The document discusses changes occurring in the cryosphere (frozen parts of the Earth's surface) including polar ice sheets, glaciers, sea ice and permafrost. It provides details on factors contributing to melting and decline of ice sheets in Greenland and Antarctica, such as rising air and ocean temperatures, increased surface meltwater, glacier acceleration and ice shelf instability. Graphs and maps show decreasing trends in Arctic sea ice extent, thickness and concentration over recent decades, as well as rising ice loss from both the Greenland and Antarctic ice sheets.
The total volume of water on Earth is estimated at 1.386 billion km³ (333 million cubic miles), with 97.5% being salt water and 2.5% being fresh water. Of the fresh water, only 0.3% is in liquid form on the surface. In addition, the lower mantle of inner earth may hold as much as 5 times more water than all surface water combined (all oceans, all lakes, all rivers).
S6E3. Students will recognize the significant role of water in earth processes.
Explain that a large portion of the Earth’s surface is water, consisting of oceans, rivers, lakes, underground water, and ice.
c. Describe the composition, location, and subsurface topography of the world’s oceans.
The Earth’s climate is dynamic and characterised by trends, aberrations and quasi-periodic oscillations varying over a broad range of time-scales [1], which are governed by external (extraterrestrial systems) and/or internal(ocean, atmosphere and land system). Trends are largely controlled by plate tectonics, and thus to change gradually on million year time scale. Aberrations occur when the certain thresholds are passed and are manifested in the geological record as the unusual rapid (less than a few thousands of years) or extreme change in climate. The quasi-periodic oscillations are mostly astronomically paced; they are driven by astronomical perturbations that affect the earth’s orbit around the sun and the orientation of earth’s rotation axis with respect to its orbital plane. These perturbations are described by the three main astronomical cycles: eccentricity, precession and obliquity, which together determine the spatial and seasonal pattern of insolation received by the earth [2], eventually resulting in climatic oscillations of ten to hundreds of thousands of year [3].Sun being the main source of energy for the earth system controls the climate of it. Variation in solar activity and cosmic ray intensity has direct influence over climatic features such as cloudiness, temperature and rainfall [4]. Volcanic eruptions also force all elements of the climatic systems up to a varying degree but producing long term climatic signals in the ocean. The cumulative volcanic cooling effect at present offsets about one third of anthropogenic warming [5].Other than these causes paleoclimatologists also relates the past climate changes with movement of solar system[6], interplanetary dusts and influence of asteroids[7].However the recent variability in climate what earth is experiencing is unlikely due to any of the individual above factors rather it is due to the compound effect of complex interactions of all the natural as well as anthropogenic forcings.
References:
1. J. C. Zachos, M. Pagani, L. Sloan, E. Thomas, K. Billups, Science 292 (2001) 686-693.
2. G. Kukla, Nature (London) 253, 600 (1975).
3. J. D. Hays, J. Imbrie, N. J. Shackleton, Science 194 (1876) 1121-1132.
4. N. Marsh, H. Swensmark, Space Sci. Rev. 94 (2000) 215-230.
5. T. L. Delworth, V. Ramaswamy, G. L. Stenchikov, Geophys. Res. Lett. 32 (2005) L24709.
6. K. Fuhrer, E. W. Wolf, S. J. Johnsen, J. Geophys. Res. 104(D24) (1999) 31043-31052
7. P. Hut, W. Alvarez, W. P. Elder, T. Hansen, E. G. Kauffman, G. Keller, E. M. Shoemaker & P. R. Weissman, Nature Vol. 329, 10 September, 1987
The total volume of water on Earth is estimated at 1.386 billion km³ (333 million cubic miles), with 97.5% being salt water and 2.5% being fresh water. Of the fresh water, only 0.3% is in liquid form on the surface. In addition, the lower mantle of inner earth may hold as much as 5 times more water than all surface water combined (all oceans, all lakes, all rivers).
S6E3. Students will recognize the significant role of water in earth processes.
Explain that a large portion of the Earth’s surface is water, consisting of oceans, rivers, lakes, underground water, and ice.
c. Describe the composition, location, and subsurface topography of the world’s oceans.
The Earth’s climate is dynamic and characterised by trends, aberrations and quasi-periodic oscillations varying over a broad range of time-scales [1], which are governed by external (extraterrestrial systems) and/or internal(ocean, atmosphere and land system). Trends are largely controlled by plate tectonics, and thus to change gradually on million year time scale. Aberrations occur when the certain thresholds are passed and are manifested in the geological record as the unusual rapid (less than a few thousands of years) or extreme change in climate. The quasi-periodic oscillations are mostly astronomically paced; they are driven by astronomical perturbations that affect the earth’s orbit around the sun and the orientation of earth’s rotation axis with respect to its orbital plane. These perturbations are described by the three main astronomical cycles: eccentricity, precession and obliquity, which together determine the spatial and seasonal pattern of insolation received by the earth [2], eventually resulting in climatic oscillations of ten to hundreds of thousands of year [3].Sun being the main source of energy for the earth system controls the climate of it. Variation in solar activity and cosmic ray intensity has direct influence over climatic features such as cloudiness, temperature and rainfall [4]. Volcanic eruptions also force all elements of the climatic systems up to a varying degree but producing long term climatic signals in the ocean. The cumulative volcanic cooling effect at present offsets about one third of anthropogenic warming [5].Other than these causes paleoclimatologists also relates the past climate changes with movement of solar system[6], interplanetary dusts and influence of asteroids[7].However the recent variability in climate what earth is experiencing is unlikely due to any of the individual above factors rather it is due to the compound effect of complex interactions of all the natural as well as anthropogenic forcings.
References:
1. J. C. Zachos, M. Pagani, L. Sloan, E. Thomas, K. Billups, Science 292 (2001) 686-693.
2. G. Kukla, Nature (London) 253, 600 (1975).
3. J. D. Hays, J. Imbrie, N. J. Shackleton, Science 194 (1876) 1121-1132.
4. N. Marsh, H. Swensmark, Space Sci. Rev. 94 (2000) 215-230.
5. T. L. Delworth, V. Ramaswamy, G. L. Stenchikov, Geophys. Res. Lett. 32 (2005) L24709.
6. K. Fuhrer, E. W. Wolf, S. J. Johnsen, J. Geophys. Res. 104(D24) (1999) 31043-31052
7. P. Hut, W. Alvarez, W. P. Elder, T. Hansen, E. G. Kauffman, G. Keller, E. M. Shoemaker & P. R. Weissman, Nature Vol. 329, 10 September, 1987
"Le climat, ma planète... et moi !" est un projet d'éducation au développement durable, destiné à sensibiliser enseignants, enfants et parents à une des principales menaces écologiques, sanitaires et sociales du XXIe siècle : le changement climatique.
http://www.leclimatmaplaneteetmoi.fr
Les entreprises qui, dans leur domaine d’activité, ont l’ambition de se positionner parmi les meilleures, prennent en compte tous les aspects pouvant augmenter la productivité et réduire leurs charges. Les services de maintenance ou d’entretien qui ont en charge la pérennisation des équipements et outils de productions ne seront pas en reste. La gestion de la maintenance a fini de sortir la maintenance de son statut de « recoin » ou vous trouvez les débarras et les hommes aux tenues tachées. Aujourd’hui les agents de la maintenance contribuent de maniere visuelle a l’accroissement de la rentabilité de leur entreprise.
Avec l’avenement de l’informatique, les outils de GMAO (gestion de la maintenance assistée par ordinateur) font partie des solutions incontournables pour une gestion efficace de la maintenance (suivi des équipements, suivi des budgets, gestion des stocks, tableaux de bord..)
Hydrologic Cycle is also called as Water Cycle. It basically deals with transformation of water in different forms starting from gaseous stage (water vapor) to liquid state (water on earth's surface), and water inside soil as underground water.and again back to gaseous stage. The cycle has no starting or end.
The hydrological cycle is the system which describes the distribution and movement of water between the earth and its atmosphere. The model involves the continual circulation of water between the oceans, the atmosphere, vegetation and land.
El 12 de noviembre de 2015 dedicamos una jornada en la Fundación Ramón Areces a analizar la actual situación del Ártico. El Simposio Internacional se ocupó de las oportunidades y riesgos derivados del cambio climático. En este encuentro participaron expertos de Canadá, Estados Unidos, Finlandia, Noruega, Suecia, Alemania, Portugal y España.
Simon Haslett, Professor of Physical Geography and Director of the Centre for Excellence in Learning and Teaching at the University of Wales, Newport, outlines sea ice formation and its influence on climate. The climate change impacts are examined, particularly the albedo effect, and also includes clouds. The presentation includes a video of a flight Professor Haslett took over the North Atlantic and a visit to eastern Canada to discuss sea ice, clouds, and their albedo effect on climate, and contribution to climate change.
Sample Environmental Events Log Entries
Ocean Acidification
This article from the Environmental News Network caught my attention because I rarely hear
about the oceanic events beyond comments concerning the ocean's temperature. The article
draws attention to the acidification of the ocean that occurs when the waters absorb carbon
dioxide. In history, the ocean's pH balance changed with pollutant CO2, but the rate and amount
of change was less than current increases. If the rate of pollution continues, calcifiers already
struggling may go extinct as some species did in historically when the chemical changes were
less dramatic. This item relates directly to what we covered in Chapter 7.
Source: Winter, Allison. "Ocean Acidification Occurring at Unprecedented rates".ENN. Sept.
25,2012 http://www.enn.com/ecosystems/article/45006!
Ocean Salinity and Climate Change
NASA is taking an expedition to the saltiest part of the North Atlantic to study how the saltiness
of the ocean relates to climate change as a part of their Salinity Processes in the Upper Ocean
Regional Study (SPURS). I find this interesting because biologists already use pH as a
measurement of health for aquatic biomes, why not test salt-to-water variation to view oceanic
changes? This voyage will increase knowledge of the acceleration of the Earth's water cycle.
Oceanographers claim that the ocean records rainfall better than landmasses and translates these
fluctuations in to salinity changes. Along with recording new salinity levels, the researchers are
delving into the drivers of these changes. Hopefully, the results of the SPURS expedition will
yield information that helps studies of other areas with major salinity changes and how they will
affect the water cycle in surrounding areas. This topic relates to material in Chapter 11.
Source: Cole, Steve. NASA - NASA Voyage Set To Explore Link Between Sea Saltiness And
Climate. (n.d.). Retrieved October 6, 2012, from
http://www.nasa.gov/home/hqnews/2012/sep/HQ_12-305_Ocean_Salinity_SPURS.html
Changes in Arctic Winds
According to a study by "scientists from Rutgers University in New Jersey, the University of
Sheffield in the United Kingdom, and the Joint Institute for the Study of the Atmosphere and
Ocean, a partnership of NOAA and the University of Washington.", Arctic winds that normally
travel west to east circulating the cold air are now moving south to north. This change further
warms the Arctic from the warmer air currents. Since 2007, the air currents from the south are
increasing contributing the record ice loss this summer. The article caught my eye because the
change in air currents and their immediate results of ice loss will dramatically affect the Northern
hemisphere causing drastic climate changes. This topic relates to what we covered in Chapter 5.
Source: Arctic summer wind shift could affect sea ice loss and U.S./European weather, says
NOAA-led study. (n.d.). Retrieved Oc.
The effect of human ecological footprint is not only limited to tropical and temperate regions but we can also see climate changes in polar regions despite the fact that there is very less human interference but still the consequences are disastrous.
Embracing GenAI - A Strategic ImperativePeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
Model Attribute Check Company Auto PropertyCeline George
In Odoo, the multi-company feature allows you to manage multiple companies within a single Odoo database instance. Each company can have its own configurations while still sharing common resources such as products, customers, and suppliers.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
5. Polar ice sheets and sea ice
Ice sheets on land of the polar zones of the Earth (Greenland and Antarctica) are
formed from snow that is compressed and converted to ice by gravity. The ice sheet
incorporates glaciers that flow down and release ice at the front into the sea. Ice
sheets grow by new snow during winter, while the loss is caused by increased surface
temperature during the summer, by ice flow runoff and by calving into the surrounding
ocean. For a climate in equilibrium average growth and loss are equal.
Look at video
of glacier
calving
Image from
Wikipedia
5
6. Ice can melt and sublimate. Melt water on the ice sheet can run off directly into the
ocean at the edges of the ice sheet and via ‘Moulins’ into the ice interior. A moulin or
glacier mill is a roughly circular, vertical to nearly vertical well-like shaft within a glacier
through which water enters from the surface. Moulins can reach the bottom of the
glacier, hundreds of metres deep. Melting water can accumulate in ice lakes or exit
the glacier at the base level and runoff into the sea. Flowing water makes ice to melt
faster.
The ice sheet itself flows down by gravity to the coastline and onto the ocean surface
where it makes ice shelves. These are thick platforms of ice of about 100 to 1000 m
thick floating on the sea. Shelves may break off (calving), releasing large pieces of
ice into the sea (icebergs). Vast ice shelves sometimes abruptly collapse, releasing
massive amounts of ice into the sea.
A significant proportion of the ice volume is fast-moving ice or ice streams that move
significantly faster than the rest of the ice sheet. For example, the Whillans Ice
Stream moves about 0.5 m within approximately 30 minutes,[2] remains still for 12
hours, and then moves another 0.5 m and so on.
Sea ice is frozen seawater. It may be attached to land or drift off-shore and move with
currents and winds. Because ice is less dense than liquid water, sea ice floats on the
ocean's surface. Sea ice covers about 7% of the Earth’s surface, or about 12% of the
world’s oceans.[1][2] It may incorporate icebergs.
6
9. Average daily Arctic temperature
The Figure shows the daily mean temperature (in °K) north of the 80th northern
parallel, as a function of the day of year for 2012. The blue line is the freezing point of
water. The green line is the overall average of data between 1958 and 2008. The red
line are the data for 2012.
Source9
10. Arctic temperature by region and season
Average January temperatures range from about −40 to 0 °C, and can drop below −50 °C.
Average July temperatures range from about −10 to +10 °C, with some land areas occasionally
exceeding 30 °C. The freezing point of sea water is about −2 °C.[1] So, there is considerable sea
ice melting during the summer. In the right panel, the dark blue zone is Greenland.
Average January temperature Average July temperature Source10
11. Loss of Greenland ice sheet mass and thickness
The Figures underneath show ice sheet loss, as estimated by three different methods.
Ice sheet loss is mainly in the coastal regions. From IPCC AR5 Figure 4.13
Changes in ice sheet surface
elevation for 2003–2008
determined from ICESat laser
altimetry
Ice loss determined from gravimetry,
in cm of water per year for the period
2003-2012
Mean surface mass balance
for 1989–2004
11
12. Melting area of Greenland ice sheet expands
The summer melt zone (area where melting is observed) has been expanding at an
accelerating rate in recent years.
Image source
Greenland melt area
Image source
12
13. Greenland ice sheet melting days increase in number
Source: National Snow and Ice Data Centre13
14. Causes of Greenland ice loss
According to IPCC AR5 WG1 ice sheet loss may be caused by the increased land and
sea suface temperature above the freezing point of sea water, by accelerated
discharge of ice in ice streams, by accelerated retreat of glaciers and by increased
ice shelve calving.
Abundant summer meltwater on the surface of the ice sheet forms moulins and
large lakes. This water drains to the ice sheet bed, thus providing heat in deep ice
layers and fastening further melting. Moreover, this process increases basal water
pressure and reduces basal friction on the glaciers, resulting in increased ice flow
speed and, hence, more ice loss into the sea. Even when it does not melt there, it will
increase sea level.
Surface melt that becomes runoff at the edges is a major contributor to mass loss
from the periphery of the ice sheet
Due to ocean warming, margin regions of ice sheets that are grounded below sea
level most likely experience more rapid ice mass loss.
Increased temperature in ocean waters beneath ice shelves increase melt rates of
the shelves.
Increased ice loss is in part due to strongly increased glacier retreat (melting, glacier
flow and iceberg calving). The recent rapid retreat of Jakobshavn Glacier was most
likely caused by the intrusion of warm ocean water beneath the floating ice tongue of
14
15. this glacier. The glacier seemed to be in balance from 1955-1985,[13] with a speed of
around 20 m/day.[11] After 1997 it began to accelerate rapidly, reaching an average
velocity of 34 m/day in the terminus region. It also thinned at a rate of up to 15 m/year
and retreated 5 km in six years.
In July 2012, the melt zone extended to 97 percent of the ice cover.[12] Ice core-based
reconstruction studies showed that events such as this occur approximately every 150
years on average. The last time a melt this large happened was in 1889. This
particular melt may be part of cyclical behavior, but it cannot be excluded that similar
events will get more frequent[13]
Look the video of the collapse of
Ilulissat Glacier in Western Greenland
Look at a video of water
runoff in Greenland
15
16. According to Dr. C Zender black carbon
(BC) is a significant contributor to Arctic
ice-melt.[72] BC decreases the snow/ice
albedo, leading to an increased warming
trend. The radiative forcing induced by BC is
presently of the order of 1 W/m2 at middle-
and high-latitudes in the Northern
Hemisphere and over the Arctic Ocean.[73] BC
deposition on ice and snow increases surface
melt of ice, and the meltwater in turn
accelerates ice disintegration.[75] There are
long-range pollution pathways to the Arctic
during winter and spring,[Ref] causing haze
containing BC, which increases surface
temperature by 0.5 °C.[77]
Albedo has been shown to have decreased
in Greenland (see Figure on the right),
consistent with the relative higher impact of
global warming on Greenland. Decreased
albedo leads to more sunlight absorbed by
the snow, leading to further melting.
Difference from average reflectivity in percent
16
17. Arctic sea ice extent steadily decreases
Sea ice is frozen ocean water that melts each summer and refreezes each winter.
September displays on average the lowest sea ice extent and Februari-March the
largest. The image below shows Arctic sea ice on September 12th, 2013 with a yellow
line identifying the 30-year average extent, which is much larger. Source
17
18. September sea ice has
decreased with >30 % since
1979.
Plots of decadal averages of
daily sea ice extent in the
Arctic (1979 to 1988 in red,
1989 to 1998 in blue, 1999 to
2008 in gold and 2009 to 2011
in black) From IPCC AR5
Figure 4.2
Months18
19. Arctic sea ice volume decreases
Both season-dependent maximum and minimum sea ice volumes are steadily
decreasing since 1990.
From Wikipedia19
20. Arctic sea ice concentration decreases
The sea ice concentration index
gives the % of the arctic sea surface
that is covered with ice. It is
regionally uneven ,as shown in the
figure (snapshot in August 2013).
(Source:National Snow and Ice Data
Center).
20
21. The Figure shows the trend in %
change per decade. The trend is
negative particularly above Alaska
and East-Asia (Source:National
Snow and Ice Data Center).
21
22. Sea ice concentration (IC) decreases unevenly. The trend is particularly strong
above Alaska in the autumn and above N-Europe in the spring. The figure shows
trends (1979–2011) in Autumn and Spring. From IPCC AR5 Figure 4.2
22
24. Arctic ice melts considerably faster than IPCC predicted
in 2007 !
Ice melting is 50
years ahead of
what the IPCC
climate models
(AR4/CMIP3
models) predicted
for 2100 ! The
record lowest sea
ice extent was in
2012. The black
lines in the Figure
are the modelled
data, the red line
represents the
observed data.
Source
210024
25. Topography of Antarctica
Antarctica consists of 3 main parts:1. The East Antarctic ice sheet, largely resting on ground
above sea level, and therefore relatively stable; 2. The West Antarctic ice sheet, resting on
ground that can extend up to more than 2,500 m below sea level, due to the weight of the ice,
and therefore vulnerable to ocean-induced melting. 3. The Antarctic Peninsula ice sheet, a smaller
land-based ice sheet.
From IPCC AR5 Fig. 4.18
25
27. Antarctic ice sheet, shelves and glaciers
The Antarctic ice sheet has been in existence for at
least 40 million years. It covers about 98% of the
Antarctic continent, an area of almost 14 million km2,
and contains 26.5 million km3 of ice (26 million
gigatons).[2] That is ~61 % of all fresh water on the
Earth. Antarctic ice is over 4,200 m thick in some
areas. If all Antarctic ice would melt, sea level would
rise with 60-70 m.
A total of 44 percent of the Antarctic coastline are ice
shelves. Their aggregate area is 1,541,700 km² [1]
and are about 100 to 1000 m thick. Antarctic ice
shelves may calve icebergs that are over 80
kilometers long. Calving accounts for about half the
mass lost from ice sheets.
Presently, 10% of land area is covered with glaciers
that flow and may calve ice. About 10% of the ice
volume is fast-moving ice or ice streams that move
significantly faster than the surrounding ice. Entire ice
shelves or glaciers may suddenly collapse, over
hours to days or weeks, releasing massive amounts of
ice into the sea, where it drifts away and melts. That
happened recently to the Larsen A and B shelve.
Large Ice shelves distribution.
Image from Ted Scambos, National Snow and Ice
Data Center, University of Colorado, Boulder.
Look at animation of
glacier flow
27
28. Antarctic ice sheet losses
Based on satellite altimetry, interferometry, and gravimetry data, it was estimated that between
1992 and 2011, the ice sheets of East Antarctica, West Antarctica, and the Antarctic Peninsula
changed in mass by +14 ± 43, –65 ± 26, and –20 ± 14 gigatonnes per year, respectively.
(Science 30 November 2012).
IPCC AR5 comes to a similar conclusion from studies made by 10 different groups with
satellite gravimetry, satellite altimetry and the mass balance method. Over the period 1992–
2012 there is “very high confidence that [ice] losses are mainly from the northern Antarctic
Peninsula and the Amundsen Sea sector of West Antarctica, and high confidence that they
result from the acceleration of outlet ” through fast-moving ice or ice stream. Ice flow can
reach velocities of higher than 1 km/year.
Satellite records and in situ observations from ocean buoys indicate warming of the Southern
Ocean since the 1950s. The mean temperature of the Antarctic Circumpolar Current ranges
from -1 to 5°C and studies suggest an ocean warming of 1°C could activate the natural
process of basal melting of ice shelves by 10 m/year (IPCC AR4). Melting is due to the
interaction between warmer ocean waters and the base of the shelves. Ice-shelf melting is the
largest ablation process in Antarctica (Science, 19 July 2013). Basal melt of shelves was
estimated to be 1325 ± 235 gigatons per year (Gt/year), while calving flux was 1089 ± 139
Gt/year. Note that shelves that melt no longer impede glacier flow off the continent, so that
glacier flow will accelerate and lead to further ice loss.
28
29. Ice sheet velocity
for 2007–2009
Ice loss as estimated from changes
in ice sheet surface elevation for
2003–2008 determined by ICESat
satellite altimetry
Ice loss determined by
satellite gravimetry, in cm
of water per year for the
period 2003-2012
Images from IPCC AR5 Figure 4.14
29
30. According to IPCC AR5, ice shelves are thinning in the Amundsen Sea region of West
Antarctica . “There is high confidence that ice shelves round the Antarctic Peninsula
continue a long-term trend of retreat and partial collapse that began decades ago.”
Ice loss is also related to glacier retreat. Melted water pools increasingly cut through
the surface of glaciers, which destabilize it and increase the likelihood of calving. This
is believed to have played a role in the rapid disintegration of the Larsen B ice shelf,
which crumbled over about six weeks in 2002. Massive amounts of ice were released
into the ocean, contributing substantially to sea level rise. Moreover, glaciers, melting
from contact with tide water, may destabilize and collapse.
30
31. Super warming in Antarctic Peninsula
The Antarctic Peninsula is one of the most warming areas of the World. Seven ice shelves
have retreated or disintegrated in the last two decades.[20] Every ice front on the southern
half of the peninsula experienced a retreat between 1947 and 2009.[24] Glaciers on the
Peninsula are also increasing their flow rate.[25]
The present warming, however, is not unprecedented. A recent paper in Nature (Nature
489, 141–144, 2012) reports an Antarctic Peninsula ice core study on the temperature
trends during the entire Holocene period. About 2,000 years ago average temperatures
were as warm as at present. From about 12000 to 9500 years ago it was considerably
warmer than today. Another relatively warm period similar to modern-day levels was from
about 9,200 to 2,500 years ago. There was a pronounced cooling from 2,500 to 600 years
ago, Since then there was again warming over the last 600 years, the rate of which became
steeper during the last 100 years (1.56 °C). Although this steep rise is not unprecedented,
it is highly unusual in the context of natural variability in the Antarctic Peninsula. Importantly,
during the cooling period a permanent ice shelf was established (based on marine
sediments studies) on the eastern part of the Peninsula, while it was not conspicuous during
the warm periods. This observation suggests that present warming may drive the partial
collapse of ice shelves that began decades ago, into a full collapse, which would seriously
fasten sea level rise.
31
33. Antarctica ice shelf calving
The photo underneath shows the Filchner Ice Shelf, on the Antarctic coast facing the
Atlantic Ocean, as taken by satellites. It is the largest ice shelf by volume on Earth. In
the austral winter of 1986, its front edge broke off, forming three large icebergs.
Images taken by Landsat 1 (left) and Landsat 5 (right). Source: Earthshots: Satellite
Images of Environmental Change, U.S. Geological Survey.
33
34. Antarctic sea ice concentration is only slightly affected
Sea ice concentration (IC) is slightly
decreasing West of the Antarctic
Peninsula, and in the sea of West
Antarctica, consistent with the high
warming rate in this location. The
Figure shows the Ice concentration
trends (1979–2011) in winter,
spring, summer and autumn.
From IPCC AR5 Figure 4.7
However, there is no change in
total Antarctic sea ice extent (see
IPCC AR5 Figure 4.7).
34
35. Moutain Glaciers
Glaciers store about 75% of the world's freshwater.
Total glacier area covers over 15,000,000 km2.
During the last Ice Age, glaciers covered 32% of the global land area.
North America's longest glacier is the Bering Glacier in Alaska, measuring 204
kilometers long.
When glacier ice is white, it usually means that there are many tiny air bubbles still in
the ice. Years of compression gradually make the ice denser over time, forcing out the
tiny air pockets. When glacier ice becomes extremely dense, it gets a blue color (the
ice absorbs all other colors in the spectrum and reflects primarily blue).
35
36. Glacier mass loss
The left Figure shows the cumulative change in mass balance of a set of "reference"
glaciers worldwide beginning in 1945. The line on the graph represents the average of all
the glaciers that were measured. Negative values in later years indicate a net loss of ice
and snow compared with the base year of 1945. Measurements are in meters of water
equivalent, which represent changes in the average thickness of a glacier. The small
chart below shows how many glaciers were measured in each year. The right Figure
shows the evolution of reference glaciers in the U.S. Read more
from EPA, Data sources: WGMS, 2011,
2012 (World Glacier Monitoring Service
36
37. Glaciers area loss
Mean annual area for 14 glacier regions show decrease without exception. Each line in the
Figure refers to the observed relative area loss from a specific publication and its length is
related to the period used for averaging. From IPCC AR5 Figure 4.10
37
38. Photographs of glacier area loss
Shrinkage of the Bear Glacier, Alaska,
from 1980 to 2011.
Left image taken by Landsat 3. Center
image taken by Landsat 4. Right image
taken by Landsat 7. Source: U.S.
Geological Survey (USGS) Landsat
Missions Gallery
The Cotopaxi Glacier, Equador (5,897
m) . The glacier has considerable
economic, social, and environmental
importance. Its melt waters provide fresh
water and hydroelectric power to
Ecuador’s capital city of Quito. The ice
mass decreased 30 % between 1956 and
1976 and another 38.5 % between 1976
and 2006. Source: United Nations
Environment Programme (UNEP). From
Latin America and the Caribbean Atlas of
our Changing Environment (2010).
June 5, 1980 May 16, 1989 May 13, 2011
23 March 1986 5 Feb 2007
38
39. Glacier length loss
The Figure shows the decrease of
cumulative glacier length as compiled from
long-term in situ measurements in various
regions. The lines represent individual
glaciers. From IPCC AR5 Figure 4.9
39
40. Photographs of mountain ice and snow loss
Mount Kilimanjaro in Tanzania. Images taken by the NASA/USGS Landsat satellite. Credit:
Jim Williams, NASA GSFC Scientific Visualization Studio, and the Landsat 7 Science Team.
The Matterhorn mountain, located in the Alps. 1960 photo taken by Bradford Washburn;
2005 photo taken by David Arnold. Source: Panopticon Gallery, Boston, MA.
16 Aug
1960
18 Aug
2005
February 17,
1993
February 21,
2000
40
41. Lake ice loss
This figure (from EPA, Data source: NSIDC, 2011 (National Snow and Ice Data
Center) ) displays the duration (in days) of ice cover for eight U.S. lakes. They freeze
later and thaw earlier than they used to do. Read more
41
42. Land snow cover extent
Snow cover tends to decrease over the globe, which means that winter albedo will be
weaker, favoring warming.
The left Figure shows the trend in March-April Northern Hemisphere snow cover extent
(SCE) (circles) over the period of available data, and in June snow cover extent (x’s)
from satellite data alone. The mean and 95% confidence intervals are given. The right
Figure shows that the decrease in snow cover highly correlates with the temperature
anomaly between 40° and 60° latitude. From IPCC AR5 Figure 4.19 and 4.20
42
43. Permafrost
Permafrost is defined as soil that is either frozen for 2 or more years or
permanently. Permafrost is mainly found in the Arctic region (land and sea bottom)
and contains carbon deposits. There are two variants in carbon deposition: old
organic carbon deposits and methane hydrates occurring in deep permafrost soils,
ocean shelves, shelf slopes and deeper ocean bottom sediments.
Permafrost organic carbon deposits store twice the amount of atmospheric carbon.
Permafrost is covered by a surface 'active layer', which thaws during summer, allowing
microorganisms to decompose the organic carbon, generating CO2 and, when
oxygen is limited, also methane. If spring and summer temperature rises, the active
layer will thicken, making more organic carbon available for microbial decomposition.
Methane hydrates consist of methane and water clusters, which are only stable at
low temperature and high pressure. On land and in the ocean, most of these hydrates
originate from marine or terrestrial organic carbon, decomposed in the absence of
oxygen to methane, and then trapped as water clusters at low temperatures and high
pressure. Warming and/or changes in pressure could destabilize the hydrates,
releasing their methane to the ocean. A fraction of that methane might be outgassed
to the atmosphere. The amount of methane hydrates is more than 10 times greater
than that of present atmospheric methane. Thus, thawing of permafrost represents a
serious threat for further warming.
43
44. Seasonally frozen ground depth anomalies
Thickness of seasonally frozen ground in Russia/Siberia is decreasing (From,
Frauenfeld and Zhang, 2011). IPCC AR5 Figure 4.24
44
45. Permafrost ground temperature
Mean annual ground
temperatures at depths between
10 and 20 m increases, as
measured in boreholes
throughout the circumpolar
northern permafrost regions
(Romanovsky et al., 2010).
Measurement depth is 10 m for
Russian boreholes, 15 m for
Gulkana and Oldman, and 20 m
for all other boreholes. From
IPCC AR5 Figure 4.22
45
46. Permafrost retreat (Berkeley Earth study)
Regions colored in red are regions where the annual air temperature averaged ≤0 °C for the
period 1901-1910 but not anymore for the period 2001-2010. Areas in white remain
permafrost in 2001-2010.
From Berkeley Earth46
47.
Summary as published by IPCC AR5 WG1 Ch. 4
Text and Figure from IPCC AR5 Figure 4.25
Summary
47