Summary

Question 1

Effects of Global Warming

Answer 1

1. Global surface temperature and SST up.
   (Short-wave radiation from sun hits earth and
   bounces back as long-wave heat that tries to
   escape and is blocked by GHGs.)
   –Note: Air temp. has not gone up in 15 years,
   but SST has.
2. Stronger convection so ET up, especially from
   tropical seas, land surface in northern
   hemisphere (surface drying).
   –More CO2 causes plants to open stomata,
   more water loss. But when hot, plants close
   stomata and limit CO2 intake, increased water
   efficiency (use less water), thus more runoff.
   –Forest mortality up, esp. arid ecotones, drought
   makes trees more vulnerable to other factors
   (competition for water, infestation), with +
   feedback CO2.
   Note: Tropical forest mitigates warming with
   more evaporative cooling, CO2 storage.
   Boreal forest will enhance warming Arctic.
   Role of temperate forest unknown.
   –Soil moisture, groundwater levels down.
   –More drought, heat waves, wild fires.
3. Water-holding capacity up [C-C (7%/1-deg C)]
   –More vapor, more GHG.
   –More latent heat & moisture in atmosphere for
   storms.
   –Vapor less dense than rain, storms draw
   moisture from larger area (moisture
   convergence), but less circulation/movement
   needed for rain because air warmer, has more
   energy/pressure.
   –Narrowing convergence zones, storm tracks
   shift pole-ward.
4. Precipitation greater in already wet regions
   (higher latitudes, tropical monsoon trough).
   –1-2% increase with 1-deg C rise.
   –Storms more intense, less frequent.
   –Increased flooding, infrastructure damage.
5. Precipitation decrease in already dry areas
   (subtropics, tropics outside of monsoon trough).
   –Hadley cell increases in latitude N & S, 1 deg.
   per decade.
   –Less water available in water-stressed regions
   that have most demand from population
   increase and economic development, Asia,
   India, Africa.
   –More intense droughts.
   Note: P, RFWR-uneven distribution time, space.
   Overall, more variability, shift in patterns.
6. Snow/ice cover down in northern hemisphere.
   –Less albedo, so + feedback of more heat
   absorbed/ less reflected. Less P as snow.
   –Earlier snowmelt/run off, less water storage for
   when demand greatest in late summer.
   –More water available for regions depending on
   glacial melt for summer water, but once melted,
   nothing. (Generally latitudes > 45 deg,)
   –Melting permafrost-more water, more CO2.
7. Rise in sea level.
   –Coastal flooding.
   –Saline intrusion of coastal water supplies.
   –Coral bleaching from warming, acidification.
8. Species extinction, migrations.

Question 2

External driver

Answer 2

Creates trend, climate change signal, which is response to external forcing of climate system.

1. GHGs (Burning fossil fuels, more CO2).
2. Deforestation.
3. Solar activity.
4. Volcanic activity.