Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

PolyU study raises alert for further increase in city's temperature

01.08.2012
The temperature in the inner urban areas of Hong Kong is predicted to rise by two to three Celsius degree in 30 years' time, according to the latest scientific study by researchers at the Department of Land Surveying and Geo-Informatics of The Hong Kong Polytechnic University.
The temperature in the inner urban areas of Hong Kong is predicted to rise by two to three Celsius degree in 30 years' time, according to the latest scientific study by researchers at the Department of Land Surveying and Geo-Informatics (LSGI) of The Hong Kong Polytechnic University (PolyU).

The study was done by PolyU Professor Janet Nichol and her research student Mr To Pui-hang, together with Chinese University's Professor Edward Ng Yan-yung, using remote sensing technology and satellite images. They have mapped the distribution of temperatures for both daytime and nighttime over Hong Kong at decadal intervals up to 2039, taking into consideration the temperature change due to greenhouse-induced warming as well as the impact of urbanization. The latter is known as the Urban Heat Island (UHI) effect.

Professor Janet Nichol said the UHI effect means an urban area is significantly warmer than its rural surroundings. The temperature difference is usually larger at night and in winter. There are several causes leading to UHI. These include high-rise buildings which block thermal radiation at night, materials with thermal bulk properties such as asphalt and concrete, and the lack of vegetation in urban areas. With its densely populated urban area, Hong Kong provides a typical example of the UHI effect.

While temperature projections for the city carried out by the Hong Kong Observatory have reflected the expected temperature change due to greenhouse-induced warming, they have failed to address the direct effects of urban development. In contrast, PolyU research has examined temperature changes due to both global warming and urbanization effects independently.

"Urbanization is an additional factor in causing temperature rise, and if current trends are continued, temperatures could increase much faster in the future," said Professor Nichol.

Given no further urbanization, the annual mean temperature in Hong Kong will rise by 3.0 to 6.0 Celsius degrees by 2100 (according to a study of the Hong Kong Observatory in 2007). However, the mean temperature is predicted to rise by 3.7 to 6.8 Celsius degrees within the same period with a constant urbanization rate as before. The impact of urbanization effect or UHI magnitude is estimated at 0.08 Celsius degrees per decade.

In predicting future rise in temperature, Professor Nichol has made use of satellite images for baseline air temperature mapping, global climate models for the projection of greenhouse-induced warming, and plot ratio to reflect the degree of urbanization. She also noted that air temperature is more sensitive to the density rather than the height of buildings, though the latter cannot be fully neglected.

The study found that in 2039 (please compare Figure 1 and Figure 2) most urban areas in Hong Kong would have a two to three Celsius degree increase in daytime air temperature, indicated by the original dark green areas changed to yellow. This indicates an average increase of temperature on a summer day in urban districts, from currently 35 Celsius degrees to just less than 38 Celsius degrees in 2039.

Moreover, over the next three decades night time temperatures in the centre of Kowloon are expected to show at least an increase by two Celsius degrees, reaching over 31.5 degrees at night. This means that most urban districts in the city that are currently "comfortable" at night will become "uncomfortable" by 2039. As a result, those people who cannot afford air conditioners will suffer heat stress both during the day and at night.

Professor Janet Nichol also urged city planners to take into consideration the wind speed requirements for residential buildings in urban areas so as to achieve a more favourable living environment for city dwellers. This is called "sustainable urbanization".

This research is funded by the Public Policy Research Grants of the Research Grants Council.

Professor Janet Nichol
Department of Land Surveying and Geo-Informatics

Tel: (852) 2766 5952
Email: lsjanet@polyu.edu.hk

Regina Yu | Research asia research news
Further information:
http://www.polyu.edu.hk

More articles from Studies and Analyses:

nachricht Win-win strategies for climate and food security
02.10.2017 | International Institute for Applied Systems Analysis (IIASA)

nachricht The personality factor: How to foster the sharing of research data
06.09.2017 | ZBW – Leibniz-Informationszentrum Wirtschaft

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Ocean atmosphere rife with microbes

17.10.2017 | Life Sciences

Neutrons observe vitamin B6-dependent enzyme activity useful for drug development

17.10.2017 | Life Sciences

NASA finds newly formed tropical storm lan over open waters

17.10.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>