This may not be the first time that October is so hot but experts say that it’s not just global warming but a whole lot of other factors that are making Delhiites sweat it out. Climatologists tell SHAlINI SAKSENA that India should be prepared for an increase in temperature on a constant basis
For the last few years, North India has been witnessing unprecedented heat — the temperature hovering around 35°C in September and October. There was a time, and many Delhiites would remember, that schools would introduce winter uniforms by mid-October with some students wearing sweaters by the end of September, to protect themselves from the early morning chill.
Cut to 2015. Not only are the children not wearing anything remotely resembling a sweater, air-conditioners are still on at homes, offices and cars. Experts say that there can’t be just one reason for this kind of weather across North India. Of course, global warming is a major contributor but there are other factors as well, though not directly related.
Air pollution can be linked to extended summer months. “Usually pollutants lead to an increase in the minimum temperature. This is because the particles get scattered leading to the rise in temperature. On the other hand, the maximum temperature gets reduced. But this is not the case now. Though one needs more study and analyses to be absolutely sure that there is a direct link, it can’t be denied either that it is a distinct possibility,” Dr Arvind Kumar Srivastava, director National Climate Centre, Indian Meteorological Department, Pune, says.
He also tells you that since the effect of air pollution on temperatures is a subject of a recent study. “One has to understand that with 2014 being the hottest globally, there is no way that India can escape the effects to global warming. The onset can be delayed but to say that we will not be affected is farfetched,” Srivastava says.
Up to 1960, the effect of global warming was restricted to a rise in maximum temperature. After 1960, there was an increase in the minimum temperature as well. In India, we saw this effect starting from the 1990s. This means that qualitatively, we should be prepared for increased temperatures in the coming years.
Having said that, climatologists say that there is a difference in the levels of increase in temperatures globally and at the national level. According to an ongoing temperature analysis conducted by scientists at NASA’s Goddard Institute for Space Studies, the average global temperature on Earth has increased by about 0.8°C (1.4° Fahrenheit) since 1880. Two-thirds of the warming has occurred since 1975, at a rate of roughly 0.15-0.20°C per decade. Because oceans tend to warm and cool more slowly than land areas, continents have warmed the most. In the Northern Hemisphere, where most of Earth’s land mass is located, the three decades from 1983 to 2012 were likely the warmest 30-year period of the last 1,400 years, according to the Intergovernmental Panel on Climate Change. In India, there has been an increasing trend of the order of 0.35°C was observed over the last 100 years.
According to IPCC (2001), rise in greenhouse gas concentrations increased the annual mean global temperature by 0.6 ± 0.2°C since the late 19th century. Available records show that the 1990s have been the warmest decade of the millennium in the Northern Hemisphere and 1998 was the warmest year. Some of the largest changes have occurred in the high-latitude Northern Hemisphere land areas, where winter temperatures increased at rates greater than 0.8°C decade across large parts of high-latitude North America, Europe and Asia since 1976.
“As for specifically, the North-west region usually sees a rainfall of 3-4 cm during this time. But so far, the rainfall has only been 1 cm; one-third the normal. This means that there is no cloud cover. Clouds ensure that the day temperature doesn’t rise. Since October has been a cloudless month so far, it leading to high temperatures,” Dr Srivastava explains.
Also, the fact that there was deficit rainfall in country — the country ended up with 14 per cent shortfall implies that there is less moisture in the air. This is also leading to an increase in temperature and pushing the onset of winters and restricting it to end of January instead of till March end.
“One has to understand that the land surface is getting hotter. Analysing daytime temperature extremes, we see a reduction in the number of cool days and an increased frequency of warm days. The changes in cool and warm days appear to be somewhat smaller compared to the cool and warm night frequency changes,” Srivastava says.
Erratic rainfall is part and parcel of climate in India. As are cyclones, typhoons, floods and drought. These are trends that one has witnessed in the recent past. But to conclusively say that these can be attributed to climate change, climatologists say, requires more in-depth study. The examination and analyses of climate change in South Asia has to be understood against the physical, economical and societal environments of many nations located in this region. The socio-economic environment of several countries in this region is characterised by high population density and relatively low rates of economic growth. Many countries here are quite vulnerable to extreme climate events such as cyclones and floods under current climate.
Climatologists say that short winters, scorching summers and erratic rainfall are getting common in India. But it is not just the Capital that is facing this extreme climate.
The entire world is facing a major climate change. According to the UN’s World Meteorological Organisation (WMO), which monitors global weather, the first six weeks of 2014 have seen an unusual number of extremes of heat, cold and rain in most parts of the globe.
The WMO assessment reported that Melbourne, Adelaide and Canberra recorded a heatwave in January, while temperatures in Moscow were 11° C above normal. Germany and Spain were 2° C above normal for January and February saw six major depressions develop over the Atlantic. However, the anomaly in weather continued beyond the first two months of 2014. According to the Japan Meteorological Agency’s (JMA) April 2014 report, the deviation in temperature continued in many major cities across the world.
Climatologist Prof Murari lal says India has distinct wet and dry seasons and relies on the summer monsoon for crop growth and water supply before the drier post-monsoon and winter season sets in.
“The persistent El Niño conditions over equatorial Pacific also intensified through late August and the month of September, causing more sinking air over India and southeastern Asia, in general, which suppressed rainfall and early cessation of monsoon rainfall from North and Central India. This, irrespective of the fact that the arrival of summer monsoon across India as a whole was advanced by almost two weeks, led to the monsoon withdrawing faster than normal. The monsoon typically departs far northwestern India by mid-September and along a pattern which joins Goa to eastern Uttar Pradesh.
“The drought areas of India depicting the cumulative rainfall departure from normal at the end of August 2015 with the early withdrawal of summer (SW) monsoon this year has given
rise to the unusually dry and hotter October month than normal,” Prof lal explains.
The northern States (south of the Himalayas), the southwest coast and south-central India had a rainfall shortage of 20 to 60 per cent below normal this summer. The dry (post-monsoon like) season started sooner than normal over most of India this year with heavy to very heavy rainfall in isolated areas of India during early to late September.
“I would attribute the abnormal weather — hotter and drier October — in India to rather late but significant intensification of El Nino conditions (cessation of coastal upwelling along the coast of Peru resulting in warmer equatorial east Pacific) in Pacific as a precursor to a complex air-sea interaction process resulting in warmer Pacific due to climate change,” Prof lal says adding that it is too early to call it a shift in season given that Asian summer monsoon is a very robust component of global circulation system and a major shift in India Monsoon Circulation from any known processes in the weather and climate science can be ruled out at this stage.
“In India, the coming years and decades are going to bring in enhanced intra-seasonal and inter-annual variability due to climate change (most models used for IPCC 2013-14 suggest this). Therefore the weather and climate during seasons and months over India would be highly variable over India. None-the-less, the India Meteorological Department has made significant improvements in its daily, weekly, monthly and seasonal forecasts in recent years with more robust technical and telecommunication infrastructure at its disposal,” Prof lal says.
Interestingly, this is not the first time that Delhiites have felt the heat in October. last year, the mercury touched 29°C in the Capital on December 1, 2014 and it was declared the hottest day since 1901. This came as a shocker for the layman but environmentalists and climatologists were not surprised. All along they have been saying that hot days are on the increase and winters on the decline.
Experts say that the present weather conditions in the Capital can be the result of global warming together with other factors like variations in land use and industrialisation. This includes deforestation, pollution and several other factors. Global warming is a phenomenon one can’t ignore. It will continue and the oscillations in climate will become even more common,
Climatologists do agree that to nail a pattern in short winters needs more research. The problem, experts feel, is that the impact of climate change is seen over a long period of time. For most people it is a matter of a rise of only 2°C — instead of the temperature hovering at 45°C it will now be 47°C. But scientists know the huge impact of this increase.
There is peak in demand for electricity which means more coal is burnt to generate it which, in turn, means that we are adding to the carbon budget. last year, India’s carbon emissions shot up to 7.7 per cent.
While this figure may not be as high as in other countries, India can no longer ignore the fact that it is the third largest polluting country in the world, after China and the US.
“When one talks about climate change, various factors have to be considered. No single major cause can be linked to global warming. It is an amalgamation of a number of reasons which impact the overall climate. So while for some nations, in the northern parts, a warmer world may bring good news, for island nations, Africa and countries in the tropical belt it spells disaster,” lal points out.
One is told that since the climate is not static, any assumption made about the future based on the past may be inappropriate. Assumptions about the probability, frequency and severity of extreme events should be re-evaluated. Climate change issue has presented decision-makers with a set of formidable complications: A considerable number of uncertainties have the potential for irreversible damage to our ecosystem.
Climate change, one is told, happens over a period of time. Therefore, a steady rise in temperature or for that matter winter setting in late or its intensity reducing may not register but India can no longer ignore that it is witnessing a change and it is time that some strong measures are taken urgently.