It’s always nice to start the new year by looking at the big picture. And big pictures don’t get much bigger than this. The image below comes from NOAA’s Global Data Explorer. It shows sea surface temperature anomalies in the Pacific and Atlantic. Reds show areas with warmer than normal temperatures. Blues are cooler.
Degrees of Variation
The dark red areas are a whopping 4-5 degrees Celsius above normal. The dark blues are 3-4 degrees Celsius below normal. It takes 1.8 degrees Fahrenheit to equal 1 degree Celsius. So in terms of the temperature scale that most people in the US use, that’s up to 9 degrees warmer and 7.2 degrees cooler – a 16.2 degree spread.
This helps to explain the record warm December we just had. Houston is in that band of red that stretches across the northern hemisphere. Also notice how red the Gulf of Mexico is.
According to the EPA, an increase in sea surface temperatures can lead to an increase in the amount of atmospheric water vapor over the oceans. “This water vapor feeds weather systems that produce precipitation, increasing the risk of heavy rain and snow.” And we just had extreme snowfalls from the Sierras to the Rockies.
Role of Ocean Currents
Ocean currents help distribute this moisture around the world. According to NOAA, “almost all rain that falls on land starts off in the ocean.”
“Ocean currents act much like a conveyor belt, transporting warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics,” says NOAA. “Thus, ocean currents regulate global climate, helping to counteract the uneven distribution of solar radiation reaching Earth’s surface. Without currents in the ocean, regional temperatures would be more extreme—super hot at the equator and frigid toward the poles—and much less of Earth’s land would be habitable.”
Sea surface temperatures vary in cyclical, but irregular patterns (roughly every 3-6 years). Right now, we are under the influence of a La Niña pattern, that recurs every few years and can last as long as two years. This page on NOAA’s site explains what causes the changes. They often start with ocean currents veering off course for a period of time or stronger than normal trade winds.
The World Meteorological Association gives this La Niña an 80% chance of lasting through this spring before returning to normal (neutral) conditions.
Posted by Bob Rehak on 1/1/22
1586 Days since Hurricane Harvey