Exposed soil caused
increased atmospheric dust loads (Nicholson, 2000, 2001).
The increased atmospheric dust load during glacial times is thought to be due to a generally colder and drier atmosphere, which increased the number and strength of dust sources through reduced vegetation cover (28), and reduced washout of suspended particles during transport (7).
Not exact matches
In the clouds in her model,
atmospheric gas would sometimes condense onto the shimmering
dust particles,
increasing in size to a few millimeters big.
Ice sheet albedo forcing is estimated to have caused a global mean forcing of about — 3.2 W m — 2 (based on a range of several LGM simulations) and radiative forcing from
increased atmospheric aerosols (primarily
dust and vegetation) is estimated to have been about — 1 W m — 2 each.
This was a relatively stable climate (for several thousand years, 20,000 years ago), and a period where we have reasonable estimates of the radiative forcing (albedo changes from ice sheets and vegetation changes, greenhouse gas concentrations (derived from ice cores) and an
increase in the
atmospheric dust load) and temperature changes.
Claquin et al's model - derived findings show a change in tropical
atmospheric forcing of «-- 2.2 to — 3.2 W m — 2» between PI and LGM earth, due to the
increased albedo of
atmospheric dust.
CO2's effect of stimulating plant growth and
increasing plant tolerance of aridity contributed to revegetating large areas of land that were desert at the LGM, compounding the effects of an
increase in
atmospheric humidity, reduced land / ocean surface ocean ration, and
increased warmth, all of which combined caused the reduction of airborne
dust and atmosperic albedo.
Figure 1 shows the
increase in model
atmospheric dust when this source is added, relative to a simulation without the added
dust source.
«The beginning of the Bølling - Alleröd warm period was marked in Greenland by an abrupt rise in 18O, an abrupt drop in
dust rain, and an abrupt
increase in
atmospheric methane content.
Most of the GMT drop has been attributed to radiative forcing decreases from
increased albedo due to equatorward ice extension and from decreased greenhouse gas concentrations; vegetation and
atmospheric dust are thought to play secondary roles (20, 21).
Comment: The observed rapid climate change events, «RCCEs» are becoming stronger based on a significant
increase in
atmospheric dust in both the Antarctic and Greenland ice cores during the last glacial period, as compared to past glacial periods.
Among illustrative irreversible impacts that should be expected if
atmospheric carbon dioxide concentrations
increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450 — 600 ppmv over the coming century are irreversible dry - season rainfall reductions in several regions comparable to those of the «
dust bowl» era and inexorable sea level rise.
Its current
dust output is essentially transport - limited, but with expected changes in future
atmospheric circulation in response to
increasing greenhouse gas concentrations, changes to deflation in the Bodélé may impose critical changes on the behavior of the Earth system in response to the role that
dust plays in the biosphere and the sheer quantity emitted from this key region.