3 (PRAA) Climate Change in the Tropical Andes - Impacts and Consequences for Glaciation and Water

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Climate Change in the tropical Andes -Impacts and consequences forglaciation and water resources

Part III: Future recommendations

A report prepared by

MATHIAS VUILLE

with contributions from

RAYMOND S. BRADLEYBERNARD FRANCOUGEORG KASERBRYAN G. MARK



Climate Change in the tropical Andes –Impacts and consequences for glaciation

and water resources

Part III: Future recommendations

A report for CONAM and the World Bank

prepared by

MATHIAS VUILLE(University of Massachusetts)

with contributions from

RAYMOND S. BRADLEY (Universi ty of Massachusetts)BERNARD FRANCOU (IRD)

GEORG KASER (University of Innsbruck)BRYAN G. MARK (Ohio State University)

Amherst , Massachusetts, 29. May, 2007



TABLE OF CONTENTS

SUMMARY......................................................................................................................2

1) INTRODUCTION ...................................................................................................3

2) IMPROVE THE OBSERVATIONS .................................................................4

3) IMPROVE THE MODEL PREDICTIONS .....................................................8

4) IMPROVE COLLABORATION AND DISSEMINATION ......................12

REFERENCES............................................................................................................13

1



SUMMARY

This report recommends several research avenues that would allow for a better

assessment of future climate change and its impact on glaciation and runoff in the tropical

Andes.

First and foremost the current monitoring network needs to be expanded, replacedand improved upon. A suite of high-elevation observation stations including both

automated weather stations and glacier mass balance networks is needed. This wouldallow monitoring climate change at the elevation of the glaciers and not simply at low

elevations, where the changes are likely to be much less dramatic. Such observations

could be combined with new remote sensing data sets from space to obtain a spatially

complete picture.Secondly the climate model applications in the region need to be improved by

increased application of higher resolution (regional) climate models. It is desirable that

several different models be run in ensemble mode to assess intra-model differences. Themodel performance over a region with such complex topography as the Andes needs to

be carefully validated under modern conditions before SRES-IPCC simulations of futureclimate can be evaluated. These latter simulations should again be run based on severalmodels and under different emissions scenarios, such as A2 and B2.

Climate change simulations can tell us how climate might change in the Andes by

the end of the 21st century, but to understand what the impacts on glaciation and runoff

are they need to be coupled with a tropical glacier-climate model. When applied to

selected target catchments, coupled glacier-climate model simulations can provide us

with estimates of when and by how much glaciation and runoff will change. For example

they may be able to tell us when and in what catchments glaciers will completelydisappear, and at what fraction of their original size they may find a new equilibrium in

other catchments. The ramifications of this glacier retreat (or disappearance) for runoff

and water availability can equally be assessed with such models.To make these results relevant for water users, there needs to be a framework in

place to disseminate the results in a way, which is scientifically correct but also socially

relevant and applicable to stakeholders, decision makers and water users. Options forsuch a framework, which should include collaboration with national entities in Ecuador,

Peru, and Bolivia and capacity building through training and education of students at host

institutions involved, are discussed.

2



1) INTRODUCTION

The previous reports have outlined the current scientific knowledge of climate

change and its impacts on tropical Andean glaciers and hydrology (Part I: The scientific

basis) and the ongoing research and monitoring activities by the various institutions

currently active in the region (Part II: Climate and Glacier Monitoring). They providethe scientific basis that can be used in support of the decision-making process to find the

best adaptation and mitigation strategies for the region and an overview of the currentlyinstalled scientific network. It is clear that some practical measures to adapt and prepare

for future changes in runoff behavior need to be implemented without delay (e.g.

conservation, shift to less water-intensive agriculture, creation of water reservoirs, etc.,

see Vergara, 2005), but at the same time significant progress needs to be made on thescientific front. This third and final report (Part III: Future Recommendations) suggests a

number of research strategies that would allow answering some of the most urgent

scientific questions related to Andean climate change. These strategies include:

a) improvement and expansion of the current monitoring network,

b) combining improved surface measurements with advanced remote sensing and

GIS applications,

c) improved climate modeling at higher resolution (regional climate models), with

a variety of different models and based on a number of different IPCC-SRES

emission scenarios,

d) coupling of these regional climate models with a tropical glacier-climate model

to assess the implications for glacier mass balance and water resources at a

catchment-scale level, and finally

e) improved collaboration and dissemination of results to local stakeholders in a

fashion that is not only scientifically relevant, but also socially applicable.

All these recommendations come with significant costs, but given the observed

changes already under way and the dramatic changes projected for the future (see Part I )

it is quite obvious that adapting to these changes will be inevitable. It is our firm beliefthat implementation of adequate adaptation strategies is not possible without sufficient

knowledge and a high level of scientific understanding of the processes involved. For

example, one of the emerging results from studies performed to date is that the

hydrologic response to climate change may vary significantly from one catchment to thenext, depending on the degree of glaciation, catchment hypsometry and the sensitivity of

glaciers to various climate parameters. If we add to these differences in catchmentresponse all the uncertainties surrounding future greenhouse gas emissions (which SRES

scenario is most likely?), and all the discrepancies between different regional climatemodels, it is very clear that we still have along way to go to better understand the impacts

of future climate change on Andean glaciers. Investing in climate monitoring and basic

scientific research, therefore, in our opinion is money well spent.

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2) IMPROVE THE OBSERVATIONS

One of the most urgent tasks is to expand and improve the existing observational

network of automated weather stations and glacier mass balance networks. The currently

installed network is inadequate to accurately monitor the rapid changes that are taking

place in the Andean climate and cryosphere. Many of the weather stations and streamgauges currently operating were installed in the middle of the 20

th century (Mark and

Seltzer, 2005). They are old and outdated and need to be replaced with more up-to dateinstrumentation (see Figure 1 for an example of an automated high-elevation weather

station). It is hard to believe but true, that we are currently not in a position to accurately

monitor and document the rapid changes taking place at high-elevation sites in the

tropical Andes. The anticipated expansion of the installed network by eight stations (2each in four countries), financed by the World Bank, therefore serves as a very welcome

major step in the right direction.

Figure 1: Example of a high-elevation AWS design from the summit of Sajama volcano, 6550m, Cordillera

occidental, Bolivia (photo credit: D.R. Hardy).

Such a network, in a first phase should focus on certain target areas, buteventually it needs to be expanded to become a connected network of sites along climatic

gradients from north to south as well as across the Andes from east to west (Francou et

al., 2005; Coudrain et al., 2005; Kaser et al., 2005; Casassa et al., 2007). It is of utmost

importance that these stations be deployed at high elevation, near or on glaciers, where projected changes in climate are large, and not simply at low elevations, where the

changes are likely to be much less dramatic (Bradley et al., 2004, 2006). The planned

Global Climate Observing System (GCOS) of the World Meteorological Organization for

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example, does not adequately address this problem. GCOS is a plan for long-term, high

quality observations at rural locations to establish a global climate monitoring networkthat will provide unequivocal data to assess climate changes (Bradley et al., 2004). As

shown in Figure 2 all planned GCOS stations are well below the freezing levels and only

3 stations are currently planned for elevations above 3000 m in the entire transect. It is

evident from Figure 2 that the GCOS network will not adequately sample the higherelevation zones of the American Cordillera where the impact of changes in climate are

likely to be greatest.

Figure 2: Mean annual change in temperature (2× CO2 minus control runs) derived from 7 models, and

compared to the planned GCOS network (squares). More stations at higher elevations are needed

to properly assess the model projections and monitor the large changes that the models indicate

will affect high montane regions. The small black triangles represent the highest elevation

mountains in countries along the transect (Bradley et al., 2004).

Finally these stations would provide valuable information not only for climate

change detection and attribution, but also for validation of model studies. Currently it is

very difficult to asses how realistic climate models simulate climate at such highelevations sites, simply because of the lack of in-situ climate observations. Interpreting

model projections of future climate change however, fist requires an accurate model

validation of the present-day control runs.An additional benefit of installing such a network on glaciers would be that they

could be equipped to record much needed information on glacier energy balance. So faronly a handful of stations with these capabilities have been installed on tropical Andeanglaciers (see Part II: Climate and Glacier Monitoring). The network installed and

maintained by the IRD seems a logical starting point from where to expand. However, it

is important that the glacier monitoring network, in a next step be extended to include

larger glaciers as well. We desperately need more data on the behavior of large glaciers,which may show less sensitivity to climate change and therefore offer the best hope to

retain some catchments water retention capacity in a warmer world. Despite the logistic

5



difficulties, these large glaciers must also be monitored in the future, albeit probably

based on new techniques, such as repeated laser scanning.Installing new AWS is urgent, but it is equally important that a commitment for

maintaining these stations for a number of years (preferable a decade or longer) is made.

The value of theses stations increases with the length of their climate record retrieved,

and installing new stations is rather pointless if their maintenance and proper functioningcan not be guaranteed for at least the next 5-10 years.

Servicing and repairing stations is costly and labor-intensive, but without such a

maintenance data quality will rapidly deteriorate and the stations will eventually be lost.AWS located on glaciers for example need to be constantly raised or lowered in order to

prevent them from being buried by snow or melting out and tipping over (depending

whether they are installed on the ablation or accumulation zone). Frequent exchange ofinstruments is necessary in order to recalibrate sensors or replace damaged instruments.

In summary, the financial costs involved in maintaining such a network for several years

are high and go well beyond the initial costs of station deployment. It involves costs for

spare parts and instruments, costs for training local personnel and finally a commitment

for financial support of the persons in charge of maintaining these stations over a periodof several years.

To effectively discern the changing climatic impact on glaciers and hydrologythat affects human society, glacier mass balance and climate monitoring need to be

combined with instrumentation throughout the watershed, culminating in stream

discharge. Stream discharge measurements are a critical component of the network because they are an effective net yield of the hydrological cycle for the watershed.

Combined with good precipitation gauges, these provide first order mass flux terms to

determine the relative role of glacier melt water where people utilize the water resource.Finally, while networks of glacier, climate and runoff measurements sites are

important and needed, they are also costly, labor-intensive and by their very naturelimited in space. They should therefore be complemented by increased use and

application of available remote sensing techniques and data sets from space. New

advances in combining digital elevation models, SRTM data, GPS and satellite data such

as Landsat, ASTER and SPOT, offer the opportunity to give a more detailed large-scale picture of changes in both the atmosphere and the cryosphere. While they are no

substitute for on-site measurements, they can provide a much needed complementary

picture. The Peruvian Andes, for example have been selected as a priority site to monitorglaciers with ASTER data under the Global Land Ice Measurements from Space

(GLIMS) umbrella (Mark and Seltzer, 2005). Initial studies of glacier monitoring from

space have shown very encouraging results (e.g. Georges, 2004; Jordan et al., 2005;Silverio and Jaquet, 2005; Raup et al., 2006, Racoviteanu et al., 2007). New initiatives,

such as the Japanese Space Agency Advanced Land Observing Satellite (ALOS) will

provide additional, high-resolution remote sensing capabilities to monitor glacier changein the tropical Andes (W. Vergara, pers. comm., 2007).

6



3) IMPROVE THE MODEL PREDICTIONS

Apart from the needed improvements in on-site and remote monitoring, it has also

become increasingly clear that we need better and more detailed scenarios of future

climate change in this region of steep and complex topography. Output from GCM’s can

at best provide us with a broad-brush perspective. High-resolution regional climatemodels, which allow for a better simulation of climate in mountain regions, coupled with

tropical glacier-mass balance models, such as the one used by Juen et al. (2007) could provide the necessary scientific breakthrough to better understand and predict future

climate changes and their impacts on tropical Andean glaciers and associated runoff.

Vuille (2006) recently proposed such a modeling strategy, which should allow us to

establish robust projections of how glaciation and runoff will change in this region at theend of the 21

st century. Figure 3 shows how such a research strategy, involving a

multidisciplinary team, could provide much needed information for policy- and decision-

makers, with potentially far reaching implications.

Figure 3: Flow chart of proposed modeling and validation studies, and participation of members during

the stages of the project (Vuille, 2006).

Step 1 – Regional Climate Modeling. Regional climate models (RCMs) can be

used to simulate both current and future climate in the tropical Andes. They can providemuch more realistic simulations of present and future climate change in the Andes than

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would be possible based on GCMs. There are however, significant differences between

models, which makes it imperative to compare results from more than just one model(Roads et al., 2003). Results can also differ depending on model resolution (Rojas, 2006),

domain choice (Rauscher et al., 2006), or whether the driving model is based on

reanalysis data or data from a GCM (Seth and Rojas, 2003; Rojas and Seth, 2003; Seth et

al., 2004, 2006). To date no comprehensive assessment exists regarding regional climatemodel performance for the Andes. Clearly the Andes provide a particularly difficult

challenge, given the complex topography with steep climatic gradients ranging from

tropical rainforest in the east to absolute desert on the Pacific coast. On the other hand,however, the Andes are also a region where regional climate models could yield the most

significant improvement, as the coarse GCMs are not capable of resolving the geographic

complexity of regional climate. For the central Andes (~300 km wide) for example, atleast 6 (12) grid-points are placed over the mountain range and its slopes for a 50 (25) km

resolution; in contrast the Andes are represented by only 2 or 3 grid points in a coarser

GCM of 2.5° resolution. Figure 4 illustrates the improved spatial resolution of a regionalmodel, by showing the remarkably detailed total cloud cover fields along the Andes.

These fields show significantly more spatial detail and structure, especially along theAndes, than similar diagnostics in a GCM or in reanalysis data.

Fig. 4: Total fractional cloud cover simulated in PRECIS for DJF 1979/80 (left) and JJA 1980 (right).

In the research strategy proposed in Figure 3 two regional climate models areused: PRECIS, which is a new version of the Hadley Center Regional Climate Modeling

System, and RegCM3. Both models are available at the Climate System Research Center

and could therefore be run at the University of Massachusetts, Amherst. PRECIS can be

run under Linux on a high-end PC at either 50 × 50 km or 25 × 25 km resolution.RegCM3 is commonly run at 50 × 50 km or 80 × 80 km resolution. Potentially, if

8



available, a third model, such the Earth Simulator from the Meteorological Research

Institute, Japan could supplement this suggested modeling strategy.

Step 2 – Model validation. All climate models intended for use in future climate

change scenarios need to be validated under present day conditions first, to assess their

capabilities of accurately simulating current climate. A model which can not reproducetoday’s observed climate with reasonable accuracy will likely not provide adequate

projections of future climate change either. In addition, if certain biases in the regional

climate model (e.g. excess precipitation in the tropical Andes) are known, these can betaken into account when interpreting results from future climate change scenarios.

Validation of regional climate models with observational data (both in-situ and from

space) is therefore an important step toward a realistic prediction of regional climatechange. Finally it is important to keep in mind that a higher resolution does not

automatically imply a better model performance. If the GCM produces an erroneous

climate over South America, so will the RCM. Any errors in the GCM predictions will be

carried through to the RCM simulation.

Step 3 – Glacier climate Modeling. Once the models have been validated and

their biases are known, the modeled climate data can serve as input into a glacier-climatemodel to evaluate how glaciers and glacial runoff respond to climate. The best currently

available model is the ITGG 2.0-R, developed by the Innsbruck Tropical Glaciology

Group. It has the advantage of being specifically designed to meet the particular climaticconditions of glaciers in the tropics (Kaser et al., 2005). The ITGG 2.0-R model

simulates tropical glacier mass balance with reasonable accuracy and it has been

successfully applied to simulate the seasonal cycle of mass balance (Kaser, 2001), as wellas seasonal and interannual variations of glacial runoff (Juen, 2006; Juen et al., 2007) in

the Cordillera Blanca in Peru. The glacier-climate model is applied to selectedcatchments, which will have to be selected based on certain requirements and priorities.

Obviously catchments where downstream water use is heavily dependent on glacial

runoff are of highest priority, but validation of the glacier-climate model requires that

mass balance and runoff records of sufficient quality are available from the catchments(see step 4). The main challenge which up to now has precluded the more wide-spread

use of this and other glacier-climate models in the tropics is the need to feed them with

climatic input data of high enough quality so that accurate predictions of glacier advanceor retreat are possible. Unfortunately the necessary input variables, such as accumulation,

albedo, atmospheric emissivity, incoming solar radiation and air temperature are not

routinely measured in the tropical Andes. Hence very little is known how these parameters have changed in recent decades, let alone how they might be affected by

increased greenhouse gas concentrations. This is where regional climate models can

provide a significant scientific advance as they offer the opportunity to improve thesimulation of these parameters, but also to assess how they might change under various

greenhouse gas scenarios.

Step 4 – Model –Data Comparison. Similar to the RCM, the ITGG 2.0-R modelalso needs to be calibrated and validated before it can be used for future glacier-climate

scenarios. This validation is done by comparing the simulated mass balance and runoff

9



(when fed with data from the regional model) with observational records. This necessary

validation procedure explains why the application of the model is restricted to catchmentswhere mass balance or runoff records are available. Juen et al. (2007) for example

successfully simulated the observed runoff in the Llanganucco catchment in the

Cordillera Blanca with this model (Fig. 5). The comparison of mass balance and runoff

simulations fed with data from the regional climate model with observational recordsallows assessing the uncertainty and accuracy of the present-day simulations. This is an

important step to quantify the error bars in the climate change simulations (Step 5).

Figure 5: Modeled (qmod) and measured (qmeas) monthly mean runoff depths for the validation period

1975 to 1985 in the Llanganucco catchment, Cordillera Blanca, Peru (Juen et al., 2007).

Step 5 – Climate Change Assessment and Impacts on Glaciation and Runoff .

Once the ITGG 2.0-R model simulates streamflow that is comparable to observations

(Figure 5), the entire cascade of the flow chart in Figure 3 is rerun, but this time based onIPCC- SRES scenarios. These final analyses will yield estimates of how glacier mass

balance at selected target sites in the Andes will change under different greenhouse gasemission scenarios (for example for the years 2070-2100) and how it might affectstreamflow and water resources in these previously glaciated watersheds. Vuille (2006)

suggested focusing on the A2 and B2 simulations, as these are high and low emissions

scenarios, which can bracket the most likely climate change, but theoretically these

simulations can be run with any emission scenario. While the IPCC SRES-A2 scenario is based on a medium-high emission and high population-growth scenario (15 billion

people by 2100), greenhouse gas emissions and population growth are much lower in the

B2 scenario (10.4 billion by 2100). Although there is no ‘most likely’ scenario, theSRES-A2 simulation is expected to give a clear signal of climate change against the noise

of natural variability, thereby providing robust patterns of change. The B2 scenario on the

other hand will provide a lower-end projection of climate change. When combined andrun as ensembles based on different RCMs , the two scenarios span a broad range of

future changes in emissions and population growth and will yield an estimate of the upper

and lower bounds of the expected change in climate, glaciation and runoff.

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4) IMPROVE COLLABORATION AND DISSEMINATION

A number of recent workshops have tried to establish a collaborative research

network in the Andes to improve collaboration and integration, and to facilitate

information and data-sharing between agencies and institutions (Francou and Coudrain,

2005, Diaz et al., 2006, Casassa et al., 2007). The research frame work proposed in the previous sections could equally be used to initiate a closer collaboration and jump-start

this process, once adequate funding is in place. It is a research strategy which combinesthe scientific strengths of the various institutions involved, such as climate dynamics and

climate modeling (UMass-Amherst), on-site climate- and glacier- monitoring (IRD),

glacier-climate modeling (ITGG Innsbruck), and glacier-runoff hydrology (Ohio State). It

is only by having such a multi-disciplinary team, where every partner involved brings hisor her scientific expertise to the table, that scientific breakthroughs and significant

advances will be made. Given the challenges that nations such as Peru or Bolivia face,

such an effort will yield a high return compared to the costs required. Much of the proposed work could be done in collaboration with local partner agencies in Ecuador,

Peru and Bolivia. Such collaboration should include exchange of scientific expertise,education and capacity building. This could be achieved, for example, through summerschools (one is already planned by IRD for September 2007 in Lima), fellowships, and

through training and education of South American students at the involved partner

universities in the U.S., Austria or France. A successful training course in mass balancemeasurements for example, was organized in La Paz in 2005 by IRD, the International

Commission on Snow and Ice (ICSI) and UNESCO (Francou and Ramirez, 2005).

To be truly relevant and successful, scientific results need to be disseminated to

the public, especially to local populations affected by climate change, but also tostakeholders and decision makers at various levels. After all the glacier-climate research

in the tropical Andes is relevant not only from a purely scientific stand point but has very

direct and immediate applications in the region. In addition the problems surrounding afuture water shortage in Andean countries are not only climatic in nature but also a result

of the economic and social developments in the region. One of the challenges to scientists

is therefore to provide scientific information which is not only scientifically relevant butalso socially applicable (Mark, 2007). One starting point for such an exchange would be

to organize a meeting of all partners involved (scientists, decision makers, users), with

visits to selected catchments where the most significant impacts on glacier hydrology are

expected. This could be a meeting under the umbrella of the Mountain Research Initiative(MRI), or organized by the World Bank, CONAM or the IRD. This would ascertain that

both climatic and socio-economic factors be taken into consideration when discussing

adaptation and mitigation strategies. Such a discourse between scientists, policy- and

decision makers and water users might also help closing the disjuncture, often observed between scientific and technical studies examining hydrologic resources, the national

institutions involved in water management and the demands and needs of the local population (Young and Lipton, 2006). It is our hope that the three reports provided here

will in some way contribute to this goal.

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Documents

3 (PRAA) Climate Change in the Tropical Andes - Impacts and Consequences for Glaciation and Water