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: [email protected]) or else to the Climatic Research Unit, UEA, Norwich NR4 7TJ, UK (tel: +44 1603 593162; [email protected]) 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
