 Report: A Cambridge City Council proposal to legalize six-story buildings. Everywhere. One of the most impactful up-zonings of any U.S. City. How it will impact residents lives around issues related to the environment here. In this post we address critical environmental impacts of this up-zoning petition that are likely to greatly increase heat island impacts and climate change destruction. concerns in city climate change and flooding impacts, but will exacerbate problems. SOME OF THE CORE PROPOSED UP-ZONING FEATURES
TREE MATTERS CITY TREE TOTALS •19,095 City Trees •60,095 Private or Institutional Trees MINING THE CITY TREE DATABASE WITH CHATGPTThe City of Cambridge has an excellent database of our city street and park trees, with up-to-date information on locations, types of trees, ages of trees, dead trees, newly planted trees and other information. We can use this date to address critical information addressing the city's environment related to trees today and into the future. We can also mine this information as related to likely impacts of the proposed citywide up-zoning. Below are two maps showing the types of trees found on city streets and parks.  Below we see two graphs showing on the left the ages of our city trees, and on the right the diameters of our city trees. What this reveals in part is how much of our historic tree canopy on public spaces has been lost, and the part of it that has been replaced, largely entails new saplings (1-4 years old) followed by 5-10 year old trees which offer little of any shade bearing foliage that will help the city for another 30-40 years. We no longer have any trees on public city land over 20 years old (with diameters above 30 inches). The vast proportion of 1-4 year trees (0-5 inches in diameter) is also problematic because they have a much higher probability of dying, needing to be replaced in turn, at some point in the future.  When we look at tree locations across the city based on the ages and diameters of these trees, we can see just how wide spread this older tree loss is city wide, since there are very few colors other than dark purple that are visible.  If we look at the differences in the maps showing "retired" tree sites (those areas that once had trees, but will no longer, versus those areas where the city plans to plant new trees, we can readily understand how much this legacy of tree destruction in the City of Cambridge is impacting the city now and the future well being of its residents. Based on this date, it is clear that the city has no intent to increase its tree count even to the levels we had a few years ago.  When we look at the data on dead trees, damaged trees, and "retired tree sites"alongside the date of those current trees in need trimming (one of the important factors in maintaining the health of city and private residential trees the situation looks even more devastating. One can also see this devastating situation clearly from the graph showing this data below.
 Neighborhood differences come into play in important days as we break down the data further. Some of our neighborhoods, especially those in our denser, lower income areas have far more trees being cut on their streets than other neighborhoods, often in wealthier areas. This has potentially serious ramifications not only on the health of residents, especially infants, children, those already ailing and seniors due to a number of factors including ongoing heat island impacts of these denser housing areas. One can see on the left the neighborhoods that are hardest (Cambridgeport, and the Port, followed by Mid-Cambridge adn East Cambridge. On the right one can see the numberical differences involved with Cambridgeport bearing the loss of 60 trees, followed by The Port at 60 trees, and at the other end fo the scale, Strawberry Hill with only 15 trees cut down, followed by Cambridge Highlands with 20 trees having been cut.  Some factors regarding our public tree deaths on city streets and parks offer further insight, whether we are talking about, the choice of tree species (and their ability to survive here), or questions of placing city streets trees within grates. The London planetree followed by the Tuliptree and Serviceberry Genus have the highest death rates; the Red maple, Japanese Zelkova and Japanese Tree Lilac have had fewer deaths, but likely the number of these trees that have been planted would impact these results. We also learn from this database that park trees have higher survival rates than street trees, and that those street trees within grates do a bit better than those without grates. All of this is dependent on watering the trees in both settings.  The city provides data on the arborist or source of the tree (identified here as the tree creator. And we can see how these factors also may impact the survival rates of our newly planted trees - some of whom are clearly doing more work for the city than others. This is data that presumably the city takes into account when it is deciding on commissioning people to do this work.  Our tree inspectors also have a major impact on which trees live and die. It is hard factor in why the differences here would be so large between one inspector and another, and perhaps suggests the importance of the city requiring a second opinion of someone not in the city employ.  The Urban Heat Island Technical Report
Let's look first at City Estimates on Climate Plan Impacts (Heat Island Impacts) in the Urban Heat Island Report. As we can see below, trees are seen by the city to represent only 1 out of 6 in importance in terms of planned response to temper heat island impacts. This is quite surprising since according to current research, trees are generally considered more important than cool roofs in mitigating heat island effects, as they provide a greater cooling impact through shade and evapotranspiration, making them a more effective strategy for reducing urban temperatures compared to cool roofs alone; however, both strategies can be used together for optimal results. Equally surprising is that fact that neither cool roofs, nor surfaces, or part of city planning or environmental policy regarding areas outside of Alewife, Kendall Square, and MIT, so the residents living in the various neighborhoods throughout the city will receive little benefit from the roof and surface changes. Whereas they would benefit from far greater work in adding trees to the parts fo the city streetscape that had living trees just a few years ago.  The city's focus going forward in terms of tempering heat island impacts is focused almost exclusively on cool roofs and impervious surfaces for new buildings in our heavy commercial areas where many of the labs are found. Trees barely factor in at all, except, to try to return to the already decimated 2009/2010 period of street and park trees in the city. Even this minimal goal seems highly unlikely however considering the data on tree death and tree age addressed above in the City Tree Database. And again, very little of this is focused specifically on the residents of the city and specifically the neighborhoods in which they live.  It is hard to see the highly idealized cooling maps presented in the Heat Island Report as more than simply fantasy considering what we learn from both the report itself and the City Tree Database.  The city has identified the impacts of these proposed changes here:  NEIGHBORHOOD IMPACTS OF TREE LOSSES AND HEAT IMPACTSWhen we go to the neighborhood level to address these issues, the issues and impacts are striking. A 10 degree F difference can have striking differences on health and mortality for infants and the elderly. The fact that the HIGHEST temperatures are found in our densest and historically lower income neighborhoods is significant and should not be overlooked. The Port and East Cambridge have the highest temperatures while Strawberry Hill and Cambridge Highlands have the lowest ambient temperatures. As heat rises, the impacts are even greater, and a 10 degree Fahrenheit difference can bring not only health problems but also death to the most vulnerable - infants, children, and the elderly. When we add to this likely impacts of the loss of even more green space and trees in these same neighborhoods and others that now could be built to the property lines at each side and at the rear will mean that we will lose not only many existing trees but also future ones. And as we know it is mature trees that have an especially important role in keeping rising temperatures in check.  Below we see a map of the city's hardest hit areas in terms of heat island impacts. Nothing that the city is proposing will decrease the already consequential impacts in our densest neighborhoods such as The Port, East Cambridge, Cambridgeport, Inman Square, Mid-Cambridge, and North Cambridge. As trees are removed this will look even worse, and with the insertion of the denser C-1 dense zoning regulations (made even more dense by the up-zoning plan being proposed) are somewhat less hot regions will begin have heat impacts that complement those now found in the denser neighborhoods.  The following map makes clear the startling impacts on our residential neighborhoods with serious health implications. In the circle graph on the right, the red area addresses the health impacts of extreme heat. These impacts are seen here to include: 1) preterm birth; 2) respiratory disease; 3) mortality and hospitalization. Nothing we are doing in the city is seeking to remediate this. And, if we add more unfettered development, without regulation or oversight, as proposed in the upzoning proposal, this will aggrevate an already very problematic situation.  The City is clearly recognizing the problem that exists in our city's approach to heat island impacts. The Dity has signaled in its own mapping that the core areas of the city that will be impacted by the city's initiatives on cool roofs, impervious surfaces, and trees, will be those areas around Alewife, Kendall Square and MIT - and NOT the other areas of the city, the neighborhoods where many of our residents live. One can see this in the city map on the right where we find the circled areas. The fact that we are making no effort to impact the majority of our residents in the various neighborhoods is a significant problem.  Below we read the conclusions of the Cambridge Heat Island Impact Report. We have highlighted the findings that are most germane to the concerns we raise here.  None of this addresses the serious issues around climate change and sizable flooding possibilities in the present and years ahead. This also will be significantly impacted by the proposed citywide up-zoning, and the lack of both design oversight and immediate infrastructure changes that come with it. The city's map of likely future flooding impacts across our many neighborhoods makes this clear.
CONCLUSIONSIn conclusion, it is important to note that the City of Cambridge has provided our residents and city employees with an extraordinary rich array of data from which we can begin to understand the city. Some of this data is in the form of reports (such as the Urban Heat Island Technical Report), city wide data (in the form of excel sheets and other forms, such as the City Tree Data), as well as GIS data showing our many historic and contemporary buildings in their specific settings. We can see below an example of this GIS data in the form of a rending of buildings and an overview photograph. As we explore this data we can see not only the wonderful richness of the details but also the how devoid this view of the city of its many diverse residents. In key ways the City Tree Data and Urban Heat Island Report seem equally devoid of evidence related to residents, those who live here.  We urge our city elected officials and staff to address the residents of our city and our environmental and other features in a far more holistic way. We need to begin to include the trees and other features of our unique neighborhoods as part of our planning and discussions. Too often the the City staff and or political leaders act as if they consider both our trees (and green spaces) as well as current residents as the enemy of the City, and our city's progress, using divisive terms and character attacks of people who want a smart future. At the same time, we appreciate some of the excellent work that has been undertaken by city staff and residents to date, including the creation of the City's Urban Forest Masterplan, available HERE. We urge the city and city council to undertake new planning endeavors consistent with its guidelines and goals.  OUR CITY NEIGHBORHOODSEach of our neighborhoods can offer insights on how this. It is critical going forward that we incorporate the trees on our many city residences in our tree and climate policy going forward. It is in these properties, owned privately or in institutional hands that are so critical for our future. The example below comes from Hilliard Street near Harvard Square. The photograph below was taken in the autumn, so that the deciduous trees are largely bare. And here and elsewhere we also have an array of evergreens. This is both a very dense part of the city, with both single family homes, duplexes, row houses, and taller apartment buildings (the latter at the corners where Hilliard meets Mt. Auburn Street and Brattle. In restoring Cambridge's climate promise and moving it into the future, not only must we replant many of the "retired" street tree sites, but we also must retain and build on our many private trees and green spaces. With the proposed City up-zoning the impacts of this decision will be felt especially in our diverse neighborhoods, in the many private homes that are there of various shapes and scales. For many Cambridge residents, including those on Hilliard St., our neighbors' green spaces, garden, and trees are as important to our well-being, love of the city, and moderating ambient temperatures as are OUR OWN green spaces, garden and trees.  We must come together as residents, as neighbors, as members of diverse local civic groups to support responsible plans for our future, plans for our future that places special emphasis on the health of our residents highlight the critical importance of our trees, green spaces, and environment more generally. In addition to the environmental impacts, the proposed citywide up-zoning will significantly increase housing costs across the city, as historic housing is demolished, current tenants are forced out, and wealthier outsiders move in, with new homes and home additions adding to property values that will rise, with taxes, not only for themselves, but also for their neighbors. This will impact low and middle income city residents and seniors (or others) on fixed incomes, some of whom will also be forced out of the city. In addition every home demolition will lead to carbon impacts that will take up to 80 years to recoup even with the most environmentally forward-thinking new housing. It is critical now for urgent reflection vis-a-vis issues around the ongoing health of our current and future residents. Leaving our future to "the market" (giving investors and others of extraordinary means the main voice for our city's present and future irresponsible.  Report by Suzanne Preston Blier, President
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