Global Dimming

Alida CorpuzDiana JuarezClaire KolajaJackie MillerLaurel OolieCalvin Wong

To educate students about global dimming which is a topic that most people are not aware of.

Define global dimming Discuss how global dimming was discovered Identify possible causes of global dimming Discuss contrails Global dimming’s effect on global warming Discuss how to fight global dimming

Objectives

*Global dimming is an important public health issue that affects our environment and health*

The reduction in emittance of global solar radiation. Increase of emittance of solar radiation back into space Dominates in large urban sites. Less solar energy reaching the earth’s surface (Austin,

2006)

What is global dimming?

http://julysong.tumblr.com/post/20341548260/ecogeekery-im-afraid-you-have-humans

First scientific observations of global dimming were made in the late 1960s by independent researchers such as Dr. Gerald Stanhill who tracked temperatures and noticed climate changes.

Nobody was certain until 9/11. In response to 9/11, the U.S. Secretary of

Transportation grounded all commercial flights for three days.

The skies over the U.S.-the most heavily trafficked in the world-became clear of contrail clusters and the days seemed brighter and warmer than usual (Austin, 2006)

How was it discovered?

Possible Causes Atmospheric aerosols from

anthropogenic air pollution** are considered important contributors to global dimming (Streets et al., 2006)

Aerosol particles cause water droplets in clouds to be smaller and more numerous, changing the properties of the clouds to reflect more sunlight upwards instead of down onto Earth.

Those super-reflective clouds can, moreover, alter rainfall patterns, thereby causing droughts (Austin, 2006).

http://cas.hamptonu.edu/research/topics/images/aerosols.jpg

Condensation trails (contrails) Hot humid from the jet exhaust air

mixes with environmental air (Lohmann, 2005)

Aerosols from planes effects: Direct - contrails Indirect – freezing nuclei in

troposphere Effects:

cooling near the surface in the polluted regions of the Northern Hemisphere

changes in temperature are smaller in the tropics and the mid-latitudes of the Southern Hemisphere

Contrails

http://chemtrails.cc/2009/02/20/chemtrails-from-space/

Urbanization Affect Urbanization has

been suggested as the cause of global dimming

Large cities contribute much to the production of anthropogenic aerosols, which in turn contribute to global dimming (Alpert et al., 2005)

Since 1975, the global surface temperature has increased about 0.5ºC due to greenhouse gas emissions. These have been

recorded as the highest temperatures in the last millennium (Hansen, 2000)

Global warming is the phenomenon of warming the atmosphere in the annular space in between the earth’s surface and the

modified layer of gas, where the heat emitted by the earth is trapped (Sarma, 2009).

Global Warming

Increases in air pollution and the dimming of surface solar radiation could have masked to a large extent the temperature rise induced by increasing greenhouse gases, so that the observed temperature records would not reflect the entire dimension of greenhouse warming (Wild, 2007).

Global Dimming’s Effect on Global Warming

http://www.skepticalscience.com/argument.php?a=18&p=18

Effects of Global Warming and Global Dimming on our

Planet Increase of temperature throughout the globe due to a modified layer of gas in the atmosphere.

Dimming and lowering of the temperature due to black clouds.

Less evaporation of sea water from the earth (Sarma, 2009)

Asian Brown Cloud

• The pollutants that cause global dimming can cause human health problems.

• The decrease of solar radiation may profoundly influence surface temperature, evaporation, the hydrological (H20) cycle and ecosystems (Wild, 2005).

• This may lead to drastic climate change. Earth life will struggle.

What are the effects of global dimming on our environment?

http://www.flickr.com/photos/kevineu/2734371684/http://gwichin.deviantart.com/art/apocalypse-112734832

http://sciencewithme.com/wpcontent/uploads/2010/11/photosynthesis_1.jpg

Developed countries like U.S. are affected by acid rain due to aerosol clouds

Sulfur aerosols when inhaled, can cause respiratory diseases (Shah, 2005)

Ecological problems: changes in evaporation, rainfall patterns, and photosynthesis rates.

Reduces rainfall and threatens fresh water. Famines during 1970’s and 1980’s Life-bringing rainfall and monsoons, absence of

seasonal rains affect billions of people worldwide. (Shah, 2005).

http://www.clickgreen.org.uk

Impacts of Global Dimming

http://www.bastarrachana.com/site/images/stories/india_-_drought.jpg

http://www.photobucket.com

Combating Global Dimming

The Goal is to reduce the amount of PM Urban Sprawl Lower use of aerosol cans Reduce pollutions Use public transportation Use alternative fuel Stricter industrial regulations

http://www.mustseesandiego.com/transportation.htm

http://www.kianjoocan.com.my/images/index/aerosol.html

Most of the globe has sparse population this suggests that solar dimming is basically of a local nature- not global (Alpert, 2011).

Most scientist do not believe it exists (Adam, 2003).

Most studies were done in the 1950’s not relevant to the 21st century.

We have learned that global dimming is the reduction in emittance of global solar radiation and that is mostly due to the use of aerosols and urbanization.

It impacts our environment.

There are ways to combat global dimming.

Weaknesses and Conclusions

Last but not least…

Questions??

Reduce pollution for a sunny solution!

Adam, D. (2003). Goodbye Sunshine. The Guardian. Retrieved from http://www.guardian.co.uk/science/2003/dec/18/science.research1

Alpert, P., Kishcha, P., Kaufman Y.J, & Schwarzbard R. (2005). Global dimming or local dimming?: Effect of urbanization on sunlight availability, Geophys. Res. Lett., 32, L17802, doi:10.1029/2005GL023320. Retrieved from

http://www.medclivar.eu/Final_Conference/.%5Cpresentazioni%5CConference%5C6June%5Cplenary%5CPAlpert.pdf Austin, N. (2006). Climatic 9/11. Retrieved from http

://www.journal.au.edu/au_techno/2006/july06/vol10no1_edit.pdf Hansen, J., Sato, M., Ruedy, R., Lacis, A., Oinas, V. (2000). Global Warming in the Twenty-First Century: An

Alternative Scenario. Retrieved from http://www.pnas.org/content/97/18/9875.short Lohmann, U., Feichter, J. (2005). Global indirect aerosol effects: a review. Retrieved from

http://hal.archivesouvertes.fr/docs/00/29/56/33/PDF/acp-5-715-2005.pdf Sarma, B. (1996). Climatic Design manual for Building Design in Bangladesh. Retrieved from http://www.bdresearchers.org/pub/files/GlobalClimateChanges.pdf Shah, A. (2005) Global Dimming. Retrieved from http://www.globalissues.org/article/529/global-dimming Streets, D. G., Y. Wu, and M. Chin (2006), Two-decadal aerosol trends as a likely explanation of the global dimming/brightening transition, Geophys. Res. Lett., 33, L15806, doi:10.1029/2006GL026471. Wild, M., Ohmura, A., & Makowski, K. (2007). Impact of global dimming and brightening on global warming.

Geophysical Research Letters, Vol. 34, L04702, doi:100.1029/2006GL028031, Retrieved from http://www.iac.ethz.ch/doc/publications/2006GL028031.pdf

Wild, M. (2007). Global Dimming and Brightening: A Review. Geophysical Research Letters, VOL. 34, L04702: doi:10.1029/2006GL028031. Retrieved from http://environmentportal.in/files/Global%20dimming%20and%20brightening.pdf

References