Climate scientists around the world are searching for an explanation for recent increases in ocean heat content and the average worldwide air temperature. During a portion of March and the first few days of June, the worldwide average air temperature exceeded the lower 1.5°C Paris Agreement threshold when compared to 1850-1900. This most recently occurred in 2020, and before that, during the powerful El Niño of 2015–16.
The fact that these most recent temperature increases took place before rather than during a predicted El Niño event in the Pacific is what makes them particularly concerning.
The Earth’s climate system is clearly out of balance right now, and we should be very concerned.
We are already aware that El Niño episodes are linked to higher-than-average global temperatures. We all need to pay closer attention to the future over the next few years because of the impending El Niño. This is particularly true given that the predicted warming event will come after the recent unusual triple La Nia event, which often results in cooler global average temperatures. As a result, the trajectory of this year’s increase in average temperatures is probably going to be considerably steeper.
The difference between the energy coming from the Sun and the energy going back into space, known as the Earth Energy Imbalance, is currently at an all-time high. The most important indicator of the likelihood of further global warming and climate change caused by humans is this.
This statistic will be essential for tracking how well we are doing overall in fulfilling the goals of the Paris Agreement, which call for humanity to limit average warming to preferably 1.5°C above pre-industrial levels or, at the very least, to as little as 2°C.
The oceans have warmed up how much this year?
About 89 percent of the extra heat in the Earth’s climate system since 1971 has been stored in the ocean (6 percent on land, 1 percent in the atmosphere, and about 4 percent is used to melt ice on land and at sea).
Because of this, any discernible increase in average ocean heat is regarded as a symptom of a more general acceleration of human-driven climate change.
By examining how much the average sea surface temperature deviates from the historical average over a significant portion of the oceans located somewhere between the Arctic Circle (60°N) and Antarctic Circle (60°S), scientists may track the condition of the Earth’s energy imbalance. Each month, “sea surface temperature anomalies” are estimated in relation to the base period of 1971–2000.
On June 13, the worldwide sea surface temperature anomaly was almost 4.5 standard deviations higher than the global mean. In other words, if the climate this month remained constant from the reference period, the chances of the current temperatures occurring completely at random are roughly 1 in 1.2 million.
It is considered practically statistically impossible for this anomaly to have occurred in a climate without human-induced global warming because it is so far above historical levels.
The current Earth Energy Imbalance 36-month running average is a record 1.36 Watts per square metre. This may seem like a modest amount, but over the last three years, the Earth’s climate system has accumulated an excess of energy equivalent to an average of 11 Hiroshima bombs every second.
Why is this occurring right now?
This unprecedented global energy imbalance is caused by a variety of natural and human climate causes. These include exceptionally warm temperatures around the planet and Antarctica’s sea ice fast melting.
Given that the warming in the central and eastern equatorial Pacific is not anticipated to reach its peak until next year, El Niño’s early arrival may also be having a less significant impact. In January 2022, the underwater volcano Hunga Tonga-Hunga Ha’apai erupted and spewed unprecedented quantities of water vapour into the stratosphere. Water vapour is a powerful greenhouse gas and may be responsible for the current warming.
New restrictions on sulphur aerosol emissions from ships and even a recent absence of Saharan dust are two other potential causes of global warming. Both of these types of atmospheric aerosols cool the atmosphere by reflecting a tiny amount of sunlight back into space.
There are warm ocean anomalies outside of the Pacific. Right now, the North Atlantic is very warm. In fact, the entire North Atlantic shattered records for year-round ocean temperatures.
This body of warm water has been connected to alterations in the jet stream, resulting in the formation of a heat dome over eastern Canada and the ignition of historically large wildfires.
Extreme climate-related occurrences will be quite likely if a severe El Niño emerges later this year and persists through 2024–2025.
The likelihood that the following five years will see the warmest year on record is likewise very strong.
An “hotspot” for El Niño exists in eastern Australia. Drought, bushfires, heat waves, crop failures, and large-scale coral bleaching events on the Great Barrier Reef are all at an elevated risk as a result.
Human-produced greenhouse gases are still rising and piling up in the atmosphere. Rising emissions will accelerate global warming and cause shifting climate baselines, or the “new normal” that is commonly attributed to climate change.
Extreme weather event risk will grow as these climate baselines change, according to climate models, which make this prediction with high confidence. As the background climate warms, effects of natural climate drivers, such as El Niño patterns in the Pacific, are anticipated to be magnified.
In light of the predicted strengthening of El Niño later this year, scientists will be closely monitoring the present increase in global ocean and air temperatures. How other climate causes might interact with the warming effects of El Niño is less clear.
In particular, how will any El Niño warming be amplified by the residual atmospheric water vapour from the Hunga Tonga-Hunga Ha’apai eruption? All we can do is get ready for more weather that will set records.