Fires, heatwaves get an early start this year
In some places, an extreme summer has already begun
Springtime in the Northern hemisphere is a momentary respite for many places—a pause before the heat of summer and potential for drought and fire. This year, however, summer arrived early, bringing with it scorching temperatures and out-of-control fires that have made national and international headlines.
Record March-April heatwave sweeps India and Pakistan
Portions of India and Pakistan already have experienced record-setting heat. Unseasonably warm weather began in March, when India recorded the hottest monthly temperatures that the country has seen in the past 122 years—hitting an average maximum of 33.1 degrees Celsius (91.6 Fahrenheit). The heatwave continued with the third hottest April on record. The hottest time for India is typically May and June, before the monsoon season begins.
In addition to the early start of summer temperatures, this heat wave is particularly concerning for its scope. The heat has settled over most of India as well as parts of neighboring Pakistan for two months.
“The most shocking part for me has been the geographical extent and the duration,” said Woodwell Assistant Scientist, Dr. Zach Zobel in an interview with CNBC.
The heat-related death toll in Maharashtra state, the second-most populous state in India, has already reached 25. Heat waves like this one become particularly dangerous when humidity is high—preventing the human body from cooling itself through sweat and evaporation.
Earlier and more intense heat waves also have the potential to disrupt India’s crop yields, particularly heat, which is vulnerable to hot, dry weather. As climate change progresses unchecked, extreme heat waves like this one will become more and more common.
Megafires in New Mexico forcing evacuations
On the other side of the globe, rising temperatures have resulted in a rash of destructive fires well before the usual summer season. The state of New Mexico is currently fighting 20 separate fires in 16 counties. Two, the Hermit’s Peak and Calf Canyon fires, recently merged into the state’s second-largest wildfire on record, which has been burning now for more than a month.
The merged “megafire” has destroyed at least 276 structures and forced the evacuation of nearly 13,000 residences.
New Mexico is used to a fire season that starts in May or June. Climate change is making out-of-season fires more common and big fires were seen this year in Colorado and California as early as December and January. The United Nations declared a global wildfire crisis in February.
Climate change is warming and drying out western U.S. states, increasing the number of “fire weather days.” This has made fire management harder, limiting the possible timeframe for prescribed burns that reduce fuel loads. Intense winds also played a large role in fanning the New Mexico fires, one of which began as a prescribed burn that escaped.
Heat rising, summers lengthening with climate change
As temperatures rise, the risks from deadly heatwaves and wildfire are growing. Fire seasons and extreme heat seasons are lengthening, frequently starting earlier and ending later, giving the land no time to recover from dry winters or the prior year’s heat. The response to both the fires in New Mexico and heat in India and Pakistan is the same—rapidly reducing global emissions by 15% every year to hit the IPCC target of 1.5 degrees of warming.
“There is no question that heat waves are made worse by fossil fuels and climate change everywhere in the globe,” said Dr. Zobel. “India and Pakistan are two of the hottest places in the world and will likely continue to see heat waves of this magnitude and worse over the next several decades.”
Woodwell workshop brings Indigenous firefighters to Brasilia
A week-long workshop encourages knowledge sharing between Indigenous Brazilian fire brigades
On March 28, 2022, firefighters from Indigenous communities across Brazil gathered in Brasília, the country’s capitol, for a week-long geography and cartography workshop. The workshop, a collaboration between the Coordination of Indigenous Organizations of the Brazilian Amazon (COIAB) and the Amazon River Basin (COICA), IPAM Amazônia, and Woodwell Climate Research Center, walked participants through the basics of using Global Information Systems technology to monitor and manage their own lands and forests.
Forests and native vegetation on Indigenous lands have been sustainably managed for millenia, and studies have found Indigenous stewardship of forests is an effective measure for preventing deforestation and degradation. Escaped fires can present a threat to forests, and many Indigenous communities have their own brigades that work on detecting and preventing runaway fires. In some places, prescribed burns are used as a tool for shaping and cultivating the land.
Participants attended from Indigenous lands located in a variety of Brazilian landscapes—from the Cerrado to the heart of the Amazon. Despite differences, participants found learning from other Indigenous communities extremely valuable.
“People came with a variety of skill sets,” said Woodwell Water Program Director Dr. Marcia Macedo. “What was most meaningful for participants was seeing other people like them, who do the same work and are also Indigenous people, already dominating material, knowing how to make the maps, and helping others. It gave them confidence that they could also figure it out.”
After a day of introduction to the core concepts of GIS and mapping, participants headed out to Brasília National Park to test their newfound skills. They visited burned areas from both an escaped fire and a prescribed burn, compared the two, marked GPS points, and took pictures. The data gathered on the field trip was used over the next few days to practice making maps.
“The goal was to not only teach the theory and help them understand the steps for making maps, but also mainly to develop the skills for them to be able to apply to their own lands on their own time,” said Woodwell postdoctoral researcher, Dr. Manoela Machado, who helped organize the event.
The workshop also fostered discussions about the complexity of management when fire can be both a threat and a tool. Because fire manifests differently in different biomes, well-managed fires look different for each community.
“On the final day, we had a discussion of values. Is fire good or bad? For whom—ants, forests, human health?” said Dr. Machado. “You can’t just criminalize fire if it’s a part of traditional knowledge and used as a tool for providing food, for example. So it’s a complex issue.”
Dr. Machado hopes the conversations will continue. She says the goal would be to host this workshop again to expand its reach, potentially beyond Brazil to include participants in other Amazonian countries.
Nitrogen retaining soil property protects tropical streams from impacts of agricultural intensification
Quick facts
- Some soils in the Amazon rainforest contain deep stores of nitrogen in the form of nitrate (NO3-), accumulating at a depth of 6-20 feet. Soil retains the ability to store large amounts of nitrate even after land is converted from forest to agriculture.
- A new paper quantified the mechanism, a chemical characteristic of highly weathered clay soils called anion exchange capacity, which captures negatively charged nitrate ions as water passes through the positively charged soil. As a result, very little nitrate seeps into groundwater and surface streams from these soils even when croplands receive nitrogen fertilizer.
- If well stewarded, many of Brazil’s Amazon croplands have a built-in buffer against water pollution that could potentially last decades. This is crucial for increasing crop production using fertilizer to reduce pressure for new deforestation, without the added consequence of nitrogen pollution of freshwater ecosystems that accompanies increased fertilization on croplands in other parts of the world.
A recent paper from Woodwell’s Tanguro Ranch Research Station has quantified a property locked into Brazil’s deep tropical soils that protects streams and rivers from the effects of fertilizer leaching and runoff. The study, led by Dr. Alexandra Huddell, a graduate student at Columbia University at the time of the study and now a postdoctoral fellow at the U.S. Environmental Protection Agency, estimated that, if well managed, Amazonian soils could continue to hold back excess nitrogen from reaching surface waters for many years, allowing for increased crop yields with relatively little impact on the surrounding ecosystem.
In temperate croplands—the midwestern U.S. breadbasket for example—some of the nitrogen in fertilizer that isn’t taken up by plants is converted to nitrate. Nitrate moves rapidly through soil and into groundwater, streams, and rivers. Excess nitrate threatens drinking water and causes algal blooms that can lead to low oxygen levels in lakes and coastal waters of oxygen.
But studies of the soils in Tanguro showed a very different dynamic. At Tanguro, the nitrate was sticking to the soil, not moving down towards groundwater and streams. Dr. Huddell’s study quantified the mechanism that led to such a stark difference between Tanguro’s soils and those of temperate cropland regions.
“We often think about increased agricultural intensification leading to decreases in local water quality, and this is an interesting case study of why that is not happening as quickly in Brazil,” said Dr. Huddell.
The difference is due to a molecular property inherent in the soil called “anion exchange capacity.”
Clay soils like the ones under the croplands of Tanguro and much of the Amazon rainforest form over millennia of intense weathering in the hot, wet climate, Huddell explained. Weathering produces minerals that impart positive charges to tiny soil particles. Nitrate, a negatively-charged ion (anion) then adheres to the positively charged soil. Most temperate zone soils are less weathered and have more negatively charged particles that repel nitrate–allowing it to move quickly to groundwater and streams.
Tanguro’s soils extend ten or more meters deep and have a large capacity for binding nitrate. That inherent property of the soil does not change when a forest is converted to agriculture.
“The mineral and structural composition of the soil don’t change much during conversion from forest to cropland, so the nitrate-retaining property is still present,” Woodwell Senior Scientist and co-author of the study, Dr. Christopher Neill says.
Dr. Huddell calculated that in this region, that capacity could last potentially for decades based on laboratory measurements. The precise timing will depend on factors like how much fertilizer is applied to croplands, whether water flows through some pores in the soil more than others and therefore bypasses portions of this anion exchange capacity, or if soil compaction at the surface reduces the water’s infiltration into the soil.
This finding has implications for slowing deforestation. Increasing crop yields on already converted land could increase Brazil’s agricultural output without destroying more of the Amazon Rainforest— a vital carbon sink. But intensification of fertilizer use only makes sense if it does not come at the expense of healthy freshwater ecosystems.
“If soils are well managed, you have this natural asset to keep the nutrients out of the water in ways we don’t have in the temperate zone,” Dr. Neill says. “We can likely intensify with more fertilizer use up to some level, and that will allow more food to be grown on less land, which could spare additional forest, but we need to better understand what those fertilizer limits are.”
Further investigation at Tanguro will test the limits of this capacity to narrow down the true size of this buffer.
Unchecked boreal forest fires are eating into our carbon budget
Proper management could be a cost-effective solution
What’s new?
A recent paper, published in Science Advances, has found that fires in North American boreal forests have the potential to send 3 percent of the remaining carbon budget up in smoke. The study, led by Dr. Carly Phillips, a fellow with the Union of Concerned Scientists (UCS), in collaboration with the Woodwell Climate Research Center, Tufts University, the University of California in Los Angeles, and Hamilton College, found that burned area in U.S. and Canadian boreal forests is expected to increase as much as 169 and 150 percent respectively—releasing the equivalent annual emissions of 2.6 billion cars unless fires can be managed. The study found proper fire management offers a cost-effective option, sometimes cheaper than existing options, for carbon mitigation.
Understanding boreal forest carbon
Boreal forests are incredibly carbon rich. They contain roughly two-thirds of global forest carbon and provide insulation that keeps permafrost soils cool. Burned areas are more susceptible to permafrost thaw which could in turn release even more carbon into the atmosphere. Although fires are a natural part of the boreal ecosystem, climate change is increasing the frequency and intensity of them, which threatens to overwhelm the forest’s natural adaptations.
Despite the value of boreal forests for carbon mitigation, the U.S. and Canada spend limited amounts of funding on fire suppression, usually prioritizing fire management only where people and property are at risk. Alaska accounts for one fifth of all burned area in the U.S. annually, but it receives only 4 percent of federal funding for fire management. Limiting fire size and burned area through proper management can be effective at reducing emissions.
What this means for boreal fire management
To prevent worsening emissions, fire management practices will have to be adjusted to not only protect people and property, but also to address climate change. Fire suppression in boreal forests is an incredibly cost-effective way to reduce emissions. The study found that the average cost of avoiding one ton of carbon emissions from fire was about $12. In Alaska, that means investing an average of just $696 million per year over the next decade to keep the state’s wildfire emissions at historic levels.
Increasing wildfires also pose an outsized threat to Alaska Native and First Nations communities, who may become increasingly isolated, and may lack the resources to evacuate quickly if wildfire encroaches on their lands. Many Alaska Native people already play a crucial role in existing wildfire crews, and investing in more fire suppression could create additional job opportunities for Indigenous communities.
Woodwell launches new project monitoring, combatting the effects of permafrost thaw
A $41 Million grant through The Audacious Project will fund Permafrost Pathways work
It’s a big idea—a pan-Arctic monitoring network for permafrost emissions—but big ideas are exactly what The Audacious Project was created to foster.
This April, Woodwell Climate Research Center was awarded 41.2 million dollars through Audacious to not only build such a network, filling gaps in our understanding of how much carbon is released into the atmosphere from thawing permafrost, but also to put research to work shaping policy and helping people.
The new project, called Permafrost Pathways, combines scientific prowess from Woodwell with policy, community engagement, and Indigenous knowledge from the Arctic Initiative at Harvard Kennedy School’s Belfer Center for Science and International Affairs, the Alaska Institute for Justice (AIJ), and the Alaska Native Science Commission.
Carbon emissions from permafrost thaw are one of the biggest areas of uncertainty in global climate calculations. Thawing permafrost is expected to release between 30 and 150 billion tons of carbon by 2100, the higher estimates on par with or even exceeding the United States’ cumulative emissions if allowed to continue at current rates. Yet permafrost is not accounted for in carbon budgets and international agreements. Permafrost Pathways will develop more complete data on permafrost carbon and deliver that research into the hands of those poised to decide how we deal with the warming Arctic.
Big problems require big solutions
Permafrost Pathways is led on the Woodwell side by Arctic Program Director Dr. Sue Natali and Associate Scientist Dr. Brendan Rogers, who have both been researching permafrost carbon for years. Dr. Natali found her way to the Arctic through a desire to work in a place significant to the global carbon story. The rapid changes she has witnessed in the past decade have underscored the Arctic as ground zero for climate change.
“I’ve seen dramatic changes from one year to the next in the places where I work, and Arctic residents have been observing these changes for decades,” Dr. Natali says. “You can measure something one year and then the ground there collapses the next. The physical changes across the landscape are really startling to see.”
Drs. Natali and Rogers have seen eroded hillslopes, research trips abandoned due to wildfire, community meetings with Arctic residents whose homes are sinking—every experience reinforced the fact that there was still much more to learn about how thawing permafrost feeds into climate change and is impacting Arctic communities.
The Audacious grant will allow Drs. Natali and Rogers to pull together the threads of their prior research into a project that starts to tackle the issue on a grander scale.
“When you’re focused on individual problems or hypotheses, you’re not able to really think big about something like monitoring across the Arctic,” says Dr. Rogers. “Opening up a funding source like this lets you think at a scale that matches the problems we face.”
The project is thinking really big, with the goal of installing 10 new eddy covariance towers—structures with instruments that measure carbon flux—in key areas where data is currently lacking. Pathways will also maintain existing key towers that would otherwise be decommissioned, and augment others to measure carbon fluxes year-round.
“There are a lot of existing towers that are either not running through the winter, or they’re not measuring methane, or they’re on hold for instrumentation upgrades or lack of funding,” Dr. Natali says. “We will get even more new data by maintaining old towers than constructing new ones.”
In parallel, Woodwell will work with a team at University of Alaska Fairbanks to develop a novel permafrost model that fully harnesses the data, accounting for important but currently neglected processes, and ultimately delivers more accurate projections of permafrost emissions to inform policy makers and Arctic communities.
‘It’s an awful decision’
While the science team ramps up new data collection, AIJ will be breaking down the issue of adaptation. The Arctic is warming faster than anywhere else on Earth, and it is not waiting for exact measurements to make the consequences known.
The land upon which many Alaska Native communities are located is destabilizing in the face of usteq—a Yupik word for the catastrophic ground collapse that occurs when thawing permafrost, erosion, and flooding combine to pull the ground out from under them. In many places the formerly solid cornerstones of villages—houses, roads, airports, cemeteries— have had to be picked up and moved to more stable ground.
“It is an awful, awful decision that communities are being faced with because the land on which they’re living is becoming uninhabitable,” says Executive Director of AIJ, Dr. Robin Bronen.
On top of the trauma of watching their villages sink into the Earth, there is no clear path for Arctic communities deciding they must completely relocate.
“It’s become painfully clear that we in the United States have no institutional or governance structure to facilitate this type of movement of people,” says Dr. Bronen. There is no standardized way for people displaced by the climate crisis seeking resettlement to apply for funding and technical assistance for a community-wide relocation.
“If policy changes aren’t made nationally, then a lot of communities in the United States are going to be experiencing this incredible disconnect between making the decision that they are ready to leave, but having no resources to implement that decision,” says Dr. Bronen.
Permafrost Pathways will be working with Arctic residents to help them adapt to their rapidly shifting landscape. Through AIJ and the Alaska Native Science Commission, the project will connect with communities, collaborate to generate data they can use in their decision making and, if they make the choice to move, work with them to secure the resources needed for relocation.
Factoring Permafrost Thaw into our Global Future
Permafrost Pathways isn’t the first to tackle these issues but, Dr. Natali says, it does represent a unique combination of expertise that could push forward both carbon mitigation and climate adaptation policies.
Leader of the Arctic Initiative, professor, and Senior Advisor to Woodwell’s president, Dr. John Holdren understands the value of connections in making lasting change; he has been speaking to top policy makers in the U.S. and abroad for much of his career.
“All of us at the Belfer Center have been linking science and policy for a long time and communication is important to that,” says Dr. Holdren. “In my view, it’s going to remain important to have personal connections at high levels.”
Working through these connections, Permafrost Pathways will put the project’s science into the hands of policymakers to impress upon them the issue’s urgency.
“All the news coming out about permafrost carbon has been bad news,” says Dr. Holdren. “I think what we are going to find is that the high estimates are much more likely to be right than the low estimates. We’ve got to get that factored into the policy process.”
For Dr. Natali, the most important outcome of Permafrost Pathways is a future in which the threats presented by permafrost thaw are taken seriously by governments.
“I want to see permafrost thaw emissions accounted for,” says Dr. Natali. “I want to see the national and international community actually wrestle with the effects of permafrost thaw and to take action to respond to the climate hazards.”
Dr. Rogers says he hopes the collaborative nature of this already-big project will have even larger, rippling effects— paving the way for new partnerships and policy change.
“There’s the critical work that we will be doing, and then there are the new doors that a project of this scope opens,” says Dr. Rogers. “And we aren’t reaching our end goal without those open doors.”
The Audacious Project is an initiative of the non-profit TED that funds large-scale solutions to the world’s most challenging problems. Every year, the Project selects a cohort of big ideas to nurture with funding and resources.
Despite centuries of successful Indigenous management, the Xingu’s fire regimes are changing
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What’s new?
The first designated Indigenous land in Brazil, Território Indígena do Xingu (TIX), has been cited by studies for decades as a successful buffer against the deforestation, degradation, and fires that plague other parts of the Amazon. A recent study, co-authored by Dr. Divino Silvério, Professor at the Universidade Federal Rural da Amazônia, and Dr. Marcia Macedo, Woodwell Water Program Director, shows that fire regimes are changing in the Xingu region, leading to more forest loss and degradation.
The paper shows roughly 7 percent of the TIX has been degraded by drought and fire. Degradation is part of a feedback loop wherein damaged forests become drier and more susceptible to burning in future fires.
“I remember when I started my Ph.D., a 2006 paper showed that Indigenous lands were extremely effective fire breaks—the Xingu just never saw fire. Climate change has completely changed that story,” said Dr. Marcia Macedo.
Understanding: Changing fire regimes
Indigenous communities in the TIX have been managing the rainforest for centuries with finely adapted slash and burn cycles that create space for agriculture and promote the growth of natural species used in construction, medicine, and cooking. These cycles can last three to four decades before an area is burned again. Traditionally, burns were well controlled and the rainforests surrounding burned areas were healthy enough to prevent flames from escaping.
But over the past two decades, the paper observed, escaped fires have occurred more often within the reserve and the likelihood that forest is lost post-fire is rising, particularly in seasonally flooded forests. Indigenous management practices have not changed significantly, the paper explains, so why the increased prevalence of fire and degradation?
Climate change is drying out forests, making them more susceptible to escaped burning from management practices. The other factor driving degradation within the territory is growing population. Indigenous communities are becoming less nomadic, and village populations are rising, increasing the area of forest used for subsistence. Degradation was higher in areas surrounding villages.
“The way Indigenous people manage fire has stayed the same, but we now have a different climate,” said Dr. Divino Silvério. “Indigenous people have been in these regions for many decades or centuries. And all this time they have had their own fire management to produce food that usually doesn’t end in these huge forest fires.”
What this means for Indigenous fire management
Climate change will force Indigenous communities within the reserve to adapt traditional practices to protect the forest against more frequent, intensifying fires—despite these communities not contributing to global emissions.
Previous attempts to manage increasing fires through prescribed burning have clashed with the needs of residents of the TIX. Burning at a different time of year does not cultivate the same species, and residents were concerned it was jeopardizing the growth of plants used for medicine.
Dr. Silvério is working with residents of the Xingu to understand how to integrate changes to fire management practices with traditional strategies in a way that supports community needs. One example, he said, could be shifting the primary construction material from grasses (that grow after fire) to palms.
“Indigenous people will probably need to learn how to live in this new reality, an environment with more drought and more fires. We are trying to work in a participative way to construct solutions with them.”
A warmer world means snow, rain will be much less predictable
When and where precipitation falls can determine whether or not people have enough drinking water, aquifers can support agriculture, and rivers keep running. Climate change is breaking down the predictability of weather patterns across the globe. Two new releases this week, from the Woodwell Climate Research Center and Probable Futures, flesh out our understanding of how the shifting seasonality of precipitation might impact our future.
Rainy seasons are fluctuating more
A new volume of maps, data, and educational materials launched on the Probable Futures platform today. The volume provides information that helps readers better understand local, regional, and global precipitation trends, showing how they will change with climate change.
The impact of a warmer world on precipitation patterns is not uniform—in some places dry spells will become more common, in others, intense storms, and some places will fluctuate between both. Rainy seasons may start earlier or later in different parts of the world, which will have impacts on growing seasons and agricultural yields.
“Climate change is reshaping both local precipitation patterns and the global water system—and everyone on Earth will be affected,” said Alison Smar, executive director of Probable Futures. “It may seem counterintuitive, but knowing that the future is less predictable is a valuable forecast. Communities need to be more resilient, adaptable, and prepared. It’s within our power today to prepare for the events that are probable, and prevent those with irreversible impacts.”
Snow is melting earlier
Woodwell Associate Scientist, Dr. Anna Liljedahl and Assistant Scientist Dr. Jenny Watts, were co-authors on a paper also released today that documents the impacts of earlier snowmelt in the Arctic. The Arctic is warming more rapidly than anywhere else on earth, which has led to earlier snow melts and longer growing seasons in the tundra.
Conventional hypotheses have predicted that lengthening summers would allow more time for vegetation to grow and sequester carbon, perhaps offsetting emissions elsewhere.
“Our results show that the expected increased CO2 sequestration arising from Arctic warming and the associated increase in growing length may not materialize if tundra ecosystems are not able to continue capturing CO2 later in the season,” said Dr. Donatella Zona, lead author on the paper from the University of Sheffield’s School of Biosciences and the Department of Biology at San Diego State University.
Dr. Liljedahl says that the results highlight the fact that the impacts of climate change will be complex across ecosystems.
“This work shows how important it is to continually assess our assumptions and terminology on how the Arctic system will respond to warming. We often say that warming will lead to a “longer growing season”. We need to be more careful in making that connection,” said Dr. Liljedahl.
Unequal heat
A visit to Worcester, Massachusetts in the heat of summer highlights the inequities of rising temperatures
It’s a hot, humid day in late August and we’re all already sweating as Arman Bajracharya begins to tell us about his project.
Bajracharya is a second year Ph.D. student in the geography department at Clark University in Worcester, MA, where we’re standing now. He pulls out a green and orange map of the city and points to our location on one of the orange blocks that signals industrial land use and impervious land cover.
We’re standing in the sparse shade of some trees ringing the edge of an old millpond, but we had to walk across a hot, cracked parking lot to access it. The neighborhood is called Webster Square. It is located in the southern reaches of Worcester, which was once a vibrant epicenter of the industrial revolution.
That industrial heritage is evident both on the maps Bajracharya shows us as well as in our surroundings. Truck beds and spare pvc piping and gravel piles rest at the edge of the water. It’s also scorching hot.
Temperature varies with land cover. In cities, the presence of impervious surfaces like asphalt, concrete, and metal trap heat, while natural surfaces—water or vegetation—can help buffer it. The distribution of these hotspots and heat buffers in Worcester, as in many cities, is not equal. Some neighborhoods endure much higher temperatures than others during the summer months.
Bajracharya’s research during the Summer of 2021 made possible by the Edna Bailey Sussman Fund employed remote sensing and census data to determine what features make a neighborhood more susceptible to extreme heat. He mapped temperature, land cover, and land use onto areas of greatest social vulnerability in Worcester, as well as two other post-industrial cities in Massachusetts, Haverhill and New Bedford. The results show that as climate change warms cities, the communities that have already experienced environmental inequities are likely to face more.
A gateway to the American dream
Worcester, Haverhill, and New Bedford are designated as gateway cities. These places, often important centers of the industrial revolution, have served as “gateways to the American dream,” offering job opportunities and housing for many who immigrated to the region.
Worcester began its industrial life as a mill town but soon grew into a manufacturing center for a variety of goods. It was also a crossroads of canal, and later, rail thoroughfares connecting the rest of Massachusetts with Providence and New York. Today, at the edge of the millpond in Webster Square, the remnants of an old rail bridge are still visible and active trains can be heard traveling the present day rail lines in the distance.
Industrial neighborhoods built to serve mills and factories often filled in with minority populations, and over time, wealthier families moved to quieter and more suburban areas of town. In the case of Haverhill, some communities also suffered the consequences of redlining, a discriminatory Federal Housing policy during the post-Depression era that limited financial services available to people, overwhelmingly African-American and people of color, deemed “hazardous to investment,” limiting social mobility and enforcing racial housing segregation. These factors often intensified the overlap between areas of high social vulnerability and industrial infrastructure.
“In the 1930s, these practices delineated which areas were defined to be good for financial services like loans,” Bajracharya says. “Which is why there is a historical divide between which areas are favorable and which areas are not. That can impact how we see the land being used today, especially where the greenspaces are.”
Mapping the heat
Bajracharya used available satellite data to show the relationship between land cover and social vulnerability. Examining the imagery, he created an index of relative heat in the city. Areas with high tree cover correlated with lower land surface temperatures. He then overlaid social vulnerability and environmental justice datasets that index communities in Massachusetts based on socioeconomic status, minority status, primary language, and other demographic information.
“Throughout many or most U.S. cities, neighborhoods facing greater environmental risks (such as from heat waves, urban flooding, and hazardous wastes) were historically settled by poorer families or racial and ethnic minorities,” Bajracharya says. “And there really is a lot of evidence for communities of color, or low-income communities, continuing to be disproportionately exposed to risk.”
According to Bajracharya, the analysis showed a startling overlap between the hottest areas of the city and the most vulnerable. Neighborhoods classified as Environmental Justice Communities tended to have a lower percentage of green vegetation (especially tree cover), with higher average temperatures. The most vulnerable areas are clustered in the core of the city.
The satellite maps only tell part of the story, however, which is why Bajracharya and his advisor Dr. Rinku Roy Chowdhury have brought us out onto the streets of Worcester. A few blocks away from the millpond, a grassy field rolls out behind a chain-link fence. In Bajacharya’s maps, this appears as a patch of vegetation interspersed among the developed land uses. The field sits under metal towers belonging to a nearby power station.
Often, Roy Chowdhury reminds us, the “green” and “blue” spaces that do exist in vulnerable areas may be inaccessible to residents, either cordoned off as private property or unsuitable for use due to safety concerns or an absence of trails or paths. The sign on the chain-link fence here warns of danger from high voltage.
This is where the distinction between land cover and land use becomes important. Land cover refers to what is currently on the land— whether that’s forest, grassland, or concrete. Land use data shows how humans are interacting with an area of land. For example, an area of grassy land cover could be used for conservation, residential or commercial purposes.
When natural land covers such as trees and water bodies are present but inaccessible, it limits potential social co-benefits that green and blue spaces can offer. Beyond regulating temperature, these spaces can reduce air pollution and provide recreational opportunities. Bajracharya and Dr. Roy Chowdhury emphasize the importance of field trips like this one, along with more in-depth work to ground truth satellite image analysis in local realities.
“There’s a really interesting mix of industrial and commercial uses interspersed with areas important for conservation and recreation, that could also potentially help in bringing down surface temperatures,” Dr. Roy Chowdhury says. “Tree cover and water are really helpful for buffering against the urban heat island, but so much more needs to be done to understand and steward such ‘ecosystem services,’ especially in underserved areas of cities.”
Building an Emerald City
With climate change accelerating, every patch of green and blue on the map will become indispensable in regulating city temperatures. To prevent a crisis of infrastructure failures and heat-related illnesses and even deaths from unfolding during brutal summers, cities like Worcester are going to have to get greener, faster—and do so in a way that benefits residents equitably.
Dr. Roy Chowdhury and Bajracharya are interested in investigating further to figure out the most promising pathways towards greener, more equitable cities. Questions still remain around finding the best proportion and distribution of land cover and implementation strategies that will improve environmental equity and encourage citizen participation. Woodwell’s Dr. Chris Neill has been collaborating with Dr. Roy Chowdhury and Clark University over the last decade to analyze land cover and ecological structure of urban vegetation in several US cities.
“Every tree makes a difference, but there are scale effects as well. What is the minimum threshold to make a difference? What’s the mix in different cities or neighborhoods? What do local residents value and want? These are really interesting and important questions to ask,” says Dr. Roy Chowdhury.
Research into the interactions between these green spaces and rising temperatures could help city planners make more conscious decisions about climate adaptation. Baracharya’s future projects may also examine flooding risk in cities, which adds another dimension to potential inequities in climate risk. Future research could also incorporate social interviews in different neighborhoods to understand residents’ concerns regarding their environment, climate change, and quality of life.
The last stop on our Worcester tour is Beaver Brook Park— an example of what’s possible when a city decides to reinvest in its natural spaces. The neighborhood surrounding the park was a primary destination for Black Americans moving north after the Civil War and has a history as a vibrant minority community. The titular brook had been paved over years ago, running in darkness under the city until 1990, when it was daylighted again to serve as a central feature of the park.
The area is now a green haven for recreation in the neighborhood and a stop on Worcester’s East-West trail, which Dr. Roy Chowdhury describes as “an emerald necklace” running through Worcester—one of the ways the city and numerous environmental stewardship organizations are working towards broader greenspace protections and access.
The feel of the air here contrasts sharply with where we started the day—a hint of the power urban greenspaces hold. Despite the heat warping off the street pavement, in the shade of old oak trees by the gurgling brook, it’s easy to stop sweating for a moment and just feel the breeze.