Lecture 10: Contemporary climate change

Question 1

AEROSOL DIRECT EFFECTS

Answer 1

• Eruption of Mt Pinatubo in 1991
• Approximately 10 km3 of material were ejected
• noticeable drop in global average temperatures in subsequent years
• this reduction in temperatures is called a “volcanic winter”
• impressive sunsets worldwide

Question 2

INDIRECT EFFECTS FROM AEROSOL

Answer 2

• Indirect effects from aerosol describe all effects that are not related to direct interference of the particle with radiation.
• An important effect is the impact on cloud droplet size which affects both the cloud’s albedo and the amount of precipitation.
• Further effects include e.g. impacts on heterogeneous chemistry, cloud condensation processes etc.

Question 3

OZONE PHOTOSMOG (LOS-ANGELES-TYPE SMOG)

Answer 3

 First investigated in Los Angeles during 1950s (e.g., Haagen-Smit, 1952) 

High NOX emissions required, i.e. large amount of motor vehicle traffic  Large concentration of VOCs required (motor vehicles, industry, etc)

 Lots of sunlight (summer time)

 Low wind speed and atmospheric stable conditions (inversion)

Question 4

OZONE PHOTOSMOG (LOS-ANGELES-TYPE SMOG) 2

Answer 4

 Smog can last for several days
 High ozone concentrations cause respiratory problems (e.g., asthma)
 Can affect plants and crop yields (effects on agriculture)
 Oxidation of materials (e.g., structures, buildings, monuments)

Question 5

ATMOSPHERIC BROWN CLOUDS

Answer 5

Indoor and outdoor pollution consisting of particles and gases (NOX, CO, SO2, NH3, and many other VOCs and acids)

Five regional hotspots for Atmospheric Brown Clouds

 East Asia
 Indo-Gangetic Plain in South Asia  Southeast Asia
 Southern Africa
 the Amazon Basin

Question 6

ATMOSPHERIC BROWN CLOUDS: Radiative IMPACTS

Answer 6

Radiative Impacts
 Dimming of solar irradiance at the surface (sulphate aerosols)  Increase in atmospheric solar heating (black carbon, soot)
Dimming effect about 6% in China and India.
Absorbed solar radiation is today lower by 15 W m-2 compared with pre-industrial values.
By contrast, black carbon is believed to be responsible for an increase in the vertically averaged annual mean solar absorption in the troposphere by about 15%.

Question 7

ATMOSPHERIC BROWN CLOUDS: Meteorological IMPACTS

Answer 7

 Change in rainfall patterns
 Increased receding and thinning of glaciers
Rainfall in the northern half of India has decreased, rainfall patterns in China have shifted (believed to be caused by dimming).
Albedo changes and temperature increase affects glaciers and snowpacks in the Hindu Kush- Himalayan-Tibetan Region.

Question 8

ATMOSPHERIC BROWN CLOUDS: IMPACTS

Answer 8

consequences
 Changes in monsoon rainfall
and glacier extent will affect
water levels required for irrigation of crops
 Ground level ozone increases will affect crop yields
1985-1998 rice production decreased by 6.2 million tonnes in 9 South and East Asian
countries, including India (equal to the annual consumption of 72 million people)  Health effects from indoor and outdoor pollution
Affecting pulmonary and cardiovascular systems, leading to chronic respiratory problems, hospital admissions and deaths.

Question 9

ATMOSPHERIC AEROSOL LOADING PLANETARY BOUNDARY

Answer 9

Control variable:
• Overall particulate concentration in the
atmosphere (on a regional basis)
Thresholds of concern:
• Disruption of monsoon systems
• Human health effects
• Interacts with climate change
and freshwater supplies