We may have never seen heat like this before in the Equatorial Pacific. And as for atmospheric temperatures, 2015 is already locking in to shatter all-time global records set just last year. But despite a Monster El Nino raging across the world’s mid-section, despite a strengthening Jet Stream and a roaring storm track, the greatest warm atmospheric temperature anomalies are still centering in on the Arctic.
In other words, it appears that human-forced warming has taken so much cold out of the poles that there isn’t much of it left for the strengthening circumpolar winds to lock in.
A Godzilla El Nino
(The angry red scar of anomalous ocean heat that is the tell-tale of a monster El Nino is plainly visible in today’s Climate Reanalyzer Sea Surface Temperature Anomaly [SSTA] graphic.)
All you have to do is look at the great red scar spanning more than half of the Equatorial Pacific Ocean on the upper Climate Reanalyzer map to tell it’s a Monster El Nino year. A zone that in this measure is now showing an amazing +1.26 C sea surface temperature anomaly above the already hotter than normal 1979-to-2000 average. A region where weekly average sea surface temperatures in NOAA’s El Nino monitor are now tied with the record 1997 event. There, according to NOAA, temperatures last week hit 2.8 degrees Celsius above average along an Equatorial band stretching from 120 to 180 West Longitude. As a result, the Equatorial atmosphere continued to heat up, continued to contribute to global temperatures that for 2015 will be the hottest ever recorded over the past 135 years.
Considering such a massive amount of heat boiling up off this key Equatorial zone, we’d tend to think that this region would also show atmospheric temperatures that are much warmer than average. And it does. But strangely, perhaps ominously, the highest average atmospheric temperature departures do not reside over these record hot waters. They instead show up where we might least expect them during a record El Nino year — at or near the poles.
Odd Polar Amplification
(El Nino is already contributing to stronger circumpolar wind fields, so why are the Antarctic and Arctic regions still so warm? Image source: Climate Reanalyzer.)
For both within the Arctic and Antarctic — it’s still much warmer than normal. In the Antarctic, a zone from 70 to 90 South features air temperatures that are between 10 and 20 degrees Celsius hotter than average. In the northern polar zone an even warmer region ranging from 14 to 20+ degrees Celsius above average stretches over the fractured and greatly thinned sea ice along an arc just north of Svalbard and on into Russian Siberia. Overall, the Arctic as a whole shows an extraordinary +1.27 C positive anomaly. The Antarctic is at +0.90 C. And the tropics, which includes our massive El Nino still lags at an admittedly impressive +0.64 C above the already hotter than normal 1979 to 2000 average.
Why is this temperature anomaly pattern so darn weird? It all has to do with atmospheric physics. During times of strong El Ninos, the temperature difference between the poles and the Equator tends to increase as the Equator warms. This, in turn, strengthens the Jet Stream. A strong Jet Stream, for its part, tends to keep cold air locked away at the poles. So, ironically, as the Equator warms with El Nino, the poles have a tendency to cool off a bit.
So far, for the Fall of 2015, this isn’t really what we’ve seen. Sure, the Equator has warmed up quite a bit. Concordantly, the Jet Stream appears to have strengthened somewhat. We still have a big ridge that tends to keep forming over the ridiculously and persistently warm Northeastern Pacific, but it’s not stretching all the way into the Arctic like it did last year. Meanwhile, Jet Stream velocities and related storm track intensities are hitting rather high values. Arctic Oscillation has also recently hit extremely high positive values. A strongly positive Arctic Oscillation traditionally tends to result in cold air remaining locked away in the Arctic, but considering the temperature anomaly maps, Arctic cold hasn’t really been all that cold of late.
(North America — surrounded on all sides by ridiculously hot water. How will the influences of this off the charts ocean warming impact North American and North Atlantic weather systems this Winter? Image source: Earth Nullschool.)
Is Human Forced Warming Meddling with the El Nino-Polar Interplay?
So why are the poles still tending to remain very warm even as the Equator warms? The first answer is that high greenhouse gas concentrations from human fossil fuel emissions tend to preferentially warm these regions. This is due to the fact that greenhouse gasses have their greatest warming impact during times of darkness or when the sun is at a low angle. Compounding this impact for the Arctic is the fact that a high overburden of both CO2 and methane hangs over the region — possibly due to heightening emissions from thawing permafrost, increasing forest fires, and increasing ocean-to-atmosphere carbon fluxes.
A second answer is that the overall atmospheric impacts of the current Monster El Nino may not have come into full swing yet. We do still have a very warm pool of water in the Northeastern Pacific and this warm pool has tended to somewhat resist the polar wind field intensifying effects of a strong El Nino. This warm pool has also given the current El Nino a springboard upon which to further intensify. So the push and pull between these two hot water zones may not be over yet.
All in all, this pattern points to more and more weather weirding on tap for this Winter. Jet Streams and storm tracks may run further to the north as a result — especially in the areas of the Pacific Northwest and in Northern Europe. Troughs may also tend to dig a bit deeper along the Central and Eastern US and on out into the North Atlantic. This is not exactly the forecast we would expect with such a strongly positive Arctic Oscillation. But the related cool air pool has retreated so far north as to, at least for now, not fully result in a strong El Nino + strong Arctic Oscillation related weather pattern. Instead, for now, what we are seeing is a weird kind of hybrid weather pattern that appears to be incorporating the influences of a Monster El Nino, of ongoing polar amplification, of the cool pool in the North Atlantic, of the abnormally warm Barents Sea, and of the Hot Blob still firmly entrenched in the Northeastern Pacific.
Hat Tip to Ryan in New England