Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Urban Heat Islands Make Cities Greener


Some people think cities and nature don’t mix, but a new NASA-funded study finds that concrete jungles create warmer conditions that cause plants to stay green longer each year, compared to surrounding rural areas.

Urban areas with high concentrations of buildings, roads and other artificial surfaces retain heat, creating urban heat islands. Satellite data reveal that urban heat islands increase surface temperatures compared to rural surroundings.

Using information from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on the Terra satellite, Boston University, Boston, researchers discovered that city climates have a noticeable influence on plant growing seasons up to 10 kilometers (6 miles) away from a city’s edges. Growing seasons in 70 cities in eastern North America were about 15 days longer in urban areas compared to rural areas outside of a city’s influence.

"If you live in a rural area and drive regularly into the city, and if you pay attention to vegetation, you will see a difference in the growing seasons in early spring and late autumn," said Xiaoyang Zhang, the study’s lead author and a researcher at Boston University. The study appeared in a recent issue of the American Geophysical Union’s Geophysical Research Letters journal.

Zhang added that urban heat islands provide a very good model to assess the effects of global warming on plant growing seasons and ecosystems. As temperatures warm due to climate change, growing seasons will likely change as well. Zhang and colleagues found that for every 1 degree Celsius (C) or 1.8 Fahrenheit (F) that temperatures rose on average during the early springtime, vegetation bloomed 3 days earlier.

Springtime land surface temperatures in eastern North American cities were on average 2.3°C (4.1°F) warmer than surrounding rural areas, according to the study. In late autumn to winter, the city temperatures were 1.5°C (2.7°F) higher than the surrounding areas. These higher urban temperatures caused plants to start greening-up on average seven days earlier in spring. Similarly, in urban heat island areas, the growing season lasted eight days longer in the fall than the rural areas.

The researchers used MODIS surface reflectance data to measure seasonal changes in plant growth for the entire year of 2001. By accounting for angles of views from the satellite, varying sunlight, land surface temperatures, cloud cover, and the presence of snow, the scientists were able to detect daily variations in the green color of plants.

The researchers classified urban areas using MODIS data from October 2000 to October 2001, as well as Defense Meteorological Satellite Program’s (DMSP) nighttime lights imagery and population density data. Only eastern North American cities with urban areas larger than 10 square kilometers (4 square miles) were included in the study.

The researchers found that the effect urban heat islands have on plants’ growing seasons is exponentially weaker the further away from the city one travels. Significant effects were seen up to 10 kilometers (6 miles) from city lines. In other words, the impact of urban climates on ecosystems extended out 2.4 times the size of a city itself.

"Warming from global climate change will definitely impact ecosystems," Zhang said. "Thus, urban areas provide us with some measures of how changes in temperature might affect vegetation," he added.

NASA is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather, and natural hazards using the unique vantage point of space.

Krishna Ramanujan | NASAs Earth Science News Team
Further information:

More articles from Earth Sciences:

nachricht Receding glaciers in Bolivia leave communities at risk
20.10.2016 | European Geosciences Union

nachricht UM researchers study vast carbon residue of ocean life
19.10.2016 | University of Miami Rosenstiel School of Marine & Atmospheric Science

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Novel mechanisms of action discovered for the skin cancer medication Imiquimod

21.10.2016 | Life Sciences

Second research flight into zero gravity

21.10.2016 | Life Sciences

How Does Friendly Fire Happen in the Pancreas?

21.10.2016 | Life Sciences

More VideoLinks >>>