NASA: Melting, Darkening Arctic Ocean Turns Up Solar Heat by 5 Percent

Atop the world lies a thinning veil of ice. A gossamer lid covering a deep, dark Arctic Ocean. It is a reflector screen for incoming solar radiation during the months-long-day of Polar Summer. And a recent NASA study shows that this heat shield is starting to fail.

Ever since the late 1970s an Arctic warming at 2-3 times the rate of the rest of the globe has set off a 13.3 percent decline of sea ice at end summer during each and every following decade. And that cumulative loss is having an extraordinary impact. For the white, reflective ice cover by September has now, on average, fallen by nearly 50%. What remains is a thinner ice cover. One full of holes and interspersed with great and widening expanses of dark water.

Dark water and thinner, less contiguous, ice absorbs more of the sun’s heat. NASA notes that this added absorption can have far-flung impacts:

While sea ice is mostly white and reflects the sun’s rays, ocean water is dark and absorbs the sun’s energy at a higher rate. A decline in the region’s albedo – its reflectivity, in effect – has been a key concern among scientists since the summer Arctic sea ice cover began shrinking in recent decades. As more of the sun’s energy is absorbed by the climate system, it enhances ongoing warming in the region, which is more pronounced than anywhere else on the planet.

For years, polar scientists have been warning of signs this powerful amplifying feedback was speeding an already drastic warming for the Arctic environment. Now, a 15 year satellite survey conducted by NASA provides direct evidence that this is indeed the case — with the Arctic now absorbing 5% more incoming solar energy than it did in the year 2000.

Arctic Sea Ice Changes

(Click Image to Enlarge. Left frame shows summer sea ice fraction change with measures in dark blue showing a greater than 50% loss on average. Right frame shows changes in absorbed solar radiation with most of the Arctic showing a 5 watt per meter squared or greater increase in solar radiation absorption and sections of the Beaufort Sea peaking at 50 watts per meter squared additional solar radiation absorption. Image source: NASA.)

Averaged over the Arctic, the failing summer sea ice and newly revealed dark waters absorb an extra 10 watts per meter squared of solar heat radiation. That extra heat is equivalent to having a 10 watt light bulb burning on every square meter of the Arctic Ocean surface throughout the entire polar summer. Twenty four hours per day, seven days a week for the seasonal period.

In some regions, like the Beaufort Sea near Northern Canada and Alaska, the extra heat absorption is as much as 50 watts per meter squared greater than year 2000 levels. An extraordinary increase in Arctic Ocean heat uptake and, perhaps, one of the chief reasons why higher Latitude ocean surface temperatures have tended to range so high in recent years.

It’s a massive realignment of the Earth’s radiative balance and one that has occurred in only a relatively short period.

NASA scientists are quick to caution that to fully take into account climate variability, the study will need to continue for another 15 years. But when taking into account the massive 35 year drop off in sea ice since 1979, it appears likely that radiative balance changes are even greater than the 15 year NASA study indicates.

September Arctic Sea Ice Loss 1979-2014

(NSIDC sea ice extent losses for Arctic since 1979 showing a 13.3% decadal rate of decline. Image source: NSIDC. Note NSIDC adds a linear trend line. However, historic rates likely show a more rapidly down curving melt progression — see image below.)

Overall, this loss of sea ice and related increased heat absorption has pushed melt season onset times a full week sooner than 1982 onsets 32 years ago. Earlier melt season starts lead to more heat absorption — a classic feedback cycle also recognized in the new NASA report.

In addition, the report links added Arctic Ocean summer heat absorption to loss of older, thicker ice observed throughout the Arctic region. Since 2000, more than 1.4 million square kilometers of 3 meter or thicker ice has melted out of the Arctic Ocean system. That ice has been replaced by coverages of less than 2 meters in thickness — another aspect of amplifying warming feedbacks at play in the Arctic.

Walt Meier, a sea ice scientist at NASA Goddard Space Flight Center in Greenbelt Maryland, notes:

Having younger and thus thinner ice during winter makes the system more vulnerable to ice loss during the summer melt season.

Whether these amplifying feedbacks will result in ice free summer conditions sooner rather than later is still a matter of some discussion among scientists. Following the 13.3 percent per decade trend puts us at ice free summers sometime around 2030-2035. But the large swings in annual variability could result in an earlier year in which ice free conditions occur. In addition, some scientists assert that amplifying heat feedbacks in the Arctic are enough to result in ice free summers as soon as 2017 to 2020.

To this point it may be worth considering that the 13.3 percent per decade rate may be steepening as is hinted at in the below long term graph:

2014_sea_ice_NSIDC_extended

(Long term melt trend compiled by Larry Hamilton. Image source: Here.)

Regardless of timing, the historic loss of Arctic sea ice is already resulting in dramatic impacts to the Earth’s radiative balance and to the distribution of global surface heat absorption. A circumstance that a number of studies have implicated in changing Jet Stream patterns and enhanced meridional (north to south and south to north) air flows.

Links:

Satellites Measure Increase of Sun’s Energy Absorbed in the Arctic

2014 Melt Season in Review

Arctic Melt Trends

Hat tip to TodaysGuestIs

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July 2014 Shows Hottest Ocean Surface Temperatures on Record as New Warm Kelvin Wave Forms

According to NOAA’s Climate Prediction Center, July of 2014 was the 4th hottest in the 135 year global temperature record. Land surface temperatures measured 10th hottest in the global record while ocean surface temperatures remained extraordinarily hot, tying July of 2009 as the hottest on record for all years on measure over the past two centuries.

Overall, land temperatures were 0.74 C above the 1950 to 1981 average and ocean surface temperatures were 0.59 C above the same average.

These new record or near record highs come after the hottest second quarter year in the global temperature record where combined land and ocean temperatures exceeded all previous global high temperatures in the measure.

Much Hotter Than Normal July

Few regions around the globe showed cooler than average temperatures during July with zones over the east-central US, in the Atlantic just south of Greenland, and off South America in the Southern Ocean as the only regions showing cooler than normal temperatures. Record warmest temperatures ranged from Scandinavia to Iceland to Northeast Siberia, from California to Alaska to the Northeast Pacific, along a broad stretch of Pacific Ocean waters east of the Philippines and New Guinea, in pools in the North and South Atlantic Oceans off the coasts of North and South America, and in spots from Australia through the Indian Ocean to South Africa.

Land Ocean Temperature Percentiles July 2014

(Land and Ocean temperature anomalies for July of 2014. Image source: NOAA’s Climate Prediction Center.)

Overall, most of the surface of the Earth featured above average to record warmest conditions, while a minority of the Earth’s surface showed average or below average temperatures.

These new global heat records were reached even as slightly cooler than average waters began to up-well in the critical Eastern Equatorial Pacific region. A powerful Kelvin Wave that initiated during late winter and spring of 2014 failed to set off a summer El Nino and finally faded out, reducing heat transfer from Pacific Ocean waters to atmosphere. Even so, the ocean to atmosphere heat dump was enough to set off two record hot months for May and June and a record hot ocean surface month for July as ocean surface waters remained extraordinarily warm across many regions.

Hot Water August 18, 2014

(Ocean surface temperatures remained at or near record hot levels during July and August of 2014 despite a failed El Nino development in the Equatorial Pacific. The above graphic shows global water temperatures for August 18 at an extraordinary +1.13 C above the already hotter than normal 1979 to 2000 average. Image source: University of Maine.)

New Warm Kelvin Wave Begins to Form

Though the atmosphere failed to respond to a powerful Kelvin Wave issuing across the Pacific earlier this year, stifling the development of a predicted El Nino, it appears a new warm Kelvin Wave is now beginning to form. Moderate west wind back bursts near New Guinea initiated warm water down-welling and propagation across the Pacific Ocean during July and early August. The down-welling warmth appeared to link up with warm water upwelling west of New Guinea and began a thrust across the Pacific over the past week.

As of the most recent sub-sea float analysis, anomalies in the new Kelvin Wave ranged as warm as 4-5 C above average:

Kelvin Wave August 14, 2014

(New warm Kelvin Wave forming in the Equatorial Pacific. Image source: Climate Prediction Center.)

These sub-sea temps are rather warm for an early phase Kelvin Wave and may indicate another ocean to atmosphere heat delivery is on its way, despite a broader failure of El Nino to form by this summer.

Typically, strong Kelvin Waves provide the energy necessary for El Nino to form. The heating of surface waters due to warm water upwelling in the Equatorial Pacific tends to set off atmospheric feedbacks that perpetuate an El Nino pattern in which waters remain warmer than average in the Central and Eastern Equatorial Pacific for many months. Without these atmospheric responses, El Nino cannot form.

During 2013 and 2014, strong Kelvin Waves forming during spring time were not enough to over-ride prevailing and historically strong trade wind patterns thereby allowing El Nino to emerge.

Atmospheric ‘Hiatus’ is No Halt to Global Warming

During recent years, scientific analysis has confirmed that a negative Pacific Decadal Oscillation together with record strength trade winds has suppressed El Nino formation and ocean to atmosphere heat transfer, leading to a temporary slow down in atmospheric temperature increases even as world ocean temperatures spiked.

heat_content2000m

(Global ocean heat content for 0-2000 meters of depth shows inexorable upward trend despite the so-called atmospheric warming hiatus. Image source: NOAA Ocean Heat Content.)

This natural variability, which typically lasts for 20-30 years began around the year 2000 and has continued through 2014. During such periods of negative PDO, we would expect rates of atmospheric warming to cease or even to go slightly negative. Unfortunately, even though PDO has been negative for nearly 15 years, a phase which during the 1940s to 1970s drove 0.35 C of transient atmospheric cooling against an overall larger warming trend, we have still seen atmospheric warming in the range of 0.1 C per decade.

This is bad news. For as ocean heat content is spiking, the transfer from atmosphere to ocean has not been enough to even briefly cut off atmospheric warming. And at some point, the oceans will deliver a portion of their latent heat back to the atmosphere, causing an even more rapid pace of temperature increase than was seen during the 1980s through 2000s period.

In other words, we’ve bent the cycle of natural variability to the point where we see warming, albeit slower warming, during times when we should have seen atmospheric cooling. And all indicators — radiative balance measured by satellite, deep ocean water temperatures, glacial melt, and atmosphere — show ongoing and inexorable warming.

Links:

NOAA’s Climate Prediction Center

University of Maine

NASA: ‘Haitus’ in Global Surface Temperatures Likely Temporary

NOAA Ocean Heat Content

 

 

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