The northern region of the state is part of the Great Himalayan Range, covered in snow and glaciers. Two of the Indian subcontinent’s most important rivers (the Ganga and the Yamuna) also originate from the glaciers of Uttarakhand. The natural resources of the region provide life supporting, provisioning, regulating and cultural ‘eco-system’ services to millions of local as well as downstream people. The state lies between the longitudes 77°34′-81°02′E and latitudes 28°43′-31°27′N having a maximum dimension of east-west 310 km and north-south 255 km. It covers an area of 53,484 km² with the elevation ranging from 210 to 7817 mt. The state shares border with China (Tibet) in the North and Nepal in the East and inter-state boundaries with Himachal Pradesh in the West, Northwest and Uttar Pradesh in the South. Broadly, the region constitutes of 13 districts falling in two major administrative unit viz., Garhwal (northwest portion) and Kumaon (southeast portion).

The climate of Uttarakhand is temperate, marked by seasonal variations in temperature but also affected by tropical monsoons. January is the coldest month, with daily high temperatures averaging below freezing in the north and near 21°C in the southeast. In the north, July is the hottest month, with temperatures typically rising from 7 to about 21°C daily. In the southeast, May is the warmest month, with daily temperatures normally reaching the highest around 38°C from a low around 27°C. In most of the states, roughly 1,500 mm of annual precipitation are brought by the southwest monsoon, which blows from July through September.

Although climate represents a set of factors and determinants showing long term averaged state of the atmosphere over a region but temperature and rainfall are the two most prominent elements among them. The present study examines trends of rainfall and temperature at annual and monthly time scales for the periods of 1911-2012 to understand the climatic variability of the region.

Uttarakhand has two physiographic zones montane and non-montane. The mountainous regions have recorded more significant warming and declining rainfall trend, while Hardwar, which is almost plain, noticed positive rainfall trend (Table 1). It is evident that the temperature and rainfall departures from centennial average are significantly high in higher altitudes (Figure 3).

 

 

 

Data shows four distinct phases of temperature patterns during the last century- no warming or cooling up to 1950, warming trend during 1950-1080, cooling trend between 1980-2000 and again warming after 2000. On the other hand, the rainfall patterns recorded no significant shift from natural variability at centennial scale (1911-2012) (Figure 4).

 

 

Analysis of monthly average temperature data shows very striking results. Colder months: January, February, November and December, have recorded significant warming while the hottest months: June, July, August and September, have shown cooling trend. The study area receives most of its rainfall during the months of July and August but during last century (1911-2011), these months have recorded declining precipitation trend. The months of March and May on the other hand have received more rainfall than normal (Figure 5). Interestingly, the districts of non-montane physiographic zone have shown lowest departures.

 

 

The state has recorded a continuous growth in population during the last century except in 1921-31, however the urban population has grown at faster rate. Most of the population lives in the lower districts where urban share is high (Figure 6).

 

 

Hardwar and Dehradun districts record the highest population and percent urbanisation, and have the highest number of census towns (Table 2). These two districts have noticed less warming than others. Contrary to other districts, Hardwar has recorded an increasing rainfall trend although this trend is insignificant. Evidently urbanisation holds no significant association with temperature and rainfall trends.

 

 

Heavy forest diversion for basic infrastructures is also being accused for deteriorating local climate’s stability. But data suggests that green cover removal is not directly related with the warming. Dehradun and Hardwar which have recorded largest forest diversion are not the warmest districts of the region (Table 3). Forests attract rainfall, but here Hardwar having the noticeable forest diversion, has shown an increasing rainfall trend.

 

 

Uttarakhand is famous for religious and adventure tourism. Noticeably the tourist pressure at four major religious centres of the state has been almost doubled during the last twelve years (Table 4).

 

 

The three districts – Uttarkashi, Rudraprayag and Chamoli, where these religious centres are located, have recorded very significant warming during past decade. Increasing vehicular pollution seems fuelling temperature rise in these areas. Although growing industrialisation and vehicular density in Dehradun and Hardwar districts have no significant impression on temperature trend on the other hand, it can be said that vehicular pollution is more significantly correlated with temperature patterns in hilly areas while in the plain region, it has less impact on the atmospheric state. In other words, neutralising capacity of plain ecosystem seems greater than mountainous ecosystem.

Analysis shows noticeable departures in temperature and rainfall patterns. Months of March and May have recorded more rainfall and significant warming. Temperature of June, July, August and September are at cooler side. Result shows that surface temperatures have risen significantly during the last century, but this may be result of various cooling and warming phases. Besides having significant temperature-time correlations, R² values are very weak because of very noisy data. The ARIMA models predicted warming up to 0.3°C till 2035, being maximum for Chamoli district. Results show that this change is almost natural rather than anthropogenic. Warming is unequivocal with decreasing rainfall (except Hardwar), however, temperature and rainfall patterns do not fully support the hypothesis that urbanisation, industrialisation or green cover removal have great bearing on this warming or drying trend. Although increasing vehicular pollution in temperature-sensitive high altitude areas seems to have some impact on these trends, we can say while human interference has fuelled some variations in patterns, natural factors are the major cause behind climatic variability and changes. IPCC’s claim that due to human intervention in the Himalayan ecosystem, by 2035 we are going to lose large volume of glaciers, thus, does not seem a real claim. 

The authors did not declare any conflict of interest.