Snow cover and Ole Humlum

The Northern Hemisphere snow cover extent is subject to large local and regional variations from year to year. However, the overall tendency (since 1972) is towards stable Northern Hemisphere snow conditions, as illustrated in Figure 41.

Snow cover extent in the Northern Hemisphere has declined significantly over the past 90 years, with most of the reductions occurring since 1980. Over the period 1967–2015, snow cover extent in the Northern Hemisphere has decreased by 7 % on average in March and April and by 47 % in June; the observed reductions in Europe are even larger, at 13 % for March and April and 76 % for June.

Snow mass in the Northern Hemisphere is estimated to have decreased by 7 % in March from 1982 to 2009; snow mass in Europe has decreased more rapidly than the average for the Northern Hemisphere, but with large interannual variation.

Model simulations project widespread reductions in the extent and duration of snow cover in the Northern Hemisphere and in Europe over the 21st century.

Changes in snow cover affect the Earth's surface reflectivity, water resources, flora and fauna and their ecology, agriculture, forestry, tourism, snow sports, transport and power generation.

Satellite observations of monthly snow cover extent in the Northern Hemisphere are available from 1967 onwards [i]. A detailed analysis based on multiple sources shows there have been significant decreases in Northern Hemisphere snow cover extent during the spring melt season since about 1980 (March to June; Figure 1, left) [ii]; in other seasons, the snow cover extent has remained stable or even slightly increased. A separate analysis for Europe (EEA-39 region) shows even larger reductions of 13 % for March and April, and 76 % for June between 1980 and 2015 (Figure 1, right).

Decreases in snow cover extent are caused by an earlier onset of melting and a shorter duration of the snow season. Since 1972, the duration of the snow season averaged over the Northern Hemisphere declined by five days per decade, but with substantial regional variation. The duration of the snow season has decreased by up to 25 days in western, northern and eastern Europe due to earlier spring melt, whereas it has increased by up to 15 days in south-eastern Europe due to an earlier onset of the snow season [iii].

The snow mass (i.e. the amount of water that the snow contains) is an important variable, as it affects the role of snow in the hydrological cycle. For the whole of the Northern Hemisphere, a 7 % decrease in March snow mass was observed between 1982 and 2009 [iv]. An extension of this data focusing on EEA member countries demonstrates a stronger average decline of 30 % for the period 1980–2015, although the year-to-year variation is large (Figure 2). Winter increases in precipitation have also led to an increase in snow mass at higher altitudes in Norway.

Satellite observations of monthly snow cover extent in the Northern Hemisphere are available from 1967 onwards [i]. A detailed analysis based on multiple sources shows there have been significant decreases in Northern Hemisphere snow cover extent during the spring melt season since about 1980 (March to June; Figure 1, left) [ii]; in other seasons, the snow cover extent has remained stable or even slightly increased. A separate analysis for Europe (EEA-39 region) shows even larger reductions of 13 % for March and April, and 76 % for June between 1980 and 2015 (Figure 1, right).

Decreases in snow cover extent are caused by an earlier onset of melting and a shorter duration of the snow season. Since 1972, the duration of the snow season averaged over the Northern Hemisphere declined by five days per decade, but with substantial regional variation. The duration of the snow season has decreased by up to 25 days in western, northern and eastern Europe due to earlier spring melt, whereas it has increased by up to 15 days in south-eastern Europe due to an earlier onset of the snow season [iii].

The snow mass (i.e. the amount of water that the snow contains) is an important variable, as it affects the role of snow in the hydrological cycle. For the whole of the Northern Hemisphere, a 7 % decrease in March snow mass was observed between 1982 and 2009 [iv]. An extension of this data focusing on EEA member countries demonstrates a stronger average decline of 30 % for the period 1980–2015, although the year-to-year variation is large (Figure 2). Winter increases in precipitation have also led to an increase in snow mass at higher altitudes in Norway.

Satellite observations of monthly snow cover extent in the Northern Hemisphere are available from 1967 onwards [i]. A detailed analysis based on multiple sources shows there have been significant decreases in Northern Hemisphere snow cover extent during the spring melt season since about 1980 (March to June; Figure 1, left) [ii]; in other seasons, the snow cover extent has remained stable or even slightly increased. A separate analysis for Europe (EEA-39 region) shows even larger reductions of 13 % for March and April, and 76 % for June between 1980 and 2015 (Figure 1, right).

Decreases in snow cover extent are caused by an earlier onset of melting and a shorter duration of the snow season. Since 1972, the duration of the snow season averaged over the Northern Hemisphere declined by five days per decade, but with substantial regional variation. The duration of the snow season has decreased by up to 25 days in western, northern and eastern Europe due to earlier spring melt, whereas it has increased by up to 15 days in south-eastern Europe due to an earlier onset of the snow season [iii].

The snow mass (i.e. the amount of water that the snow contains) is an important variable, as it affects the role of snow in the hydrological cycle. For the whole of the Northern Hemisphere, a 7 % decrease in March snow mass was observed between 1982 and 2009 [iv]. An extension of this data focusing on EEA member countries demonstrates a stronger average decline of 30 % for the period 1980–2015, although the year-to-year variation is large (Figure 2). Winter increases in precipitation have also led to an increase in snow mass at higher altitudes in Norway.

Jo sørme der er et betydeligt fald om sommeren af et næsten mikroskopisk snedække for den nordlige halvkugle.

Men hvis det er " forfalskningerne" så har du vel link og dokumentation for en sådan påstand.

Jørgen Petersen skrev:
Bullshit

Jørgen Petersen skrev:
Vi kan da starte med at kigge på udviklingen i antallet af mennesker som mister livet pga. naturkatastroffer og ekstrem vejrs hændelser med mere.

delphi skrev:

Jørgen Petersen skrev:
Vi kan da starte med at kigge på udviklingen i antallet af mennesker som mister livet pga. naturkatastroffer og ekstrem vejrs hændelser med mere.

På alle klimarelaterede forhold i naturen ser vi en massiv aftagende tendens: arealer som er tørkeramt, kraftige vejrfenomener, nedgang i fødevareproduktionen, oversvømmelser, skovbrænde, dyr som dør som følge af brænde osv.

Jørgen Petersen skrev:
Faldet er så kraftigt at det sidste årti i princippet er ligegyldigt.