ellisbrown/BDML25SP_hw1_processed_data

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conﬁdence ), retreating glaciers ( very high conﬁdence ), and thawing
of permafrost ( medium conﬁdence ). Reductions in glacier and
snow cover have directly altered the structure of many freshwater
communities ( high conﬁdence ). Reduced snow cover has negatively
impacted the reproductive ﬁtness of some snow-dependent
plant and animal species, including foraging and predator-prey
relationships of mammals ( high conﬁdence ). Upslope migration
of individual species, mostly due to warming and to a lesser extent
due to cryosphere-related changes, has often increased local species
richness ( very high conﬁdence ). Some cold-adapted species, including
endemics, in terrestrial and freshwater communities have declined
in abundance ( high conﬁdence ). While the plant productivity has
generally increased, the actual impact on provisioning, regulating and
cultural ecosystem services varies greatly ( high conﬁdence ). {2.3.3}
Tourism and recreation activities such as skiing, glacier
tourism and mountaineering have been negatively impacted
by declining snow cover, glaciers and permafrost ( medium
conﬁdence ). In several regions, worsening route safety has reduced
mountaineering opportunities ( medium conﬁdence ). Variability and
decline in natural snow cover have compromised the operation of
low-elevation ski resorts ( high conﬁdence ). Glacier and snow decline
have impacted aesthetic, spiritual and other cultural aspects of
mountain landscapes ( medium conﬁdence ), reducing the well-being
of people (e.g., in the Himalaya, eastern Africa, and the tropical
Andes). {2.3.5, 2.3.6}
Adaptation in agriculture, tourism and drinking water supply
has aimed to reduce the impacts of cryosphere change
(medium conﬁdence ), though there is limited evidence on their
effectiveness owing to a lack of formal evaluations, or technical,
ﬁnancial and institutional barriers to implementation. In some
places, artiﬁcial snowmaking has reduced the negative impacts on
ski tourism ( medium conﬁdence ). Release and storage of water from
reservoirs according to sectoral needs (agriculture, drinking water,
ecosystems) has reduced the impact of seasonal variability on runoff (medium conﬁdence ). {2.3.1, 2.3.5}
Future projections of cryospheric changes, their impacts
and risks, and adaptation in high mountain areas
Snow cover, glaciers and permafrost are projected to continue
to decline in almost all regions throughout the 21st century
(high conﬁdence ). Compared to 1986–2005, low elevation snow
depth will likely decrease by 10–40% for 2031–2050, regardless of Representative Concentration Pathway (RCP) and for 2081–2100,
likely by 10–40 % for RCP2.6 and by 50–90% for RCP8.5. Projected
glacier mass reductions between 2015–2100 are likely 22–44% for
RCP2.6 and 37–57% for RCP8.5. In regions with mostly smaller glaciers and relatively little ice cover (e.g., European Alps, Pyrenees, Caucasus, North Asia, Scandinavia, tropical Andes, Mexico, eastern Africa and Indonesia), glaciers will lose more than 80% of their current mass by 2100 under RCP8.5 ( medium conﬁdence ), and
many glaciers will disappear regardless emission scenario ( very high
conﬁdence ). Permafrost thaw and degradation will increase during
the 21st century ( very high conﬁdence ) but quantitative projections
are scarce. {2.2.2, 2.2.3, 2.2.4}
Most types of natural hazards are projected to change in
frequency, magnitude and areas affected as the cryosphere
continues to decline (high conﬁdence ). Glacier retreat and
permafrost thaw are projected to decrease the stability of mountain
slopes and increase the number and area of glacier lakes ( high
conﬁdence ). Resulting landslides and ﬂoods, and cascading events,
will also emerge where there is no record of previous events ( high
conﬁdence ). Snow avalanches are projected to decline in number
and runout distance at lower elevation, and avalanches involving wet snow even in winter will occur more frequently ( medium conﬁdence ).
Rain-on-snow ﬂoods will occur earlier in spring and later in autumn,
and be more frequent at higher elevations and less frequent at lower
elevations ( high conﬁdence ). {2.3.2, 2.3.3}
River runoff in snow dominated and glacier-fed river basins
will change further in amount and seasonality in response to
projected snow cover and glacier decline ( very high conﬁdence )
with negative impacts on agriculture, hydropower and water
quality in some regions ( medium conﬁdence ). The average
winter snowmelt runoff is projected to increase ( high conﬁdence ), and
spring peaks to occur earlier ( very high conﬁdence ). Projected trends
in annual runoff vary substantially among regions, and can even be opposite in direction, but there is high conﬁdence that in all regions
average annual runoff from glaciers will have reached a peak that
will be followed by declining runoff at the latest by the end of the
21st century. Declining runoff is expected to reduce the productivity
of irrigated agriculture in some regions ( medium conﬁdence ).
Hydropower operations will increasingly be impacted by altered
amount and seasonality of water supply from snow and glacier melt
(high conﬁdence ). The release of heavy metals, particularly mercury,
and other legacy contaminants currently stored in glaciers and permafrost, is projected to reduce water quality for freshwater biota, household use and irrigation ( medium conﬁdence ). {2.3.1}
Current trends in cryosphere-related changes in high mountain
ecosystems are expected to continue and impacts to intensify
(very high conﬁdence ). While high mountains will provide new and
greater habitat area, including refugia for lowland species, both range
expansion and shrinkage are projected, and at high elevations this
will lead to population declines ( high conﬁdence ). The latter increases
the risk of local extinctions, in particular for freshwater cold-adapted
species ( medium conﬁdence ). Without genetic plasticity and/or
behavioural shifts, cryospheric changes will continue to negatively
impact endemic and native species, such as some coldwater ﬁsh

49Technical Summary
TS(e.g., trout) and species whose traits directly depend on snow
(e.g., snowshoe hares) or many large mammals ( medium conﬁdence ).
The survival of such species will depend on appropriate conservation and adaptation measures ( medium conﬁdence ). Many projected
ecological changes will alter ecosystem services ( high conﬁdence ),
affecting ecological disturbances (e.g., ﬁre, rock fall, slope erosion) with considerable impacts on people ( medium conﬁdence ). {2.3.3}
Cultural assets, such as snow- and ice-covered peaks in many
UNESCO World Heritage sites, and tourism and recreation
activities, are expected to be negatively affected by future
cryospheric change in many regions ( high conﬁdence ). Current
snowmaking technologies are projected to be less effective in
a warmer climate in reducing risks to ski tourism in most parts of
Europe, North America and Japan, in particular at 2ºC global warming
and beyond ( high conﬁdence ). Diversiﬁcation through year-round

conﬁdence ), retreating glaciers ( very high conﬁdence ), and thawing

of permafrost ( medium conﬁdence ). Reductions in glacier and

snow cover have directly altered the structure of many freshwater

communities ( high conﬁdence ). Reduced snow cover has negatively

impacted the reproductive ﬁtness of some snow-dependent

plant and animal species, including foraging and predator-prey

relationships of mammals ( high conﬁdence ). Upslope migration

of individual species, mostly due to warming and to a lesser extent

due to cryosphere-related changes, has often increased local species

richness ( very high conﬁdence ). Some cold-adapted species, including

endemics, in terrestrial and freshwater communities have declined

in abundance ( high conﬁdence ). While the plant productivity has

generally increased, the actual impact on provisioning, regulating and

cultural ecosystem services varies greatly ( high conﬁdence ). {2.3.3}

Tourism and recreation activities such as skiing, glacier

tourism and mountaineering have been negatively impacted

by declining snow cover, glaciers and permafrost ( medium

conﬁdence ). In several regions, worsening route safety has reduced

mountaineering opportunities ( medium conﬁdence ). Variability and

decline in natural snow cover have compromised the operation of

low-elevation ski resorts ( high conﬁdence ). Glacier and snow decline

have impacted aesthetic, spiritual and other cultural aspects of

mountain landscapes ( medium conﬁdence ), reducing the well-being

of people (e.g., in the Himalaya, eastern Africa, and the tropical

Andes). {2.3.5, 2.3.6}

Adaptation in agriculture, tourism and drinking water supply

has aimed to reduce the impacts of cryosphere change

(medium conﬁdence ), though there is limited evidence on their

effectiveness owing to a lack of formal evaluations, or technical,

ﬁnancial and institutional barriers to implementation. In some

places, artiﬁcial snowmaking has reduced the negative impacts on

ski tourism ( medium conﬁdence ). Release and storage of water from

reservoirs according to sectoral needs (agriculture, drinking water,

ecosystems) has reduced the impact of seasonal variability on runoff (medium conﬁdence ). {2.3.1, 2.3.5}

Future projections of cryospheric changes, their impacts

and risks, and adaptation in high mountain areas

Snow cover, glaciers and permafrost are projected to continue

to decline in almost all regions throughout the 21st century

(high conﬁdence ). Compared to 1986–2005, low elevation snow

depth will likely decrease by 10–40% for 2031–2050, regardless of Representative Concentration Pathway (RCP) and for 2081–2100,

likely by 10–40 % for RCP2.6 and by 50–90% for RCP8.5. Projected

glacier mass reductions between 2015–2100 are likely 22–44% for

RCP2.6 and 37–57% for RCP8.5. In regions with mostly smaller glaciers and relatively little ice cover (e.g., European Alps, Pyrenees, Caucasus, North Asia, Scandinavia, tropical Andes, Mexico, eastern Africa and Indonesia), glaciers will lose more than 80% of their current mass by 2100 under RCP8.5 ( medium conﬁdence ), and

many glaciers will disappear regardless emission scenario ( very high

conﬁdence ). Permafrost thaw and degradation will increase during

the 21st century ( very high conﬁdence ) but quantitative projections

are scarce. {2.2.2, 2.2.3, 2.2.4}

Most types of natural hazards are projected to change in

frequency, magnitude and areas affected as the cryosphere

continues to decline (high conﬁdence ). Glacier retreat and

permafrost thaw are projected to decrease the stability of mountain

slopes and increase the number and area of glacier lakes ( high

conﬁdence ). Resulting landslides and ﬂoods, and cascading events,

will also emerge where there is no record of previous events ( high

conﬁdence ). Snow avalanches are projected to decline in number

and runout distance at lower elevation, and avalanches involving wet snow even in winter will occur more frequently ( medium conﬁdence ).

Rain-on-snow ﬂoods will occur earlier in spring and later in autumn,

and be more frequent at higher elevations and less frequent at lower

elevations ( high conﬁdence ). {2.3.2, 2.3.3}

River runoff in snow dominated and glacier-fed river basins

will change further in amount and seasonality in response to

projected snow cover and glacier decline ( very high conﬁdence )

with negative impacts on agriculture, hydropower and water

quality in some regions ( medium conﬁdence ). The average

winter snowmelt runoff is projected to increase ( high conﬁdence ), and

spring peaks to occur earlier ( very high conﬁdence ). Projected trends

in annual runoff vary substantially among regions, and can even be opposite in direction, but there is high conﬁdence that in all regions

average annual runoff from glaciers will have reached a peak that

will be followed by declining runoff at the latest by the end of the

21st century. Declining runoff is expected to reduce the productivity

of irrigated agriculture in some regions ( medium conﬁdence ).

Hydropower operations will increasingly be impacted by altered

amount and seasonality of water supply from snow and glacier melt

(high conﬁdence ). The release of heavy metals, particularly mercury,

and other legacy contaminants currently stored in glaciers and permafrost, is projected to reduce water quality for freshwater biota, household use and irrigation ( medium conﬁdence ). {2.3.1}

Current trends in cryosphere-related changes in high mountain

ecosystems are expected to continue and impacts to intensify

(very high conﬁdence ). While high mountains will provide new and

greater habitat area, including refugia for lowland species, both range

expansion and shrinkage are projected, and at high elevations this

will lead to population declines ( high conﬁdence ). The latter increases

the risk of local extinctions, in particular for freshwater cold-adapted

species ( medium conﬁdence ). Without genetic plasticity and/or

behavioural shifts, cryospheric changes will continue to negatively

impact endemic and native species, such as some coldwater ﬁsh

49Technical Summary

TS(e.g., trout) and species whose traits directly depend on snow

(e.g., snowshoe hares) or many large mammals ( medium conﬁdence ).

The survival of such species will depend on appropriate conservation and adaptation measures ( medium conﬁdence ). Many projected

ecological changes will alter ecosystem services ( high conﬁdence ),

affecting ecological disturbances (e.g., ﬁre, rock fall, slope erosion) with considerable impacts on people ( medium conﬁdence ). {2.3.3}

Cultural assets, such as snow- and ice-covered peaks in many

UNESCO World Heritage sites, and tourism and recreation

activities, are expected to be negatively affected by future

cryospheric change in many regions ( high conﬁdence ). Current

snowmaking technologies are projected to be less effective in

a warmer climate in reducing risks to ski tourism in most parts of

Europe, North America and Japan, in particular at 2ºC global warming

and beyond ( high conﬁdence ). Diversiﬁcation through year-round