Large swathes of Europe, the U.K. and the U.S. are sweltering under extreme heat wave conditions.
- Devastation due to extreme weather has been particularly acute in western Europe, which has been hit by raging wildfires, drought, and hundreds of heat-related deaths, ringing alarm bells about a looming climate emergency.
GS III- Environment and Ecology
Dimensions of the Article:
- About Heat Wave
- What is behind the extreme heat waves?
- Criteria for Heat Waves
- Health Impacts
About Heat Wave
- A heat wave is a period of abnormally high temperatures, more than the normal maximum temperature that occurs during the summer season in the North-Western and South Central parts of India.
- Heat waves typically occur between March and June, and in some rare cases even extend till July.
- Higher daily peak temperatures and longer, more intense heat waves are becoming increasingly frequent globally due to climate change.
What is behind the extreme heat waves?
- Scientists are near-unanimous that the heat waves are a result of climate change caused by human activity.
- Global temperatures have already risen by more than 1°C , and studies in the U.K. had shown that a one degree rise in temperature raises the probability of the country witnessing 40°C by ten times.
- The rising global temperature, which this year led to deviations above the normal by as much as 15 degrees in Antarctica, and by more than 3 degrees in the north pole, have also induced changes in old wind patterns.
- These changes turned western Europe into what has been described as a “heat dome” — a low pressure area that began to attract hot air from northern Africa.
- In the case of the U.S., the record temperatures are being linked to changes in the jet stream — a narrow band of westerly air currents that circulate several kilometers above the earth’s surface.
- While a conventionally strong jet stream would bring cooler air from the northern Atlantic, in recent years the jet stream has weakened and split into two, leading to intense and more frequent heat waves over parts of the American continent.
Criteria for Heat Waves
- The heat wave is considered when the maximum temperature of a station reaches at least 40°C for Plains and at least 30°C for Hilly regions.
- If the normal maximum temperature of a station is less than or equal to 40°C, then an increase of 5°C to 6°C from the normal temperature is considered to be heat wave condition.
- Further, an increase of 7°C or more from the normal temperature is considered as severe heat wave condition.
- If the normal maximum temperature of a station is more than 40°C, then an increase of 4°C to 5°C from the normal temperature is considered to be heat wave condition. Further, an increase of 6°C or more is considered as severe heat wave condition.
- Additionally, if the actual maximum temperature remains 45°C or more irrespective of normal maximum temperature, a heat wave is declared.
- The health impacts of Heat Waves typically involve dehydration, heat cramps, heat exhaustion and/or heat stroke.
- It also causes heat cramps, fatigue, weakness, dizziness, headache, nausea, vomiting, muscle cramps and sweating.
- The extreme temperatures and resultant atmospheric conditions adversely affect people living in these regions as they cause physiological stress, sometimes resulting in death.
-Source: The Hindu