While Alaska straddles the Arctic Circle and is covered by vast expanses of frozen land, the state also has a lot of liquid water. In fact, Alaska holds about 40% of U.S. surface water resources. This includes more than 12,000 rivers, thousands more streams and creeks, and hundreds of thousands of lakes.

So when the Surface Water and Ocean Topography (SWOT) satellite launches this month from California’s Vandenberg Space Force Base, it’s only natural that Alaska will be among the first beneficiaries of this mission led by NASA and the French space agency Centre National d’Études Spatiales (CNES), with contributions from the Canadian Space Agency and the UK Space Agency.

SWOT will measure the height of nearly all water on Earth’s surface, from large rivers to lakes and reservoirs to the ocean. It will fill in gaps in remote places like Alaska and in many countries where surface water data are sparse or nonexistent. These measurements will be valuable to water management and disaster preparedness agencies, universities, civil engineers, and others who need to track water in their local areas.

Alaska’s sheer size, rugged terrain, and limited transportation infrastructure make traditional stream gauging cost prohibitive. While streamflows in most of the United States are continuously monitored by a U.S. Geological Survey (USGS) network of more than 8,500 stations, there are currently only 113 gauges in Alaska, and many big rivers aren’t monitored. The amount of water flowing through such rivers affects everything from the health and biodiversity of fish species to transportation and drinking water availability.

This dearth of Alaskan river information made USGS a logical choice to serve as a SWOT early adopter. SWOT data will complement a system currently in development to monitor those rivers, using radar altimetry data from the U.S.-European Jason-2 and -3 and European Space Agency Sentinel satellites (developed in the context of the European Copernicus program led by the European Commission), and visible imagery from the NASA-USGS Landsat satellites. The project, in its third year, involves using space-borne instruments to measure the elevation and flow of rivers. USGS partners include the Alaska Department of Transportation and Public Facilities, National Weather Service’s Alaska-Pacific River Forecast Center, U.S. Fish and Wildlife Service, and Alaska Department of Fish and Game.

“Alaska is a place that could particularly benefit from remote observation for streamflow estimates,” said USGS hydrologist Robert Dudley. Dudley said Alaska is a great test case for scientists and water managers to work with new space-based tools like SWOT and put them to immediate use.

USGS is compiling a historical record of estimated stream discharges, building on more than two decades of NASA research to measure water surface levels in lakes and rivers. The data will allow scientists and water managers to understand how often streams experience low- and high-flow conditions and to develop a reference point to evaluate current conditions.

The SWOT Advantage

Dudley says SWOT has numerous advantages over current satellite-based river measurement techniques. Altimeters like those on the Jason series of satellites can measure how water levels vary in some large rivers, and Landsat can measure how river widths vary. But neither data source by itself provides all the information needed to calculate a reasonable estimate of how much water is flowing through a river without doing difficult and costly on-the-ground calibration. SWOT changes that by measuring both water levels and width simultaneously.

For example, if a river has steep banks, it won’t necessarily appear wider or narrower as its discharge rate changes. Conversely, even a tiny change in water elevation in a shallow-banked river can mean a lot more water is flowing through it.

SWOT will also measure a river’s slope, which provides scientists a means to estimate how fast water is running off the landscape. Generally speaking, the steeper the slope, the faster the water.

And SWOT will collect the data needed to estimate stream flows all at once, every time it flies over a river, which in Alaska will be about once every five days. SWOT’s radar also can see through clouds, eliminating data gaps caused by clouds in Landsat and other visible-light imagery.

Climate change is causing numerous hydrological changes in Alaska that SWOT will help study, said Jack Eggleston, chief of the USGS Hydrologic Remote Sensing Branch. “Rapidly increasing temperatures are causing streamflows to increase on the North Slope, where permafrost is melting,” he said. “This is also changing the seasonality of streamflow, with high flows caused by snow melt occurring earlier in the year.”

“SWOT is going to allow us to see what’s going on in Alaska hydrologically in ways that we haven’t before,” said Tamlin Pavelsky, NASA’s SWOT freshwater science lead, based at the University of North Carolina, Chapel Hill. “That’s important, because Alaska, being in the Arctic, is also the place in the United States experiencing the most climate change right now. If you want to know why that matters, think about how many resources we get from Alaska.”

More About the Mission

SWOT is being jointly developed by NASA and CNES, with contributions from the CSA and the UK Space Agency. JPL, which is managed for NASA by Caltech in Pasadena, California, leads the U.S. component of the project. For the flight system payload, NASA is providing the Ka-band Radar Interferometer (KaRIn) instrument, a GPS science receiver, a laser retroreflector, a two-beam microwave radiometer, and NASA instrument operations. CNES is providing the Doppler Orbitography and Radioposition Integrated by Satellite (DORIS) system, the dual frequency Poseidon altimeter (developed by Thales Alenia Space), the KaRIn radio-frequency subsystem (together with Thales Alenia Space and with support from the UK Space Agency), the satellite platform, and ground control segment. CSA is providing the KaRIn high-power transmitter assembly. NASA is providing the launch vehicle and associated launch services.

For more on SWOT, visit:

https://swot.jpl.nasa.gov/

News Media Contacts

Jane J. Lee / Andrew Wang

Jet Propulsion Laboratory, Pasadena, Calif.

818-354-0307 / 626-379-6874

[email protected] / [email protected]

With all the hustle and bustle of the holidays, it’s easy to forget the big picture. Remember the environment and those in need this season by taking a moment to give back. Even small acts can make a big difference. Here are five waste-free ways to give back this season.

1. Clear Your Cupboard To Feed the Hungry

Canned and dried foods that have been sitting in your pantry for months aren’t technically “food waste” — yet. After all, they’re still perfectly edible and have yet to be tossed in the trash.

But with the growing demands on food banks across the country, all that nonperishable food could definitely be put to better use than sitting forgotten on the back of a shelf.

Clear out your cupboards and set aside nonperishable food you are unlikely to use in the near future for donation to your local food bank, food pantry, or soup kitchen. A few minutes of pantry purging will help these organizations feed people in need of nutritious food. You can also check out a variety of food waste apps to find organizations that can help distribute your unwanted or extra food.

By donating food you aren’t using, you can help prevent future food waste — even canned food expires eventually. Most food banks won’t accept food that is past its expiration date.

2. Donate Toys to Make a Child’s Day

Kids in low-income families often go without during the holidays. Help make sure every child in your community receives a gift this season by donating toys and clothes to charities or thrift stores in your area.

Parents on tight budgets may be doing some of their holiday shopping at secondhand stores, and charities that collect toys will surely be distributing them during the holidays. You’ll prevent unwanted toys from going to waste and just may make a child’s holiday a little more special.

3. Volunteer for Neighborhood Treecycling

An ever-increasing number of communities now offer Christmas tree recycling (often called “treecycling”) programs that transform discarded trees into mulch for playgrounds, parks, and other public spaces.

Many of these programs depend on volunteers. By giving a few hours of your time, you help ensure that your neighbors can recycle their trees rather than send them to the landfill.

Use Earth911’s recycling directory to find your local treecycling program, and check out its website to see if the program needs volunteers. A bit of time spent mulching trees isn’t bad for burning off all those holiday calories either.

4. Fight Litter While Making Merry

Holiday schedules are often packed with parties, community activities, and seasonal shopping. While you’re out and about, make it a point to pick up litter when you see it. Bring a bag with you while shopping or caroling with the kids, or de-litter rest areas when traveling to visit family and friends.

It may seem simple, but the planet and your community will be far better off as a result.

5. Choose Charitable Gifts

If you’re stumped on what to give to a friend or family member this season, think outside the box and choose a non-material gift such as a charitable donation.

Provide clean water to a family in need through The Water Project, or donate livestock and seeds with Heifer International. Kiva now offers Kiva Cards, which are like gift cards that allow recipients to choose from a library of micro-financing projects around the world.

Choose a cause that suits your loved one best for a thoughtful gift that’s entirely waste-free.

Originally published on December 13, 2013, this article was updated in December 2022.

NASA’s Images of Change gallery has added a new feature: “Google Timelapse” view. In addition to comparison views of before-and-after images, you can now view selected scenes as time-lapse sequences generated via the Google Earth engine.

The following collection features examples of global change as observed by NASA satellites, including urbanization, natural hazards, weather events, and the effects of global warming.

These images show the latter stages of the decline of Okjökull, a melting glacier atop Ok volcano in west-central Iceland. (“Jökull” is Icelandic for “glacier.”) A 1901 geological map estimated that Okjökull spanned about 15 square miles (38 square kilometers). In 1978, aerial photography showed the glacier had shrunk to about 1 square mile (3 square kilometers). Today, less than half a square mile (less than 1 square kilometer) remains. Read more at NASA’s Earth Observatory.

The southeastern coast of Cape Cod, Massachusetts, changes constantly under the influence of currents, tides, waves, and storms. For example, in the 1984 image, the barrier spit (the long, narrow strip at the eastern edge) known as North Beach is unbroken. The Patriot’s Day storm in 2007 cut an inlet through it, and the southern part became North Beach Island. Researchers have identified a cycle that repeats roughly every 150 years, in which the barrier is breached, regenerates, stretches southward, and is breached again. The lower islands, too, reform under the ever-changing conditions.

Hudson Bay, which is considered a sea of the Arctic Ocean despite being surrounded by land, freezes over completely in winter and thaws in summer. These images show the decrease in ice over the course of 16 days in July 2020. During the thaw, polar bears travel over the slowly melting sea ice to hunt for ringed seals and other prey. When the ice becomes too scarce, the bears fast and wait for it to return. The area has lost about a third of the polar bear population since the 1980s, dropping the count from about 1200 to 800, apparently because declining summer sea ice has given them less opportunity to feed.

Starting in 1970, Cancún, Mexico, transformed from an impoverished town of about 100 people into a vacation destination with a permanent population of 740,000 and 2 million visitors per year. Cancún accounts for a quarter of Mexico’s tourism revenue, but its growth has brought environmental costs that include water pollution and beach erosion. These images show the town’s growth from 1985 to 2019.

Lake Mead, the largest reservoir in the United States, was at a mere 27% of its capacity as of July 18, 2022. The result of a multi-decade drought in the country’s West, this is the lake’s lowest level since it was first filled in April 1937. This striking visual highlights climate change’s impact on a vital water source in the West, which last approached full capacity in the summer of 1999. Read more at NASA’s Earth Observatory. Also see Lake Mead at record low and Lake Mead shrinkage, Nevada.

Scientists use a set of 47 glaciers around the globe to monitor the state of the world’s mountain glaciers. Peyto Glacier in Banff National Park, Canada, is one such reference glacier that’s been measured continuously since 1968. Peyto Glacier has lost about 70% of its mass over the past 50 years. These images show ice loss from Peyto and surrounding glaciers over the past 22 years. Both images were taken during the same time of year.

Nevada.

Unrelenting drought and increased water usage in the Western U.S. has shattered another record: By Aug. 10, 2022, the Great Salt Lake’s water level dropped under 4,190 feet (1,277 meters). In 1985, heavy rains and plentiful water runoff from melting snow helped to fill the lake to an unusually high water level of around 4,210 feet (1,283 meters).

Differences in water depth and the amounts of sediment, salt, bacteria, and algae throughout the lake, divided by the Union Pacific Railroad causeway, give it a patchwork of colors from above.

National climate strategies set out how countries plan to reduce emissions, for example by phasing out fossil-fuel use, to get to net-zero in 2050. The study found, once the bulk of emissions have been reduced, countries plan to ‘cancel out’ the left-over difficult to decarbonise emissions, such as those from agriculture, by using forests and soils to remove carbon from the atmosphere.

However, this may prove risky because forests and soils are also threatened by a range of impacts, such as fire, disease, changes in farming practices or deforestation. These mean forests and soils could lose their stored carbon back to the atmosphere.

There is also a risk of being over optimistic about the amount of carbon forests and soils can remove to reach net zero, especially if combined with delays to reducing emissions from coal, oil, and gas.

The findings, published in the journal Communications Earth & Environment, show that most of the strategies submitted to the United Nations Framework Convention on Climate Change (UNFCCC) do not quantify the amount of carbon ‘removals’ needed in 2050.

With progress on reducing emissions stalling at COP27, the researchers call for the reporting requirements on long-term national climate plans to be urgently strengthened.

“The deployment of carbon dioxide removal is essential to reach global and national net-zero emissions targets, but little attention has been paid to its practical deployment by countries,” said the study’s lead author Harry Smith, a Leverhulme Trust Doctoral Scholar in the School of Environmental Sciences and Tyndall Centre for Climate Change Research at UEA.

“Nature-based removals, such as using forests and soils, remain vital to address challenges in biodiversity and climate adaptation, but may be risky if used as the only way to remove carbon. Countries should also explore engineered carbon removal methods. To meet the challenge of net-zero, we need both.”

The study analysed how Carbon Dioxide Removal (CDR) methods — which remove CO₂ from the atmosphere and permanently store it in forests, soils, the oceans, or underground geological formations — are integrated into climate strategies.

It groups the methods into ‘nature-based CDR’, for example storing carbon in forests, soils, or coastal habitats, and ‘engineered-CDR’, storing carbon deep underground through biomass energy with carbon capture and storage or direct air carbon capture and storage.

Despite being central to net-zero ambitions, the research finds CDR is rarely made explicit in policy plans. Some countries such as France look to engineered removals as a possible long-term solution. Others, such as Australia and Latvia, look to the potential of international cooperation and the creation of carbon markets to transfer removals between countries.

Meanwhile the UK is investing in research and development for engineered-CDR and has a near-term 2030 target for the amount of carbon removed by these methods.

Since the adoption of the Paris Agreement in 2015, more than 124 countries have agreed to a net-zero emissions target, defined as a balance of emission sources and anthropogenic removals.

Unlike many studies, which focus on short-term pledges to 2030 published by countries, otherwise known as ‘Nationally Determined Contributions’ or ‘NDCs’, this study focuses on long-term national climate strategies.

Officially called ‘long-term low emission development strategies’ or ‘LT-LEDS’, these often represent modelled scenarios or pathways to 2050 or beyond, providing for greater engagement with CDR than NDCs.

“Long-term national climate strategies are an important tool to think through carbon dioxide removal at the national level and we advocate that they should be made compulsory under the UNFCCC, as opposed to their current optional status,” said Mr Smith.

The study examined 41 LT-LEDS submitted to the UNFCCC before the start of 2022, capturing those published in and around COP26 — and totalling 3,885 pages — to determine how countries quantify and discuss CDR. The analysed strategies are mostly from the Global North and cover 58% of global 2019 greenhouse gas emissions and around 74% of global GDP.

The findings show that enhancing forest and soil carbon sinks are the most advocated strategies but are only explicitly quantified in 12. Remaining difficult to decarbonise emissions by 2050 are only quantified in 20 strategies and most of them use forests to achieve national net-zero targets.

Strategies that quantify both the remaining difficult to decarbonise emissions and carbon dioxide removal identify national constraints, such as wildfire risks to forests and limited geological CO₂ storage capacity. Strategies also highlight the need for international cooperation.

Co-author Dr Naomi Vaughan, Associate Professor in Climate Change at UEA, said: “With more countries submitting long-term national climate strategies during COP27, the UNFCCC should urgently strengthen its reporting requirements.

“Carbon dioxide removal is an important part, together with reducing emissions, of how countries will reach net zero. National level analysis is needed to determine how countries plan on incentivising different CDR methods.

“This combines with an urgent need to scale-up efforts to reduce emissions and develop CDR methods to meet the scales needed to reach Paris Agreement temperature targets.”

Using computer models, the team, led by Panos Georgopoulos, a professor of Environmental and Occupational Health and Justice at the Rutgers School of Public Health, found that by 2050 climate change significantly will increase airborne pollen loads, with some of the largest surges occurring in areas where pollen is historically uncommon.

“Pollen is an excellent sentinel for the impacts of climate change because shifts in variables like carbon dioxide and temperature affect the way plants behave,” said Georgopoulos, who also is director of the Computational Chemodynamics Laboratory at Rutgers and faculty at Robert Wood Johnson Medical School. “At the same time, the production of pollen and pollen’s influence on allergic disease has been increasing due to climate change, and this is one of few studies to forecast this trend into the future.”

Previous efforts to connect pollen indices with climate change have been limited by a scarcity of data. For instance, there are about 80 pollen sampling stations in the U.S., operated by a variety of private and public agencies using different sampling methods.

To overcome this challenge, the researchers adapted the Community Multiscale Air Quality modeling system, an open-source tool managed by the U.S. Environmental Protection Agency (EPA) to simulate distributions of allergenic oak and ragweed pollen for historical (2004) and future (2047) conditions.

Results showed that even under moderate warming conditions, pollen season will start earlier and last longer throughout the U.S., with increasing average pollen concentrations in most parts of the nation. Mean concentrations of oak pollen could climb by more than 40 percent in the Northeast and Southwest and mean concentrations of ragweed could jump by more than 20 percent in these areas.

Regional pollen shifts were observed, too. In parts of Nevada and northern Texas, oak pollen levels could double by mid-century, while Massachusetts and Virginia could see an 80 percent increase in ragweed pollen by 2050.

The pollen research was part of an ongoing project by the Rutgers Ozone Research Center, which is funded by the EPA and New Jersey to study how climate change will influence air quality in the state. The bulk of that work examines the state’s struggles with ground level ozone, a byproduct of fossil fuel combustion that can damage the lungs.

“New Jersey’s air quality is going to be adversely impacted by climate change, both in terms of anthropogenic pollution and increased levels of pollen,” Georgopoulos said. “For people with asthma, exposure to pollen and irritants like ozone increases the odds of respiratory illness. To protect the most vulnerable, we need to understand how these irritants will behave in a warming world.”

Story Source:

Materials provided by Rutgers University. Original written by Greg Bruno. Note: Content may be edited for style and length.

The study, led by civil and environmental engineering professor and Prairie Research Institute executive director Praveen Kumar, evaluated 14 water-stressed locations across the globe for the feasibility of a hypothetical structure capable of capturing water vapor from above the ocean and condensing it into fresh water — and do so in a manner that will remain feasible in the face of continued climate change.

Kumar, graduate student Afeefa Rahman and atmospheric sciences professor Francina Dominguez published their findings in the journal Nature Scientific Reports.

“Water scarcity is a global problem and hits close to home here in the U.S. regarding the sinking water levels in the Colorado River basin, which affects the whole Western U.S.,” Kumar said. “However, in subtropical regions, like the Western U.S., nearby oceans are continuously evaporating water because there is enough solar radiation due to the very little cloud coverage throughout the year.”

Previous wastewater recycling, cloud seeding and desalination techniques have met only limited success, the researchers said. Though deployed in some areas across the globe, desalination plants face sustainability issues because of the brine and heavy metal-laden wastewater produced — so much so that California has recently rejected measures to add new desalination plants.

“Eventually, we will need to find a way to increase the supply of fresh water as conservation and recycled water from existing sources, albeit essential, will not be sufficient to meet human needs. We think our newly proposed method can do that at large scales,” Kumar said.

The researchers performed atmospheric and economic analyses of the placement of hypothetical offshore structures 210 meters in width and 100 meters in height.

Through their analyses, the researchers concluded that capturing moisture over ocean surfaces is feasible for many water-stressed regions worldwide. The estimated water yield of the proposed structures could provide fresh water for large population centers in the subtropics.

One of the more robust projections of climate change is that dry regions will get drier, and wet areas will get wetter. “The current regions experiencing water scarcity will likely be even drier in the future, exacerbating the problem,” Dominguez said. “And unfortunately, people continue moving to water-limited areas, like the Southwestern U.S.”

However, this projection of increasingly arid conditions favors the new ocean vapor-harvesting technology.

“The climate projections show that the oceanic vapor flux will only increase over time, providing even more fresh water supply,” Rahman said. “So, the idea we are proposing will be feasible under climate change. This provides a much needed and effective approach for adaptation to climate change, particularly to vulnerable populations living in arid and semi-arid regions of the world.”

The researchers said one of the more elegant features of this proposed solution is that it works like the natural water cycle.

“The difference is that we can guide where the evaporated water from the ocean goes,” Dominguez said. “When Praveen approached me with this idea, we both wondered why nobody had thought about it before because it seemed like such an obvious solution. But it hasn’t been done before, and I think it is because researchers are so focused on land-based solutions — but our study shows other options do, in fact, exist.”

The researchers said this study opens the door for novel infrastructure investments that can effectively address the increasing global scarcity of fresh water.

The University of Illinois Urbana-Champaign, the Lovell Professorship in the department of civil and environmental engineering, The University Scholar Program and the National Science Foundation supported this research.

Researchers at the University of Bern have now developed a new method to determine the necessary reduction in emissions on a continuous basis. The main idea: Instead of complex climate models and scenarios, the observed relationship between warming and emissions is applied, and the reduction path is adapted repeatedly according to the latest observations. This new approach has just been published in the journal Nature Climate Change.

A new calculation method for the emission reduction path

To date, climate models have been used to calculate possible emissions pathways to the net zero goal. These pathways are based on scenarios including economic and social developments. “These calculations for the emission paths are subject to large uncertainties. This makes the decision-making more difficult and might be one reason why the promised reductions made by the 194 signatory countries to the Paris Agreement remain insufficient,” says lead author Jens Terhaar, explaining the background to the study. Like most of the other authors, Terhaar is a member of the Oeschger Center for Climate Change Research at the University of Bern.

“Since the climate agreement actually aims at regulating temperature, we thought to specify an optimal emissions reduction path for this purpose which is independent of model-based projections,” continues Terhaar. According to this initial idea, a calculation method has emerged which is based exclusively on observation data: on the one hand, global surface temperatures in the past, and on the other hand, CO2 emissions statistics.

The Paris Agreement calls for a stocktake of the necessary reductions in global emissions every five years. “The new Bern calculation method is ideally suited to support the stocktake mechanism of the Paris Agreement, as it enables the emission reductions to be recalculated regularly on an adaptive basis,” explains co-author Fortunat Joos of the Oeschger Center. For this purpose, a new algorithm has been developed which is known as the AERA (adaptive emissions reduction approach). In simple terms, the algorithm correlates CO2 emissions with rising temperatures, and is adjusted using a control mechanism. In this way, the current uncertainties in the interaction between these variables can be put aside.

“Our adaptive approach circumvents the uncertainties, so to speak,” explains Fortunat Joos. “In the same way that a thermostat continuously adjusts the heating to the required room temperature, our algorithm adjusts the emission reductions according to the latest temperature and emissions data. This will allow us to approach a temperature goal, such as the 2°C goal, step-by-step and with specific interim goals.”

Stronger emissions goals and effective implementation

“The AERA method already confirms that international climate policy must be far more ambitious,” demands Terhaar. According to the Bern study, to achieve the 2°C goal, global CO2 emissions would have to fall by 7 percent between 2020 and 2025. They actually increased by approximately 1 percent in 2021 in comparison with 2020, though. According to the algorithm, limiting global warming to 1.5°C would require as much as a 27 percent reduction by 2025. “We need far stricter emissions goals than those to which nations have committed,” explains Thomas Frölicher, co-author of the study from the Oeschger Center, “and above all else, effective implementation of the goals.”

The Researchers in Bern hope that the new calculation method will succeed in finding its way into international climate policy. “The AERA algorithm is already attracting a lot of interest in the climate research community, as it can also be applied to climate modelling,” explains Jens Terhaar. Until now, climate models with prescribed greenhouse gas concentrations have been used. This meant that at the end of the 21st century, the warming for a specific greenhouse gas concentration was very uncertain. When using the climate models with the AERA, however, emissions are continuously adjusted according to the calculated temperature and the intended temperature goal. On this basis, the model temperature is eventually stabilised at the intended level and all the models simulate the same warming, but with different emission pathways. “The AERA enables us to study impacts such as heat waves or ocean acidification for different temperature goals — such as 1.5°C versus 2°C versus 3°C — on a consistent basis and with state-of-the-art models,” explains Terhaar.

Worldwide, 11 research groups have already started to apply the algorithm under the leadership of the University of Bern in order to study such impacts.

Story Source:

Materials provided by University of Bern. Note: Content may be edited for style and length.

There are many reasons why natural gas is the most common home heating source in America while fewer than 10% of U.S. homes burn wood as a primary heat source. If your home is in the wood-burning camp, you already know that fireplaces are not the best home heating system. Fuel availability is often the driving force behind choosing to heat with wood — either because you have your own woodlot, or because heating with electricity or pulling gas to a remote home is prohibitively expensive.

In some cases, wood stoves can be an ecological choice, if you choose your stove wisely and burn your wood properly. Take a few minutes to assess your choices, because some wood-burning options are far better for the environment.

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Stoves vs. Fireplaces

Sometimes people refer to wood stoves and fireplaces interchangeably. They are both hearth appliances (that is, safe containment systems for burning fires) and the fuel they both burn is generally wood. Sometimes they even look the same when wood stoves are placed inside a fireplace structure.

But there is a world of difference between the two. A fireplace is essentially an indoor campfire. At best, a fireplace achieves about 10% efficiency in its use of the energy stored in the wood. They can even operate at negative efficiency, meaning they actually draw more heat out of the house than they create. By contrast, a wood stove is a fully-enclosed appliance whose efficiency can be up to 50% higher than the fireplace. Wood stoves are rated by the EPA.

Measuring Wood Stove Efficiency

There are two ways of measuring the efficiency of wood-burning appliances.

Combustion efficiency refers to how much of the energy embodied in the fuel is converted to heat (rather than smoke, ash, or other byproducts). Overall efficiency is the percentage of the available energy that is actually transferred to the space to be heated.

Overall efficiency will always be lower than the combustion efficiency — by as much as 20%. So, when you are shopping for a wood stove, be sure to find out which efficiency the number on the tag refers to.

Good Wood

There is no Energy Star system for wood stoves because they generally do not draw electric power. But the EPA has established standards for wood stove efficiency. An EPA certified wood stove is independently tested by an accredited laboratory to meet the New Source Performance Standards (NSPS) emission limits that govern how many particulates a stove can release into the air. Basically, NSPS requires all but a few grams of your wood is completely burned instead of going up the chimney as soot and ash.

In 2020, the NSPS emission limit for new room heaters was lowered to 2.5 grams of particulate per hour burning cordwood. Wood stoves certified under the 2015 NSPS meet a particulate emissions limit of no more than 4.5 grams per hour. So stoves manufactured before 1990 should be replaced, however aesthetically pleasing their design may be, to meet the new standards. They burn wood much less efficiently than contemporary models, wasting fuel and polluting the air inside your home and outdoors.

Currently certified wood stoves produce heat 50% more efficiently, require 30% less wood, decrease pollution by 70% and reduce the risk of creosote buildup compared to older stoves.

Alternate Fuels

Pellet stoves, which burn pellets of compressed sawdust, are still your best choice. They are the cleanest burning solid-fuel stove option.

Some models of EPA-certified pellet stoves can reach efficiencies in the range of 70% to 83% — comparable to a gas fireplace. You do have to buy pellets, which eliminates the savings from cutting your own wood. And some pellet stoves do require a small amount of electricity to operate the hopper that feeds pellets into the fire, which is a drawback if your home frequently loses power. But there is no question that operating a pellet stove is much less work than burning logs.

Choosing a Wood Stove

There are two types of high-efficiency wood stoves. Non-catalytic stoves are more common. They achieve high combustion rates by using firebox insulation and a large baffle to produce a longer, hotter gas flow path; and by introducing pre-heated air through small holes above the fuel in the firebox. Catalytic stoves tend to be more expensive and depend more on correct maintenance by the user. But they produce the long, even output that homeowners want from a heat source. Catalytic stoves pass the smoky exhaust through a coated ceramic honeycomb inside the stove. There, gases and particles in the smoke ignite and burn.

Proper sizing is also critical to choosing the right stove. Small stoves are best for heating individual rooms or for “zone heating.” Big stoves are best for heating the whole home, but only if you have an open-plan home. In homes with numerous rooms, a large stove can cause one area of the home to overheat while the rest remains cold. You can use a BTU calculator to estimate your heating needs, but it’s best to consult a professional who can help match your particular situation to a right-sized hearth appliance.

This article was originally published on February 12, 2021.