Urban Cooling in Pune, India

Fear of increasing summer temperatures in Pune, Maharashtra, India, being a threat has been expressed, a threat that has to be met and managed in one way or another. Summer temperatures over 40 degrees C are said to be normal nowadays, which was not the case 20 or 30 years ago. Eleven days in April 2010 have witnessed above 40 degrees Celsius temperature. The highest temperature of the season reached 41.5 degrees on April 16th. In total 24 days of April were above normal and only 6 days below normal. The city recorded its highest temperature of the 2009 season on April 20th with the mercury touching 41.6 degree Celsius. The highest April temperature recorded in the last 10 years in the city was 42.1°C on April 25, 2008. The highest-ever maximum temperature in the city was 43.3 degrees Celsius was recorded in April in 1897.
Climate and urban temperature
Discussing possible impacts of increasing summer heat it is essential to distinguish between climate and weather. Temperature is normally varying from day to day and from year to year but climate only change gradually and very slowly. Climate is often defined as the average weather conditions during a comparably long period of at least 30 years. High summer temperatures during 2008-2010 do not imply increasing summer heat.
It is also important to distinguish between global and regional climate changes from the situation on a specific weather station in one certain location. The commonly known fact that climate change implies a global warming of approximately 0.7oC during the last century, this fact tells nothing on the situation in a certain location like Pune. What is more important than global warming for the situation in an urban agglomeration of 5 million inhabitants like Pune is what internationally is known as the Urban Heat Island phenomenon, i.e. that the average temperature in an urban agglomeration is higher than the temperature in the surrounding rural areas.
Urban Heat Island Phenomenon
An Urban Heat Island (UHI) is a metropolitan area which is significantly warmer than its surrounding rural areas. A typical Urban Heat Island profile is showing highest temperature in downtown and clear low temperature in parks and surrounding rural areas. The main cause of the UHI is modification of the land surface by urban development which uses materials which effectively retain heat. Waste heat generated by energy usage is a secondary contributor. UHI has become more and more significant during the last 50 years, due to urban growth and increase in energy consumption in urban areas.
A typical Urban Heat Island profile showing highest temperature in downtown and clear low temperature in parks and surrounding rural areas.
It is very difficult to measure the real impact of UHI, since it is an effect of the location of the city, the local land use and the energy consumption in the city. However, the variations between tropical cities are quite high. Not all cities show a warming relative to their rural surroundings. Temperature data measured in urban weather stations around the world are generally adjusted, in an effort to homogenise the temperature record. Urban areas are heterogeneous, and weather stations are sometimes located in "cool islands" like parks within urban areas.
The urban growth of the city of Pune during the last century is remarkable. The population has increased from was slightly more than 100,000 in the year 1900 to more than 2.5 million 100 years later. Population in the total agglomeration of Pune and Pimpri-Chinchwad is now appr. 5.0 million inhabitants. Most of the population growth, the increased use of energy and the growth motorized traffic flows have occurred after 1950. The expected effect of UHI in Pune would be seen mainly during the second half of the 20th century and increasing until now.
Temperature in Pune
As mentioned already in the introduction of this paper temperatures in Pune is said to be increasing, and high summer temperatures has been registered during 2008-2010. The highest-ever maximum temperature in the city was on the other hand registered in 1897, more than 100 years ago.
The climate of the city is on the whole dry and invigorating. The mean monthly temperature is high (29.8 degrees C) in May while December witnesses a low (20.5 degrees C). However, the mean maximum temperature for April is (37.9 degrees C) more than that of May (37.2 degrees C).
The temperature in Pune has actually been decreasing, not increasing during the last 100 years, according to a recent study of temporal variation in temperature over Pune city, India, during the period 1901–2000 (Alaka Gadgil, Amit Dhorde, Temperature trends in twentieth century at Pune, India, Department of Geography, University of Pune, 2005.). The analysis reveals significant decrease in mean annual, mean minimum and mean maximum temperature.
Annual Mean temperature in Pune 1900-2000. Broken line showing 11-year running mean, unbroken line the linear trend.
This decrease in temperature is more pronounced during the winter season, which can be ascribed to a significant increase in the amount of suspended particulate matter (SPM) in the ambient air during the last decade. The summer mean temperature also shows a significant decreasing trend. However, unlike winter season this decrease is caused by significant fall in maximum temperature. The temperature during summer was higher during 1940’s to early 1960’s after which it has come down.
Summer mean temperature in Pune 1900-2000. Broken line showing 11-year running mean, unbroken line the linear trend.
On the contrary, monsoon season shows warming. This indicates that the night temperatures during recent years have gone up during monsoon. This warming can be attributed to a significant increase in the low cloud amount. Thus, all the trends are also well-supported statistically.
Monsoon mean temperature in Pune 1900-2000. Broken line showing 11-year running mean, unbroken line the linear trend.
The cooling trend in Pune’s temperature seems to be slightly accelerating. The conclusion can be made by comparing with other studies for Pune during the period 1876–1986. Contrary to this, the monsoon season shows warming trend. This may be due to significant increase in the low cloud amount during this season. Recently, anthropogenic aerosols are recognized as providing a significant and yet uncertain perturbation on the global radiation balance in terms of overall cooling effect. It is observed that SPM levels at Pune are significantly increasing since 1994. The observed cooling trend for the city, therefore, may be attributed to the upward trend of SPM in the ambient air, which the city has witnessed, due to increase in urbanization during the last two decades.
What are the possible explanations behind the cooling trend in Pune, different from most large cities including Indian cities like Mumbai and Kolkata? The referred studies give no clear answer to this. The character of Pune as a comparably green city with a lot of shading trees in the streets may be of importance. The location of the weather station in Pune can be located in an area not very affected by urban heat, perhaps located in a park or a rural area within the city. The urban heat effect can be hidden behind a more significant cooling trend, caused by natural climate variations. Without deeper studies there is no real answer.
Even without increasing temperatures in Pune urban heat may be a problem of importance for urban planning. Maximum summer temperatures are sometimes over 40 oC, high enough to cause impacts on health, energy consumption and environment. But the urban heat problem is at least not becoming more important than earlier because of increasing temperatures.
The conclusions are that the average annual temperature in Pune is decreasing between 1900 and 2000 and so are the average annual maximum temperature, average summer temperature and maximum summer temperature. Urban heat island in Pune is not an increasing problem. There is no simple explanation behind the cooling trend in Pune. An UHI effect can be hidden behind a more significant cooling trend, caused by natural climate variations. Urban heat may still be a problem of importance for urban planning. Extreme maximum summer temperatures might cause impacts on health, energy consumption and environment. High summer and maximum temperatures in Pune might cause an increased number of deaths due to periods of extreme heat, but residents of tropic cities like Pune tend to be acclimated to hot weather conditions and therefore less vulnerable to heat related deaths.


Indian lions and Swedish wolves

Yesterday the Swedish daily newspaper Svenska Dagbladet writes about Swedish wolf population. There are as many wolf pairs that last year despite the wolf hunt, 27 couples. The figures are as yet uncertain, as most the 27 couples gave birth to pups last year or at least 20. Last year 22 couples did multiply. It is also unclear as yet whether there are more wolves than the 210 that the government has determined should be the limit in Sweden. As I have previously stated, it is not a high goal in view of Sweden's sparse population and large surface area. With 210 wolves in Sweden, we have 0.5 wolves per 1,000 square kilometres. Many European countries have 10-15 wolves per 1 000 square kilometres; with this wolf density, we would have 4,000-6,000 wolves in Sweden. In an international perspective, Swedish ceiling of 210 wolves is quite modest. Many other countries also take on responsibility for preserving threatened species. Take for example India, which is one of the world's most densely populated countries. There are a number of big cats which are all endangered, tigers, lions and leopards.
Asiatic lion
Many believe that there are lions only in Africa. But there are 359 Asiatic lions in the wild in Gir forest, a national park in the Indian state of Gujarat. At least that many existed there in 2005. The park is only 1.412 km². It is a small remaining remnant of a tribe that once existed throughout western Asia, and even in Greece, where the extinct around AD 80-100. They were in the Caucasus, Azerbaijan in the current until the year AD 1000. In the late 1800’s lions disappeared from Turkey. The last time lions were seen in Iran was in 1941.
Gir Forest
The Asiatic lion is a separate species, slightly smaller than the African. The strain suffered heavily by inbreeding, the individuals are almost equally closely related to one another as identical twins, but despite this seemingly healthy. The trunk is nearly twice that of the Swedish wolf population, in an area similar to Östhammar municipality in East Sweden. Lion strain decreased slowly until the 1800s when it decreased rapidly because of hunting with firearms. Lion hunting was a favourite amusement among British colonialists and Indian princes. The growing Indian population has turned most of the remainder lived in the jungle for farmland. They are still hunted illegally by peasants who live nearby. A second sanctuary for the Asiatic lion has been proposed in Palpur-Kuno in Madhya Pradesh, where they were prior to 1873 when they were eradicated.
Area of Asiatic linon compared to African lion
The Bengal tiger in India, Bangladesh, Nepal and Bhutan. It is the most frequent tiger species with approximately 2,100 wild animals, of which 1,411 in India, 450 in Bangladesh, 150 in Nepal and 100 in Bhutan. India has around two-thirds of the world's wild tigers tiger reserves in 37 in 17 Indian states. Of the eight species were a hundred years ago, three extinct and only ten percent of the population remains. As late as 2003 there were 3,600 animals. In 2006 all 26 tigers were killed in Sariska Tiger Reserve. Last year reported gone all the tigers in Panna Tiger Reserve. Indian government has now decided to create eight new reserves. But still hunted tigers illegally, around 50-100 tigers are killed each year.
Bengal tiger
India has 1.2 billion people and a population density of 360 inhabitants per square kilometer, compared to Sweden's 23. India is 15 times denser. The Indian challenge is certainly much tougher than Sweden's goal of 210 wolves.


Iris’ Finnish Turnip Pudding for Christmas

Iris was born in northern Finland and spent her childhood in Turku in southern Finland. Amongst the Finnish traditions she brought with her to Sweden when she married my father in 1935 were Finnish sour rye crisp (Oululaininen) with Finnish Emmenthaler cheese, mämmi, the traditional Finnish Easter dessert, and turnip pudding for Christmas. I have tasted other turnip puddings many times but Iris’ recipe is, so far, superior to all others. Some people make the mistake to include carrot or even potatoes. Forget it. You should only use turnip roots (Brassica Napus).

A Swedish turnip root.
The turnip pudding is mandatory at Christmas in our home. Usually it is eaten together with Christmas ham, but it can stand on its own as well.

The turnip pudding ready for the oven.

This is her recipe

Two big turnip roots or three smaller ones
100 gram margarine
1 dl wheat flour
1-3 tbsp syrup
2 dl milk mixed with cream
1 ml measuring spoon white pepper
A pinch of grated nutmeg according to taste

Cut the turnip roots in cubes. Steam in salted water appr. 30 minutes. Mash the turnip (or use a food processor, but Iris never did). Add the flour, then the other ingredients and mix. Pour in a greased casserole. Smoothen the surface and pour brown dried crumbs on top. Make a nice pattern with a knife on the surface. Bake in the oven, 200 degrees centigrade for one hour.

The turnip pudding baked in the oven.
After I published Iris’ recipe for the turnip pudding on my Swedish blog, I have received several appreciating comments, not only from readers in Sweden, but also from Finland. This is especially honourable, since Finland is the homeland of the turnip pudding.