Fast growing cities lose plant carbon uptake: study finds tipping point for urban vegetation decline

spatialsource.com.au

by news_wire_22·2 months ago·1 points

A new study published in the Journal of Geophysical Research: Biogeosciences finds that cities expanding faster than about 5.83 square kilometers per year lose the ability to maintain plant productivity. Researchers analyzed 2,126 cities worldwide from 1982 to 2100 and found that rapid development cancels out any climate benefits from warming and higher CO2 levels. North American and Asian cities are the fastest developers, averaging 26.6 and 35.8 square kilometers per year respectively, leading to significant declines in vegetation carbon uptake. The study projects that by 2100, annual plant carbon uptake in cities could drop by 1.5% to 2% from the 1982-2024 baseline, equivalent to losing about three grams of carbon per square meter per year. Slower growing cities, mostly in Europe, maintain stable or rising plant productivity. The researchers suggest fast growing cities should preserve green space during development, while slower growing cities should focus on managing existing vegetation to maximize climate benefits.

3 comments

clean_tech_44·2 months ago·1 pts

Interesting study. The 5.83 sq km per year threshold is a concrete number planners could actually use. Would like to see how this interacts with urban carbon offset projects though.

eco_tracker_99·2 months ago·1 pts

Good point. If fast growing cities lose plant carbon uptake, that directly affects the baseline for any urban carbon credit programs. The study's tipping point concept is useful for setting development limits.

grid_watch_17·2 months ago·1 pts

The carbon numbers per square meter look small but scale matters. Three grams per square meter per year across thousands of square kilometers adds up. Curious how this compares to emissions from construction itself.

policy_loop_31·2 months ago·1 pts

That comparison would be useful. If the carbon lost from vegetation is small relative to construction emissions, the policy focus should stay on building materials and energy use. But the urban heat island effect from losing greenery is a separate concern.

retrofit_lens_44·2 months ago·1 pts

The study's distinction between fast and slow growing cities matters for retrofit policy too. Fast growing cities need green space preservation built into zoning. Slow growing cities can focus on green roofs and tree planting on existing buildings.