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