organic hemp that's raised without pesticides and is tested by third-party labs for purity.
Why buy: With natural strawberry flavoring, these gummies are a great option for those who want to take CBD for sleep but don't enjoy the taste of oil tinctures. They're are also 100% THC free.
These full spectrum CBD softgels from R+R Medicinals contain full spectrum CBD from USDA organic hemp grown in Colorado. Each softgel includes 15 mg of CBD plus over 3 mg of minor cannabinoids, like CBC, CBN, THC, and CBG, that combine in what's known as the "entourage effect" to help you relax as you wind down for the day. R+R Medicinals' CBD is extracted using a supercritical CO2 method to retain more of these beneficial plant compounds.
Why buy: We like these softgels because they make it convenient to add CBD to your nightly routine. They have a slower effect than some other products, but typically last longer. They are also available in a 30 mg strength for added relief.
Why buy: We like that this oil is specifically formulated for sleep. Additionally, this brand is a good choice for a CBD consumer who wants a full spectrum oil geared toward a particular cannabinoid blend, like CBN for sleep.
We love these Prima Sleep Tight softgels because they offer a doctor-formulated blend of CBD and natural botanicals, but are also melatonin-free. This makes them a great option for anyone with a sensitivity or allergy to melatonin. Each softgel serving contains 20 mg of broad spectrum CBD, as well as chamomile, passion flower, lavender, and amino acid compounds like 5-HTP and GABA, that all naturally promote sleep.
Why buy: We recommend these Prima softgels because they provide a plant-based sleep aid without THC or melatonin, and they come in sustainable and recycled packaging.
Spruce CBD is a family-owned and operated brand, and all of their tinctures are full-spectrum, made in the United States, lab grade, organic, contain no pesticides, and are third-party tested. Spruce Rest is specifically made to help you fall and stay asleep, with a powerful combination of CBD and CBN. Each bottle contains 1,200 mg of CBD and 150 mg of CBN for a potent sleep aid, and comes in a natural vanilla flavor.
Why buy: We like that this oil contains high concentrations of CBD and CBN for extra strength relief from sleeplessness. This CBD for insomnia product is best for those with experience using CBD oils.
Cornbread Hemp offers a whole flower CBD oil that is USDA organic, vegan, gluten-free, non-GMO, and third-party lab tested. It contains higher levels of naturally-occurring cannabinoids, terpenes, flavonoids, and fatty acids than more processed oils, providing you with more of the healthy plant compounds that can help you sleep. The 375 mg and 750 mg bottles contains 25 mg of CBD per serving, and the 1500 mg bottle contains 50 mg of CBD per serving.
The Green Roads Peace CBD bath bomb is a perfect way to relax and destress before bedtime. Made with 150 mg of CBD isolate, meaning it contains no THC. We like that this bath bomb also includes lavender for a luxuriously calming experience. These bath bombs use CBD from hemp grown on American farms and were developed with no animal testing. All Green Roads products do undergo third-party lab testing to ensure potency and quality.
Why buy: We recommend this CBD bath bomb as a way to start a naturally calming routine before bed, especially for those who prefer not to ingest CBD oils or capsules.
Can CBD Improve Your Sleep?
According to research in a 2019 study published in The Permanente Journal on behalf of the National Institutes of Health, CBD was examined for its efficacy in not only treating anxiety problems and post-traumatic stress disorder but also sleep disorders. The results of the study displayed that patients treated through the use of CBD over the course of three months saw an improvement in their sleep cycles, as well as a lessening of their anxiety and other mental anguish. Administered in doses of 25 mg of CBD, the cannabidiol was well received. Side effects were minimal and typically related to daytime sleepiness on higher doses of CBD.
It is believed that CBD for insomnia can improve sleep processes because it triggers the body's endocannabinoid system, a biological system that is comprised of receptors and enzymes that regulate a variety of bodily functions, including sleep, memory, appetite, and mood.
Phytocannabinoids, like CBD and CBN, have the potential to interact on an indirect basis with cannabinoid receptors in the endocannabinoid system, thereby encouraging the body to sleep by helping to manage anxiety, pain, and stress hormones that contribute to sleep loss.
Why is Sleep Important?
According to the American Sleep Apnea Association, an estimated 50 to 70 million people in the United States spanning all ages and socioeconomic classes suffer from sleeplessness. Both men and women are impacted by sleep disturbances, and according to the American Academy of Sleep Medicine and the Sleep Research Society, adults aged 18-60 years old need at least seven hours of sleep each night to realize optimal health and well-being.
Sleep plays an important role in your mental and physical health. When you have a healthy sleep cycle, your body and mind are able to engage in many restorative processes including healing and repairing cognitive and cardiac functions. During sleep, your body is actively working by boosting your immune system, fighting inflammation, regulating digestive processes, and so much more.
When a person does not get the sleep they need, they run the risk of developing many chronic health conditions, including:
- High blood pressure
- Heart disease
- Mental health issues
Insomnia is a serious sleep disorder that can be acute (short-term) or chronic (long-term). Right now, one in four Americans develops insomnia annually, according to Science Daily. Insomnia can cause a person to have problems falling asleep, staying asleep, or waking far too early. This can drastically impact your energy level, your work performance, your quality of life, and has the potential to cause negative physical and mental health outcomes.
According to the Mayo Clinic, chronic insomnia can result in many of the health conditions we have referenced, and can also cause depression and anxiety. CBD for insomnia not only has the potential to help as a sleep aid to improve sleep quality, but it can also help to mitigate and manage anxiety and assist with chronic pain relief to help you achieve a calm and restful night's sleep.
How to Choose For You
If you are looking for the best CBD for sleep, then it is important to do your research and realize that not all CBD products are created equal.
What to Look For
In order to feel confident knowing that you purchased a high-quality CBD product, only buy from a brand that engages in accredited, third-party lab testing and subsequently publishes its lab reports on its website. You must be able to see that what is on the label of your CBD oil actually is validated through testing processes.
This also ensures that the CBD is free of toxins, including pesticides, heavy metals, microbials, and solvents, and contains the concentration of CBD, terpenes, and other cannabinoids and plant parts that it claims. Always look for brands that use CBD from hemp grown in the United States, as these products undergo more rigorous testing than in some other countries.
In addition to CBD, look for products that include other natural ingredients like lavender, chamomile, passion flower, and lemon balm that are help to promote calm and rest. Make certain that all ingredients, including any flavorings, are all natural and labeled clearly. Also consider products that contain melatonin, a natural hormone that regulates sleep alongside wakefulness. Boosting this particular hormone, which is already found in your body, can truly improve your sleep-wake cycle.
How to Read Labels
It's important to know what kind of CBD is used in the product you choose. When comparing labels, look for one of the following:
- Full spectrum CBD - contains all of the plant compounds found in hemp including THC
- Broad spectrum CBD - contains some additional plant compounds, but no THC
- CBD isolate - pure CBD that contains no additional compounds
Some people find that full-spectrum CBD offers a better experience promoting sleep thanks to the entourage effect, while others may want to avoid THC entirely.
Here are some additional pieces of information to look for on each product.
How much CBD the product contains and how much is included, in mg, per serving. It's recommended that those new to CBD start with a lower dose and slowly increase the amount taken to identify the right dosage for your body.
Look for information about additional cannabinoids included, like CBN or CBG. These are naturally found in the hemp plant in certain dosages, but some products have higher amounts to help promote sleep.
Additionally, CBD oil tinctures use carrier oils, frequently olive oil, MCT oil or hemp seed oil. Make sure you know what type of carrier oil is used in case you are allergic to certain ingredients like coconut.
How to Use
Depending on the type of CBD product you choose, you will use it differently to help you sleep. Most CBD sleep products recommend use an hour or so before bed to allow it to take effect.
If you are using a CBD oil tincture, this is taken with an included dropper to place a small amount under your tongue. Keep the CBD under your tongue for 30 seconds or so, for better absorption, before swallowing. In terms of dosage amounts, the oil should come with a dropper with mL measurements. To start, take a single mL drop for a single serving of CBD. Again, it's important to start low and go slow when adding CBD to your routine.
For capsules and gummies, simply take the recommended serving (typically 1 or 2) about an hour before bedtime. Some work better when taken with food, so be sure to check the directions on the packaging.
For CBD bath bombs, you simply add one of these to a hot bath as part of your evening routine before bed.
Note that CBD typically works best by building up in your system over time, so it may take up to a month for you to experience the full effects.
The primary side effects associated with CBD are rare and typically mild. These can include, but are not limited to, the following:
- Dry Mouth
Should I Try CBD for Sleep?
There is no denying that we live in stressful times and that many people in the United States are experiencing problems with sleep. However, there is no need to suffer through another night tossing and turning. CBD for insomnia could help you regulate sleep cycles, promote restful sleep, and manage anxiety. Plus, with a number of different CBD products available, you can easily find the right one for your nightly routine.
Keep in mind that since CBD oil is not regulated by the FDA, you must do your due diligence. When considering CBD for sleep in your life, consult with a doctor if you have any existing medical conditions prior to beginning use.
On Thursday, April 22, the world will celebrate Earth Day, the largest non-religious holiday on the globe.
This Earth Day falls at a critical turning point. It is the second Earth Day since the start of the coronavirus pandemic and follows a year of devastating climate disasters, such as the wildfires that scorched California and the hurricanes that battered Central America. But the day's organizers still have hope, and they have chosen a theme to match.
"At the heart of Earth Day's 2021 theme, Restore Our Earth, is optimism, a critically needed sentiment in a world ravaged by both climate change and the pandemic," EarthDay.org president Kathleen Rogers told USA TODAY.
Last Earth Day marked the first time that the holiday was celebrated digitally to prevent the spread of COVID-19. This will largely be the case this year as well.
"Most of our Earth Day events will be virtual with the exception of individual and small group cleanups through our 'Great Global Cleanup' program," EarthDay.org's Olivia Altman told USA TODAY.
Tuesday, April 20: A Global Youth Summit begins at 2:30 p.m. ET featuring young climate activists like Greta Thunberg and Alexandria Villaseñor. This will be followed at 7 p.m. ET by "We Shall Breathe," a virtual summit organized by the Hip Hop Caucus to look at issues like the climate crisis, pollution and the pandemic through an environmental justice lens.
Wednesday, April 22: Beginning at 7 a.m. ET, Education International will lead the "Teach for the Planet: Global Education Summit." Talks will be offered in multiple languages and across multiple time zones to emphasize the importance of education in fighting the climate crisis.
Thursday, April 22: On the day itself, EarthDay.org will host its second ever Earth Day Live digital event beginning at 12 p.m. ET. This event will feature discussions, performances and workshops focusing on the day's theme of restoring our Earth through natural solutions, technological innovations and new ideas.
"EARTHDAY.ORG looks forward to contributing to the success of this historic climate summit and making active progress to Restore Our Earth," Rogers said in a press release. "We must see every country rapidly raise their ambition across all climate issues — and that must include climate education which would lead to a green jobs-ready workforce, a green consumer movement, and an educated and civically engaged citizenry around the world."
EarthDay.org grew out of the first Earth Day in 1970, which drew 20 million U.S. residents to call for greater environmental protections. The movement has been credited with helping to establish the U.S. Environmental Protection Agency and to pass landmark environmental legislation like the Clean Air and Water Acts. It has since gone on to be a banner day for environmental action, such as the signing of the Paris agreement in 2016. More than one billion people in more than 192 countries celebrate Earth Day each year.
This legacy continues. The organization called the scheduling of Biden's summit a "clear acknowledgement of the power of Earth Day."
"This is a critical stepping stone for the U.S. to rejoin the world in combating the climate crisis. In concert with several planned parallel EARTHDAY.ORG events worldwide, Earth Day 2021 will accelerate global action on climate change," EarthDay.org wrote.
Super-emitters are individual sources such as leaking pipelines, landfills or dairy farms that produce a disproportionate amount of planet-warming emissions, especially methane and carbon dioxide. Carbon Mapper, the non-profit leading the effort, hopes to provide a more targeted guide to reducing emissions by launching special satellites that hunt for sources of climate pollution.
"What we've learned is that decision support systems that focus just at the level of nation states, or countries, are necessary but not sufficient. We really need to get down to the scale of individual facilities, and even individual pieces of equipment, if we're going to have an impact across civil society," Riley Duren, Carbon Mapper CEO and University of Arizona researcher, told BBC News. "Super-emitters are often intermittent but they are also disproportionately responsible for the total emissions. That suggests low-hanging fruit, because if you can identify and fix them you can get a big bang for your buck."
The new project, announced Thursday, is a partnership between multiple entities, including Carbon Mapper, the state of California, NASA's Jet Propulsion Laboratory (JPL) and Planet, a company that designs, builds and launches satellites, according to a press release. The project is being implemented in three stages.
The initial stage, which is already complete, involved the initial engineering development. NASA and Planet will work together in the second stage to build two satellites for a 2023 launch. The third phase will launch an entire constellation of satellites starting in 2025.
The satellites will include an imaging spectrometer built by NASA's JPL, NASA explained in a press release. This is a device that can break down visible light into hundreds of colors, providing a unique signature for chemicals such as methane and carbon dioxide. Most imaging spectrometers currently in orbit have larger pixel sizes, making it difficult to locate emission sources that are not always visible from the ground. However, Carbon Mapper spectrometers will have pixels of around 98 square feet, facilitating more detailed pin-pointing.
"This technology enables researchers to identify, study and quantify the strong gas emission sources," JPL Scientist Charles Miller said in the press release.
Once the data is collected, Carbon Mapper will make it available to industry and government actors via an open data portal to help repair leaks.
"These home-grown satellites are a game-changer," California Governor Gavin Newsom said of the project. "They provide California with a powerful, state-of-the-art tool to help us slash emissions of the super-pollutant methane — within our own borders and around the world. That's exactly the kind of dynamic, forward-thinking solution we need now to address the existential crisis of climate change."
By Jenna McGuire
Commonly used herbicides across the U.S. contain highly toxic undisclosed "inert" ingredients that are lethal to bumblebees, according to a new study published Friday in the Journal of Applied Ecology.
The study reviewed several herbicide products and found that most contained glyphosate, an ingredient best recognized from Roundup products and the most widely used herbicide in the U.S. and worldwide.
While the devastating impacts of glyphosate on bee populations are more broadly recognized, the toxicity levels of inert ingredients are less understood because they are not subjected to the same mandatory testing by the U.S. Environmental Protection Agency (EPA).
"Pesticides are manufactured and sold as formulations that contain a mixture of compounds, including one or more active ingredients and, potentially, many inert ingredients," explained the Center for Food Safety in a statement. "The inert ingredients are added to pesticides to aid in mixing and to enhance the products' ability to stick to plant leaves, among other purposes."
The study found that these inert substances can be highly toxic and even block bees' breathing capacity, essentially causing them to drown. While researchers found that some of the combinations of inert ingredients had no negative impacts on the bees, one of the herbicide formulations killed 96% of the bees within 24 hours.
According to the abstract of the study:
Bees exhibited 94% mortality with Roundup® Ready‐To‐Use® and 30% mortality with Roundup® ProActive®, over 24 hr. Weedol® did not cause significant mortality, demonstrating that the active ingredient, glyphosate, is not the cause of the mortality. The 96% mortality caused by Roundup® No Glyphosate supports this conclusion.
"This important new study exposes a fatal flaw in how pesticide products are regulated here in the U.S.," said Jess Tyler, a staff scientist at the Center for Biological Diversity. "Now the question is, will the Biden administration fix this problem, or will it allow the EPA to continue its past practice of ignoring the real-world harms of pesticides?"
According to the Center for Food Safety, there are currently 1,102 registered formulations that contain the active ingredient glyphosate, each with a proprietary mixture of inert ingredients. In 2017, the group filed a legal petition calling for the EPA to force companies to provide safety data on pesticide formulations that include inert ingredients.
"The EPA must begin requiring tests of every pesticide formulation for bee toxicity, divulge the identity of 'secret' formulation additives so scientists can study them, and prohibit application of Roundup herbicides to flowering plants when bees might be present and killed," said Bill Freese, science director at the Center for Food Safety. "Our legal petition gave the EPA a blueprint for acting on this issue of whole formulations. Now they need to take that blueprint and turn it into action, before it's too late for pollinators."
ATTN @EPA: Undisclosed "inert" ingredients in #pesticide products warrant further scrutiny! ➡️ A new study compared… https://t.co/bdFwXCVHsD— Center 4 Food Safety (@Center 4 Food Safety)1618592343.0
Roundup — also linked to cancer in humans — was originally produced by agrochemical giant Monsanto, which was acquired by the German pharmaceutical and biotech company Bayer in 2018.
The merger of the two companies was condemned by environmentalists and food safety groups who warned it would cultivate the greatest purveyor of genetically modified seeds and toxic pesticides in the world.
Reposted with permission from Common Dreams.
By Ayesha Tandon
New research shows that lake "stratification periods" – a seasonal separation of water into layers – will last longer in a warmer climate.
These longer periods of stratification could have "far-reaching implications" for lake ecosystems, the paper says, and can drive toxic algal blooms, fish die-offs and increased methane emissions.
The study, published in Nature Communications, finds that the average seasonal lake stratification period in the northern hemisphere could last almost two weeks longer by the end of the century, even under a low emission scenario. It finds that stratification could last over a month longer if emissions are extremely high.
If stratification periods continue to lengthen, "we can expect catastrophic changes to some lake ecosystems, which may have irreversible impacts on ecological communities," the lead author of the study tells Carbon Brief.
The study also finds that larger lakes will see more notable changes. For example, the North American Great Lakes, which house "irreplaceable biodiversity" and represent some of the world's largest freshwater ecosystems, are already experiencing "rapid changes" in their stratification periods, according to the study.
As temperatures rise in the spring, many lakes begin the process of "stratification." Warm air heats the surface of the lake, heating the top layer of water, which separates out from the cooler layers of water beneath.
The stratified layers do not mix easily and the greater the temperature difference between the layers, the less mixing there is. Lakes generally stratify between spring and autumn, when hot weather maintains the temperature gradient between warm surface water and colder water deeper down.
Dr Richard Woolway from the European Space Agency is the lead author of the paper, which finds that climate change is driving stratification to begin earlier and end later. He tells Carbon Brief that the impacts of stratification are "widespread and extensive," and that longer periods of stratification could have "irreversible impacts" on ecosystems.
For example, Dr Dominic Vachon – a postdoctoral fellow from the Climate Impacts Research Centre at Umea University, who was not involved in the study – explains that stratification can create a "physical barrier" that makes it harder for dissolved gases and particles to move between the layers of water.
This can prevent the oxygen from the surface of the water from sinking deeper into the lake and can lead to "deoxygenation" in the depths of the water, where oxygen levels are lower and respiration becomes more difficult.
Oxygen depletion can have "fatal consequences for living organisms," according to Dr Bertram Boehrer, a researcher at the Helmholtz Centre for Environmental Research, who was not involved in the study.
Lead author Woolway tells Carbon Brief that the decrease in oxygen levels at deeper depths traps fish in the warmer surface waters:
"Fish often migrate to deeper waters during the summer to escape warmer conditions at the surface – for example during a lake heatwave. A decrease in oxygen at depth will mean that fish will have no thermal refuge, as they often can't survive when oxygen concentrations are too low."
This can be very harmful for lake life and can even increase "fish die-off events" the study notes.
However, the impacts of stratification are not limited to fish. The study notes that a shift to earlier stratification in spring can also encourage communities of phytoplankton – a type of algae – to grow sooner, and can put them out of sync with the species that rely on them for food. This is called a "trophic mismatch."
Prof Catherine O'Reilly, a professor of geography, geology and the environment at Illinois State University, who was not involved in the study, adds that longer stratified periods could also "increase the likelihood of harmful algae blooms."
The impact of climate change on lakes also extends beyond ecosystems. Low oxygen levels in lakes can enhance the production of methane, which is "produced in and emitted from lakes at globally significant rates," according to the study.
Woolway explains that higher levels of warming could therefore create a positive climate feedback in lakes, where rising temperatures mean larger planet-warming emissions:
"Low oxygen levels at depth also promotes methane production in lake sediments, which can then be released to the surface either via bubbles or by diffusion, resulting in a positive feedback to climate change."
Onset and Breakup
In the study, the authors determine historical changes in lake stratification periods using long-term observational data from some of the "best-monitored lakes in the world" and daily simulations from a collection of lake models.
They also run simulations of future changes in lake stratification period under three different emission scenarios, to determine how the process could change in the future. The study focuses on lakes in the northern hemisphere.
The figure below shows the average change in lake stratification days between 1900 and 2099, compared to the 1970-1999 average. The plot shows historical measurements (black), and the low emission RCP2.6 (blue), mid emissions RCP6.0 (yellow) and extremely high emissions RCP8.5 (red) scenarios.
Change in lake stratification duration compared to the 1970-1999 average, for historical measurements (black), the low emission RCP2.6 (blue) moderate emissions RCP6.0 (yellow) and extremely high emissions RCP8.5 (red). Credit: Woolway et al (2021).
The plot shows that the average lake stratification period has already lengthened. However, the study adds that some lakes are seeing more significant impacts than others.
For example, Blelham Tarn – the most well-monitored lake in the English Lake District – is now stratifying 24 days earlier and maintaining its stratification for an extra 18 days compared to its 1963-1972 averages, the study finds. Woolway tells Carbon Brief that as a result, the lake is already showing signs of oxygen depletion.
Climate change is increasing average stratification duration in lakes, the findings show, by moving the onset of stratification earlier and pushing the stratification "breakup" later. The table below shows projected changes in the onset, breakup and overall length of lake stratification under different emission scenarios, compared to a 1970-1999 baseline.
The table shows that even under the low emission scenario, the lake stratification period is expected to be 13 days longer by the end of the century. However, in the extremely high emissions scenario, it could be 33 days longer.
The table also shows that stratification onset has changed more significantly than stratification breakup. The reasons why are revealed by looking at the drivers of stratification more closely.
Warmer Weather and Weaker Winds
The timing of stratification onset and breakup in lakes is driven by two main factors – temperature and wind speed.
The impact of temperature on lake stratification is based on the fact that warm water is less dense than cool water, Woolway tells Carbon Brief:
"Warming of the water's surface by increasing air temperature causes the density of water to decrease and likewise results in distinct thermal layers within a lake to form – cooler, denser water settles to the bottom of the lake, while warmer, lighter water forms a layer on top."
This means that, as climate change causes temperatures to rise, lakes will begin to stratify earlier and remain stratified for longer. Lakes in higher altitudes are also likely to see greater changes in stratification, Woolway tells Carbon Brief, because "the prolonging of summer is very apparent in high latitude regions."
The figure below shows the expected increase in stratification duration from lakes in the northern hemisphere under the low (left), mid (center), and high (right) emission scenarios. Deeper colors indicate a larger increase in stratification period.
Expected increase in stratification duration in lakes in the northern hemisphere under the low (left), mid (centre) and high (right) emissions scenarios. Credit: Woolway et al (2021).
The figure shows that the expected impact of climate change on stratification duration becomes more pronounced at more northerly high latitudes.
The second factor is wind speed, Woolway explains:
"Wind speed also affects the timing of stratification onset and breakdown, with stronger winds acting to mix the water column, thus acting against the stratifying effect of increasing air temperature."
According to the study, wind speed is expected to decrease slightly as the planet warms. The authors note that the expected changes in near-surface wind speed are "relatively minor" compared to the likely temperature increase, but they add that it may still cause "substantial" changes in stratification.
The study finds that air temperature is the most important factor behind when a lake will begin to stratify. However, when looking at stratification breakup, it finds that wind speed is a more important driver.
Meanwhile, Vachon says that wind speeds also have implications for methane emissions from lakes. He notes that stratification prevents the methane produced on the bottom of the lake from rising and that, when the stratification period ends, methane is allowed to rise to the surface. However, according to Vachon, the speed of stratification breakup will affect how much methane is released into the atmosphere:
"My work has suggested that the amount of accumulated methane in bottom waters that will be finally emitted is related to how quickly the stratification break-up occurs. For example, a slow and progressive stratification break-up will most likely allow water oxygenation and allow the bacteria to oxidise methane into carbon dioxide. However, a stratification break-up that occurs rapidly – for example after storm events with high wind speed – will allow the accumulated methane to be emitted to the atmosphere more efficiently."
Finally, the study finds that large lakes take longer to stratify in spring and typically remain stratified for longer in the autumn – due to their higher volume of water. For example, the authors highlight the North American Great Lakes, which house "irreplaceable biodiversity" and represent some of the world's largest freshwater ecosystems.
These lakes have been stratifying 3.5 days earlier every decade since 1980, the authors find, and their stratification onset can vary by up to 48 days between some extreme years.
O'Reilly tells Carbon Brief that "it's clear that these changes will be moving lakes into uncharted territory" and adds that the paper "provides a framework for thinking about how much lakes will change under future climate scenarios."
Reposted with permission from Carbon Brief.
By Robert Glennon
Interstate water disputes are as American as apple pie. States often think a neighboring state is using more than its fair share from a river, lake or aquifer that crosses borders.
Currently the U.S. Supreme Court has on its docket a case between Texas, New Mexico and Colorado and another one between Mississippi and Tennessee. The court has already ruled this term on cases pitting Texas against New Mexico and Florida against Georgia.
Climate stresses are raising the stakes. Rising temperatures require farmers to use more water to grow the same amount of crops. Prolonged and severe droughts decrease available supplies. Wildfires are burning hotter and lasting longer. Fires bake the soil, reducing forests' ability to hold water, increasing evaporation from barren land and compromising water supplies.
As a longtime observer of interstate water negotiations, I see a basic problem: In some cases, more water rights exist on paper than as wet water – even before factoring in shortages caused by climate change and other stresses. In my view, states should put at least as much effort into reducing water use as they do into litigation, because there are no guaranteed winners in water lawsuits.
Alabama, pay attention to Supreme Court ruling against Florida in water war #Water #SDG6 https://t.co/wIjdoY6Ccr— Noah J. Sabich (@Noah J. Sabich)1617800452.0
Dry Times in the West
The situation is most urgent in California and the Southwest, which currently face "extreme or exceptional" drought conditions. California's reservoirs are half-empty at the end of the rainy season. The Sierra snowpack sits at 60% of normal. In March 2021, federal and state agencies that oversee California's Central Valley Project and State Water Project – regional water systems that each cover hundreds of miles – issued "remarkably bleak warnings" about cutbacks to farmers' water allocations.
The Colorado River Basin is mired in a drought that began in 2000. Experts disagree as to how long it could last. What's certain is that the "Law of the River" – the body of rules, regulations and laws governing the Colorado River – has allocated more water to the states than the river reliably provides.
The 1922 Colorado River Compact allocated 7.5 million acre-feet (one acre-foot is roughly 325,000 gallons) to California, Nevada and Arizona, and another 7.5 million acre-feet to Utah, Wyoming, Colorado and New Mexico. A treaty with Mexico secured that country 1.5 million acre-feet, for a total of 16.5 million acre-feet. However, estimates based on tree ring analysis have determined that the actual yearly flow of the river over the last 1,200 years is roughly 14.6 million acre-feet.
The inevitable train wreck has not yet happened, for two reasons. First, Lakes Mead and Powell – the two largest reservoirs on the Colorado – can hold a combined 56 million acre-feet, roughly four times the river's annual flow.
But diversions and increased evaporation due to drought are reducing water levels in the reservoirs. As of Dec. 16, 2020, both lakes were less than half full.
Second, the Upper Basin states – Utah, Wyoming, Colorado and New Mexico – have never used their full allotment. Now, however, they want to use more water. Wyoming has several new dams on the drawing board. So does Colorado, which is also planning a new diversion from the headwaters of the Colorado River to Denver and other cities on the Rocky Mountains' east slope.
Utah Stakes a Claim
The most controversial proposal comes from one of the nation's fastest-growing areas: St. George, Utah, home to approximately 90,000 residents and lots of golf courses. St. George has very high water consumption rates and very low water prices. The city is proposing to augment its water supply with a 140-mile pipeline from Lake Powell, which would carry 86,000 acre-feet per year.
Truth be told, that's not a lot of water, and it would not exceed Utah's unused allocation from the Colorado River. But the six other Colorado River Basin states have protested as though St. George were asking for their firstborn child.
In a joint letter dated Sept. 8, 2020, the other states implored the Interior Department to refrain from issuing a final environmental review of the pipeline until all seven states could "reach consensus regarding legal and operational concerns." The letter explicitly threatened a high "probability of multi-year litigation."
Utah blinked. Having earlier insisted on an expedited pipeline review, the state asked federal officials on Sept. 24, 2020 to delay a decision. But Utah has not given up: In March 2021, Gov. Spencer Cox signed a bill creating a Colorado River Authority of Utah, armed with a $9 million legal defense fund, to protect Utah's share of Colorado River water. One observer predicted "huge, huge litigation."
How huge could it be? In 1930, Arizona sued California in an epic battle that did not end until 2006. Arizona prevailed by finally securing a fixed allocation from the water apportioned to California, Nevada and Arizona.
Litigation or Conservation
Before Utah takes the precipitous step of appealing to the Supreme Court under the court's original jurisdiction over disputes between states, it might explore other solutions. Water conservation and reuse make obvious sense in St. George, where per-person water consumption is among the nation's highest.
St. George could emulate its neighbor, Las Vegas, which has paid residents up to $3 per square foot to rip out lawns and replace them with native desert landscaping. In April 2021 Las Vegas went further, asking the Nevada Legislature to outlaw ornamental grass.
The Southern Nevada Water Authority estimates that the Las Vegas metropolitan area has eight square miles of "nonfunctional turf" – grass that no one ever walks on except the person who cuts it. Removing it would reduce the region's water consumption by 15%.
Water rights litigation is fraught with uncertainty. Just ask Florida, which thought it had a strong case that Georgia's water diversions from the Apalachicola-Chattahoochee-Flint River Basin were harming its oyster fishery downstream.
That case extended over 20 years before the U.S. Supreme Court ended the final chapter in April 2021. The court used a procedural rule that places the burden on plaintiffs to provide "clear and convincing evidence." Florida failed to convince the court, and walked away with nothing.
Robert Glennon is a Regents Professor and Morris K. Udall Professor of Law & Public Policy, University of Arizona.
Disclosure statement: Robert Glennon received funding from the National Science Foundation in the 1990s and 2000s.
Reposted with permission from The Conversation.