With a monster El Nino firing off in the Pacific and with atmospheric greenhouse gas concentrations now in excess of 480 parts per millions CO2 equivalent, global temperatures for 2015 continue to shatter new all-time records. It’s a sad upshot of continued energy dominance by myopic fossil fuel special interests and the big money investors who have backed them now for the better part of 135 years.
As of September of 2015, temperatures in the global measure provided by Japan’s Meteorological Agency rocketed to 0.5 C above the 1981 to 2000 average or about 1.2 C above average temperatures last seen at the beginning of the 20th Century.
(Japan’s Meteorological Agency shows that global temperatures sky-rocketed to a new record in September. Image source: JMA.)
This departure is a whopping 0.4 C above baseline rates of increase and a significant 0.15 C above the old record high for September set just last year (2014). Perhaps more notable is that all of the five hottest Septembers have occurred since 2009. A very strong global warming signal for the month and one that has left the 1997-1998 El Nino years in the dust.
NASA Shows September of 2015 was Second Hottest on Record
Though NOAA has yet to chime in with its monthly global temperature and climate analysis, NASA’s own GISS temperature monitor also shows September hitting near record heat. According to NASA, September of 2015 came in 0.81 C hotter than its own 20th Century benchmark average and about 1.01 C hotter than 1880s averages. This puts September of 2015 as a solid 2nd hottest in NASA’s record and just behind the new record set for September just last year.
NASA’s measure shows that four of the five hottest Septembers have all occurred since 2012 (ranking 2014 first hottest at +0.90 C, 2015 second hottest at +0.81 C, 2013 tied for third hottest with 2005 at +0.77 C, and 2012 as fourth hottest at +0.75 C). 2015’s +0.81 C departure is also well in excess of the +0.56 C departure seen in 1997 during the ramp up of what was then the strongest El Nino on record with averages for Septembers of 2014 and 2015 now at about +0.30 C above 1997 levels. A jump that falls neatly in the range of temperature increases predicted by IPCC and following the +0.15 to +0.20 C per decade accelerated rate of increase seen globally since around 1980.
Despite Strong El Nino, Northern Hemisphere Polar Amplification Really Heats up in September
NASA’s geographic distribution of temperature anomalies map tells a rather interesting tale for September. One that may have implications for Northern Hemisphere weather further down the line as Fall and Winter progress.
(NASA’s global temperature anomalies map shows strong warming at both the Equator and the Northern Hemisphere Pole during September. A signature that hints strong south to north heat transfers are at play. Image source: NASA GISS.)
As expected with a strong El Nino, we see a lot of heat building up along the Equatorial zone and especially in the Eastern Pacific where land-ocean temperatures hit a strong range of +2 to +4 C above average. A bit odd, however, is a strong heat plume visibly rising off this hot zone, traversing the western land mass of North America and entering the Arctic through the gateway of the Canadian Archipelago (CAA). Notably, high Arctic temperature anomalies in the zone north of the CAA also spike to levels in the range of +2 to +4 C above average. It’s a kind of south to north heat transfer that we would expect to see less and less of as El Nino strengthens and the storm track flattens out. But ridging over the North American West along with associated heat continued to remain in force throughout September providing a pathway for heat to enter the upper Latitudes.
Other strong, though somewhat less robust, Equator to Pole heat transfers appear visible over Europe on up through Scandinavia, and ranging along a diagonal between India, China, Mongolia and Kamchatka. It’s a heat signature picture of a mangled Jet Stream completed by trough zones and cool pools over Alaska, in the ominous region of the North Atlantic between Greenland and England, in Central Asia, and just east of Japan. Most notably, the cool pool associated with a weakening Atlantic Meridional Overturning Circulation (AMOC) and all-too-likely due to the decadally increasing rates of glacial melt outflows from Greenland remains a dominant feature in the North Atlantic. It’s a cool pool signature that was predicted in almost all the global climate models in association with overall human forced warming of the atmosphere and ocean. One that can drive weather instability in the North Atlantic. And one that has been a nearly constant features since at least 2012.
(Zonal anomalies graphic also shows strong equatorial and polar warming. Image source. NASA.)
NASA’s zonal anomalies map paints a picture of both Equatorial and Northern Hemisphere Polar heat with temperatures well above average over most regions of the world. The primary exception is Antarctica and the Southern Ocean which, during recent years, has acted as an atmosphere-to-ocean heat sink. Notably, a very strong storm track in the region of 50 South Latitude has driven powerful winds which have forced atmospheric heat into the ocean depths while also forming an atmospheric barrier to heat conveyance over Antarctica.
High Latitude regions between 85 and 90 North showed the most extreme temperature departures with a +1.6 C positive anomaly for the region. Temperatures drop somewhat to between +1 and +1.3 C from 30 to 70 North before rising again to around +1.4 C near the Equator. Anomalies drop off southward ranging from near +0.7 C around 30 South before dropping into negative values in the atmosphere to ocean heat uptake zone in the Southern Ocean near 60 South.
Winter Weather for 2015 May Feature Some Unexpected Twists
Overall dispersal of heat shows a notably high degree of Northern Hemisphere polar amplification at a time when El Nino should be spiking heat at the Equator, increasing Jet Stream strength, and pushing the Northern Hemisphere Polar zone to cool somewhat. The fact that the Pole remained at higher positive temperature anomalies than the Equator during September even as El Nino cracked +2 C above average heat in the Nino 3.4 zone hints that this Winter may show more waviness in the Jet Stream than is typical during a strong El Nino year. As a result, weather patterns typical to El Nino during Northern Hemisphere Winter may show marked variance.
If this is the case, rainfall amounts for Southern and Central California may be less than expected for a typical strong El Nino year. Heavy rainfall events may shift northward toward Oregon, Washington, British Columbia and Alaska. A northward angling storm track over Western North America would tend to reinforce trough development in the east while providing major storms for the US East Coast and Northeast as the higher amplitude Jet Stream wave taps more Arctic air than is typical. Meanwhile, warm waters off the US East Coast in the range of +2 to +5 C above average will provide both heat and moisture as fuel for storms moving down any trough feature. Extra heat and moisture provided by El Nino will also tend to preferentially increase storm intensity all along the storm track even as temperature differentials at the sea surface in the North Atlantic provide further instability for storms that are likely to hit high intensity along a track between Iceland and the United Kingdom. Meanwhile, these features, combined with warmer than normal sea surface temperatures in the newly ice-liberated Barents, could result in warmer and stormier conditions for Northern Europe and Scandinavia.
Globally, we are likely in for a record hot Northern Hemisphere winter for 2015. Combined with one of the strongest El Ninos on record, such a high temperature excession may well put us into a number of entirely new, and potentially very stormy, weather contexts. Comprehensive monitoring and updates to follow.