For the Endangered American Eel,
A Long, Slippery Road to Recovery
The American eel isn’t just a U.S. native. It’s also indigenous to Greenland, Iceland, eastern Canada, and parts of Central and South America. Despite this expansive range, the International Union for Conservation of Nature lists the species as “endangered.”
It would be in even worse shape without the Delaware River, which flows unimpeded 330 miles through New York, Pennsylvania, New Jersey, and Delaware. Few, if any, eel refuges are more important, and management on the Delaware provides a global blueprint for eel recovery. The upper watershed is protected as a Wild and Scenic River corridor and as the water supply for New York City, and last June, New York State banned fracking in its part of the basin. Compare the Delaware with the nearby Susquehanna River, where the Conowingo Dam has wiped out 400 miles of eel habitat on the main river. But here and elsewhere eel recovery is underway.
24 May 2016:
Peru Declares Emergency to
Fight Mercury Pollution from Gold Mines
Peru has declared a 60-day emergency in the Amazon due to widespread mercury pollution from the region’s booming gold mining industry, the country's environment minister announced this week
Several studies have confirmed dangerously high levels of the neurotoxin in waterways, fish, and people living in the Madres de Dios region, near Peru’s southeast border. Members of the Harakmbut indigenous group, for example, have mercury levels in their bodies six times higher than what doctors deem safe
. Mercury is used to separate gold from ore, but it can have serious health impacts
, including damaging brain, kidney, and lung function. In illegal mining operations — which make up the majority of mines in the Peruvian Amazon — workers often handle the substance with bare hands, and dump excess mercury into nearby rivers. During the 60-day emergency period, the government will supply uncontaminated fish to local communities and set up mobile health clinics.
19 May 2016:
Brewing Company Creates
Edible Six-Pack Rings to Save Wildlife
Plastic six-pack rings have long been a nuisance to wildlife and ecosystems, fouling oceans and shorelines, and entangling and choking wildlife.
Now, a brewery in Florida has developed an edible version from the byproducts of making beer
, including wheat and barely. If not eaten by marine creatures, the six-pack ring biodegrades. Saltwater Brewery
3-D printed 500 of the holders in April and plans to scale up production to package all of its 400,000 cans of beer per month in the edible rings. The material is just as strong as traditional plastics, the brewery says, but is more expensive. The price would drop, however, as more companies use the edible rings, the brewery said. “We want to influence the big guys,” Chris Goves, president of Saltwater Brewery, said in a video about the new project. “And hopefully inspire them to get on board.”
25 Apr 2016:
Scientists Discover Antarctic
Lake That Could Contain Unique Life Forms
Scientists have discovered what they think is a massive, ribbon-shaped lake under the Antarctic ice sheet that could lead to the discovery of a bevy of new unique life forms.
The lake, which measures 60 miles long by 6 miles wide, was discovered using satellite imagery, and scientists plan to confirm its existence using ice-penetrating radar this spring. The lake has likely been locked under the ice for millions of years — allowing bacteria and other life forms to evolve in complete isolation from the rest of the world, according to a report released at the European Geosciences Union meeting. Unlike the continent’s largest under-ice lake, Vostok, the newly discovered waterbody — located in East Antarctica — is relatively close to a research station, making it easier to explore. “It’s the last un-researched part of Antarctica, so it’s very exciting news,” Bryn Hubbard of the University of Aberystwyth UK told the New Scientist
22 Apr 2016:
Brazilian Officials Put a
Hold on Mega-Dam Project in the Amazon
A proposed 8,000-megawatt hydroelectric dam in the Amazon was put on hold this week by Brazil’s environmental agency out of concerns over its impact on a local indigenous tribe.
The São Luiz do Tapajós project — which would be Brazil’s second-largest dam and a cornerstone of government efforts to expand hydroelectric power — would require developers to flood an area the size of New York City and home to thousands of Munduruku people. The environmental agency, Ibama, said they were suspending the project’s licensing because of “the infeasibility of the project from the prospective of indigenous issues.” Brent Millikan, the Amazon program director for International Rivers, told Reuters
, "The areas that would have been flooded include sites of important religious and cultural significance. The local communities have a huge amount of knowledge about the resources where they are — if they were forced off the land and into cities they would become unskilled workers."
20 Apr 2016:
Entries Invited for Third
Annual Yale Environment 360 Video Contest
The third annual Yale Environment 360
Video Contest is now accepting entries. The contest honors the year's best environmental videos. Submissions must focus on an environmental issue or theme, have not been widely viewed online, and be a maximum of 15 minutes in length. Videos that are funded by an organization or company and are primarily about that organization or company are not eligible. The first-place winner will receive $2,000, and two runners-up will each receive $500. The winning entries will be posted on Yale Environment 360
. The contest judges will be Yale Environment 360
editor Roger Cohn, New Yorker
writer and e360
contributor Elizabeth Kolbert, and documentary filmmaker Thomas Lennon. Deadline for entries is June 10, 2016. Read More.
12 Apr 2016:
Scientists Reimagine The
Tree of Life With New Microbe Knowledge
Following years of intense exploration and research into the microbial world, scientists have reimagined the tree of life
—the iconic visual representation of the living world first proposed by Charles Darwin in 1859.
The new tree of life.
The project was led by researchers at the University of California, Berkeley, who over the last decade have been gathering DNA from across the globe—from everywhere from meadow soils and river mud to deep sea vents—to reconstruct genomes and describe thousands of new microbial species. Curious how their findings fit into the tree of life, the scientists used a supercomputer
to visualize how more than 3,000 new and known species related to one another. They discovered that eukaryotes, the group that includes humans, exist on a thin twig compared to the microbial branch of the tree. “The tree of life as we know it has dramatically expanded due to new genomic sampling of previously enigmatic or unknown microbial lineages,” the authors wrote
29 Mar 2016:
As U.S. Oil Production Increases,
More Americans At Risk of Man-Made Quakes
As U.S.-based production of oil and gas has boomed over the last decade, millions of gallons of chemical-laden wastewater has been pumped and stored deep underground.
The risk of experiencing an earthquake in 2016.
It turns out, however, that this disposal method—popular for fracking waste—is causing a spike in the number of earthquakes across the country, according to a new set of maps from the U.S. Geological Survey
. Seven million Americans are now at risk from man-made quakes, particularly in Oklahoma, Kansas, Texas, Colorado, New Mexico and Arkansas. "My first thought was actually, ‘Holy crap, Oklahoma is redder than California,’" USGS geologist Susan Hough told The Washington Post
about seeing the maps for the first time. Unlike California, however, most of these states don’t have earthquake-ready structures, experts said, so communities are having to update building codes and purchase new insurance.
In Flint Crisis, A New Model
For Environmental Journalism
Last summer, investigative journalist Curt Guyette found himself knocking on doors of families in Flint, Michigan, carrying not only a pen and notebook, but water-testing kits. Residents had realized there was something wrong with their drinking water but Michigan officials insisted it was safe.
Guyette, the first investigative reporter in the nation hired by an American Civil Liberties Union (ACLU) chapter, broke the story on possible widespread lead contamination in July. He then helped organize door-to-door testing for lead and filed Freedom of Information Act requests in search of the truth. In an interview with Yale Environment 360
, Guyette explains how he chased the story, his unique position as a Ford Foundation-funded journalist employed by ACLU Michigan, and whether this approach to journalism could be a model for rescuing in-depth, local reporting on complex environmental and public health issues.
Read the interview.
07 Mar 2016:
Climate Change Will Threaten Key Crops Across Sub-Saharan Africa
Climate change’s rising temperatures and more frequent and intense droughts could leave parts of sub-Saharan Africa unable to grow staple crops such as maize, bananas, and beans by the end of the century,
A woman holds maize, a staple crop, in Ghana.
according to new research
published Monday in the journal Nature Climate Change. Up to 60 percent of bean-producing areas and 30 percent of maize and banana farms could become unviable by 2100, and farmers should start growing more climate change-resistant crops, improve irrigation systems, or switch to raising livestock, the scientists said. “Agriculture and farming are critical not only for the livelihoods of farmers but also more broadly for the diets of the region’s population,” said
Julián Ramírez-Villegas, a scientist at the International Center for Tropical Agriculture and lead author of the study. “Unless timely adaptation actions are taken, we’re looking at a bleak picture in terms of food security and poverty throughout many areas of sub-Saharan Africa.”
17 Feb 2016:
Reintroduction of Beavers Can Be
Beneficial to the Environment, Study Finds
The reintroduction of beavers to Scotland has proven beneficial to the environment, according to a new study
by researchers at the
Beavers have been reintroduced to Scotland
University of Stirling. Beaver dams increased the retention of organic matter by as much as seven times, and the level of aquatic plant life by 20-fold, researchers said. They also found that the levels of pollutants from agricultural runoff were reduced, with concentrations of phosphorus halved, and nitrate levels lowered by more than 40 percent. “Their dam building skills help restore degraded streams and increase the complexity of the surrounding habitat, increasing the number of species by 28 percent,” lead researcher Nigel Willby said. “The beavers’ engineering is transforming low-quality habitats in regions where the animals have long been absent
15 Feb 2016:
Global Water Shortages Affect
At Least Four Billion People, Study Says
Global water shortages are far worse than previously thought, with at least two-thirds of the world’s population — four billion people — living with severe water scarcity for at least one month every year, according to new research published in the journal Science Advances
. “If you look at environmental problems, [water scarcity] is certainly the top problem,” said Prof Arjen Hoekstra
of the University of Twente in the Netherlands, who led the study. The new research also revealed that 500 million people live in places where water consumption was twice the amount replenished by rain. Hoekstra said that many areas are living on borrowed time, such as Yemen, Pakistan, Iran, Mexico, and Saudi Arabia. Other areas of particular concern include large swaths of Australia and the American Great Plains, which are dependent on the diminishing Ogallala aquifer. These water problems are exacerbated by population growth and raising meat for consumption, which is highly water-intensive, according to the study.
11 Jan 2016:
Scientists Warn of Biodiversity
Impacts of Major Hydropower Projects
Hydropower is considered by many to be a key ingredient to reducing carbon emissions and meeting global climate goals,
The Belo Monte dam under construction in the Amazon
but it comes at a great cost to biodiversity, particularly in tropical rainforests, according to a new report
published in the journal Science
. “Far too often in developing tropical countries, major hydropower projects have been approved and their construction begun before any serious assessments of environmental and socioeconomic impacts had been conducted,” says the report's lead author Kirk Winemiller, an aquatic ecologist at Texas A&M University. The dam-building rush, with more than 450 dams planned for the Amazon, Congo, and Mekong river basins alone, impedes tropical fish migration and vastly expands deforestation due to road construction, according to the authors. Other concerns include development of previously inaccessible terrain, as well as methane emissions from newly built reservoirs.
05 Jan 2016:
NASA Images Show Swelling
Of Mississippi From Massive Flooding
A historic flood has sent the highest water levels ever recorded through the Mississippi River south of St. Louis, toppling records
Satellite image of flooding along the Mississippi River
set during the devastating floods of 1993. The massive surge follows heavy rains that dropped up to 12 inches of water across the region during a three-day period in late December. A NASA satellite
recently acquired this image of flooding along the Mississippi River from January 3rd, which shows floodwaters as blue and vegetation as green. The previous day, the waters caused the highest flood on record at Cape Girardeau, a Missouri town south of St. Louis. The flood water will continue to move southward, National Weather Service forecasters say, cresting in northwestern Tennessee today and in Memphis, Tennessee, by the end of the week. Some researchers
point to modern river management strategies enacted by the U.S. Army Corps of Engineers, such as levees and dams that constrain the river, for exacerbating the effects of the heavy rainfall.
04 Jan 2016:
More Than Half of Power Plants Could be Hampered by Climate Change
More than 60 percent of the world's power plants could be hampered by changes in climate and water distribution by the middle
Canada's Toba Montrose hydroelectric project
of the century, according to a new analysis published in the journal Nature Climate Change
. Hydropower plants and thermoelectric power plants — nuclear, fossil-, and biomass-fueled plants that convert heat to electricity — rely on freshwater from rivers and streams to produce energy and effectively cool equipment. Together, these types of power plants produce 98 percent of the world's electricity, the researchers note. Changes in climate that lead to water shortages and increased water temperatures will affect electricity generation in some regions more than others, says lead researcher Michelle Van Vliet of Wageningen University in the Netherlands. She notes that adaptation measures focused on making power plants more efficient and flexible — such as switching from freshwater cooling to air or seawater cooling — could mitigate the decline.
04 Jan 2016:
More than Half of Power Plants
Could be Hampered by Climate Change
More than 60 percent of the world's power plants could be hampered by changes in climate and water distribution by the middle
Canada's Toba Montrose hydroelectric project
of the century, according to a new analysis published in the journal Nature Climate Change
. Hydropower plants and thermoelectric power plants — nuclear, fossil-, and biomass-fueled plants that convert heat to electricity — rely on freshwater from rivers and streams to produce energy and effectively cool equipment. Together, these types of power plants produce 98 percent of the world's electricity, the researchers note. Changes in climate that lead to water shortages and increased water temperatures will affect electricity generation in some regions more than others — the U.S., southern South America, southern Africa, and parts of Europe are particularly vulnerable, says lead researcher Michelle Van Vliet of Wageningen University in the Netherlands. She notes that adaptation measures focused on making power plants more efficient and flexible — such as switching from freshwater cooling to air or seawater cooling — could mitigate the decline.
18 Dec 2015:
Marshes Likely More Resilient
To Sea Level Rise Than Thought, Study Says
Marshes may be more resilient to climate change and associated rises in sea level than previously thought, according to recent research
An aerial view of Venice showing elevation by color
published in the Proceedings of the National Academy of Sciences.
The study shows that as levels of atmospheric carbon dioxide increase, more CO2 gets taken in by marsh plants. This spurs higher rates of photosynthesis and plant growth, causing marsh plants to trap more sediment above ground and generate more organic soil below ground, the researchers explain. The process can increase the rate of soil accretion nearly enough to allow marshes to keep up with rising sea levels. In fact, the researchers say, it may increase a marsh's threshold for water inundation by up to 60 percent. "Essentially, we found it's a self-rising mechanism marshes use to build themselves up," said Marco Marani, a researcher at Duke University who helped conduct the study.
17 Dec 2015:
Severe Toxic Algal Blooms
Likely To Double in Lake Erie with Warming
The number of severe harmful algal blooms in Lake Erie will likely double over the next century, according to
Sampling lake water during a toxic algal bloom
Ohio State University. As soon as 2050, toxic algal blooms like the one that cut off Toledo's drinking water supply in 2014 will no longer be the exception, but rather the norm, the researchers say. Although several states and Canadian provinces have agreed to significantly cut nutrient runoff into the Great Lakes, the study suggests that nutrient reductions alone might not be enough to stop the toxic blooms. That's because factors associated with climate change — less winter snow, heavier spring rains, and hotter summers — supercharge the blooms, the researchers explain. "Those are perfect growing conditions for algae," said Noel Aloysius, a member of the research team. "We can reduce phosphorus by 40 percent, but the algae won't suffer as much as you might hope."
18 Nov 2015:
Icelandic Ice Cap Gains Mass for
First Time in Two Decades, Researchers Say
An Icelandic ice cap known as Hofsjökull, shown in this NASA satellite image, has gained mass for the first time since 1993,
Iceland's Hofsjökull ice cap
measurements taken last month. All ice caps in Iceland had been retreating rapidly and losing volume since 1995, due to decreasing precipitation and rising temperatures. Hofsjökull’s resurgence this year is the result of abundant winter precipitation and cooler than normal summer temperatures, explained Thorsteinn Thorsteinsson, a glaciologist at the Icelandic Meteorologial Office. Last winter, snowfall in the region of the ice cap was 25 to 60 percent thicker than the 1995-2014 average. Cool northerly winds slowed Hofsjökull’s summer melt rate, contributing to the positive measurements obtained last month.
17 Nov 2015:
New Study Finds Limited and
Uneven Water Reserves Near Earth's Surface
Roughly 5.5 million cubic miles of groundwater are stored in the earth’s crust, according to
new research published in
the journal Nature Geoscience
, but the resource is distributed unevenly across the globe, as shown in this map. Combining data with models on the permeability and porosity of rocks and soils, and on water table gradients, researchers illustrated the depth of groundwater around the world. If earth's groundwater were to cover the planet's surface evenly, the scientists predicted that the pool would be approximately 600 feet deep. However, only six percent of this groundwater is usable for most purposes. This water, which is closer to the surface, is also more sensitive to climate change and human contamination. The research highlights how unevenly this resource is distributed across the globe, scientists say, as well as the need to manage water reserves in a sustainable way.
12 Nov 2015:
Two Billion People at Risk of
Losing Water Supplies Due to Snowpack Loss
Roughly 2 billion people are at risk of declining water supplies in the northern hemisphere due to decreasing snowpack, according to
Snowpack in the Lesser Caucasus mountains.
researchers at Columbia's Lamont-Doherty Earth Observatory
. Researchers identified 97 basins with at least a two-thirds chance of declining water supplies. Nearly 1.45 billion people rely on snowpack in just 32 of those basins for a substantial proportion of their water. Among them are the basins of northern and central California, where much of U.S. produce is grown; the basins of the Colorado and Rio Grande rivers, which serve much of the American West and northern Mexico; the Atlas basin of Morocco; the Ebro-Duero basin, which feeds water to Portugal and much of Spain and southern France; and the volatile Shatt al Arab basin, which channels meltwater from the Zagros Mountains to Iraq, Syria, eastern Turkey, northern Saudi Arabia, and Iran.
30 Oct 2015:
Thousand-Year Storm Event
Leads to Striking Flooding in Death Valley
A system of storms this month caused significant flooding in most of Death Valley National Park in southeastern California. These images,
obtained via a U.S. Geological Survey-NASA satellite
, contrast the region's moisture content in October 2015 and October 2014, which was a year with typical precipitation. The images have been enhanced with false color to highlight water at or near the surface of the earth; green and blue indicate locations with high moisture content. Especially striking is Badwater Basin, the lowest point in North America at an elevation of 279 feet below sea level, which is usually a dry lakebed. In the 2015 image, Badwater Basin is full of water. Flash floods from the so-called "1,000-year" flood event destroyed roads and utilities, and damaged several historical structures, according to the USGS.
29 Oct 2015:
Southeast Asian Nations Plan
Major Hydropower Projects Along Mekong
Although China's hydroelectric
development — particularly the world's largest power plant at Three Gorges Dam — has garnered significant attention,
Hydropower projects planned by smaller Southeast Asian nations
other Southeast Asian nations have relatively large hydropower expansion plans of their own, the U.S. Energy Information Administration
says. Those smaller nations plan to construct 61 gigawatts of new capacity through 2020, primarily along the Mekong River and its tributaries. If all planned projects are completed, these countries will more than double their 2012 hydroelectric capacity. As of 2010, 71 Mekong hydroelectric dams were proposed for completion by 2030. Vietnam has the most ambitious hydroelectric development plan, with 205 hydroelectric projects — 6.2 gigawatts — slated for development by 2017 and nearly 4 gigawatts of additional capacity by 2030. Environmental groups have major concerns
about the environmental impacts of damming the Mekong River system and other rivers in Southeast Asia.
22 Oct 2015:
The Hard-Working Beaver
Is A Fighter Against Nitrogen Pollution
As beaver populations rebound across North America, the ponds they create are proving to be an important factor in removing rapidly
growing levels of nitrogen
A beaver dam in Alaska.
from waterways and estuaries, according to a new study. By creating ponds that slow down the movement of water, the beavers enable nitrogen — which comes from agricultural runoff, septic systems, and other human sources — to seep into soil, where much of it is broken down by bacteria. Reporting in the Journal of Environmental Quality
, researchers at the University of Rhode Island said that beaver ponds can remove up to 45 percent of nitrogen in the water. One scientist said that when they began to consider the widespread presence of beaver ponds, “we realized that the ponds can make a notable difference in the amount of nitrate that flows from our streams to our estuaries.”
09 Oct 2015:
‘Land Grabbing’ Is Accelerating
As Pressure on Agriculture Resources Grows
An area about the size of Japan — roughly 140,000 square miles — has been purchased or
A land-grabbing operation in Uganda
leased by foreign entities for agricultural use during the last 15 years, according to a report
by the Worldwatch Institute. An additional 58,000 square miles are under negotiation, the report found. “Land grabbing,” a term for the purchase or lease of agricultural land by foreign interests, has emerged as a threat to food security in several nations. Globally, over half of this land is in Africa, especially in water-rich countries like the Congo. The largest area acquired in a single country is in Papua New Guinea, with nearly 15,500 square miles (over 8 percent of the nation’s total land cover) sold or leased to foreign entities. Foreign purchase of land in developing countries has surged since 2005 in response to rising food prices and growing biofuel demand in the U.S. and the European Union, as well as droughts in the U.S., Argentina, and Australia. “Essentially no additional suitable [agricultural] land remains in a belt around much of the middle of the planet,” writes Gary Gardner, a contributing author to the report.
01 Oct 2015:
International Space Station
Gives Glimpse of China's Aquaculture Sector
A slew of grid-patterned fish farms line the coast of Liaoning Province in northeast China, as shown in this photograph
Aquaculture in China's Liaoning Province
an astronaut aboard the International Space Station. The aquaculture operations have been built out from the highly agricultural coast to a distance of roughly 4 miles. Liaoning Province ranks sixth in China in terms of aquaculture production, and this group of fish farms, which face the Yellow Sea, is the largest set constructed along the province's coastline. The fish farm basins are built on shallow seabeds, mudflats, and bays. Outer barriers protect the basins from winter storms and large waves generated by passing ships. Most aquaculture products are purchased live in China, with less than 5 percent being killed and processed for selling in local or foreign markets, the U.N. Food and Agriculture Organization (FAO), says. Shellfish, a traditional marine food source, still dominates China's marine production, according to the FAO's Fisheries and Aquaculture Department, accounting for 77 percent of the market.
25 Sep 2015:
‘Pop-up’ Wetlands Will
Help Millions of Migrating Birds This Fall
Birds migrating south from the Arctic this fall will have access to 7,000 new acres of temporary wetland habitat for their California
stopovers, according to
researchers with NASA, The Nature Conservancy, and other academic and conservation organizations. The BirdReturns program creates “pop-up habitats” — temporarily flooded rice fields — for some of the millions of sandpipers, plovers, and other shorebirds that migrate each year from their summer Arctic breeding grounds to winter homes in California, which is in the midst of a severe drought, Mexico, and Central and South America. By combining on-the-ground observations and NASA satellite data, researchers can identify areas where birds flocked during previous migrations. Matching the location and timing of the pop-up wetland habitats with the route and timing of migrating shorebirds is critical, researchers say.
11 Sep 2015:
Flooding Fields in Winter May
Help California Water Woes, Study Suggests
Deliberately flooding California farmland in winter could replenish aquifers without harming crops or affecting drinking water, according to
This flooded alfalfa field is part of the study.
from a study by University of California, Davis, researchers. Winter months, when crops are dormant, typically see more precipitation than summer months, when crops are actively growing and farmers rely on groundwater reserves for irrigation. Several water districts have attempted to sequester excess surface water during storms and floods by diverting it into infiltration basins — confined areas of sandy soil — but those basins are scarce. Instead, researchers suggest that some some 3.6 million acres of farmland could serve a similar purpose — particularly fields of wine grapes, almonds, peaches, and plums — because those lands allow deep percolation with little risk to crops or groundwater quality.
In Northern Canada Peaks, Scientists
Are Tracking Impact of Vanishing Ice
Earlier this month, a team of Canadian scientists braved a cold-weather thunderstorm, snow, rain, and high winds to spend a week working on the last extensive icefield in the interior of the Northwest Territories. Accompanying them was Yale Environment 360
contributor Ed Struzik, who reports on the trip and the importance of the research team’s investigations. The group worked on the Brintnell/Bologna icefield, which has shrunk by more than a third over the last three decades and continues to melt at a rapid clip. The scientists hope to determine how the melting of these glaciers and the loss of snowpack in the surrounding mountains might affect the region’s ecology and rivers, including the huge Mackenzie River, Canada’s largest.
20 Aug 2015:
Global Warming Has Worsened
California Drought By Roughly 25 Percent
Rising temperatures driven by climate change have measurably worsened the California drought by increasing evaporation rates and
A Central Valley orchard stricken by the drought.
exacerbating the state's lack of rainfall by up to 27 percent, according to a study
from Columbia University's Lamont-Doherty Earth Observatory. While natural weather variations are largely thought to have caused the state's precipitation deficit, rising temperatures appear to be intensifying the situation by driving moisture from plants and soil into the air. The new study is the first to estimate how much worse increasing evaporation rates are making the drought: potentially as much as 27 percent, and most likely 15 to 20 percent worse. Scientists expect higher rainfall levels to resume as soon as this winter, but evaporation will more than overpower any increase in precipitation. This means that by around the 2060s, a drought that is essentially permanent will set in, interrupted only by sporadic rainy years.