Understanding Temperature Anomalies

In News

• March 2023 was the second warmest March on record. 

More about the news

• Warm March:
  • March 2023 was the second warmest in the instrumental record. 
  • The warmest March occurred just a few years ago in 2016, when the biggest El Niño of the 21st century triggered a ‘mini’ global warming. 
  • In India, we expect March to be the beginning of the scorching summer season. 
  • But a particular year’s March may be cooler due to some other climate factors, such as a La Niña, and especially when averaged over a region as large as India or even an Indian State.
• Heating of the Arabian Sea:
  • The Arabian Sea has also warmed more than expected this March. 
  • This situation can favour a stronger monsoon but may also enhance cyclogenesis (i.e. birth of cyclonic circulation) over the Arabian Sea.
• Temperature anomaly:
  • The January-to-March average temperature anomaly ranks 2023 as the fourth warmest such period on record. 

About the “Temperature anomalies”

• What is a temperature anomaly?
  • The term temperature anomaly means a departure from a reference value or long-term average. 
    • A positive anomaly indicates that the observed temperature was warmer than the reference value, while a negative anomaly indicates that the observed temperature was cooler than the reference value.
• Significance:
  • This product is a global-scale climate diagnostic tool and provides a big picture overview of average global temperatures compared to a reference value.
  • Global warming does not mean each month or each year will be warmer than the previous month or the previous year. 
  • Instead, a better place to begin would be by averaging the weather over a decade. 
    • Decade-to-decade warming clearly shows that humans are now ensuring each decade is warmer than the one before.

• What causes the anomalies?
  • The global distribution of temperature anomalies is due to land-ocean-atmosphere processes that dynamically determine the weather and climate. 

Rising global temperatures

• Human induced warming:
  • Air temperatures on Earth have been rising since the Industrial Revolution. 
  • While natural variability plays some part, the preponderance of evidence indicates that human activities—particularly emissions of heat-trapping greenhouse gases—are mostly responsible for making our planet warmer.
• What does the analysis say?
  • According to an ongoing temperature analysis led by scientists, the average global temperature on Earth has increased by at least 1.1° Celsius (1.9° Fahrenheit) since 1880. 
  • The majority of the warming has occurred since 1975, at a rate of roughly 0.15 to 0.20°C per decade.
• Pattern of warming:
  • Global warming does not mean temperatures rise everywhere at every time at the same rate. Temperatures might rise 5 degrees in one region and drop 2 degrees in another. 
    • For instance, exceptionally cold winters in one place might be balanced by extremely warm winters in another part of the world. 
  • Generally, warming is greater over land than over the oceans because water is slower to absorb and release heat (thermal inertia). 
    • Warming may also differ substantially within specific land masses and ocean basins.
• Influence of rise:
  • The temperatures we experience locally and in short periods can fluctuate significantly due to predictable, cyclical events (night and day, summer and winter) and hard-to-predict wind and precipitation patterns. 
• Challenge for India:
  • India’s large population experiences adaptation challenges due to severe heat waves in the summer and extreme rainfall during the monsoon season.
    • Heatwaves cause mortality and pose challenges for public health infrastructure.
    • Prolonged extreme rainfall results in floods, which damage agriculture and infrastructure and cause human migration and loss of lives.

Possibility of intense heatwaves

• Excessively hot summer:
  • The summer this year is predicted to be excessively hot because of the end of the strong La Nina phase in equatorial Pacific Ocean, something that has a general cooling effect on the earth’s atmosphere. 
• Possibility of El Nino’s occurrence: 
  • New forecasts suggest that El Nino, which has the opposite impacts of La Nina, is expected to kick in from the May-July period itself, earlier than expected. 
  • El Nino also tends to result in suppression of monsoon rainfall over India. 
• Shortfall in rain:
  • A shortfall in rains is already being apprehended, which could exacerbate the effects of a hot summer, even though the India Meteorological Department has predicted a normal monsoon.

Way ahead

• Climate scientists need to provide the proper context when they compare and rank individual months against each other. 
• This will help the people at large better understand global warming as well as its cascading effects on the weather they experience every day. 
• And the better people understand the impact of global warming in their backyard, the likelier they can be engaged in climate action.

Source: TH