Editing Snow (section)

===Distribution===
[[File:Snow-covered fir trees.jpg|thumb|Snow-covered trees in [[Kuusamo]], [[Finland]]]]
Glaciers with their permanent snowpacks cover about 10% of the earth's surface, while seasonal snow covers about nine percent,<ref name = Snowenclyclopedia/> mostly in the Northern Hemisphere, where seasonal snow covers about {{convert|40|e6km2}}, according to a 1987 estimate.<ref>
{{cite journal
 |last1        = Chang
 |first1       = A.T.C.
 |last2       = Foster
 |first2      = J.L.
 |last3       = Hall
 |first3      = D.K.
 |title       = NIMBUS-7 SMMR derived global snow parameters
 |journal     = Annals of Glaciology
 |volume      = 9
 |date        = 1987
 |df          = mdy-all
|doi = 10.1017/S0260305500200736
 |pages = 39–44
 |doi-access= free
 }}</ref> A 2007 estimate of snow cover over the Northern Hemisphere suggested that, on average, snow cover ranges from a minimum extent of {{convert|2|e6km2}} each August to a maximum extent of {{convert|45|e6km2}} each January or nearly half of the land surface in that hemisphere.<ref>
{{Citation
 | last = Lemke
 | first = P.
 | display-authors = etal
 | editor-last = Solomon
 | editor-first = S.
 | display-editors = etal
 | contribution = Observations: Changes in snow, ice and frozen ground
 | title = Climate Change 2007: The Physical Science Basis
 | year = 2007
 | pages = 337–383
 | place = New York
 | publisher = Cambridge Univ. Press
 }}</ref><ref name=Déry>
{{Citation
 |last1        = Déry
 |first1       = S. J
 |last2       = Brown
 |first2      = R. D.
 |title       = Recent Northern Hemisphere snow cover extent trends and implications for the snow-albedo feedback
 |journal     = Geophysical Research Letters
 |volume      = 34
 |issue       = L22504
 |pages       = L22504
 |year        = 2007
 |doi         = 10.1029/2007GL031474
 |bibcode       = 2007GeoRL..3422504D
 |doi-access= free
 }}</ref> A study of Northern Hemisphere snow cover extent for the period 1972–2006 suggests a reduction of {{convert|0.5|e6km2}} over the 35-year period.<ref name = Déry/>