Abstract: It is well known that the long-term variations of the Earth's climate are controlled by the geometric relationships between the Earth and the Sun.However,15%~20% of the long-term variations remain unexplained.As for the short-term variations,many hypotheses are circulating.Among them,dominant is the North Atlantic related.It states that the short-term variations have been controlled by the variations of the sea-surface temperature in the North Atlantic.Nevertheless,variations of sub-orbital timescale in ENSO of the Tropical Pacific may be more qualified in modulating the global sub-orbital changes.Furthermore,the biggest continent,Eurasia,might have played much more important role than it has been thought.For instance,the changes in both the extent of the arid-semiarid areas and the efficiency of atmospheric dust supply from these areas in the east-central Asia might have been very significant in affecting the albedo and dust supply to the mid-latitude oceans.The albedo controls the temperature and the dust supply modulates the atmospheric CO₂ level through providing the iron fertilization to nitrogen and carbon fixation that consumes atmospheric CO₂.

Key words: arid area, east-central Asia, quaternary, global change