But global warming isn’t a smooth ride: Like home prices, while the overall trend is upwards, there are ups and downs along the way.
Behind these fluctuations lies the El Niño phenomenon, a reorganization of ocean waters in a vast area of the Pacific Ocean. El Niño is crucial to the way weather works around the world, as it increases the average temperature not only in the Pacific Ocean but across the entire planet. In between El Niño events, temperatures tend to be neutral or the opposite state, called La Niña, which tends to lower global temperatures. The fluctuations between these extremes are irregular, and El Niño events tend to recur after 3 to 7 years.
The warm El Niño phase of this cycle began a year ago, peaked around the end of 2023 and is now trending neutral, ending the record-breaking streak.
The 2023-2024 El Niño was strong, but not super strong, so it doesn’t fully explain last year’s astounding temperature record-breaking, and the exact influence of other factors is still not fully understood.
We know that the Sun is in a phase of its 11-year sunspot cycle that is radiating slightly more energy to the Earth, resulting in a small positive contribution from the Sun.
Methane (a by-product of the fossil fuel industry along with cattle and wetlands) is also a significant greenhouse gas, and atmospheric concentrations of methane have risen more rapidly in the past decade than in the decade before.
Scientists are also assessing the extent to which measures to remove air pollution might add to warming, because certain particulate air pollutants can reflect sunlight and affect cloud formation.
Temperature Ratchet
2023 was a devastating summer for coral reefs and surrounding ecosystems in and around the Caribbean Sea, followed by mass bleaching events in the Great Barrier Reef off the coast of Australia during the Southern Hemisphere summer. While mass mortality on coral reefs around the world is often caused by El Niño years, it is underlying climate change trends that pose a longer-term threat, as corals struggle to adapt to rising temperatures.
