water vapor

Wrong trees in the wrong places

January 20, 2025 By EarthWise Leave a Comment

Temperatures in cities are rising around the world and urban heat stress is already a major problem. Extensive surfaces of man-made materials absorb the sun’s energy, and lead to temperatures well above those in the surrounding countryside. This is known as the urban heat island effect, and it can lead to greater energy use, higher air pollution levels, and a greater risk of heat-related illnesses, as well as death.

Some cities have already started implementing mitigation strategies, with tree planting prominent among them. Planting trees can cool the climate by absorbing carbon dioxide, providing shade, and releasing water vapor, which lowers air and surface temperatures.

However, while trees can cool cities significantly during the day, new research from the University of Cambridge in the U.K. shows that tree canopies can also trap heat and raise temperatures at night.

According to the study, which was recently published in the journal Communications Earth & Environment, planting the wrong species or the wrong combination of trees in suboptimal locations or arrangements can limit their benefits.

The researchers found that in temperate climates, trees can cool cities by up to 6°C during the day but can increase nighttime temperatures by 1.5°C. Cities with open layouts in temperate and tropical climates benefit from a mix of evergreen and deciduous trees, enhancing cooling by 0.5°C more than in cities with only deciduous or evergreen trees.

The researchers hope their findings will help urban planners choose the best combinations of trees and planting locations to combat urban heat stress.

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Wrong trees in the wrong place can make cities hotter at night, study reveals

Photo, posted October 29, 2017, courtesy of Lars Plougmann via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Fertilizer from thin air

January 16, 2025 By EarthWise Leave a Comment

Ammonia is one of the largest-volume synthetic chemicals produced in the world. Globally, manufacturing plants produce about 200 million tons of it each year. About 70% of ammonia is used to produce fertilizers.

Most ammonia is produced using the Haber-Bosch process, which converts hydrogen and nitrogen into ammonia. The process is energy-hungry, running at over 900 degrees Fahrenheit, and therefore results in lots of greenhouse gas emissions – about 1% of the world’s annual CO2 emissions.

Researchers at Stanford University and King Fahd University in Saudi Arabia have developed a prototype device that can produce ammonia using wind energy to draw air through a mesh. The method allows sustainable production of ammonia using the nitrogen in the air.

The process gets nitrogen from the air along with hydrogen from water vapor. A mesh coated with catalysts facilitates the necessary chemical reactions. The process operates at room temperature and standard atmospheric pressure, eliminating the need for the high temperatures and high pressures of the Haber-Bosch process.

In principle, farmers could run a portable device onsite, eliminating the need to purchase and ship fertilizer from a manufacturer.

The device is two or three years away from being market ready. The developers are designing increasingly large mesh systems to produce greater quantities of ammonia. Ammonia has more uses beyond fertilizers including its use as an energy carrier that can store and transport energy more efficiently than hydrogen gas.

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New device produces critical fertilizer ingredient from thin air, cutting carbon emissions

Photo, posted September 2, 2013, courtesy of Chafer Machinery via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Planting trees in Europe

January 7, 2025 By EarthWise Leave a Comment

Planting lots of trees is one of many strategies being pursued to combat climate change. Trees are storehouses of carbon from the atmosphere and planting more of them helps remove carbon dioxide. But trees do more than that. Trees are natural air conditioners in cities.

Trees significantly cool urban environments by providing shade and via a process called evapotranspiration by which they release water vapor into the air, which provides cooling. This helps mitigate the urban heat island effect. Areas under trees in cities can be as much as 25 degrees cooler than in unshaded areas covered in asphalt.

The city of Paris has laid out a plan to help the city prepare for increasing amounts of extreme heat. The goal is to replace 60,000 parking spaces across the city with trees by the end of this decade. The plan to rip up parking spaces is part of a greater aim to create more than 700 acres of green space by 2030. The Paris plan also includes creating more car-free zones and installing reflective roofs on 1,000 public buildings. Nearly 80% of the buildings in Paris have zinc roofs – an affordable, corrosion-resistant and pretty much inflammable innovation of the 19th century. However, these roofs can heat up to 194 degrees on a summer day, transferring heat into largely uninsulated top-floor garrets below.

Elsewhere in Europe, Danish lawmakers have agreed on a plan to rewild 10% of the country’s farmland and plant one billion trees. According to the Danish government, this plan would bring about the biggest change to the Danish landscape in over 100 years.

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To Cope with Extreme Heat, Paris Will Swap Parking Spaces for Trees

Photo, posted April 11, 2014, courtesy of Val H. via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Harvesting Water From The Air | Earth Wise

August 11, 2023 By EarthWise Leave a Comment

Engineers at MIT have created a superabsorbent material that can soak up significant amounts of moisture from the air, even in desert-like conditions.

The material is a transparent, rubbery substance made from hydrogel, which is a naturally absorbent material that is already widely used in disposable diapers. The MIT researchers enhanced the absorbency of hydrogel by infusing it with lithium chloride, which is a type of salt that is a powerful desiccant.

They found that they could infuse hydrogel with more salt than was possible in previous studies. Earlier studies soaked hydrogels in salty water and waited 24 to 48 hours for the salt to infuse into the gels. Not much salt ended up in the gels and the material’s ability to absorb water vapor didn’t change much. In contrast, the MIT researchers let the hydrogels soak up the salt for 30 days and found that far more salt was absorbed into the gel. The result was that the salt-laden gel could then absorb and retain unprecedented amounts of moisture, even under very dry conditions.

Under very dry conditions of 30% relative humidity, the gels captured 1.79 grams of water per gram of material. Deserts at night have those levels of relative humidity, so the material is capable of generating water in the desert.

The new material can be made quickly and at large scale. It could be used as a passive water harvester, particularly in desert and drought-prone regions. It could continuously absorb water vapor from the air which could then be condensed into drinking water. The material could also be used in air conditioners as an energy-saving, dehumidifying element.

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This salty gel could harvest water from desert air

Photo, posted July 26, 2021, courtesy of Ivan Radic via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

California Flooding | Earth Wise

February 2, 2023 By EarthWise Leave a Comment

Starting in December, a series of “atmospheric rivers” brought record storms to California producing as much rain in three weeks in some areas as they normally have in an entire year. The historic levels of rain (and snow in the mountains) have swollen rivers, flooded roads and homes, forced evacuations, knocked out electric power for millions of people, and resulted in more than 20 deaths.

Atmospheric rivers are air currents that carry large amounts of water vapor through the sky. They are not unusual for California but recurrent waves of them like those that have happened recently are very infrequent. Studies by the U.S. Geological Survey have shown that such a phenomenon recurs in California every 250 years. There were a series of storms causing disastrous floods in California in 1861-62.

The atmospheric rivers are born in the warm waters of the tropical Pacific. During La Nina phases, the atmospheric rivers typically make landfall on the northern West Coast. During El Nino phases, atmospheric rivers are more likely to end up in Southern and Central California. During transitions between the phases, as is happening now, the storms can cover large parts of the state.

Modern forecasting is pretty good at predicting the forthcoming occurrence of these storms and has led to some helpful actions, such as reservoir operators preventing dams from overflowing or bursting. But there is a gap between science and decision-making. It is pretty clear what needs to be done when tornados or hurricanes are on the way. It is less clear what actions are appropriate when there are going to be repeated heavy rainstorms.

These storms will have an effect on California’s megadrought, but just how much of an effect remains to be seen.

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Flooding in California: What Went Wrong, and What Comes Next

Photo, posted January 5, 2023, courtesy of Sarah Stierch via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Harvesting Fresh Water From Ocean Air | Earth Wise

January 19, 2023 By EarthWise Leave a Comment

Roughly three-quarters of the world population has access to a safely managed water source. That means that one-in-four people do not have access to safe drinking water. Even in the wealthy United States, persistent drought in the west is creating problems in places like Phoenix, Arizona.

Water is plentiful on Earth but more than 99% of it is unusable by humans and many other living things because it is saline, frozen, or inaccessible. Only about 0.3% of our fresh water is found in the surface water of lakes, rivers, and swamps.

There is an almost limitless supply of fresh water in the form of water vapor above the oceans, but this source is untapped. Researchers at the University of Illinois have been evaluating the feasibility of a hypothetical structure capable of capturing water vapor from above the ocean and condensing it into fresh water.

Existing ways to obtain fresh water like wastewater recycling, cloud seeding, and desalination have met only limited success and present various problems with regard to cost, environmental impact, and scalability.

The researchers have proposed hypothetical large offshore structures measuring 700 feet by 300 feet to capture water vapor that is continually evaporating from the ocean in subtropical regions. Their modeling concluded that such structures could provide fresh water for large population centers in the subtropics. Furthermore, climate projections show that the amount of water vapor over the oceans will only increase over time, providing even more fresh water supply.

This is only a theoretical study at this point, but the researchers believe it opens the door for novel infrastructure investments that could address global water scarcity.

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Researchers propose new structures to harvest untapped source of fresh water

Photo, posted June 28, 2009, courtesy of Nicolas Raymond via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Alaskan Icemageddon | Earth Wise

January 25, 2022 By EarthWise 1 Comment

December saw some wild weather in Alaska. A combination of record high temperatures and torrential rainstorms resulted in the coining of the term “Icemageddon” to describe what was going on with the weather.

Kodiak Island in southern Alaska saw a high temperature of 67 degrees on December 26, which was warmer than it was in Southern California that same day. This set an all-time record for the warmest December day in Alaska. Such a high temperature is amazing considering how little sunlight Alaska gets at this time of year. And with warmer air comes wetter air, as the atmosphere is capable of holding more water vapor as temperatures increase.

As a result, that same day saw the interior of the state get an inch of rain in just a few hours, something that hadn’t happened for decades. But then, when temperatures plummeted again, all that rainwater froze.

Huge sheets of ice blocked roads and choked traffic in Fairbanks, Alaska’s second largest city. Indeed, it was the state’s transportation department that came up with the term icemageddon to describe the situation.

The extreme warmth in December is related to the same weather pattern that brought cold, wintry weather to the Pacific Northwest and Northern California. Those weather conditions resulted in hundreds of cancelled flights in Seattle, where temperatures dropped into the 20s, and in massive amounts of snowfall in the Sierra Nevada mountains in California. A strong area of high pressure anchored in the Northern Pacific resulted in a clockwise flow around it drawing warmer, more tropical air from the Pacific up to Alaska.

Climate change continues to push the envelope on what sort of weather is possible all over the world.

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Alaska faces ‘Icemageddon’ as temperatures swing wildly

Photo, posted April 30, 2015, courtesy of Naql via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Saving Water At Power Plants | Earth Wise

September 21, 2021 By EarthWise Leave a Comment

Nearly 40% of all the water taken from lakes, rivers, and wells in the U.S. isn’t used for agriculture, drinking, or sanitation. It is used to cool power plants that produce electricity by burning fossil fuels or with nuclear reactors. Two-thirds of these power plants use evaporative cooling, which produces huge white plumes billowing from cooling towers.

A new company using technology developed at MIT has the goal of reducing the water needs of power plants and helping to alleviate water shortages in areas where power plants strain the capacity of local water systems.

The technology is relatively simple in principle but developing it to the point where it can be applied at full scale at industrial power plants was a greater challenge.

The basic idea is to capture water droplets from both natural fog and from the plumes from power plant cooling towers. The MIT researchers had to improve the efficiency of fog-harvesting systems, which previously captured only 1-3% of the water droplets that pass through them. They found that water vapor collection could be made much more efficient by zapping the tiny droplets of water with an ion beam, giving them a slight electric charge, thereby making it easy to capture them with the metal mesh of the harvesting system.

The system can essentially eliminate cooling tower plumes and produce large quantities of high-purity water in the process, which has uses at many power plants. The new company, called Infinite Cooling, has arranged to install their equipment on two operating commercial power plants later this year. They expect the system to reduce the overall need for water by 20%.

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Vapor-collection technology saves water while clearing the air

Photo, posted March 5, 2019, courtesy of Sam LaRussa via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Clouds And Global Warming | Earth Wise

March 9, 2020 By EarthWise Leave a Comment

Recent climate models from multiple organizations project that the amount of warming that doubling atmospheric carbon dioxide would cause would be much more than previously estimated. And one of the significant changes to the models relates to the role of clouds.

Clouds have long been a major uncertainty in climate calculations. Clouds can shade the earth and thereby provide cooling. But clouds can also trap heat. Which effect dominates depends on how reflective the clouds are, how high up they are, and whether it is day or night. The dynamics of clouds are complicated.

If you fly across the ocean, you will see blankets of low clouds extending for hundreds of miles. These marine stratus and stratocumulus clouds predominantly cool the Earth. In fact, they shade roughly a fifth of the oceans and reflect 30-60% of the solar radiation that hits them back into space.

Recent studies indicate that as global temperatures rise, these clouds are likely to become thinner or burn off entirely, leaving more clear skies through which the sun may add another degree Celsius or more to global warming.

The concerns about clouds are part of the larger issue about feedbacks in warming the world. It has long been clear that the greenhouse effect of doubling CO2 levels in the atmosphere would raise global temperature. But there are amplifying feedback effects. Melting large areas of snow and ice reduces reflectivity and allows the land and oceans to absorb more heat. More water vapor entering the atmosphere traps more heat. And now clouds are another concern.

Overall, these effects are leading to climate models predicting much larger global temperature increases, which is a scary prospect for the world.

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Why Clouds Are the Key to New Troubling Projections on Warming

Photo, posted September 10, 2006, courtesy of Nicholas A. Tonelli via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And Hurricanes

October 4, 2017 By EarthWise Leave a Comment

No single weather event can be attributed to climate change. Storms, floods and droughts have always happened and some of them have always been severe. However, two centuries of people burning fossil fuels has altered temperatures just enough that some of the storms we have seen in recent times have been much worse than they otherwise would have been.