Snowmelt

In

There are several energy fluxes involved in the melting of snow.

Evergreen trees tend to produce larger thaw circles than deciduous trees. This involves largely a different mechanism and spring ephemeral plants don't occur there.^[4]

The snow melts earlier in forest also for example on microtopographic mounds (small elevations) or in wet places like edges of creeks or in seeps. These microsites affect distribution of many herbs too.^[4]

Historical cases

In northern Alaska, the melt-date has advanced by 8 days since the mid-1960s. Decreased snowfall in winter followed by warmer spring conditions seems to be the cause for the advance.^[5] In Europe, the 2012 heat wave has especially been anomalous at higher altitudes. For the first time on record, some of the highest Alpine peaks in Europe were snow-free. Although it would seem that the two were related, the question of how much of this is due to climate change firmly remains a center of debate.^[6]

Increased water runoff due to snowmelt was a cause of many famous floods. One well-known example is the

The date of annual melt is of great interest as a potential indicator of climate change. In order to determine whether the earlier disappearance of spring snow cover in northern Alaska is related to global warming versus an appearance of a more natural, continual cycle of the climate, further study and monitoring is necessary.[8]

Large year-to-year variability complicates the picture and furthers the debate. Inter-annual variability of springtime snow pack comes largely from variability of winter month precipitation which is in turn related to the variability of key patterns of atmospheric circulation.

A study of the mountains in the western United States show a region wide decline in spring snow-pack since the mid-1900s, dominated by loss at low elevations where winter temperatures are near freezing. These losses are an indication of increased temperatures which lead to snow loss via some combination of increased regularity of rain versus snow and increased melting during winter months. These natural variations make it challenging to quantify trends with confidence, to deduce observed changes to predict future climate, or to clearly detect changes in snow-pack due to human impact on warming trends.^[9]

See also

• Albedo
• Ice melt
• Snowmelt system
• Snowpack

Gallery

• Dust accelerates snow melt in the San Juan Mountains
• 
  2005 (Less dust)
• 
  2006 (More dust)
• 
  2008 (Less dust)
• 
  2009 (More dust)

References