Weather and Climate

1. The Climate System andClimate ChangeM.Abdel wahabUsama AnberFaculty of Science Cairo University

2. Weather and Climate Weather is what you get, Climate is what you expect E.Lorenz

4. The Climate System and Influences

5. Global warming  Heating  Temperature & Evaporation  water holding capacity  atmospheric moisture   greenhouse effect & rain intensity  Floods & Droughts

6. Climate change and its manifestation in terms of weather (climate extremes)

7. Greenhouse Gases • Nitrogen, Oxygen and Argon (99.9% volume mixing • ratio) have only limited interaction with incoming • solar radiation, and they do not interact with the • infrared radiation emitted by the Earth • A number of trace gases (carbon dioxide, methane, • nitrous oxide, and ozone) do absorb and emit • infrared radiation (as does water vapor) • Water vapor, carbon dioxide and ozone also absorb • solar shortwave radiation • Because they emit infrared radiation up- and • downward, these greenhouse gases increase the • energy received at the Earth’s surface, thus raising • the temperature

8. The carbon cycle • Humans put vast amounts of CO2 into the atmosphere. • The earth/atmosphere removes about half of it. • Exponential rise in concentration 250 - 370 ppm in last 150 Y. • Concentration increases by about 3.5 ppm/year. • Atmosphere oceans plantsanimalsearth. • Humans and volcanoes return CO2 to the atmosphere.

9. CO2 CH4 N2O Changing Atmospheric Composition: Indicators of the Human Influence Global, well-mixed greenhouse gas (GHG) concentrations • 31% increase since 1750: Highest levels • since at least 420,000 years ago • Rate of increase unprecedented over • at least the last 20,000 years • Increased 150% since 1750 to its highest • levels in at least 420,000 years • Increased 16% since 1750 to its highest • levels in at least 1,000 years 1000 1200 1400 1600 1800 2000 Year

11. Negative feedback

12. Positive feedback

13. Causesof Climate Change • Variation in solar output. • Period of about 11 years. • .1 - .2% due to sunspot activity. • Drought in Great Plains and Nile River drainage areas have been linked to this cycle. • The "Maunder Minimum" coincided with the Little Ice Age. • Fairly strong link between the sunspot cycle and the quasi-biennial oscillation of the stratosphere. • The sun's output has increased by about 1/3 since earth formed, yet warmest temperatures were in the past

14. Changes in Earth's Orbit • Milankovitch cycle • Eccentricity -- about 100 TY cycle. • Circular to highly elliptical. • Aphelion distance varied between 1 and 11% during last 600 TY. • Earth Sun distance varies  3% between Aphelion in July and Perihelion in January. • Earth receives about 7% more insolation in January than in July. • Has decreased for about 15 TY • Will decrease for another 35 TY.

15. Obliquity -- tilt of Earth's axis with respect to the orbital plane. • Varies 22.1° to 24.5°. • 41000-year cycle. • Higher latitudes effected more than lower. • Receive as much as 15% more radiation in summer when the tilt is greatest. • The most recent maximum tilt occurred about 10000 years ago.

16. Changes in Atmospheric Turbidity -- affect the surface and atmospheric energy balances. • Tropospheric Aerosols -- Cool the surface, short residence time. • Stratospheric Aerosols -- Cool the surface, long residence time.

17. Changes in Radiation Absorbing Gases -- Increases may warm the lower troposphere and cool the stratosphere. • Carbon Dioxide and other Green House Gases • Gases such as methane, nitrous oxide, and chlorofluorocarbons combined, produce as large an effect as carbon dioxide but carbon dioxide gets most of the press. • Atmospheric concentrations of these gases have increased steadily since the industrial revolution. • Green house gases directly affect the energy budget, but perhaps more important, the increase in lower tropospheric temperature raises water vapor concentrations. Since water vapor is a better green house gas than any of the others, this further raises temperatures.

19. Figure 2: Annual Temperature Trends, (°C / century) 1901-1999 Source: P. Jones, et. al. 2000.

21. Annual Global Mean Surface Temperature and Carbon Dioxide Concentrations CO2 Concentration (ppmv) Global Temperature (°C) T CO2 Year

22. Confidence in the ability of models to project future climate has increased Simulated Annual Global Mean Surface Temperatures

23. Will all regions in the world experience the same amount of climate change?NO • Some regions will response to global climate change more than do others. What are they ? • Regional Climate Change Index (RCCI) was developed to measure the so called Hotspots, that is, regions that are more responsive to global change. • Regional Climate Change Index (RCCI) is a comparative index based on: changes in mean precipitation, changes in mean regional temperature compared to global temperature change, changes in precipitation and temperature inter-annual variability.

24. Output Data from 14 GCMs. • Three Emission Scenarios, B1, A2 and A1B. (Scenario Ensemble ) • Applying the RCCI to study the regional variability in climate over Africa during the 21st century. • Results show that Southern Mediterranean (SMED) and Sahara (SAH) are the most sensitive regions to global climate change than any other regions in Africa. • Egypt lies in these two regions.

25. Hotspots over Africa at the beginning of the 21st century

26. Hotspots over Africa at the end of the 21st century

27. Situation in Egypt at the beginning and at the end of the 21st century

28. Thank You!