thaw

Self-healing concrete

June 25, 2025 By EarthWise Leave a Comment

Concrete is the most widely used building material on Earth. It has a dangerous and costly flaw: it cracks easily. Cracks in concrete can lead to inconvenient damage or to catastrophic structural failures such as collapses of buildings, bridges, or highways.

Concrete is made by mixing crushed stone and sand with powdered clay and limestone and adding water. The mixture hardens and once set becomes extremely strong. However, natural forces like freeze-thaw cycles, drying shrinkage, and heavy loads can cause cracks. Even very tiny cracks can allow liquids and gases to seep into embedded steel reinforcements causing corrosion and weakness.

For over 30 years, researchers have investigated microbe-mediated self-healing concrete. It involves introducing microbial healing agents into cracks and injecting nutrients for the healing agents to produce repair materials. It is not a very practical solution.

Researchers at Texas A&M University have developed a technique inspired by the behavior of lichen systems. Their system, like lichen, uses a combination of cyanobacteria which turns air and sunlight into food, and filamentous fungi, which produces minerals that seal the cracks.

In lab tests, the paired microbes were able to grow and produce crack-filling minerals even in challenging environments such as concrete. If it is possible to produce concrete that can heal itself, it would significantly reduce maintenance costs, extend its longevity, and even protect lives through increased safety.

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Cracking the Code: Deciphering How Concrete Can Heal Itself

Photo, posted May 21, 2009, courtesy of DesignMag via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Methane From Thawing Permafrost | Earth Wise

June 29, 2022 By EarthWise Leave a Comment

The Arctic permafrost contains a massive amount of carbon in the form of frozen soil, which contains remnants of plants and animals that died millennia ago. Estimates are that there is 2 ½ times as much carbon trapped in this Arctic soil than there is in total in the atmosphere today.

As the Arctic warms, the permafrost is starting to thaw. Once that happens, microbes begin to consume the previously frozen organic matter trapped in the soil. As part of this process, the microbes produce large amounts of methane, which is an extremely potent greenhouse gas. Thus, there continues to be great concern that wide-scale thawing of the permafrost would result in massive amounts of methane being released into the atmosphere.

A recent study in northern Sweden revealed a glimmer of hope. The study gauged methane emissions from a swath of permafrost that thawed in the 1980s and another that thawed 10 or 15 years later.

In the first area, as ice melted underground, water on the surface sank down into the soil. As the surface dried out, new plants emerged that helped to keep methane emissions buried underground.

Grasses found in wet areas have straw-like structures that convey oxygen to their roots. The straws also allow methane in the soil to escape into the atmosphere. As the areas dry out, other plants lacking the straws can sometimes replace the grasses. When methane can’t escape, soil bacteria break it down into carbon dioxide.

The result is that the permafrost releases only a tenth of the methane as expected. The hope is that changes in plant cover driven by climate change may limit methane emissions from thawing permafrost.

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Thawing Permafrost In Sweden Releases Less Methane Than Feared, Study Finds

Photo, posted July 7, 2014, courtesy of NPS Climate Change Response via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Permafrost Thaw | Earth Wise

March 18, 2022 By EarthWise Leave a Comment

We’ve talked about permafrost before. It is the frozen soil, rock, or sediment piled up in the Arctic that has been there at least for two years but, for the most part, for millennia or even over a million years. Permafrost holds the carbon-filled remains of vegetation and animals that froze before they could start decomposing. Estimates are that there are nearly 2,000 billion tons of carbon trapped in Arctic permafrost. To put that in perspective, annual global carbon emissions are less than 40 billion tons.

Keeping all that carbon frozen plays a critical role in preventing the planet from rapidly heating. The ongoing warming of the Arctic is causing the subsurface ground to thaw and release long-held carbon to the atmosphere.

Scientists from Europe and the US are working together to better track permafrost carbon dynamics. They are trying to understand the mechanisms that lead to abrupt thaws in the permafrost that have taken place in some locations. These rapid thawing events are not well understood. Researchers are also studying the effects of the increasingly frequent wildfires in the Arctic on the permafrost.

Researchers are using satellites to better understand the effects climate change is having on the Arctic environment and how these changes, in turn, are adding to the climate crisis. Permafrost cannot be directly observed from space, so that its presence has to be inferred from measurements like land-surface temperature and soil moisture readings. Terrestrial observations are also necessary for understanding how greenhouse gases – both CO2 and methane – are being emitted from the Arctic.

Thawing permafrost is a ticking timebomb for the environment that demands the growing attention of the scientific community.

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Permafrost thaw: it’s complicated

Photo, posted January 24, 2014, courtesy of Brandt Meixell / USGS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Arctic Communities And Permafrost Thaw | Earth Wise

December 16, 2021 By EarthWise Leave a Comment

Permafrost is frozen soil, rock or sediment that can be as much as a few thousand feet thick. To qualify as permafrost , the material has to have been at or below the freezing point of water for two or more years. Most of it is located in high latitudes in the Arctic and Antarctic regions. Permafrost covers nearly a quarter of the exposed land in the Northern Hemisphere.

Permafrost contains enormous amounts of carbon in the form of frozen soil that includes remnants of plants and animals, in some cases that have been there for more than 20,000 years.

The Arctic region has been warming faster than any place else on earth and thawing permafrost is already unleashing methane and carbon dioxide to the atmosphere, adding to the global temperature rise.

Apart from the impact on the global climate, thawing permafrost is making the ground unstable and is causing serious problems for local communities.

Recent research using satellite observations provides an overview of the Arctic to identify communities and infrastructure that will be at risk over the next 30 years.

Using high-resolution data from the Copernicus Sentinel satellite missions along with ground-based data going back to 1997, researchers modeled the permafrost ground temperature trends and extrapolated them out to 2050. The results were that 55% of the infrastructure currently located on permafrost and within 60 miles of the Arctic coastline – infrastructure on which many communities rely – is likely to be affected.

Most human activity in the Arctic takes place along permafrost coasts. Permafrost thaw is exposing these coasts to rapid change that threatens biodiversity and puts pressure on communities.

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Satellites pinpoint communities at risk of permafrost thaw

Photo, posted January 24, 2014, courtesy of Brandt Meixell / USGS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Alaska Is Getting Wetter | Earth Wise

August 31, 2020 By EarthWise Leave a Comment

Siberia has been in the news for record-setting heat waves and wildfires, but it is not the only northern region experiencing unusual weather. Alaska, apart from setting its own warm weather records, is experiencing the rainiest five years in its century-long meteorological record.

Extreme weather in the Arctic is being driven by an aspect of climate change called Arctic amplification, which leads to temperatures rising faster than the global average. The physical basis of Arctic amplification is well understood, but its effects over time are much less predictable.

The past five years included two summers with average precipitation, one that was a little drier than usual, and two of the wettest summers on record. Researchers have taken measurements of how far below the surface permafrost has thawed by the end of summer over a wide range of Alaskan environments.

About 85% of Alaska sits upon permafrost and the increasing rainfall over the past five years is leading to a deeper thaw of permafrost across the state. The wettest summer on record was 2014 and permafrost didn’t freeze back to previous levels even when the next couple of summers were relatively drier.

The study demonstrated how different types of land cover govern relationships between summer rainfall and permafrost thaw. As Alaska becomes warmer and wetter, the vegetation cover is projected to change, and the increasing occurrence of wildfires will disturb larger areas of the landscape. These conditions are likely to lead to a feedback loop driving more and more permafrost thawing.

Fundamental changes to Alaskan ecosystems are occurring on an unprecedented timescale – not gradually over decades or lifetimes, but over mere months or years.

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Alaska is getting wetter. That’s bad news for permafrost and the climate.

Photo, posted June 10, 2011, courtesy of Peter Rintels via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Saving The Arctic Permafrost | Earth Wise

April 17, 2020 By EarthWise Leave a Comment

Permafrost is frozen ground – a combination of soil, rock, sand, and ice – that remains at or below freezing for at least two consecutive years. Approximately 25% of the land in the Northern Hemisphere meets this criterion, the majority of which can be found in northern Russia, Canada, Alaska, Iceland, and Scandinavia.

But as a result of the changing climate, these permafrost soils in the Arctic are beginning to thaw. As they thaw, large quantities of greenhouse gases could be released, further accelerating climate change.

A new study recently published in the journal Scientific Reports explores an unconventional countermeasure: resettling massive herds of large herbivores. According to researchers from the University of Hamburg in Germany, herds of horses, bison, and reindeer could be used to significantly slow the loss of permafrost soils.

During Arctic winters, the air temperature is often much colder than the permafrost. Thick layers of snow can insulate the ground from the frigid air, keeping the permafrost warm (relatively speaking). But when the snow cover is scattered and compressed by the hooves of grazing animals, the insulating effect is reduced, which intensifies the freezing of the permafrost.

If climate change continues unchecked, the research team expects permafrost temperatures to rise 3.8-degrees Celsius. This would result in half of the world’s permafrost thawing by the year 2100. But in contrast, researchers found that the permafrost would only warm by 2.1 degrees Celsius with the resettled animals. This 44% reduction in permafrost temperature would preserve 80% of the existing permafrost by 2100.

Natural manipulations of ecosystems could have tremendous results.

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How horses can save the permafrost

Photo, posted July 17, 2012, courtesy of Kitty Terwolbeck via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Maple Syrup And Climate Change

October 11, 2019 By EarthWise Leave a Comment

According to a study recently published in the journal Forest Ecology and Management, scientists are predicting another casualty of climate change: the U.S. maple industry. By the year 2100, the maple syrup season in the United States may be less productive and arrive one month earlier than it has between 1950 and 2017.

Maple syrup production is impacted by two climate-sensitive factors: sugar content and sap flow. Sugar content is determined by the previous year’s carbohydrate stores. Sap flow depends on the freeze/thaw cycle. Sap begins to flow in sugar maples when winter nights dip below freezing and the days warm above freezing.

The researchers studied six sugar maple stands from Virginia to Quebec, Canada over a six year period. They created a model that predicted the timing of optimal sap flow based on historical temperature data on freeze/thaw days, actual sap collection from their field work, and monthly climate.

According to modeling projections, the maple syrup season is expected to be, on average, one month earlier by the end of the century. States like Indiana and Virginia will barely produce any sap. New Hampshire and Vermont are likely to be least affected, but are still expected to experience a decrease in production. In fact, most areas of maple production in the United States are projected to see decreases in production by the year 2100, while areas in northern Ontario and Quebec should see moderate to large increases in production.

Currently, Canada is responsible for approximately 80% of global maple syrup production while the U.S. produces 20%. The shifting climate for optimal maple production will leave many scrambling to find the sweet spot.

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Climate change study finds that maple syrup season may come earlier

Photo, posted March 24, 2019, courtesy of Paul VanDerWerf via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Carbon From The Alaskan Tundra

June 15, 2017 By EarthWise

The soils that encircle the northern reaches of the Arctic are a vast repository for carbon in the form of undecayed organic matter from dead vegetation. The enormous amount of material trapped in the permafrost contains enough carbon to double the current amount of carbon dioxide in the Earth’s atmosphere.