How Climate Works: Upwellings in the Eastern Pacific and Natural Ocean Warming

I’m sometimes asked how ocean circulation can naturally cause global warming, with many assuming solar variability or under sea volcanoes to be the indirect immediate cause.

My New Theory of Climate Resilience will focus instead on ocean upwelling dynamics, particularly in the Eastern Equatorial Pacific (EEP), and their modulation by lunar cycles. And I’m thinking in terms of a wind-driven climate.

These lunar cycles will be a topic for another day, in this short note I want to just introduce the idea of upwellings, and specifically for the eastern Pacific Ocean affecting global temperatures.

For centuries, Peruvian fisherman have noticed an increase in surface ocean temperature every so many years that impacts their catch.

The other years there are major deep ocean upwelling with the trade winds thought to drive cold, nutrient- and CO₂-rich deep waters (>1000 m, 2–4°C) to the surface. However, during El Niño years, weakened trade winds are thought to reduce upwelling, allowing warmer intermediate waters (100–500 m, 12–20°C) to dominate, raising sea surface temperatures (SSTs).

To be sure the ocean is layered! Temperatures change with the seasons and other cycles.

The surface mixed layer (0–65 m, 24–28°C) absorbs solar radiation; the intermediate layer is thought to be warmed by western Pacific currents, while the cold deep waters are the source of upwellings bringing nutrient rich waters that feed Peruvian anchoveta.

The Peruvian anchoveta (Engraulis ringens) is a species of fish of the anchovy family, Engraulidae, from the Southeast Pacific Ocean. It is one of the most commercially important fish species in the world, with annual harvests varying significantly between 3.14 and 8.32 million tonnes depending on ocean upwellings with cycles that appear to be little changed over the millennia. Most of the anchoveta catch is processed into fishmeal and fish oil, which is then exported to feed fish and livestock around the world including even farmed salmon in Chile and pigs in the United States and China.

There are robotic ARGO buoys that float with the currents; individual buoys can drift at depths of between 1 and 2 km, before ascending to the surface every ten days, measuring temperature and salinity as they rise. According to published studies, this ARGO data shows a general increase in sea surface temperatures with further rises of 1–2°C during El Niño years. So, the change is broadly consistent with the UAH satellite temperature data that shows warming since at least 1979 that has occurred as step changes, rather than as a general linear increase.

Last night Australia conservative politics suffered a devastating defeat to the Australian Labour Party in the federal election, though neither side managed to garner very much of the primary vote.

For sure, there are cycles in politics just as there are cycles in life. Recovery, if it is to occur, will perhaps require some reconnecting with core values that once upon a time placed a premium on evidence-based public policies developed with reference to the traditional scientific method while encouraging debate.

For sure, given the importance of energy and that the energy transition is apparently being forced by a climate emergency there is a need for a new theory of climate change that begins with an understanding of natural cycles. To simply claim, however, that climate change is natural is not a theory or even a proper rebuttal. It represents lazy politics currently favoured by conservative opinion leaders who are mostly frightened of my climate science. Shame.

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The image featured at the top of this post is from Nasa Flickr, with thanks. More information at:
https://www.nasa.gov/nasa-brand-center/images-and-media/