1. Climate Change slides for Exam Two

2. GCMs General Circulation Models or Global Climate Models
Atmospheric Ocean GCMs (AOGCMs)
Modeling groups worldwide have developed GCMs
IPCC assesses impacts of projected increases in gg and consequences for 21st Century

3. podcast

5. Models have become increasingly sophisticated since first IPCC report in 1990
New models use range of gg emission scenarios (RCPs : Representative Concentration Pathways)
GG concentration trajectories; represent a range of climate outcomes

6. RCPs used in Fifth report (2013):
2100 RF relative to 1750
RCP2.6
2.6
RF peaks and declines
RCP4.5
4.5
RF stabilizes by 2100
RCP6.0
6.0
RF doesn’t peak by 2100
RCP8.5
8.5

7. What the models tell us:
Temperature
Water Cycle
Ocean
Cryosphere
Sea Level
Carbon Cycle
Climate Change Stabilization, Commitment and Irreversibility

8. A. Temperature Global surface temperature change by 2100:
exceed +1.5°C (relative to 1850 – 1900)
Warming will continue beyond 2100
Warming will still show variability and will not be regionally uniform
WHAT’S THE BIG DEAL ABOUT 1.5 DEGREES???
“A one-degree global change is significant because it takes a vast amount of heat to warm all the oceans, atmosphere, and land by that much. In the past, a one- to two-degree drop was all it took to plunge the Earth into the Little Ice Age. A five-degree drop was enough to bury a large part of North America under a towering mass of ice 20,000 years ago”.

9. Increase of global mean surface temperatures for 2081–2100 (late 21st Century) relative to 1986–2005 is projected to be:
0.3°C to 1.7°C
1.1°C to 2.6°C
1.4°C to 3.1°C
2.6°C to 4.8°C
Different RCPs

10. 6. Arctic region will warm more rapidly than the global mean
warming over land greater than over the ocean
8. more frequent hot and fewer cold temperature extremes over most land areas
9. heat waves will occur with a higher frequency and duration. Occasional cold winter extremes will continue to occur IPCC

11. B. Water Cycle
Changes in the global water cycle will not be uniform. The contrast in precipitation between wet and dry regions and between wet and dry seasons will increase.
1. high latitudes and the equatorial Pacific Ocean are likely to experience an increase in annual mean precipitation by the end of 21st century

12. 2. mid-latitude and subtropical dry regions, mean ppt will likely decrease 3. mid-latitude wet regions, mean ppt will likely increase 4. Extreme precipitation events over most of the mid-latitude land masses and wet tropical regions become more intense and more frequent

13. 5. area experiencing monsoon systems will increase over the 21st century. (While monsoon winds are likely to weaken, monsoon precipitation is likely to intensify ) 6. El Niño-Southern Oscillation (ENSO) will remain the dominant mode of interannual variability in the tropical Pacific IPCC

14. C. Ocean
“global ocean will continue to warm during the 21st century. Heat will penetrate from the surface to the deep ocean and affect ocean circulation”.
strongest surface ocean warming in tropical and Northern Hemisphere subtropical regions.
warming in the top 100 meters: 0.6°C to 2.0°C
At greater depth the warming in the Southern Ocean.
1000 m : 0.3°C to 0.6°C

15. 3. Atlantic Meridional Overturning Circulation (AMOC) will weaken
AMOC will undergo collapse in the 21st century. animation

16. D. Cryosphere
Arctic sea ice cover will continue to shrink and thin; Northern Hemisphere spring snow cover will decrease during the 21st century as global mean surface temperature rises. Global glacier volume will further decrease”.
Year-round reductions in Arctic sea ice extent are projected by the end of the 21st century
43% to 94% in September and from 8% to 34% in February
Arctic sea ice