NASA dropped a bombshell of a climate report on March 11. February 2016 has soared past all rivals as the warmest seasonally adjusted month in more than a century of global recordkeeping. NASA's analysis showed that February ran 1.35°C above the 1951-1980 global average for the month, as can be seen in the graph of monthly anomalies going back to 1880.
The previous record was set just last month. January came in 1.14°C above the 1951-1980 average for the month. In other words, February has dispensed with this one-month-old record by a full 0.21°C — an extraordinary margin by which to beat a monthly world temperature record. Perhaps even more remarkable is that February last year crushed the previous February record, set in 1998.
An ominous milestone
Because there is so much land in the Northern Hemisphere, and since land temperatures rise and fall more sharply with the seasons than ocean temperatures, global readings tend to average about 4°C cooler in January and February than they do in July or August. Thus, February is not the absolute warmest global temperature: that record was set in July last year.
The real significance of the February record is in its departure from the seasonal norms that people, plants, animals, and the Earth system are accustomed to dealing with at a given time of year.
The 1.35°C figure from NASA is from the norm for 1950-1980. The instrumental temperature record goes back to 1880 and early instrumental data and model simulations allow a reasonable estimate for the northern hemisphere for warming since 1750, which is the "pre-industrial" starting point.
The record shows 0.3°C warming from 1900 to the NASA 1950-1980 baseline, If we add 0.3°C as an estimate of the amount of human-produced warming that occurred between the late 1800s and 1950, then the February result winds up at 1.65°C above average.
The proxy data shows about another 0.3°C from 1750 when industrialisation was ramping up, to the end of the nineteenth century for the northern hemisphere If we add them together, then February sits at 1.95°C warmer than the 1750 pre-industrial level for the northern hemisphere.
This result is a true shocker, and yet another reminder of the incessant long-term rise in global temperature resulting from human-produced greenhouse gases.
Making matters worse, even if we could somehow manage to slash emissions enough to stabilise concentrations of carbon dioxide at their current level, we are still committed to at least 0.5°C of additional atmospheric warming as heat stored in the ocean makes its way into the air. In short, we are now hurtling at a frightening pace toward the globally agreed maximum of 2.0°C warming over pre-industrial levels.
El Nino and La Nina are responsible for many of the spikes we see in global temperature. By spreading warm surface water across a large swath of the tropical Pacific, El Nino allows the global oceans to transfer heat more readily into the atmosphere. El Nino's effects on global temperature typically peak several months after the highest temperatures occur in the eastern tropical Pacific. The weekly anomalies peaked in mid-November at a record +3.1°C, so it is possible that February will stand as the apex of the influence of the 2015-16 El Nino on global temperature, although the first half of March appears to be giving February a run for its money.
We can expect the next several months to remain well above the long-term average, and it remains very possible (though not yet certain) that 2016 will top 2015 as the warmest year in global record-keeping.
Arctic leads the way
The map shows a big factor in the February result: a superheated Arctic. As shown by the darkest-red splotches in the figure, large parts of Alaska, Canada, eastern Europe, and Russia, as well as much of the Arctic Ocean, were more than 4.0°C above average for the month.
This unusual warmth helped drive Arctic sea ice to its lowest February extent on record in February. The tremendous Arctic warmth was probably related to interactions among warm air streaming into the Arctic, warm water extending poleward from the far northeast Atlantic, and the record-low extent of Arctic sea ice. Ground Zero for this pattern was the Barents and Kara seas, north of Scandinavia and western Russia, where sea ice extent was far below average in February.
Typically, the Norwegian archipelago of Svalbard — which includes the northernmost civilian settlements on Earth — is largely surrounded by ice from early winter into spring. This winter, the edge of the persistent ice has stayed to the north of Svalbard, which has helped an absurd level of mildness to persist over the islands for months.
Air temperatures at the Longyearbyen airport (latitude 78°N) have been close to 10°C above average for the past three months. This is the single most astounding season-long anomaly we've seen for any station anywhere on Earth.
Impacts of February's heat
It has long been agreed upon in international climate negotiations that a 2°C warming of the Earth above modern pre-industrial levels represents a "dangerous" level of warming that the nations of the world should work diligently to avoid. The December 2015 Paris Climate Accord, signed by 195 nations, recommended that we should keep our planet from warming more than 1.5°C, if possible.
Although the science of attributing extreme weather events to a warming climate is still evolving, February gave us a number of extreme weather events that were made more probable by a warmer climate. They give us an excellent example of how a 2°C warming of the climate can potentially lead to dangerous impacts. As we have been repeatedly warned might be the case, these impacts came primarily in less developed nations — the ones with the least resources available to deal with dangerous climate change.
Three nations suffered extreme weather disasters in February that cost at least 4% of their GDP. According to the International Disaster Database, these disasters set records for the all-time most expensive weather-related disaster in their nations' history. These nations set records in February for their most expensive weather-related natural disaster in history.
Vietnam suffered $6.7 billion in damage from a drought, which has hit farmers especially hard in the crucial southern Mekong Delta. This cost is about 4% of Vietnam's GDP, and beats the $785 million cost of Typhoon Ketsana of 2009 for most expensive disaster in their history.
Zimbabwe has suffered $1.6 billion in damage from its drought. This is about 12% of their GDP, and beats the $200 million cost of a 2003 flood for most expensive disaster in their history. Zimbabwe's President Robert Mugabe declared a “state of disaster” on February 5 in many rural areas hit by a severe drought, with more than a quarter of the population facing food shortages.
Fiji suffered $470 million in damage from Category 5 Cyclone Winston's impact in February. This is approximately 10% of their GDP. The previous costliest disaster in Fiji was Tropical Cyclone Kina in January 1993, at $182 million in damage.
One other severe impact from February's record heat is the on-going global coral bleaching episode, just the third such event in recorded history — 1998 and 2010 were the others. NOAA's Coral Reef Watch has placed portions of the Great Barrier Reef under their "Alert Level 1", meaning that widespread coral bleaching capable of causing coral death is likely to occur. Widespread but minor bleaching has already been reported on the reef, and the coming month will be critical for determining whether or not the reef will experience its third major mass bleaching event on record.
Highest carbon rise ever
Despite efforts to slow down human emissions of carbon dioxide, 2015 saw the biggest yearly jump in global CO2 levels ever measured. The annual growth rate of atmospheric carbon dioxide measured at NOAA's Mauna Loa Observatory in Hawaii jumped by 3.05 parts per million last year, the largest one year increase since measurements began there in 1958.
In another first, last year was the fourth consecutive year that CO2 grew more than 2 ppm. Pieter Tans, lead scientist of NOAA's Global Greenhouse Gas Reference Network, said: “Carbon dioxide levels are increasing faster than they have in hundreds of thousands of years. It's explosive compared to natural processes.”
The last time the Earth experienced such a sustained CO2 increase was between 17,000 and 11,000 years ago, when CO2 levels increased by 80 ppm. Today's rate of increase is 200 times faster, said Tans. In February, the average global atmospheric CO2 level stood at 402.59 ppm. Prior to 1800, atmospheric CO2 averaged about 280 ppm.
The big jump in CO2 in 2015 is partially due to the current El Niño weather pattern, as forests, plant life and other terrestrial systems responded to changes in weather, precipitation and drought. In particular, El Nino-driven drought and massive wildfires in Indonesia were a huge source of CO2 to the atmosphere last year. The largest previous global increase in CO2 levels occurred in 1998, which was also a strong El Nino year.
However, continued high emissions from human-caused burning of fossil fuels are driving the underlying growth rate. We are now approaching the annual peak in global CO2 levels that occurs during northern spring, after which the value will dip by several ppm. It is quite possible that the annual minimum in late 2016 will for the first time fail to get below 400 ppm.
[Jeff Masters and Bob Henson blog at Weather Underground (www.wunderground.com/blog/JeffMasters), where this was first published.]