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2016 set to be hottest year on record
Nov 29, 2016

Why in News:

In a preliminary assessment provided by the World Meteorological Organization (WMO) in its ‘Status of the Global Climate in 2016’ report, the global UN weather agency warned that 2016 will be the hottest year on record, with global temperatures even higher than what 2015 experienced.

Key Points from report:

  • Global temperatures for January to September 2016 have been about 0.88°C above the average (14°C) for the 1961-1990 reference period, which WMO uses as a baseline.
  • The world is likely to cross 1.2°C of global warming above pre-industrial levels in 2016, coming dangerously close to breaching the 1.5°C warming level, which is an ambitious target to stay safe from the worst impacts of climate change.
  • In parts of Arctic Russia, temperatures were 6°C to 7°C above the long-term average. Many other Arctic and sub-Arctic regions in Russia, Alaska and northwest Canada were at least 3°C above average.
  • while the extra heat from the powerful El Niño event has disappeared, the heat from global warming will continue.

Nino-Event

  • Annual and long-term changes in the climate system can aggravate social, humanitarian and environmental pressure. According to International Organisation for Migration, population migration is expected to increase as a result of more frequent and potentially more intense weather-related disasters, competition and conflict over shrinking resources, and rising sea levels rendering coastal and low lying zones uninhabitable.
  • Oceanic Temperature:Temperatures were above normal over most ocean areas. This contributed to significant coral bleaching and disruption of marine ecosystems in some tropical waters, including the Great Barrier Reef off the east coast of Australia, and Pacific island countries such as Fiji and Kiribati. Coral mortality of up to 50% was reported in parts of the Great Barrier Reef.
  • Green house gas concentration: Annual average global carbon dioxide concentrations in 2015 reached 400 parts per million (ppm) for the first time. 

Warming and associated danger:

  • The WMO report outlined the major weather events associated with increasing global warming levels in 2016. 
  • The most significant, in terms of casualties, was Hurricane Matthew affecting Haiti and parts of the U.S. 
  • Typhoon Lionrock caused destructive flooding and heavy casualties in the Democratic People’s Republic of Korea
  • Cyclone Winston was the most severe tropical storm on record to affect Fiji.
  • In total, there have been 78 tropical cyclones globally in 2016 as of October 31, close to the long-term average
  • The Yangtze basin in China had its most significant summer floods since 1999. 
  • Sri Lanka experienced flooding and landslides in Sri Lanka in mid-May leaving many dead or displaced. 
  • Above-normal seasonal rainfall in the Sahel led to significant flooding in the Niger River basin, with the river reaching its highest levels in about 50 years in Mali.
  • Heat waves:There were a number of major heatwaves during 2016. The year started with an extreme heatwave in southern Africa, exacerbated by the ongoing drought. Many stations set all-time records, including 42.7°C at Pretoria and 38.9°C at Johannesburg on 7 January.
  • Drought: Major droughts affected several parts of the world, most of them associated with the El Niño event, which had a big influence on precipitation. Southern Africa experienced a second consecutive bad rainy season in 2015-16.

Is Paris Deal Enough

The Paris Agreement last year had adopted 2°C as the absolute threshold for staying within safe global warming levels. However, 1.5°C was set as an ambitious target, especially bearing in mind the fate of small island countries such as Haiti or Maldives that are threatened with submergence due to sea-level rise and extreme weather events.

What is El Nino

El Nino is oceanic phenomena observed in the southern Pacific ocean which emerges after a gap of 3 to 7 years and is associated with abnormally high rainfall in the otherwise dry condition along the coast of Peru. This phenomena result in floods in Peru while Pacific coast of Australia and Indonesia have abnormally dry conditions that forces collapse of Agriculture with instances of Forest fire. During El Niño there are on average fewer hurricanes over the Atlantic Ocean, the Caribbean Sea and the Gulf of Mexico. In the central Pacific Ocean El Niño brings more typhoons, both north and south of the equator. Their more easterly genesis makes that fewer of these tropical cyclones reach Australia. In the northern Pacific Ocean the area with typhoons also shifts east. There are no effects on the number of cyclones over the Indian Ocean. The phenomenon is not well understood but it is related to Ocean current and trade winds. In this Sea Surface Temperature (SST) increases above normal by .5 degree.

In normal years the trade winds are fairly consistent and strong. The equatorial current of Pacific are well developed which leads to development of warm Western Pacific Pool  resulting in a zone of low pressure off Australian and Indonesian Coast with rising limb of air causing rain.

Nino-affect

At the same timePeruvian coast have cold current (Humboldt current) and upwelling which brings cold current along coast of Peru resulting in High Pressure with descending air current. This is favorable to Peruvian economy as Upwelling brought up nutrients at surface which flourishes fishing population. This low Pressure at Australian Coast and High Pressure at Peruvian coast form a vertical cell called as Walker cell. (This cell is exception to otherwise general pattern of Air circulation e.g. Trade winds, westerlies and Polar circulation and tricellular meridional circulation. Here  East-West Zonal Pattern is found).

During El-Nino years, for reasons not yet known the trade winds of Pacific weakens, resulting in weak equatorial current. The Warm Pacific Pool waters flows back strengthening the Counter Equatorial current. This reverses water flows southward towards Peruvian coast and this current is Known as El Nino current. (It is warm surface current appear at the coast of Peru during December flowing from equator towards Pole) which can stop the upwelling Process.

This result in reversing the pressure cells (Now Peruvian coast have low pressure and Australian-Indonesian coast having relative High Pressure) with this Walker Cell too is reversed i.e. rising limb of air at Peruvian coast and descending limb of air along Australian coast which reverses the climatic condition along these coast which results to Peruvian coast having High rainfall and West Pacific coast have dry condition).

The atmospheric component of El Nino/La Nina is called Southern Oscillation. This component is an oscillation in surface air pressure between the tropical western and the eastern Pacific Ocean waters. In context of Monsoon the two cumulatively called as ENSO. The strength of it (Southern Oscillation) is measured by the Southern Oscillation Index (SOI). It is computed by taking air pressure Ocean difference between Tahiti in Eastern Pacific Ocean and Darwin in Western Pacific.  An El Nino year will have negative value of SOI that means eastern pacific have below normal pressure over Tahiti and above normal pressure over Darwin.

 

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