4.Global warming.pptx

Global warming

Prepared for class discussion

By

Prof.S.Suryanarayanan

Process of global warming

• The temperature of the Earth is controlled by the balance between

the input from energy of the sun and the loss of this back into

space.• Certain atmospheric gases are critical to this temperature balance

and are known as greenhouse gases. • The energy received from the sun is in the form of short-wave

radiation, i.e. in the visible spectrum and ultraviolet radiation.

• On average, about one-third of this solar radiation that hits the

Earth is reflected back to space. Of the remainder, some is

absorbed by the atmosphere, but most is absorbed by the land and

oceans. • The Earth’s surface becomes warm and as a result emits long-wave

‘infrared’ radiation. • The greenhouse gases trap and re-emit some of this long-wave radiation,

and warm the atmosphere.

Greenhouse effect

• To a certain degree, the earth acts like a greenhouse. • Energy from the Sun penetrates the glass of a greenhouse

and warms the air and objects within the greenhouse. • The same glass slows the heat from escaping, resulting in

much higher temperatures within the greenhouse than outside it.

Greenhouse EffectSun

Effect of global warming

• Climate change-- regional temperature changes, precipitation changes, storm intensity.

• Rise in sea level• Pattern of agricultural production• Human health• Loss of bio diversity • Earth temperature expected to rise by 3 -5 °C if the

concentration of CO2 doubles from present level resulting in rise in sea level, melting of mountain glaciers and expansion of oceans. ( IPCC assessed 1°above 1990 level by 2005 and 3°C by21st century ).

Global Greenhouse Gas Emissions by Gas

Greenhouse gases

1. Carbon di oxide– main greenhouse gas,burning of fossil fuels

2. Methane– arises from rice paddies, wetlands ,burning of wood ,landfills

3. Chlorofluorocarbons ( CFCs )—reaches atmosphere from refrigeration and air-conditioning industry.

4. Nitrous oxide– from coal burning, biomass burning.

Control of greenhouse gases– global initiatives

• Rio earth summit 1992.• IPCC under UNEP AND WMO ( Intergovernmental Panel

for Climate Change under Unite Nations Environmental Programme and World meteorological Organisation ).

• UN Framework Convention on Climate Change,• Kyoto protocol 1997– To reduce GHG to 5.2 % level

below 1992 level by 2008-12. ( japan by 6%,US by &%,EU by 8% ).

• Clean Development Mechanism—investment and funding developing countries, carbon credits.

The Kyoto Protocol Summary( earthfriends.com/kyotoprtocol )

• The Kyoto Protocol was adopted in Kyoto, Japan on the 11th of December, 1997, but not enacted or enforced until the 16th of February, 2005

• The essence of the Kyoto Protocol is that it calls for nations to commit themselves to reducing greenhouse gas emissions. As of November 2009, 187 states have signed and ratified the protocol.

• The United States' position on the Kyoto Protocol has been a subject of controversy and frustration amongst the international community. Primarily because, despite being a member of the UNFCCC, the U.S., while having signed the protocol in 1998, has to this day not ratified it.

• The Kyoto Protocol's main goal is to reduce the presence of 4 harmful greenhouse gases (GHG's):

• Carbon Dioxide, Methane ,Nitrous Oxide ,Hydrofluorocarbons• The goal is to reduce emissions by 5.2%, compared to 1990 levels. • In addition, ratifiers of the Kyoto Protocol can purchase carbon

credits to help offset their emissions