Glacial Inceptions: Past and Future. Lawrence A. Mysak with Z. Wang, A.-S. Cochelin and Y. Wang Atmospheric & Oceanic Sciences, McGill University, Montreal, Canada. C 2 GCR GEC3 (2004). www.esmg.mcgill.ca. Recent Collaborators:.
Lawrence A. Mysak
with Z. Wang, A.-S. Cochelin and Y. Wang
Atmospheric & Oceanic Sciences,
McGill University, Montreal, Canada
C2GCR GEC3 (2004)
last glacial inception
The natural evolution of the climate
The primary driver of ice ages is the summer solar radiation received in high northern latitudes (Milankovitch 1930, 1941).
This insolation depends on the variations of 3 orbital parameters of the Earth’s motion about the Sun:
The combined movement has a strong cycle near 23 kyr. However, this cycle is modulated by the eccentricity, resulting in a quantity called the “climatic precession”.
T = 41 kyr
T = 25.7 kyr
T = 400 kyr and 100 kyr
(Berger, 1978, JAS)
(Berger, 1978, JAS)
AGCMs with Milankovitch forcing (and prescribed atmospheric CO2); time-slice runs:
Showed vegetation important
Ice sheet growth too small
High-latitude (70°N, 80°W) snow accumulation at 115 kyr BP in coupled A-O GCM over a 40-year period (Khodri et al., 2001)
115 kyr BP
EMICs with Milankovitch forcing (and prescribed CO2); transient runs:
EMIC transient runswith vegetation continued:
1. An important time-slice investigation which looked at the role of vegetation on temperature and sea-ice cover:
2. In all the above references, the atmospheric CO2 was prescribed.
Archer and Ganopolski (2005, G3): Simulation of past and future (?) glacials using an EMIC with an interactive carbon cycle.
Earth system models of intermediate complexity: closing the gap in the spectrum of climate system models
FLORA OF THE OCEANS
FAUNA OF THE OCEANS
implemented into EMICs (Claussen et al., 2002)
(Wang and Mysak, 2000)
Paleoceanographic data reveal:
Jerry McManus, pers. comm. (2002)
Run 1 (control run – in red) produces the most rapid ice sheet growth.
Run 7 (only Milankovitch forcing – in black) produces the smallest ice volume.
For a rapid ice sheet growth, the elevation effect of mountains, freezing of rain and refreezing of meltwater, and an active ocean component are necessary.Ice sheet growth in the geophysical MPM
Figure 2. Simulated ice volume growths.
The THC is significantly intensified for run 1 (in red) due to the high latitude cooling and reduced freshwater flux.
The strong THC maintains a large land-sea thermal contrast at high latitudes and hence is favorable for rapid ice sheet growth due to moisture transport from the ocean to the land.THC response and its effect on ice sheet growth
Figure 3. The maximum THC intensities and freshwater flux anomalies.
Figure 4. Ice sheet thickness over North America and Eurasia for run 1 (control run) at 120 kyr BP (a), 116 kyr BP (b), and 110 kyr BP (c).
Simulation of glacial inception in the “green” MPM geophysical MPM
(Cochelin, 2004, MSc thesis; Wang et al., 2005, GRL)
► We want to observe the changes in the climate simulation, due to the addition of the vegetation.
120 kyr BP
100 kyr BP
90 kyr BP
116 kyr BP
110 kyr BP
80 kyr BP
“An Exceptionally Long Interglacial Ahead?”
Long-term variations of eccentricity (top), June insolation at 65°N (middle), and simulated Northern Hemisphere ice volume (increasing downward) (bottom) for 200,000 years before the present to 130,000 from now using the 2-D LLN EMIC.
Global Warming CO2
Constant CO2 (210 ppmv)
Cochelin et al. (2006, Clim. Change): Simulation of the next glacial inception.
in June, at 62.5°N
When will the next glaciation occur?
240 , 250, 260, 270, 280, 290 and 300 ppm.
240 – 270 ppm
≥ 300 ppm
280 – 290 ppm
peak of CO2
Atmospheric CO2 forcing
280 - 290 ppm
≥ 300 ppm
ICE VOLUME GROWTH
Archer and Ganopolski (2005, G kyr3): Simulation of past and future (?) glacials using an EMIC with an interactive carbon cycle.