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Climate Change Scenarios for Argentina
This leaflet is one of a series produced for WWF that describe state-of-the-art climate change
scenarios for a number of countries and regions around the world. The scenarios use observed
climate data held by the Climatic Research Unit, a set of preliminary greenhouse gas emissions
scenarios prepared for the Intergovernmental Panel on Climate Change (IPCC), and a series of
recent climate change experiments performed using seven global climate models, results from which
are available through the IPCC Data Distribution Centre.
Recent Observed Trends in Climate
Temperature
Annual-mean temperature in Argentina has increased by nearly 1ºC over the last century. The decade of the 1990s has
been the warmest this century (Figure 1), with 1995 being the single warmest year recorded over the country. This
warming has occurred in all seasons almost equally, being slightly greatest in the June to August winter season. In
parallel with the warming of climate, the frequency of frosts has been falling. Although much of northeastern
Argentina is virtually frost-free, the Andean cordillera and the southern plains and peninsulas experience many frosts
each year. When averaged across the country, there has been a decline in the number of frost days per year of nearly
10 per cent during the course of the century.
1.5
Argentina ANN Mean Temperature
deg C anomaly
1.0
0.5
0.0
-0.5
-1.0
-1.5
20.0
Days/year anomaly
Argentina ANN Frost Frequency
10.0
0.0
-10.0
-20.0
1900
1920
1940
1960
1980
2000
Figure 1: Changes in annual mean temperature, 1901-1998 (top), and annual frost frequency, 1901-1998 (bottom), over Argentina.
Changes are with respect to the average 1961-90 climate values of 14.5ºC and 69 days respectively.
Precipitation
Argentina receives over 60 per cent of its precipitation during the December-May period. Figure 2 shows that for these
summer and autumn seasons, precipitation has increased during the century by about 10 and 5 per cent respectively.
The trend in annual precipitation for the country as a whole has been about 10 per cent/century, although over parts of
the humid Pampas annual precipitation has increased by up to 15 per cent. The only exception to this increase has
occurred over parts of the Argentinian cordillera where a small declining trend in precipitation has been detected.
Changes in precipitation may be expected to have implications for Argentinian rivers. Several important rivers drain
eastward from the Andes and some riverflow records show a relationship with the El Niño/Southern Oscillation
(ENSO). Rivers in Mendoza Province, for example, are more likely to experience high flows during early stages of
warm ENSO events because of increased snowfall over the Andes.
1
40
percent anomaly
Argentina DJF Precipitation
20
0
-20
-40
40
percent anomaly
Argentina MAM Precipitation
20
0
-20
-40
1900
1920
1940
1960
1980
2000
Figure 2: Changes in seasonal precipitation over Argentina, 1901-1998; December-February summer season (top), March-May
autumn season (bottom). Changes are with respect to the average 1961-90 climate values of 211 mm and 168 mm respectively.
2
Global Climate Change Scenarios
The Choice of Scenarios
Given that humans are implicated in the cause of global warming, and recognising that the potential consequences of a
rapidly warming climate for natural and human systems are large, it becomes important to estimate the possible range
of future climates we may experience over the next one hundred years. The four climate scenarios shown here are
related to four different future greenhouse gas emissions pathways defined in the preliminary Special Report on
Emissions Scenarios (SRES) of the IPCC. These are called B1, B2, A1 and A2. The change in carbon emissions from
energy/industrial sources by 2100 compared to estimated year 2000 emissions for these four scenarios ranges from a
decrease of 4 per cent (scenario B1) to an increase of about 320 per cent (scenario A2). These estimated future
emissions rates assume no climate policy implementation. Atmospheric carbon dioxide concentration increases from
the current 1999 concentration (~370ppmv) to nearly 550ppmv by 2100 in the B1 scenario and to over 830ppmv in the
A2 scenario. Concentrations of other greenhouse gases also increase.
What effect will this growth in greenhouse gas concentrations have on global climate? It depends largely on how
sensitive the Earth's climate is to these rising concentrations. We choose three different values for this so-called
climate sensitivity - low (1.5ºC), medium (2.5ºC) and high (4.5ºC). By combining these three choices of the climate
sensitivity with the four SRES emissions scenarios, we calculate a range of future global warming and sea-level rise
curves (Figure 3; Table 1) that capture perhaps about 90 per cent of the possible range of future global climates. These
range from B1-low (the lowest emissions scenario combined with the lowest sensitivity) to A2-high (the highest
emissions scenario combined with the highest sensitivity). None of the scenarios shown here include the relatively
modest short-term effects on global and Argentinian climate of changing sulphate aerosol concentrations.
1980s
Temp.
degC
0.13
0.13
0.13
0.13
1990s
Temp.
degC
0.28
0.28
0.28
0.28
B1-low
B2-mid
A1-mid
A2-high
CO2
ppmv
421
429
448
440
2020s
Temp.
DegC
0.6
0.9
1.0
1.4
Sea-level
cm
7
20
21
38
CO2
ppmv
479
492
555
559
2050s
Temp.
degC
0.9
1.5
1.8
2.6
Sea-level
cm
13
36
39
68
CO2
ppmv
532
561
646
721
2080s
Temp.
degC
1.2
2.0
2.3
3.9
Sea-level
cm
19
53
58
104
Table 1: Summary of changes in the global environment by the 2020s, 2050s and 2080s for the four scenarios. Changes are
calculated with respect to the 1961-90 average. The effects of sulphate aerosols on climate have not been considered. The changes in
global temperature for the 1980s and 1990s are those observed. (ppmv = parts per million by volume)
Changes in Climate and Sea-level
Global-mean temperatures increase by between 1.3º and 4.6ºC by 2100 (Figure 3), representing global warming rates of
between 0.1º and 0.4ºC per decade. This compares to an observed global warming rate of 0.15ºC per decade since the
1970s. One of the most striking consequences of a warming climate will be the rise in sea-level. Our scenarios suggest
a future global-mean sea-level rise of between 2cm and 10cm per decade, compared to an observed rise over the last
century of between 1cm and 2cm per decade. The largest contribution to this rise in sea-level comes from the
expansion of warmer ocean water, a slow inexorable process that will ensure that the world's sea-level continues to rise
for centuries to come.
3
1880
1920
1960
2000
2040
2080
19
5
4
18
3
17
2
16
1
15
0
14
Actual temperature (deg C)
deg C anomaly
Global
-1
19.5
5
4
18.5
3
17.5
2
16.5
1
15.5
0
14.5
-1
13.5
-2
1880
1920
1960
2000
2040
Actual temperature (deg C)
deg C anomaly
Argentina
2080
Figure 3: Calculated changes (1960-2100) in global-mean (top) and Argentinian (bottom) annual surface air temperature for the
four scenarios shown in Table 1. The observed changes to 1998 in both cases are shown by bars and the bold black curves.
4
Future Precipitation Change over Argentina
It is likely that Argentina will warm slightly less rapidly in the future than the global average temperature (Figure 3).
Within Argentina, however, the north of the country will warm considerably more rapidly than the south. For example,
in the A2-high scenario the southern peninsula of the continent warms at a rate of about 0.25º/decade, whereas the
north of Argentina warms at the rate of about 0.4ºC/decade. For the B1-low scenario these rates of warming are
reduced by a factor of about three.
Annual Temperature
2020s
70W
25S
30S
35S
B1-low
40S
45S
50S
1.4 1.4 1.2
0.7 0.7 0.6
1.1 1.1 1.0
1.4 1.4 1.3
0.7 0.7 0.6
1.1 1.0 0.9
1.4 1.4 1.2
0.7 0.6 0.6 0.5
1.0 1.0 0.9 0.8
1.3 1.3 1.1 1.0
0.6 0.6 0.5 0.4
0.9 0.9 0.8 0.7
1.2 1.1 1.0 0.9
0.5 0.5 0.4
0.8 0.8 0.7
1.1 1.0 0.9
1.0 1.0 0.9
0.9 0.9
0.4 0.4
0.7 0.7
0.8 0.9
0.4 0.4
0.6 0.7
0.8 0.9
0.4
0.6
0.8
0.3
0.5
2.3
1.1 1.1 1.0
1.7 1.7 1.5
2.3 2.3 2.0
1.1 1.1 1.0
1.7 1.8 1.5
2.3 2.3 2.0
1.1 1.0 0.9
1.7 1.7 1.5
2.2 2.2 2.0
1.0 1.0 0.9 0.8
1.6 1.5 1.4 1.3
2.1 2.0 1.8 1.7
0.7 0.7
1.1 1.1
1.4 1.5
0.7 0.7
1.0 1.1
1.4 1.5
0.6 0.7
1.0 1.1
1.4 1.4
0.6
1.0
1.3
0.5
35S
50S
0.8
2.7
1.2 1.2 1.0
2.1 2.0 1.8
2.6 2.6 2.3
1.2 1.2 1.1
2.0 2.1 1.8
2.6 2.7 2.3
1.2 1.1 1.0
2.0 2.0 1.8
2.5 2.5 2.3
1.1 1.1 1.0 0.9
1.9 1.8 1.6 1.5
2.5 2.3 2.1 1.9
1.0 1.0 0.9 0.7
1.8 1.6 1.5 1.3
2.3 2.1 1.9 1.7
0.9 0.9 0.8
1.6 1.5 1.3
2.0 1.9 1.7
1.8 1.8 1.7
1.3 1.4
1.6 1.7
0.7 0.8
1.2 1.3
1.6 1.7
0.7 0.7
1.2 1.3
1.6 1.6
0.7
1.1
1.5
35S
1.0
50S
55S
55S
4.6
1.6 1.6 1.4
3.1 3.0 2.7
4.6 4.6 4.0
1.6 1.7 1.5
3.0 3.1 2.7
4.6 4.7 4.1
1.6 1.6 1.4
3.0 2.9 2.6
4.5 4.4 4.0
1.5 1.5 1.3 1.2
2.8 2.7 2.4 2.2
4.3 4.1 3.7 3.4
4.0 3.7 3.4 2.9
2.3 2.2 2.0
2.1 2.1 1.9
3.1 3.2 2.9
1.0 1.1
1.9 2.0
2.9 3.0
1.0 1.0
1.8 1.9
2.8 2.9
1.0 1.0
1.8 1.9
2.7 2.8
0.9
1.7
2.6
0.8
1.5
60W
70W
25S
30S
35S
3.5 3.3 2.9
1.1 1.1 1.0
70W
35S
50S
1.3
2.6 2.4 2.2 1.9
30S
45S
3.1
1.4 1.3 1.2 1.0
25S
40S
1.6
1.3 1.2 1.0
45S
55S
1.1
2.1
1.4 1.4 1.3
30S
40S
50S
0.7 0.8
25S
35S
40S
1.2
0.6
30S
45S
0.8 0.8 0.8
55S
25S
1.8 1.7 1.5
1.5 1.6 1.4
30S
45S
2.0 1.8 1.7 1.4
1.2 1.2 1.1
25S
40S
55S
1.8
1.3 1.3 1.1
35S
50S
0.7
1.5 1.4 1.3 1.1
30S
40S
1.1
0.9 0.9 0.8 0.7
25S
45S
0.7 0.8 0.7
55S
A2-high
1.1 1.1 1.0
0.8 0.8 0.7
50S
60W
1.4
0.7 0.7 0.6
0.7 0.7
35S
45S
70W
0.7 0.8 0.7
30S
40S
2080s
60W
1.1
0.4 0.5
25S
A1-mid
70W
0.5 0.5 0.4
55S
B2-mid
2050s
60W
0.7
40S
45S
50S
55S
2.2
60W
70W
60W
Degrees C change
0.5
1
1.5
2
3
4
5
6
Figure 4: Change in mean annual temperature (deg Celsius from the average 1961-90 climate) for 30-year periods centred on the
2020s, 2050s and 2080s for each of the four scenarios. The printed numbers show the estimated change for each model land gridbox
over Argentina. Changes are only shown where they are large in relation to natural temperature variability on 30-year time-scales.
5
Future Precipitation Change over Argentina
Future changes in precipitation differ between the western and eastern regions of Argentina. Annual precipitation
declines over the Andes, this decline in places reaching about 15 per cent by the 2080s under the A2-high scenario.
The east of the country – the region of the lower Rio de la Plata River Basin – experiences increased annual
precipitation. Under the B1-low scenario, and even by the 2080s, all of the precipitation changes are small – less than 5
per cent. This contrast between a drying west and a wetting east is quite consistent between the seasons.
Annual Precipitation
2020s
70W
2050s
60W
25S
70W
2080s
60W
4
70W
6
60W
-4
25S
7
30S
30S
3
35S
B1-low
40S
4
3
4
-3
-4
-6
-3
-4
45S
50S
2
55S
2
25S
-2
45S
2
50S
55S
3
-5
35S
40S
2
6
5
-6
9
25S
12
3
30S
30S
3
35S
B2-mid
-5
4
4
5
-7
3
6
6
-6
5
8
35S
-5
40S
-4
-7
-3
-5
45S
50S
2
55S
2
25S
-3
-4
-9
-5
-6
-5
40S
-3
-3
45S
3
4
50S
4
6
55S
5
-6
-7
10
25S
13
4
30S
30S
35S
A1-mid
3
-6
4
-6
4
6
-8
4
7
7
-7
6
10
-5
4
-4
40S
45S
-5
-8
-3
-5
-2
-3
-5
-7
-6
-4
-4
35S
40S
-10 -5
45S
-5
50S
2
3
55S
3
25S
-4
50S
4
4
8
-8
16
-12
-5
5
-7
-9
4
8
-8
7
11
-6
4
30S
35S
40S
25S
23
-3
7
30S
4
5
A2-high
55S
6
-4
4
-6
-4
6
-13
7
13
-13
10
17
-9
6
-12 -6
-18 -9
-8
-7
-12 -11
45S
-2
-5
-5
-7
-8
-6
2
-9
50S
3
5
-4
55S
4
70W
60W
40S
45S
50S
7
7
55S
10
70W
60W
35S
70W
60W
Percent change
-50 -30 -20 -10
0
10
20
30
50
Figure 5: Change in mean annual precipitation (per cent change from the average 1961-90 climate) for 30-year periods centred on
the 2020s, 2050s and 2080s for each of the four scenarios. The printed numbers show the estimated change for each model land
gridbox over Argentina. Changes are only shown where they are large in relation to natural precipitation variability on 30-year timescales.
6
Climate Change, Climate Variability and Biodiversity
Changes in climate variability and in extreme event frequencies are important for determining both the likely impacts
of climate change and the adaptation adjustments subsequently required. This is particularly true for many aspects of
water management and biodiversity in Argentina.
Andean Rivers and Water Supply
The provinces of Mendoza and San Juan in the arid Cuyo region of west-central Argentina rely largely upon snowmelt
from the Andes for their water. The Mendoza River, for example, provides irrigation water and electric power to a vast
region of the Argentine mid-west. The strength of the riverflows into the region is governed by winter precipitation
and by the melt of accumulated snow. Our scenarios suggest there is a real danger of reduced riverflows and therefore
of reduced water supply for the region. Precipitation decreases in these river catchments (Figure 6), and rising
temperatures leads to earlier snowmelt and increased evaporation losses in the lower parts of the catchments. These
prospects represent an additional stress on already limited freshwater availability in west-central Argentina, with
increasing water demand arising from larger urban populations and the expansion of irrigated agriculture and industry.
degC anomaly
2000
7
2020
2040
2060
2080
2100
7
6
6
5
5
4
4
3
3
2
2
1
1
0
0
-1
-1
per cent anomaly
100
100
50
50
0
0
-50
-50
-100
2000
-100
2020
2040
2060
2080
2100
Figure 6: Changing annual temperature and precipitation in the Mendoza River catchment for the B1-low and A2-high scenarios.
The changes are calculated with respect to average 1961-90 climate.
Biodiversity
The Valdes Peninsula, located on the Atlantic coast at 42ºS, contains sheltered lagoons to which large colonies of sea
lions and elephant seals flock every year to mate and raise their young. The southern right whale (see photo) also
harbours in these gulfs and this species migrates between this Argentinian peninsula and the waters of the Antarctic
during the brief summer period. Krill is the primary food source for these whales, but warming temperatures are
detrimental to this species. Any decline in Antarctic sea-ice, for example, will have a detrimental effect upon krill
since this will decrease the productivity of the algae on which they feed.
Photo – the southern right whale, which shelters in Argentinian lagoons.
The Iguazu National Park 2434 on the border with Paraguay contains over 400 bird and wild animal species, a
significant number of which are endangered, including the ocelot, the giant otter, the jaguar, the capuchin monkey and
the tapir. The Park is also rich in avifauna which comprise about 44 per cent of Argentina's bird population. Two
thousand species of flora also flourish within this jungle environment. In addition to the high species diversity, the
Park is home to one of the most complete remaining areas of Paranaense (?) forest. In the neighbouring countries of
Brazil and Paraguay, this ecosystem has been degraded to occupy less than 10 per cent of its original area. Spectacular
waterfalls dominate the Park, the most impressive being the Devils throat at 150m wide and 700m long. The climate of
7
the Park is set to warm and, although annual rainfall will increase overall, it will also become more variable with more
frequent dry seasons.
8
Uncertainties and Confidence
Climate Model Differences
The scenario maps for Argentina (Figures 4 and 5) show the median climate response of a sample of ten recent global
climate model simulations to increased greenhouse gas concentrations. These simulations have been performed by
seven climate laboratories located in six different countries. Different models sometimes yield different regional
climate responses to the same greenhouse gas forcing and these differences therefore provide one measure of
uncertainty in our scenarios. Over northern Argentina, more models show wetting than drying, while over southern
Argentina the opposite occurs (Figure 7).
southern Argentina
15
10
10
Precipitation change (%)
Precipitation change (%)
northern Argentina
15
5
0
-5
-10
-15
-1
0
1
2
3
Temperature change (deg C)
5
0
-5
-10
-15
-1
4
0
1
2
3
Temperature change (deg C)
4
Figure 7: Changes in average annual climate for northern (left) and southern Argentina (right) by the 2050s, with respect to average
1961-90 climate, for the B1-low and A2-high scenarios. Each coloured dot represents a different climate model experiment. The
bars centred on the origin define the natural variability of 30-year average climates for these zones as estimated by a climate model.
When using climate scenarios for impacts assessments, it is important to analyse the effects of natural climate
variability alongside those of human-induced climate change. The black bars centred on the origins in Figure 7 show
by how much the average annual climate of the two regions of Argentina may differ from that of today without any
human interference with climate. Few of the changes in annual precipitation exceed these levels of natural variability
by the 2050s for the B1-low scenario, but more than half of them do for the A2-high scenario.
Levels of Confidence and Surprises
There are some aspects of future climate change in which we have greater confidence than others. For example, we are
more confident about increases in carbon dioxide concentrations and rises in sea-level than we are about increases in
storminess or intense precipitation events (Table 3). The behaviour of El Niño events is not always well-represented in
climate models, so predicting how these events will change due to global warming is also difficult - any change in El
Niño behaviour could have a large impact on Argentinian climate and riverflows. The scenarios shown here have been
derived from climate models that include the best possible representation of processes in the atmosphere, ocean and
land given our present scientific knowledge and computing technology. We do not understand the climate system well
enough, however, to be able to rule out other outcomes.
Climate Variable
Level of Confidence
9
Atmospheric CO2 concentration
Global-mean sea-level
Global-mean temperature
Regional seasonal temperature
Regional temperature extremes
Regional seasonal precipitation/cloud cover
Regional potential evapotranspiration
Changes in climatic variability
(e.g. El Niño, daily precipitation regimes)
High
Rapid or non-linear changes
(e.g. disintegration of the West Antarctic Ice Sheet)
Very low or unknown
Low
Table 3: List of climate and associated scenario variables, ranked subjectively in decreasing order of confidence.
This leaflet has been prepared by Mike Hulme and Nicola Sheard of the Climatic Research Unit (http://www.cru.uea.ac.uk)
at the University of East Anglia, Norwich, UK. We thank Tom Wigley and Sarah Raper for permission to use their MAGICC climate
model and Mark New, Jenny Crossley and Nick Brooks for graphics. Translation was by Veronica Medina-Ross. Other data used in
this leaflet can be found on the web sites below. This publication is one of a series of national/regional scenario leaflets prepared
under contract to WWF. The views expressed here are solely those of the authors. This leaflet should be cited as: Hulme,M. and
Sheard,N. (1999) Climate Change Scenarios for Argentina Climatic Research Unit, Norwich, UK, 6pp. Enquiries should be
directed to Javier Corcuera at WWF-Argentina (tel/address: ????????; email: corcuera@mail.retina.ar) or else to the Climatic
Research Unit, UEA, Norwich NR4 7TJ, UK (tel: +44 1603 593162; m.hulme@uea.ac.uk)
Some Further Sources of Information on Climate Data and Scenarios on the Web
•
•
WWF climate campaign: http://www.panda.org/climate/
•
The Climate Impacts LINK Project: http://www.cru.uea.ac.uk/link/
The IPCC Data Distribution Centre (DDC): http://ipcc-ddc.cru.uea.ac.uk/
Published by the Climatic Research Unit, UEA, Norwich, UK © October 1999, Climatic Research Unit
Design: Shorthose Russell Ltd, Norwich (tel: +44 1603 785765)
10
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