This urban vegetation stores far more carbon dioxide (CO2) than previously understood, thriving both in manicured green zones and in small scattered pockets. A study conducted in New York City shows that photosynthesis within the city’s plant ecosystems absorbs more than twice the emissions from traffic and can account for a substantial share of total urban emissions. The finding underscores how urban vegetation plays a bigger part in the carbon cycle than earlier believed (Source: Environmental Research Letters).
“Even in large, dense cities like New York, biogenic CO2 flows from trees, shrubs, grasses, and lawns during the summer can exceed anthropogenic emissions,” according to the study published in Environmental Research Letters (Source: Environmental Research Letters).
Researchers note that scattered, previously unrecognized vegetation exists in abundant measure, even in highly developed areas. Small patches of greenery—from lone trees and home gardens to overgrown vacant lots and weed-strewn spaces—contribute meaningfully to carbon sequestration. The headline finding is that there is far more vegetation than was first thought, suggesting the urban ecosystem matters greatly in New York and likely in other cities as well (Source: Environmental Research Letters).
There is a perception that only large green spaces matter, yet the data show that every fragment of greenery, no matter how modest, is part of the atmospheric gas exchange. In some cases, such small vegetation networks can account for substantial air cleansing, with estimates suggesting they contribute a sizable share to urban air quality depending on the plant types present (Source: Environmental Research Letters).
street trees
Urban groundcovers are widespread and vegetation in these built environments often appears as street trees, park trees, and lawns. The report highlights how such vegetation in developed areas actively participates in the city’s carbon dynamics.
Even with New York carrying the highest anthropogenic CO2 emissions in the United States and ranking among the top globally, the study shows that biogenic CO2 uptake from sparse vegetation can offset up to 40% of total anthropogenic emissions in the metropolitan area during a summer afternoon (Source: Environmental Research Letters).
From this, the authors emphasize that urban plant ecosystems make a significant contribution to the urban carbon cycle, a finding that matters because urban areas account for a large share of human CO2 emissions. As more cities pursue aggressive emission reduction targets, accurately characterizing vegetation and biogenic carbon flows becomes essential for reliable atmospheric monitoring (Source: Environmental Research Letters).
The Madrid Caixa Forum vertical garden and similar plant architectures illustrate how plant growth can shape urban climates; researchers note that the arrangement and health of vegetation influence carbon dynamics in city spaces (Source: Environmental Research Letters).
The study determined that tree crowns cover roughly 170 square kilometers of the city, representing about 22% of the urban area’s length, with pastures accounting for about 94 square kilometers or 12%. The team analyzed vegetation interactions with carbon emissions from June to August 2018, a period when the metropolitan area emitted around 14.7 million tons of CO2. The largest sources were electricity production and building energy use, while road transport accounted for about 1.2 million tonnes (Source: Environmental Research Letters).
Promote ‘plant architecture’
Vegetation in urbanized zones, once overlooked, accounts for roughly 85% of daily carbon absorption. The scientists observed that CO2 levels rise in the morning with traffic and human activity and decline in the afternoon as lawns and trees work to remove carbon and purify the air.
The results stress the importance of promoting green roofs and plant architecture to support bioclimatic design. Vegetation across urbanized areas suggests the potential to absorb up to six times more greenhouse gases than areas lacking plant cover.
According to the authors, the summer afternoon CO2 absorption by New York’s vegetation can offset emissions from several sectors, though not every sector simultaneously. This nuance reinforces the need for precise accounting when assessing city-wide emission management (Source: Environmental Research Letters).
Researchers funded by Columbia University point to a core contribution of expanding plant surfaces to offset human-caused emissions. The study notes that doubling tree numbers in megacities tends to amplify the benefits of urban forests, including reduced pollution, greater carbon sequestration, and lower energy use in buildings (Source: Environmental Research Letters).
The findings align with earlier work showing that adding trees can significantly boost urban environmental performance. This reinforces the push for expanded urban forestry and integrated vegetation planning as part of climate strategies (Source: Environmental Research Letters).
In sum, the research highlights that urban vegetative cover plays a pivotal role in offsetting traffic-related CO2 in cities like New York, with implications for other cities embracing cleaner, greener urban futures. The broader takeaway is clear: integrating plant-rich design into city planning can materially influence carbon trajectories in busy metropolitan regions (Source: Environmental Research Letters).
Additional context and methods are available in the referenced study from the journal Environmental Research Letters (Source: Environmental Research Letters).