Climate Change: How Will it Affect Nepal?

Global IPCC Climate Change Predictions

            In 2007, the Intergovernmental Panel on Climate Change (IPCC) released the Climate Change 2007: Synthesis Report Summary for Policymakers.  In this document, the organization issued a dire warning that rising temperatures accelerated by anthropogenic activity would severely impact civilizations on a global, long-term scale.  A slight temperature fluctuation could result in shifting weather patterns, bringing drought to some areas and increased precipitation to others.  Areas experiencing drought would experience a disruption of agricultural practices leading to decreased production of food and the economic impacts associated with it.  Famine could follow.  Areas experiencing increased precipitation would be faced with flooding, increased incidences of disease-carrying insects, and sanitation issues resulting in illness.  Rising temperatures would also contribute to the melting of land ice, which would contribute to sea level rise and inundate hundreds of millions of people living in coastal regions (Bernstein et al. 2007). 

IPCC Predictions for Nepal

           The IPCC has predicted that temperatures in Nepal will increase over the next several decades in conjunction with the global trend.  The image below shows projected surface temperature changes through the end of the 21^st century.  The IPCC expects Nepal’s mean surface temperature to increase 3-4 degrees Celsius by the year 2099.  Temperature data collected at a Kathmandu weather station over the last 15 years supports the warming trend predicted by the IPCC.

Image: IPCC Summary for Policymakers 2007

A 15 year span of maximum temperature data from a Kathmandu weather
station reveals positive trends in summer and winter. Data: weatheronline.co.uk

These rising temperatures will likely cause some trouble for Nepal in the next century in the form of melting Himalayan glaciers.  Himalayan glacier melt feeds Asia’s five largest rivers, including the Ganges, which serve as drinking water and irrigation water for millions downstream.  The IPCC says, “Observational evidence from all continents and most oceans shows that many natural systems are being affected by regional climate changes, particularly temperature increases.  There is high confidence that some hydrological systems have also been affected through increased runoff and earlier spring peak discharge in many glacier and snow-fed rivers” (Bernstein et al 2).  

 Since the IPCC’s 2007 synthesis report, new research has indicated that Himalayan glaciers are not melting as quickly as anticipated.  In fact, some are growing: “The Himalayan glaciers that feed Asia's five largest rivers are in no danger of disappearing by 2035, as claimed in the Intergovernmental Panel on Climate Change's most recent report. In fact, only the glaciers that melt into the Ganges are shrinking . . .  at a rate of 22 centimeters per year.  The glaciers that sit at the head of the Indus grew at a rate of 19 centimeters per year on average, while those that melt into the other rivers in the study were unchanged” (Barley 2010). 

These glaciers, healthy now, can only physically exist under certain conditions.  Thus, melting glaciers are a long-term concern.  Receding glaciers would have significant impact on Nepal’s economy, but will not severely affect its water availability.  Nepal’s rivers are fed by glacial melt to an extent, but the country relies much more heavily on precipitation to keep streams flowing; in fact, a recent model indicates that melt accounts for less than 10 percent of the total water volume in the Ganges (Barley 2010). 

Nepal has two climate zones according to the Koppen-Geiger climate classification system: humid subtropical and highland subtropical.  The IPCC predicted “very likely precipitation increases in high latitudes and likely decreases in most subtropical land regions, continuing observed recent trends” (Bernstein et al. 8).  Although the climate of Nepal would put it in line for a decrease in precipitation according to this estimate, there is one large mitigating factor that could prevent the country from feeling the brunt of climate change. 

Nepal relies on the ITCZ to manufacture its summer monsoon.  Kathmandu receives, on average, 1250 mm of rain from May through October.  Approximately 150 mm of rain falls during the rest of the year.  According to this data, Kathmandu receives about 90 percent of its total rainfall during the summer monsoon (weather-and-climate.com 2009).

http://www.weather-and-climate.com/average-monthly-precipitationRainfall,Katmandu,Nepal

Nepal’s monsoon is significant to its survival on a warming planet.  The IPCC acknowledges that there is little evidence to conclude that monsoons will be severely affected by climate change: “Confidence is low in projections of changes in monsoons (rainfall, circulation) because there is little consensus in climate models regarding the sign of future change in the monsoons” (Field et al. 13).  In short, there is no evidence to conclude that South Asia’s summer monsoon would change in any significant way.

          While the IPCC has predicted higher temperatures and less precipitation for most subtropical regions, it has also forecasted the possibility that monsoon patterns may continue unabated.  Thus, it will likely not experience any significant water scarcity due to rainfall.


Potential Extreme Events

         
           Nepal is in less danger than much of the world in the face of rising temperatures.  There is some danger of flooding along Nepal’s riverbanks in the face of rapidly melting glaciers, which may be offset by a slight decrease in precipitation during the winter months.  The danger for flooding increases downstream in India and Bangladesh where inundation is already a significant threat.

The Kosi River flows south through Nepal and into India where it joins the Ganges.  During the summer, the river overflows with monsoon rain, flooding villages.  This is how the Kosi got its nickname, the “River of Sorrow”.  Image: http://www.southasiatimes.com.au/news/indian-armed-forces-carry-out-massive-rescue-relief-effort-to-fight-kosi-floods-in-bihar/

Bangladesh, which is largely situated on a floodplain, is in the path of the Ganges.  The Ganges, fed partially by glacial melt, is in danger of overflowing its banks as Himalayan glaciers begin to melt rapidly.
Image: http://geobytesgcse.blogspot.com/2006/12/flooding-in-ledc-1998-floods-in.html

Another effect of melting glaciers, which could affect Nepal directly, is the increased danger for mass wasting events: In its Special Report, the IPCC says “there is high confidence that changes in heat waves, glacial retreat, and/or permafrost degradation will affect high mountain phenomena such as slope instabilities, movements of mass, and glacial lake outburst floods” (Field et al. 13).  Landslides occur where soil becomes overly saturated and the soil structure beneath it can no longer support its weight.   Similarly, rock slides occur when water saturates a rock’s pore spaces and fissures and erodes it such that it breaks away and tumbles dramatically down slope.  Much of Nepal’s population resides in rural, mountain communities and are already at risk for mass wasting events.

Nepal, because of its summer monsoon, is already at risk for flood and landslide events. Image: http://www.who.int/hac/crises/npl/maps/en/

Potential Physical and Economic Effects

A developing country, Nepal lacks the resources and infrastructure to withstand any significant divergence from its established way of life.  Its ability to adapt to climate change is limited: “fatality rates and economic losses expressed as a proportion of gross product (GDP) are higher in developing countries. During the period from 1970 to 2008, over 95% of deaths from natural disasters occurred in developing countries” (Field et al. 7).  That being said, Nepal is in little danger of falling completely.  Temperatures will rise steadily and glaciers, subsequently, will melt steadily.  The risk of catastrophic flooding is therefore minimal. 

For Nepal, the most concerning aspect of climate change is the effect rising temperatures could have on its economy.  Agriculture is the mainstay of Nepal and comprises about 38 percent of its economy.  Rising temperatures could compromise Nepal’s ability to produce food goods; more irrigation will become necessary in order to sustain crops.  Although Nepal’s water supply is not currently in extreme danger, the increased demand for water could strain its rivers in the future. 

Climate change could also deal a blow to Nepal’s tourism industry.  Tourism is Nepal’s second most important industry after agriculture (ZRS 6) and about 17.5 percent of tourists come to Nepal for trekking or mountaineering (ZRS 34).  Much Himalayan trekking depends heavily on the presence of snow and glaciers.  Mount Everest, for example, cannot be climbed bare.   Nepal’s government charges $10,000 for an Everest climbing permit (Hamilton 2011).  Hundreds of climbers attempt Everest each year from the Nepal side, bringing significant income into the country.  Thus, the melting of Mt. Everest alone could severely cripple the nation.

This image shows the standard route of Mt. Everest approaching from the Nepal side.  The massive Khumbu glacier forms the initial leg of the climb.  Snow and ice covering some steeper sections of the mountain provide the traction needed to ascend. Without this snow cover, the mountain is a highly technical climb beyond most people's abilities.  Image: http://www.greatoutdoors.com/everest-2009/routes-maps

Mitigative Measures

            The National Adaptation Programme of Action to Climate Change (NAPA) is an organization that assists lesser developed countries including Nepal to “prioritize urgent and immediate adaptation actions” (NAPA 2010).  The overall structure of the NAPA has three components.  The first is the “preparation and dissemination of a NAPA document” The second is the “development and maintenance of a climate change knowledge management and learning platform for Nepal” and the third is the “development of a multi-stakeholder framework of action on climate change in Nepal” (NAPA 2010).  In short, the organization provides educational literature on preparation for climate change, assists the country in adapting to it, and assembles a support system through which to enact these mitigative measures.  The IPCC endorses this type of response: “Closer integration of disaster risk management and climate change adaptation along with the incorporation of both into local, sub-national, national, and international development policies and practices could provide benefits at all scales” (Field et al. 9).

            Some of climate change’s effects, like the detriment to Nepal’s trekking industry, cannot be avoided.  But some adaptive measures are possible including agricultural accommodation and the preparation of villages for possible flood events.

References

Barley, Shanta.  "Himalayan Ice is Stable, but Asia Faces Drought".  New Scientist.  June 2010.

http://www.newscientist.com/article/dn19029-himalayan-ice-is-stable-but-asia-faces-drought.html

Bernstein, Lenny et al.  Climate Change 2007: Synthesis Report Summary for Policymakers.  Cambridge University Press: Cambridge UK and New York USA.  IPCC, 2007.

Field, C.B. et al.  Summary for Policymakers. In: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation. Cambridge University Press: Cambridge UK and New York USA.  IPCC, 2012.

Hamilton, Leslie.  What it Costs to Climb Mt. Everest. 2012. 
http://outdoors.whatitcosts.com/mt-everest.htm.

National Adaptation Programme of Action to Climate Change (NAPA).  "About Napa".  2010. http://www.climatenepal.org.np/main/?p=aboutnapa&sp=about_napa

ZRS.  Nepal Tourism Sector Analysis. Asia Invest: European Cooperation Office, EU: 2008.

Climate Controls and Climate Classification

worldmap.com

Nepal's Climate Control Factors

Nepal's climate is controlled by a number of factors on meso, macro, and micro scales.


Macro scale factors:

• Nepal is a land-logged country.  Its capital, Kathmandu, is located at 27°42′N 85°20′E.  The country is subject to northern hemisphere seasonality.

Meso scale factors:

• Topography: Nepal is bordered on the north by a large mountain range.  The Himalayas protect the region from cold, southerly polar air. 

  

  The Kathmandu Valley, along with the rest of Nepal, is sheltered to the north by the Himalayas.  Kathmandu itself is surrounded by higher elevation terrain.  Its lower altitude allows for slightly higher temperatures in the city itself.   Image: University of Tokyo 2010



• Nepal is subject to the ITCZ as a major contributor to its weather patterns.



During the summer, the intertropical convergence zone drops equatorial moisture onto Nepal. This accounts for Nepal's summer rainy season. During the winter, the ITCZ is far off the Indian coast resulting in predominantly cooler, dry air over the region. Image: http://pages-142.unibe.ch/about/national/indonesia/itcz.html

 Micro-scale climate controls:

• Local topography: The Kathmandu valley, like all valleys, is subject to cold air accumulation.  During the day, the sun heats the valley floor.  The warm air begins to rise, creating wind, and the cold air ponds in the valley. During the summertime, this can lead to thunderstorms as warm, moist air rushes out of the valley into the higher topography.
• Urban heat island effect: in Kathmandu, a growing population in conjunction with a high rate of urban development contribute to higher city temperatures.  The images below show the factors that contribute to this heat island effect in Kathmandu including high population density and land use changes.




Kathmandu, the most densely populated region in Nepal, is subject to heat island effect as part of its micro-scale climate controls.
http://www.websters-online-dictionary.org/images/wiki/wikipedia/en/thumb/f/f5/Population_density_map_of_nepal.png/24.png

  



This map shows changes in land use in the Kathmandu valley sononymous with urban heat island effect.  Red areas indicate extreme urban development including higher incidences of paved roads and dense building structures.  Increased development has also lead to the loss of vegetation in the surrounding area, which further compounds heat island effect.  Kathmandu's population was 1,006,656 as of the 2011 Nepal Census.  Image: University of Tokyo 2010.

Climate trends:

• In conjunction with global trends, temperatures in Nepal are climing steadily. 

Ths graph reflects temperature data for Kathmandu in January and July over a span of 15 years.   This weather station's data only goes as far as back as 1997 and only provides maximum temperature data to the public.  However, when plotted on a graph, an overall positive trend is visible for both summer and winter, indicating that temperatures have been gradually increasing over this time span.  Source: weatheronline.co.uk 

Climate classification:

• The following image depicts Nepal's climate as defined by the Koppen-Geiger climate classification system.  Kathmandu is located in the humid subtropical region of Nepal.

The Koppen-Geiger climate classification system designates two climates in Nepal.  The southern-central portion of the country is classified as CWa (humid subtropical) while northeast and northwest Nepal are classified as CWb (highland subtropical).  Image: University of Melbourne

References:

http://www.wrh.noaa.gov/mso/educate/wind1.html

"National Population Census 2011". National Planning Commission Secretariat, Central Bureau of Statistics (CBS), Government of Nepal. September 2011. http://census.gov.np/

Kathmandu vs Bangalore: Climate Similarities and Differences

 



More than a thousand miles stretch between Kathmandu and Bangalore, two cities in South Asia.  But because Kathmandu is located to the south of the Himalayas, these two locations are able to share the same weather patterns.  There is a net elevation gain from Bangalore to Kathmandu as the landscape gently climbs into the foothills of the Himalayas.

This GoogleEarth image shows the spatial relationshp between Kathmandu and Bangalore.  These cities are 1,135 miles apart.  There is a net elevation loss of 1,277 feet between Kathmandu and Bangalore's city centers, although the terrain spikes sharply about 17 miles southwest of Kathmandu to almost 7,000 feet.  Kathmandu sits in a lowland region, surrounded by higher elevations to the north and south. Bangalore sits atop a plateau.

The intertropical convergence zone plays a crucial role in south Asia's climate.  In the ITCZ, warm, moist air is picked up near the equator and re-deposited elsewhere.  Both of these cities are subject to the whims of the ITCZ.  During the winter months, the ITCZ is located far south of the Indian region, as depicted in the graphic below.  As a result, Bangalore and Kathmandu are not subject to the warm, moist air currents of the ITCZ.  Instead, colder continental air flows from Asia in the direction of the Indian Ocean, resulting in dry, temperate winters.

http://milliethegeographer.blogspot.com/2012/03/atmosphere-and-circulation-help.html

This satellite image shows the ITCZ in January
(the thick band of clouds near the equator). 
The ITCZ is well south of both locations during the wintertime.

Bangalore is located in the semi-arid region of India.
 It receives little precipitation during the winter months.
 http://cee45q.stanford.edu/2003/briefing_book/india.html

Tables courtesy of climate-zone.com

 

A side-by-side comparison of the weather patterns of Kathmandu and Bangalore illustrates the fact that these two cities are subject to the same weather patterns.  Bangalore is lower in elevation and lower in latitude, which leads to slightly higher average temperatures during the summer months and much higher average temperatures during the winter months.  Bangalore maintains these warmer temperatures during the winter months because relative humidity is consistently higher than it is in Kathmandu.  Also worthy of note are the similarities in these areas' monsoon patterns.  Both locations' rainy seasons begin to ramp up during April and peak during the months of July and August before tapering off in September.

Widespread flooding often occurs in Nepal and India as a result of excessive summer rain and Himalayan snowmelt.  http://www.time.com/time/photogallery/0,29307,1650392_1422870,00.html

Air Masses in Nepal

Wind!



http://www.kuoni.co.uk/en/holiday/asia/nepal/pages/default.aspx



http://www.phoolbari.com/tourism/aboutnepal.html















Kathmandu serves as a popular destination
 for mountaineers before they ascend into the high Himalayas!


In the northern hemisphere, latitudes between thirty and zero degrees are normally subject to the northeast trades that move from subtropical high pressure to equatorial low pressure.  However, Nepal is a special exception.  The Himalayas act as a great barrier against the cold air that sweeps across Asia.  Arcing gently east-west across the region, the mountains shield Kathmandu from these air masses (cP and cA), resulting in the city's surprisingly temperate climate.  Kathmandu's climate comes as a shock to some because it seems to defy that which the region is known for: high altitude adventure. 



The temperatures of the city itself are quite moderate. 
Here, Kathmandu's cricket team enjoys a spring day



This satellite image shows how the Himalayas protect south Asia from cold, NE air masses.  Clouds are clustered near the top of the image, but cease abruptly near the base of the mountain range. 



Nepal is affected primarily by maritime tropical wind currents from the Indian Ocean and is also subject to an annual summer monsoon.  Air masses sweep to the northwest over the Indian Ocean where they become warm and moist before circling towards India, generating precipitation during the months of June-August.

This map illustrates the precipitation and wind patterns experienced during south Asia's summer monsoon season.  Kathmandu is located just below the dashed line at 27°42′N 85°20′E.  It's no coincidence that air masses suddenly change direction when they come to the dashed line--the line follows the arc of the Himalayas.
http://www.theresilientearth.com/?q=content/monsoons-megadroughts

Kathmandu is not affected by mid-latitude cyclones, as illustrated below.

This image shows the typical paths of mid-latitude cyclones (black arrows) and hurricane tracks (green).  Kathmandu is a  mid-latitude cyclone will not develop over this region because the Himalayas prevent tropical air masses from merging with the polar air masses that dominate Asia.
http://www.physicalgeography.net/fundamentals/7s.html

Welcome to Nepal!

Welcome to the beautiful Kathmandu Valley!



Overlooking Kathmandu
http://www.sacred-destinations.com/nepal/kathmandu-boudhanath-stupa



Nepal is small.  At only 147,181 km², Colorado (269,837 km²) is almost twice its size! 

Image courtesy of wunderground.com--
A weather station that serves the Kathmandu Valley is located in Patan, about 5 km south of Kathmandu.





<><><><> <><><><> <><><><>

In the heart of Nepal is the Kathmandu Valley.  The Himalayas overlook Kathmandu, Patan, and Bhaktapur (above), three of the Valley's major cities. http://parnassus-art.com/bhaktapur.html



Below are weather data from 2010 that summarize the Kathmandu Valley's climate. Kathmandu experiences a rainy season during the summer months. As a result, the "high" and "low" lines on the weather graph below come together from approximately June through September. This indicates that the higher humidity experienced in these months contributes to more latent heat and less sensible heat flux from day to night. The Bowen Ratio for this continental location would be higher during the winter, spring, and autumn months and higher during the summer. I estimate the summertime BR at about .30; for the winter, my estimate is approximately .60.

An important factor to determining latent and sensible heat flux is albedo. Using the known averages for earth's albedo (.306) and the earth's "greenhouse factor" (1), the average surface temperature of our planet is 58.9 ^◦F (determined using the GEEBIT program). If the albedo increased to .406 (with the greenhouse factor remaining constant) the average surface temperature would decrease to 39.1 ^◦F. Conversely, if the albedo were to decrease to .206, the average surface temperature would increase to 76.1 ^◦F. If the greenhouse factor were to increase by 10%, the average surface temperature of earth would increase to 63.9 ^◦F. If the greenhouse factor were to decrease by the same amount, earth's average surface temperature would decrease to 53.8 ^◦F

Any change that would affect earth on a global scale would also affect the Kathmandu Valley accordingly.  An increase in albedo, for example, might mean more snow in the wintertime, which would lower sensible heat during these months.