Drought has been generally defined as a recurring extreme climate event that occurs NATURALLY... Given the current anthropocene, one may ask if drought is still strictly a natural hazard?
Anthropocene was coined by Paul Crutzen ,"Nobel-winning Dutch chemist" in the year 2000, to denote simply this current period of time in which the human activities have impacted global climates & ecosystems since the start of the 18th century.
Since entering anthropocene, the earth have changed a lot with nature losing its ability to deal with natural hazards. During my relatively short lifetime, I have witnessed man-effected droughts year after year in recent times.
Uprooting many trees, using agricultural lands for building houses, laziness in planting new trees, and the green house effect have resulted in moving from heavy rainfalls during winters to scattered rainfalls now. By this time, in the past years, the grass on a single mountain was enough to feed a herd of cows but today it is not enough to feed ONE cow.
It is time to admit that man has participated a lot in causing harm to our earth. We cannot continue, scientifically, in the process of blaming other "hands".
Drought is commonly defined as a temporary lack of water compared to normal conditions. In the traditional definition used in the natural sciences (climate science, hydrology, earth science) only natural drivers are included and the human effect on water resources is excluded. Drought impact studies, however, using observed crop yields, wildfire data, reservoir information, etc., can hardy make this division. The interdisciplinarity of drought asks for a broader definition that considers the interplay between the hazard, impacts and management. In the IPCC-SREX report definitional issues are mentioned as one of the reasons that no clear conclusions can be drawn about historic and future changes in drought. Human activities related to drought are mentioned by IPCC, but not included in their definition of drought. In the anthropocene the human aspects of drought can no longer be neglected. The IAHS Panta Rhei initiative, for example, urges hydrologists to include the connection with human systems. We propose a paradigm shift in the definition of drought, namely to expand it to include the effects of human action. For attribution we can then distinguish between climate-induced drought and human-induced drought. In this presentation, we will present a conceptual diagram that will do justice to the interdisciplinarity of drought. We will discuss issues of variability and change, scale (both temporal and spatial scales), feedbacks, and direct and indirect anthropogenic effects. The revised definition provides recognition and a common ground to researchers in all fields of research and is better aligned with drought impacts and with stakeholders' and policy maker's views on drought.
http://adsabs.harvard.edu/abs/2014AGUFM.H33N..08V
There is no doubt 'Drought' is a natural hazard. The increased frequency of occurrence of drought and its severity can be attributed to human activities like deforestation; filling of water bodies; construction of buildings/roads; etc.
Thank you all for your very insightful contributions which are indicative of the various perspectives surrounding how we view 'drought'. From my understanding after scouring through the literature and internet, there are three major schools of thought on this:
1) Drought is a natural hazard and will always be. This school is mostly embraced by people who see little or no modification of the natural-scape by human activities
2) Drought is a natural hazard whose frequency and intensity are accelerated by the anthropocene (widely accepted by a larger cross section)
3) Drought can no longer be coined 'natural' as the anthropocene has surpased the natural causes of drought. This school is upheld by people who in particular embrace the rapid modification of natural landscapes and climates by humans.
Personally, I am slighly leaning from 2) towards 3) as my understanding of the anthropocene evolves.
This is an ongoing debate and more contributions/views are very much welcome.
Thank you
Asong
Yes Dr. Kenneth, ever increasing population growth is the root cause of many disasters, including drought and floods (in their frequency and intensity).
Dr. Kenneth, its not prediction. The analysis of rainfall data (in Kerala State, India) has shown that the flooding has become more frequent in the last 2 decades mainly due to human activities like buildings; roads; filling of paddy fields; etc. Earlier areas used to be flooded when the daily rainfall was 120 to 150 mm; but now a days even for a rainfall of 80-100 mm/day, many city areas are flooded. You may kindly note that the annual average rainfall in this State is 3000mm.
Yes, 'droughts are part of long-term weather as are floods' and off course India is not an exception. My appreciation for the list of climatic events which took place in India. Thank you for the same.
Drought - Yes, it is strictly a natural disaster like tornadoe, hurricane or flood. In simple terms, it is the deficiency of rainfall over an extended period - a season, a year or several years relative to the statistical multi-year average for a region.
Effects of drought - Drought becomes an issue when it begins to affect water supply for irrigation, municipal, industrial, energy, and ecosystem function. A drought may result in other disasters: food insecurity, famine, malnutrition, epidemics and migration of population. Migration of people also caused conflicts as migration creates tensions in host regions due to the shortage of natural resources, like land, water and food.
Causes of drought - The drought is mainly due to the natural climate variations. The primary factor is 'change of pattern of jet stream (the wind that carries the clouds)'. It is thought that influences such as differences in the amount of snow and ice cover, the amount of vegetation (trees or grasses) covering the land, the moisture in the soil, and ocean surface temperature and currents can cause the changes in patterns of jet streams. The anthropogenic activities (as Dr. Prasad mentioned) such as deforestation, urbanization, use of fresh water unmethodically etc. have also influence in the occurrence of drought.
Regards
I agree to some extent with @Kenneth M Towe that drought is a normal part of climate variations (human-induced warming affects the RATE). See this time series (Figure 1) of tree-ring reconstructed PDSI over North America, by Dai 2011. Although the mega-drought which occurred in the early to middle part of the second millennium AD over western North America is unprecedented, the major driving factors may be attributed to variations in sea surface temperatures (SST). Acknowledging well that climate variations drive drought, one should not give a blind eye to human amplification of the climate system given the current anthropocene. It is now widely accepted (although not everyone is travelling in the same wagon) that human activities are altering drought characteristics (e.g. frequency, intensity, spatial coverage). In the same vein, we are still to witness mega-drought comparable to those in the pre-instrumental period (don't forget artefacts and issues surrounding paleo-reconstruction).
My take: albeit not equally weighted, the role of humans in drought occurence, intensity and extent should be factored in a 21st century definition of drought.
"....one should not give a blind eye to human amplification of the climate system given the current anthropocene." One should open their eyes to the evidence that there has been no human amplification... - Highly significant remarks (Quoted by Dr.Kenneth).
In this context I like to quote the comments of Dr. Helen Popova of the Skobeltsyn Institute of Nuclear Physics and of the Faculty of Physics of the Lomonosov Moscow State University.
“There is no strong evidence, that global warming is caused by human activity. The study of deuterium in the Antarctic showed that there were five global warmings and four Ice Ages for the past 400 thousand years. People first appeared on the Earth about 60 thousand years ago. However, even if human activities influence the climate, we can say, that the Sun with the new minimum gives humanity more time or a second chance to reduce their industrial emissions and to prepare, when the Sun will return to normal activity”.
See the link: https://astronomynow.com/2015/07/17/diminishing-solar-activity-may-bring-new-ice-age-by-2030/
(Courtesy: Dr. Barry Turner)
Regards
Some new research coming out of Canada on the possible influence of humans on observed Canadian temperatures. Key point: ' Most of the observed warming of 1.7 °C increase in annual mean temperature during 1948–2012 [90% confidence interval (1.1°, 2.2 °C)] can only be explained by external forcing on the climate system, with anthropogenic influence being the dominant factor' https://link.springer.com/content/pdf/10.1007%2Fs00382-018-4145-z.pdf
Dear Zilefac Elvis Asong, my answer to your query is definitely yes.
In the perspective of tropical climates, where I was born and grown, drought is a result of prolonged dry season over the wet season naturally. This prolonged dry season will result in depletion of water sources, drying of plants and consequently result in drought. But we have to bear in mind that our unprecedented intervention to the natural ecosystem contributes much for drought occurrence.
Top 10 Drought Prone Countries in the World
Every country’s agriculture, national economy, ecosystem, cultural and social life is effected by the availability of the water in that country. There are countries like Colombia (3240 mm / year), Papua New Guinea, Panama, and Malaysia which receive the highest annual rainfall whereas there are countries which do not receive much rainfall. There are several causes like less rainfall, dry season, El Nino effect, human activities which lead to severe drought.
http://www.natureaxis.com/2017/01/drought-prone-countries-in-the-world/
Regards
drought is then not a natural hazard, when human activities alter the dynamics (frequency, max, min) of rainfall. I am not sure, if this is a change in paradigm as such alterations were already discussed earlier (e.g. human induced impacts on micro climate as a result of destroying vegetation cover through over-grazing....)
The traditional definition of drought in natural science, compared with the current definition where the human effect is included, i.n., (non-climate factors), because drought as an anomaly is not considered (anymore) as transitory, or more or less prolonged. Are we missing another dimension?
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