Climate Trends Report

In News

A recent Report by Climate Trends flags that Climate crisis intensifies: Coastal areas may become unlivable by 2100.

Key Findings

• The report stated that people living in and near the coastal areas in India may be compelled to stay indoors during working hours for more than half of 2100. 
  • Severe heat conditions, and not the novel coronavirus disease (COVID-19) pandemic, would be driving people to do so.

• Most parts of India experience 12-66 days of potentially deadly heat and humidity combinations in a year — expressed by ‘wet bulb temperature’. It is an index that measures the impact of heat and humidity on the human body.

Image Courtesy: TOI

• A temperature increase of 4.3 degrees Celsius by 2100 relative to pre-industrial temperatures may happen under RCP (representative concentration pathway) 8.5 scenario. The wet bulb temperature will cross the deadly threshold for six months or more by another nine decades.
• Even fit and acclimatised people can’t work at a wet bulb temperature of 32°C; at 35°C, even fit and acclimatised people sitting in the shade die within six hours.
• The report warned of a substantial worsening of the situation even by 2050. Kolkata may experience 176 deadly heat-humid days; the Sundarbans 215; Cuttack 226; Brahmapur 233; Thiruvananthapuram 314; Chennai 229; Mumbai 171; and New Delhi 99.
• India experienced 73 heat wave spells in 2019 against an average of 17 as measured during 1986-2016.

Heat Wave

• A heat wave is a period of excessively hot weather, which may be accompanied by high humidity, especially in oceanic climate countries. 
• While definitions vary, a heat wave is usually measured relative to the usual weather in the area and relative to normal temperatures for the season. 
• It is considered extreme weather that can be a natural disaster, and a danger because heat and sunlight may overheat the human body. 
• Heat waves can usually be detected using forecasting instruments so that a warning call can be issued.
• Heat wave is considered if the maximum temperature of a station reaches: 
  • at least 40 degree C or more for Plains 
  • at least 30 degree C or more for Hilly regions. 

Categories of Heat Wave

• Based on Departure from Normal 
  • Heat Wave: Departure from normal is 4.5 degree C to 6.4 degree C 
  • Severe Heat Wave: Departure from normal is >6.4 degree C 
• Based on Actual Maximum Temperature 
  • Heat Wave: When actual maximum temperature ≥ 45 degree C 
  • Severe Heat Wave: When actual maximum temperature ≥47 degree C 

Favorable conditions for Heat Wave

• Transportation / Prevalence of hot dry air over a region (There should be a region of warm dry air and appropriate flow pattern for transporting hot air over the region).
• Absence of moisture in the upper atmosphere (As the presence of moisture restricts the temperature rise).
• The sky should be practically cloudless (To allow maximum insulation over the region).
• Large amplitude anticyclonic flow over the area.
  • Heat waves generally develop over Northwest India and spread gradually eastwards & southwards but not westwards (since the prevailing winds during the season are westerly to north westerly). 
  • But on some occasions, heat waves may also develop over any region in situ under the favorable conditions.

Impact of Heat Exposure

• There are five physiological mechanisms which are triggered by heat exposure: 
  • Ischemia (reduced and restricted blood flow), 
  • heat cytotoxicity (cell death), 
  • inflammatory response (swelling), 
  • disseminated intravascular coagulation (abnormal blood clotting), and 
  • rhabdomyolysis (breakdown of muscle fibres).
• These mechanisms affect seven vital organs: Brain, heart, intestines, kidneys, liver, lungs and pancreas. 
• There are 27 lethal combinations of these mechanisms and organs that have been shown to be caused by heat.
• Severe heat waves have caused catastrophic crop failures, thousands of deaths from hyperthermia, and widespread power outages due to increased use of air conditioning.
• The signs and symptoms are as follows:
  • Heat Cramps: Ederna (swelling) and Syncope (Fainting) generally accompanied by fever below 39°C i.e.102°F.
  • Heat Exhaustion: Fatigue, weakness, dizziness, headache, nausea, vomiting, muscle cramps and sweating.
  • Heat Stroke: Body temperatures of 40°C i.e. 104°F or more along with delirium, seizures or coma. This is a potential fatal condition.

Way Ahead

• Identifying the heat hotspots by proper tracking of meteorological data and providing necessary relief.
• Encourage traditional methods of handling heat waves like wearing cotton clothes etc.
• Reviewing labour laws and other regulations taking climatic conditions into account.
• Improving the infrastructure setup like including shadowed windows, insulated houses etc.

Sources: DTE