Hunga Tonga–Hunga Haʻapai

Global average sea and air temperatures are spiking in 2023, before El Niño has fully arrived. We should be very concerned

Retrieved on: 
Tuesday, June 20, 2023
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Recent spikes in ocean heat content and average global air temperature have left climate scientists across the world scrambling to find the cause.

Key Points: 
  • Recent spikes in ocean heat content and average global air temperature have left climate scientists across the world scrambling to find the cause.
  • The global average air temperature, relative to 1850-1900, exceeded the 1.5℃ lower Paris Agreement threshold during part of March and the first days of June.
  • This last happened in 2020, and before that during the powerful 2015-16 El Niño.
  • Given the impending El Niño, we all need to take extra notice of what lies ahead for the next few years.

How much warmer are the oceans this year?

    • Because of this, any significant upward trend in average ocean heat is considered a harbinger for the acceleration of human-driven climate change more generally.
    • The global sea surface temperature anomaly on June 13 was about 4.5 standard deviations above the baseline global average.
    • The 36-month running average for the Earth Energy Imbalance is now at a record 1.36 Watts per square metre.

Why is this happening now?

    • These include rapidly declining sea ice in Antarctica and unusually warm temperatures in many parts of the world.
    • The submarine volcano Hunga Tonga-Hunga Ha'apai erupted in January 2022 and ejected record-breaking amounts of water vapour into the stratosphere.
    • Water vapour acts as a potent greenhouse gas, and this may be contributing to the currently observed warming.
    • Both these forms of atmospheric aerosols have a cooling effect, as they reflect a small percentage of sunlight back to space.
    • Notably, how will the lingering atmospheric water vapour from the Hunga Tonga-Hunga Ha'apai eruption amplify any El Niño warming?