The lush biodiversity of South America's rainforests is rooted in one of the most cataclysmic events that ever struck Earth.
- One especially mysterious thing about the asteroid impact, which killed the dinosaurs, is how it transformed Earth's tropical rainforests.
- A recent study analyzed ancient fossils collected in modern-day Colombia to determine how tropical rainforests changed after the bolide impact.
- The results highlight how nature is able to recover from cataclysmic events, though it may take millions of years.
About 66 million years ago, a massive asteroid slammed into present-day Chicxulub, Mexico, triggering the extinction of dinosaurs. Scientists estimate the impact killed 75 percent of life on Earth. But what's remained more mysterious is how the event shaped the future of plant life, specifically tropical rainforests.
A new study published in Science explores how the so-called bolide impact at the end of the Cretaceous period paved the way for the evolution of our modern rainforests, the most diverse terrestrial ecosystems on Earth.
For the study, researchers analyzed thousands of samples of fossil pollen, leaves, and spores collected from various sites across Colombia. The researchers analyzed the samples to determine which types of plants were dominant, the diversity of plant life, and how insects interacted with plants.
All samples dated back to the Cretaceous-Paleogene boundary, some 70 million to 56 million years ago. Back then, the region's climate was mostly humid and hot, as it is today. However, the composition and structure of forests were quite different before the impact, according to the study results.
Tropical jungle with river and sun beam and foggy in the gardenSASITHORN via Adobe Stock
For one, the region's rainforests used to have a roughly equal mix of angiosperms (shrubs and flowering trees) and plants like conifers and ferns. The rainforests also had a more open canopy structure, which allowed more light to reach the forest floor and meant that plants faced less competition for light.
What changed after the asteroid hit? The results suggest the impact and its aftermath led to a 45 percent decrease in plant diversity, a loss from which the region took about 6 million years to recover. But different plants came to replace the old ones, with an increasing proportion of flowering plants sprouting up over the millennia.
"A single historical accident changed the ecological and evolutionary trajectory of tropical rainforests," Carlos Jaramillo, study author and paleopalynologist at the Smithsonian Tropical Research Institute in Panama City, told Science News. "The forests that we have today are really the by-product of what happened 66 million years ago."
Today's rainforests are significantly more biodiverse than they were 66 million years ago. One potential reason is that the more densely packed canopy structure of the post-impact era increased competition among plants, "leading to the vertical complexity seen in modern rainforests," the researchers wrote.
The extinction of long-necked, leaf-eating dinosaurs probably helped maintain this closed-canopy structure. Also boosting biodiversity was ash from the impact, which effectively fertilized the soil by adding more phosphorus. This likely benefited flowering plants over the conifers and ferns of the pre-impact era.
In addition to unraveling some of the mysteries about the origins of South America's lush biodiversity, the findings highlight how, even though life finds a way to recover from catastrophe, it can take a long time.
Growing marijuana in large, climate controlled warehouses is good for production but has a massive carbon footprint.
- A new study finds that the kilo of marijuana can come with a carbon footprint of up to five tonnes.
- The exact value differs by state, with climate and the availability of clean energy being important factors.
- Alternatives to growing the plant in warehouses can drastically reduce emissions.
At the time of writing, marijuana is legal in 14 of the United States and decriminalized or permitted for medical purposes in 16 more. Several other territories have taken similar steps as well. After a long and costly drug war, the political and cultural momentum behind decriminalizing marijuana appears to be unstoppable.
However, these legal changes have ramifications for how the plant is tended. While past growing methods focused on balancing the need to keep the plant hidden with botanical concerns, modern techniques are increasingly focused on mastering industrial-scale production within legal limits. Indoor growing is a popular answer for both situations, keeping warrant-less prying eyes away in one case while also allowing for heightened security and climate control in another.
These operations cost a small fortune to maintain the needed apparatus. Since cultivators have come out of hiding and industrialized, the costs involved have only grown. Modern indoor facilities consider the temperature, humidity, and even the composition of the air and how they affect their plants — all of which call for equipment that eats electricity like it has the munchies.
Information on how much pollution these operations were creating has been lacking up until now. A new study published in Nature Sustainability measures the carbon cost of industrial marijuana production in every state and considers ways to make the green stuff a little more green.
The hippies finally got their legal weed at a high cost to the environment? How Faustian!
The study uses a model based on the actual operating procedures of a modern warehouse-style growing system, like the kind used by 41 percent of producers who sell in the legal market.
It accounts for factors like the warehouse's HVAC system, which replaces the air in the room an average of 30 times an hour, the air conditioning, the heating, the humidity control, the lighting, the cost of producing supplemental CO2 to aid plant growth, the costs of the average irrigation system, and other elements of production and distribution. Information for different locations can be plugged in, areas with climates unsuited for growing the plant will incur higher temperature control costs, and the required electricity be calculated.
This information can be compared to the known carbon cost per kilowatt-hour in a given area. The results of feeding different information into this model can be seen on this map:
The carbon price of producing marijuana in a modern warehouse by area in the 50 states and DC.
Credit: Jason Quinn et al.
As certain stereotypes would lead you to suspect, southern California can produce marijuana at the lowest environmental cost, caused both by a reduced need for climate control and the abundance of renewable energy in the local grid. The highest costs were incurred in Hawaii, partly due to the burning of oil to produce power on the islands and the large carbon footprint this creates. Differences across the country can be explained in similar terms, with some areas needing lots of carbon-intensive electricity to produce cannabis and others having cleaner energy or more suitable climates.
Across the country, the price of a kilogram of cannabis flowers, the part which is smoked, ranges from around two to five tonnes of carbon dioxide.
I spoke with several "experts" who agreed that the typical American joint has roughly .3 grams of marijuana in it. Using the above data, we can estimate that your regular smoke requires just over one kilo of greenhouse gases to produce, equivalent to burning an eighth of a gallon of gasoline. For comparison, a single bottle of beer might produce half that, and the footprint of an entire bottle of wine is only slightly higher.
What can be done about these emissions?
The authors point out that most of these environmental costs, perhaps 80 percent, are tied to the methods used to grow the plant indoors and can be reduced by making outdoor cultivation feasible. Such a shift would have noteworthy effects on a state's overall carbon footprint. As the study says:
"If indoor cannabis cultivation were to be fully converted to outdoor production, these preliminary estimates show that the state of Colorado, for example, would see a reduction of more than 1.3% in the state's annual [greenhouse gas] emissions."
Such a switch would reduce the carbon footprint of the plant's production by 96 percent. If the change were instead from warehouses into greenhouses, the cut would be a still substantial 43 percent, and the various benefits of growing the planet inside, such as security, would remain.
Additionally, large variations between indoor operations exist as well, some of which are not fully described in the above map. In Colorado, for example, the carbon cost of growing marijuana in Leadville is 19 percent higher than it is in Pueblo, primarily due to differences in climate. If state regulations allowed cannabis grown in Pueblo to be sold in Leadville, the net carbon emissions would fall even after accounting for transportation. The same might be said for interstate sales, though that seems further off.
In the heady rush to legalize marijuana, the question of how this would impact the environment seems to have slipped past state legislatures, producers, and consumers. General efforts to lower greenhouse gas emissions will have to take the production of a drug that 13 percent of American adults use each year into account.
Their success is based on us adopting a plant-based diet, too.
Natural ecosystems, such as forests, grasslands and oceans, do a pretty good job of storing carbon and supporting biodiversity.
It's therefore no surprise that Nature-based Solutions (NbS) – actions to protect, sustainably manage and restore natural or modified ecosystems, for the benefit of people and nature – are being widely discussed by NGOs, multi-stakeholder platforms and coalitions of countries as "win-win" solutions to the climate and biodiversity crises. But implementing NbS alone is not enough. Their success or failure ultimately depends on the extent to which the world transitions to healthier, more sustainable planet-based diets.
The connection between NbS and dietary patterns comes down to land. Land-use has generally been considered a local environmental issue, but it is becoming a force of global importance and may be the single most pressing environmental issue of our day. Nature-positive farming methods are often promoted as a way to feed humanity while reducing the environmental impact of food production. This includes sequestering more carbon in the soils and above-ground biomass such as trees, supporting biodiversity through wildlife corridors or riparian buffers, and reducing inputs such as nitrogen or pesticides. Yet even these types of NbS will drive an increase in demand for land if trends in food consumption patterns continue.
Food for thought
The OECD-FAO Agricultural Outlook estimates that rising national GDPs will drive an increase in global meat consumption of 12% by 2030, with continued growth until 2050. Such increased demand would nearly double food-related greenhouse gas emissions and preclude any chance of keeping the global temperature increase to no more than 1.5 degrees Celsius. This increase in demand for meat will also continue to drive deforestation in the tropics, with devastating consequences for biodiversity.
We also need land to plant trees – and we need to plant lots of them. Tree planting has been promoted as another important NbS because trees can absorb and store greenhouse gases from the atmosphere, which is critical in our fight against climate change. In several studies, reforestation is offered as the most promising solution for storing carbon, including the potential to store up to 200 gigatonnes (Gt) of carbon – two-thirds of all the carbon released into the atmosphere since the Industrial Revolution – but only if a trillion trees are planted. This sounds great; however, feeding 10 billion people by 2050 requires that we figure out where we can expand the land needed to sequester carbon and reverse biodiversity loss, while guaranteeing food security.
Despite the global call for reforestation, we continue to deforest our planet. Between 2004 and 2017, an area of forest roughly the size of Morocco was lost, primarily in the tropics and sub-tropics. The biggest cause is agricultural expansion, in particular for cattle ranching in areas like the Amazon, Gran Chaco, Cerrado and Eastern Australia. There will only be enough land for reforestation at scale if we halt agricultural expansion and reduce the amount of land currently used to produce food. Again, this is largely dependent on changing what we eat.
A global shift to diets that contain a larger proportion of plant-based foods relative to animal-source foods could release enough agricultural land to sequester 5 Gt to 10 Gt of CO2-equivalent per year if this land was restored to native vegetation. This finding is consistent with several studies, including one that determined that a shift to plant-based diets has the potential to sequester 332 Gt to 574 Gt CO2, an amount equivalent to 99-163% of the CO2 emissions budget consistent with a 55% chance of limiting warming to 1.5 degrees Celsius.
Global carbon sequestration potential for current diets, those recommended by National Dietary Guidelines and others.
No magic fix
There are already many efforts underway to implement NbS. For instance, the Global Future Council on Nature-Based Solutions is building support to "unlock more finance and catalyse meaningful action to enable a nature-positive economy". The WWF Global Grasslands and Savannahs Initiative is elevating the importance of these often overlooked biomes to ensure that the pursuit of NbS and other activities doesn't drive more loss of grassland ecosystems, while the 1t.org initiative aims to plant a trillion trees. These are but a few examples of important global efforts to implement NbS. However, these efforts must also be accompanied with a renewed emphasis on dietary change to ensure a significant reduction in overall demand for land for food production.
There is no magic 'fix' to widespread adoption of healthy and sustainable diets. It requires hard work, political will and resources. There are some lessons, however, that can be drawn from past global transformations.
The first lesson is that no single actor or breakthrough is likely to catalyse systems change. Systems change will require actors at all scales and sectors engaged and working toward a shared set of goals. Secondly, science and evidence-gathering are keys to change, but lack of evidence must not be an excuse to delay action. The third lesson is that the full range of policy levers will be needed. It won't be enough to rely mainly on soft policy approaches, such as education campaigns or behavioural change initiatives. This must also be accompanied by regulatory or fiscal measures to ensure widespread adoption of healthy and sustainable diets.
It has been recently noted that achieving success in the climate crisis is like playing chess and requires 'seeing the whole board'. The same analogy works for the food system. Too often, and by far too many, diets are considered as pawns in the global game of food system transformation – the least significant pieces on the board. But in fact, pawns are the soul of the game and how they are arranged depends whether the game is won or lost.
The same holds true for diets. Without changing what we eat, we can't deliver a thriving future for people and planet. We ignore this strategy at our peril. It's time to realize the power of planet-based diets.
Masks are great, but what happens when we try to throw out a billion masks at once?
- A new study suggests that the huge numbers of disposable masks we're using may end up polluting the environment.
- The materials used to make some of these masks may be especially disposed to break down into microplastic bits.
- Once those plastic bits get into the environment they end up everywhere, including inside people.
The face mask might be the quintessential image of this pandemic. Required attire for almost every activity taking place outside your home, masks are now made by high-end fashion companies in a variety of colors and will likely continue to be worn by many people even after COVID-19 is brought under control.
For those of us who aren't willing to shell out for a Louis Vuitton face mask, cheaper and often disposable options have become the norm. Many of these surgical masks are made of a combination of absorbent fabrics, polyester, and common plastics such as polypropylene or polystyrene.
Despite their life-saving qualities, the incredible consumption of these masks is likely to create a new problem: what to do with the plastics in them as we toss them aside after use. A new study suggests that this might be a bigger problem than we expect.
Remember all that “Nature is healing” stuff from last year? It didn't last long.
Gary Stokes, founder of the environmental group Oceans Asia, poses with discarded face masks he found on a beach in the residential area of Discovery Bay on the outlying Lantau island in Hong Kong.
Credit: ANTHONY WALLACE/AFP via Getty Images
According to recent studies, humanity is going through 129 billion face masks a month, which works out to three million a minute. While we go through a lot of plastics in a month, the number of plastic bottles we use has been estimated at 43 billion a month, a large fraction of those have well-known guidelines around them promoting recycling.
Such information doesn't exist for masks, making it likely that most of them are ending up in the trash.
Like any other object with plastic in it, improper disposal can cause the plastic to enter the environment. Where the tiny bits of plastics spread into water and soil before eventually working their way into animals. The authors of this study, doctors Elvis Genbo Xu of the University of Southern Denmark and Zhiyong Jason Ren of Princeton, argue that the specifications of these masks make them particularly likely to contribute to plastic pollution:
"A newer and bigger concern is that the masks are directly made from microsized plastic fibers (thickness of ~1 to 10 micrometers). When breaking down in the environment, the mask may release more micro-sized plastics, easier and faster than bulk plastics like plastic bags. Such impacts can be worsened by a new-generation mask, nanomasks, which directly use nano-sized plastic fibers (with a diameter smaller than 1 micrometer) and add a new source of nanoplastic pollution."
At the moment, no data on how much masks have contributed to the amount of plastic in the environment exists.
The authors suggest that there are steps to be taken to prevent this problem from getting out of control. They include helping people switch from disposable plastic masks to reusable cloth ones, inventing biodegradable masks, designating special disposal areas for masks, and standardizing waste processing procedures concerning these plastics.
Why should we care?
Plastic pollution is pretty terrible for the environment. Animals can confuse small bits of plastic for food, consuming it instead of something nourishing and starving to death as their stomachs fill. The chemicals in plastics can also cause various ailments if consumed, even if the amount eaten isn't enough to kill the animal.
Before you say that you don't care about fish, birds, or any other kind of wildlife, remember that studies are finding ever-increasing amounts of plastic in people, too. Many of the chemicals in these plastics are associated with health risks, including cardiovascular diseases and cancer.
The benefits of face masks are beyond debate, but the side effects of throwing out so many disposable masks may prove to be quite terrible if we're not careful.
A reversal in Earth's magnetic field 42,000 years ago triggered climate catastrophes and mass extinctions. Can the field flip again?
About 42,000 years ago, Earth's magnetic field broke down temporarily, according to a new study. This lead to environmental cataclysms and mass extinctions, including the demise of the Neanderthals. The dramatic period was a turning point in Earth's history, claim the scientists, full of resplendent auroras, electrical storms, and strong cosmic radiation. These changes were caused by the reversal of the planet's magnetic poles and variations in solar winds.
Amusingly, the researchers behind the international study (which involved scientists from Australia, New Zealand, Switzerland, the U.K., Germany, U.S., Argentina, China, and Russia) called this period the "Adams Transitional Geomagnetic Event' or simply "Adams Event." The Adams they are referring to is the science fiction writer Douglas Adams, who famously wrote in "The Hitchhiker's Guide to the Galaxy" that 42 was the answer to "the Ultimate Question of Life, the Universe, and Everything."
Chris Turney, a professor at UNSW Sydney and co-leader of the study, remarked that their study was the first "to precisely date the timing and environmental impacts of the last magnetic pole switch."
Interestingly, their discovery was aided by ancient New Zealand kauri trees, which have been sitting preserved in sediments for more than 40,000 years.
"Using the ancient trees we could measure, and date, the spike in atmospheric radiocarbon levels caused by the collapse of Earth's magnetic field," said Turney.
What the trees helped the scientists understand were the effects of the magnetic pole switch, which was already known as "The Laschamps Excursion." Using radiocarbon dating to analyze the kauri tree rings, they could gauge how the planet's atmosphere changed.
Paleopocalypse! - Narrated by Stephen Fry.
The study's co-lead Professor Alan Cooper, Honorary Researcher at the South Australian Museum, highlighted the significance of the ancient trees to their work.
"The kauri trees are like the Rosetta Stone, helping us tie together records of environmental change in caves, ice cores and peat bogs around the world," explained Cooper.
Using the trees, the researchers were able to create global climate models that showed how the growth of ice sheets and glaciers across North America, differences in wind belts and tropical systems, and even the extinction of Neanderthals could all be linked to the climate changes brought on by the Adams Event.
"Earth's magnetic field dropped to only 0-6 per cent strength during the Adams Event," pointed out Professor Turney. "We essentially had no magnetic field at all – our cosmic radiation shield was totally gone."
According to the researchers, another fascinating consequence of the Adams Event is that early humans would have been both inspired and terrified by the amazing auroras seen in the sky, brought on by the magnetic field fluctuations. "It must have seemed like the end of days," said Cooper.
He also supposes that the calamities would have forced our ancestors into the caves, leading to the amazing cave art that came about approximately 42,000 years ago.
Could such a magnetic pole reversal happen today? Professor Cooper thinks there are some indications like the weakening of the field by 9 percent over the past 170 years that tells us a reversal may be coming.
"If a similar event happened today, the consequences would be huge for modern society," shared Cooper. "Incoming cosmic radiation would destroy our electric power grids and satellite networks."
Check out the study published in Science.