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Wind Farms Slowing Each Other Down | Earth Wise

July 13, 2021 By EarthWise Leave a Comment

Offshore wind is booming in Europe. The expansion of wind energy in the German Bight and Baltic Sea has been especially dramatic. At this point, there are about 8 gigawatts of wind turbines in German waters, the equivalent of about 8 nuclear power plants. But space in this region is limited so that wind farms are sometimes built very close to one another.

A team of researchers from the Helmholtz Center Hereon, a major German research institute, has found that wind speeds downstream from large windfarms are significantly slowed down. In a study published in the journal Nature Scientific Reports, they found that this braking effect can result in astonishingly large-scale lowering of wind speeds.

On average, the regions of lowered wind can extend 20-30 miles and, under certain weather conditions, can even extend up to 60 miles. As a result, the output of a neighboring wind farm located within this distance can be reduced by 20 to 25 percent.

These wake effects are weather dependent. During stable weather conditions, which are typically the case in the spring in German waters, the effects can be especially large. During stormy times, such as in November and December, the atmosphere is so mixed that the wind farm wake effects are relatively small.

Based on their modeling, it is clear that if wind farms are planned to be located close together, these wake effects need to be taken into account. The researchers next want to investigate the effects that reduced wind speeds have on life in the sea. Ocean winds affect salt and oxygen content, temperatures, and nutrients in the water. It is important to find out how reduced winds might affect marine ecosystems.

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Are wind farms slowing each other down?

Photo, posted November 23, 2011, courtesy of David J Laporte via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

A New Fishway Technology | Earth Wise

February 5, 2021 By EarthWise Leave a Comment

Freshwater fish populations have declined by more than 80% over the past forty years across the globe. This is in part due to hundreds of thousands of dams, weirs, and barriers stopping their movements. These river barriers have disrupted fish reproduction cycles the world over by preventing river fish from migrating to spawn.

Fishways or fish ladders are waterways constructed on or around obstructions in order to provide passageways for fish and other aquatic species. Often, they consist of a series of small overflow weirs and pools constructed in the form of steps. Fish need to jump from one pool to another to migrate to the upstream. Such fish ladders require a large space to construct. These and several other types of fishways tend to be expensive to install and maintain and are not always successful in allowing fish to get to where they need to go.

Researchers at the University of New South Wales in Australia have come up with an ingenious new type of fishway. Called a “tube fishway”, it is a low-cost and low-energy installation that works by pumping fish at high velocity – protected by a cushion of bubbly water – through a tube running over the obstructing barrier to deliver them safely into the water on the other side.

They successfully demonstrated a prototype system on a rugged slope behind a campus building that transported fish from one tank to another about 25 feet up the slope.

Fish are attracted into the chamber by suitable geometry and the system uses the energy available from the upper reservoir to lift the fish. Modeling shows that the system will work for pipes as large as three feet in diameter and could lift fish more than 300 feet vertically.

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New fishway technology to get fish up and over those dam walls

Photo, posted October 19, 2019, courtesy of Andrew Harvey via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Carbon In The Ocean | Earth Wise

October 13, 2020 By EarthWise Leave a Comment

New research from the University of Exeter in the UK reveals that the world’s oceans soak up more carbon than previously believed. Previous estimates of the movement of carbon between the atmosphere and the oceans did not account for the temperature differences between the water’s surface and a few meters below.

The new model includes this factor and finds that there is a significantly higher flux of carbon into the oceans.

The study calculated carbon dioxide fluxes from 1992 to 2018 and found that at certain times and locations there was up to twice as much CO2 contained in the ocean as determined from previous models.

The temperature differences between the surface of the ocean and the water at a depth of a few meters is important because the amount of carbon dioxide that can be absorbed in water depends very strongly on the temperature of the water. Anyone with a home soda maker knows this well as the devices always work much better with refrigerated water than room temperature water.

The difference in ocean carbon dioxide uptake measured from satellite data and calculated in the new modeling amounts to about 10% of global fossil fuel emissions, so it is a very significant revision. The revised estimate for carbon dioxide uptake actually agrees much better with an independent method for calculating the amount of carbon dioxide in the oceans. Those measurements came from a global ocean survey performed by research ships over decades.

Now that two so-called big data estimates of the ocean sink for CO₂agree pretty well, there is greater confidence that we understand this important aspect of the planet’s carbon cycle.

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Ocean carbon uptake widely underestimated

Photo, posted December 30, 2012, courtesy of Jerome Decq via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

The Arctic As A Carbon Source

December 16, 2019 By EarthWise Leave a Comment

According to a new NASA-funded study, the Arctic may now be a source for carbon in the atmosphere rather than being the sink for it that is has been for tens of thousands of years.

The study, published in Nature Climate Change, warns that carbon dioxide loss from the world’s permafrost regions could increase by more than 40% over the next century if human-caused greenhouse gas emissions continue at their current pace. Worse yet, carbon emitted from thawing permafrost has not even been included in most climate models.

Permafrost is the carbon-rich frozen soil and organic matter that covers nearly a quarter of Northern Hemisphere land area, mostly in Alaska, Canada, Siberia, and Greenland. Permafrost holds more carbon than has ever been released by humans from fossil fuel burning, but it has been safely locked away by ice for tens of thousands of years.

As global temperatures rise, the permafrost is starting to thaw and release greenhouse gases into the atmosphere.

The recent findings indicate that the loss of carbon dioxide during the winter in the Arctic may already be offsetting carbon uptake during the growing season. The researchers compiled on-the-ground observations of carbon dioxide emissions across many sites and combined these with remote sensing data and modeling. They estimate that the permafrost region is now losing 1.7 billion metric tons of carbon during the winter season but taking up only 1 billion during the growing season.

The major concern is that as the Arctic continues to warm, more carbon will be released into the atmosphere from the permafrost region, which will further the warming. Climate modeling teams across the globe are trying to incorporate these findings into their projections.

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Arctic Shifts to a Carbon Source due to Winter Soil Emissions

Photo, posted July 27, 2015, courtesy of Gary Bembridge 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.

The ‘Biggest Ever’ Arctic Expedition

October 3, 2019 By EarthWise Leave a Comment

The Arctic is warming faster than any other region on Earth. In fact, it’s warming at a rate of almost twice the global average. And, since what happens in the Arctic doesn’t stay in the Arctic, the world is already feeling the effects: rising sea levels, changes in climate and precipitation patterns, increasing severe weather events, and so on.

As a result, researchers from more than a dozen countries have launched the biggest and most complex expedition ever attempted in the Arctic. They plan to freeze Germany’s largest research vessel, the Polarstern, into Arctic sea ice, where it will remain trapped for twelve months. The ship will drift with the sea ice as the sea ice drifts. The vessel will serve as a research laboratory, hosting a rotating crew of 300 scientists. The ice, the ocean, the atmosphere, and even the wildlife will all be sampled. This year-long journey will give researchers their closest look at how the polar climate and its fragile ecosystems are changing.

Led by the Alfred Wegener Institute for Polar and Marine Research in Germany, the Multidisciplinary drifting Observatory for the Study of Arctic Climate project (or MOSAiC) is expected to cost about $150 million.

One major goal of MOSAiC is to improve strikingly uncertain climate projections for the Arctic. Climate models disagree on how much more the Arctic will warm as the concentration of greenhouse gases in the atmosphere rises and sea ice shrinks. Some project a 5ºC rise by 2100 relative to the 1986-2005 average. Others predict a 10ºC increase.

Understanding the complex processes occurring in the Arctic is essential for projecting the future impacts of climate change.

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Climate scientists prepare for largest ever Arctic expedition

Climate change: Polarstern leaves for ‘biggest ever’ Arctic expedition

Image courtesy of the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) user facility.

Earth Wise is a production of WAMC Northeast Public Radio.

Wildfires And Carbon

September 17, 2019 By EarthWise Leave a Comment

This summer has been an unprecedented year for fires in the Arctic. Major fires have burned throughout the Arctic in Russia, Canada, and Greenland. In total these fires released 50 million tons of carbon dioxide in June alone, which is as much as Sweden emits in an entire year.

In an average year, wildfires around the world burn an area equivalent to the size of India and emit more carbon dioxide to the atmosphere than global road, rail, shipping and air transport combined.

Ordinarily, this is part of a natural cycle. As vegetation in burned areas regrows, it draws CO2 back out of the atmosphere through photosynthesis. This is part of the fire-recovery cycle, which can take less than a year in grasslands, but decades in forests. But in Arctic or tropical peatlands, full recovery may not occur for centuries.

A recent study looked at and quantified the important role that charcoal plays in helping to compensate for carbon emissions from fires. In wildfires, some of the vegetation is not consumed by burning, but instead is transformed to charcoal – referred to as pyrogenic carbon. This carbon-rich material can be stored in soils and oceans over very long time periods.

Researchers have combined field studies, satellite data, and modelling to quantify the amount of carbon that is placed in storage in the form of charcoal. Their results are that the production of pyrogenic carbon amounts to about 12% of the CO2 emissions from fires and can be considered a significant buffer for landscape fire emissions.

Charcoal does not represent a solution to the problem of increasingly intense wildfires, but it is important to take it into account in understanding what is happening.

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How wildfires trap carbon for centuries to millennia

Photo, posted August 17, 2018, courtesy of the Bureau of Land Management Oregon and Washington via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Climate Change And The Bottom Line

July 31, 2019 By EarthWise Leave a Comment

Large companies around the world are facing up to the fact that climate change could substantially affect their bottom lines within the next five years. Shareholders and regulators have been applying pressure to companies to disclose the specific financial impacts they could face as the planet warms and companies are increasingly making those disclosures.

A non-profit charity called CDP (formerly known as the Carbon Disclosure Project) runs the global disclosure system for investors, companies, cities, states, and regions to manage their environmental impacts. In 2018, more than 7,000 companies submitted reports to CDP and, for the first time, CDP explicitly asked firms to try to calculate how a warming planet might affect them financially.

Analysis of the reports from 215 of the world’s 500 largest corporations revealed that these companies alone potentially faced roughly $1 trillion in costs related to climate change in the decades ahead unless they took proactive steps to prepare.

Climate-related risks range from extreme weather that could disrupt supply chains to stricter climate regulations that could hurt the value of coal, oil, and gas investments. Technology companies like Google’s parent company, Alphabet, Inc., face increased costs to cool energy-hungry data centers as temperatures rise.

In all, the world’s largest companies estimated that at least $250 billion of assets may need to be written off or retired early as the planet heats up. Previous studies, based on computer climate modeling, have estimated that the risks of global warming, if left unmanaged, could cost the world’s financial sector between $1.7 trillion to $24.2 trillion in net present value terms.

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Companies See Climate Change Hitting Their Bottom Lines in the Next 5 Years

Photo, posted February 29, 2016, courtesy of Ben Nuttall via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.