Albedo Feedback In The Arctic?

Ice cover is near its minimum in The Arctic. The Sun is also setting in the Arctic.

Put those two pieces of information together, and it becomes clear that the September minimum has very little effect on the Earth’s shortwave radiation budget.

On the other hand, areas of open water allow longwave radiation to escape.

Put those two pieces of information together, and it is not at all clear whether late summer Arctic ice loss is a negative or positive climate feedback.

About stevengoddard

Just having fun
This entry was posted in Uncategorized. Bookmark the permalink.

13 Responses to Albedo Feedback In The Arctic?

  1. fishnski says:

    Add the extra moisture in the air due to the open water which in turn gives above ave snow extent which secures the cold for ice growth…Mother Nature Rules..Not Man!

    • Rod says:

      I’m curious about this topic. Since about 2002, the ice extent in the Arctic has been below normal by quite a bit at the minimum.

      Simultaneously, the DMI temperature records show that the air temps in the Arctic during the refreezing period (say, Sep to Jan) have generally been well above average during those years.

      I started from the position that the air temps determined the ice cover and that higher air temps during the refreeze resulted in less ice, thinner ice, etc., so it wouldn’t be surprising that the next season’s minimum extent would come in lower than average once again.

      However, is there a feedback from the above-average amount of open water to the air temperature? That is, are the higher than normal Oct-Jan temps possibly kept high due to the higher than normal open water area?

      If that’s the case, then whatever is causing the reduced summer extent (say sea currents, for example) would have to change first, driving higher ice volume and only then would air temperatures return to their long-term averages. So, which is it? Ice extent drives air temps or air temps drive ice extent? Or both?

      Any insights?

      Incidentally, it’s fairly clear that ice strongly influences air temps in the summer, because no matter how sunny it is, the DMI air temp rarely moves more than a degree or so above the long-term averages.

  2. barry says:

    I don’t understand the top post at all. A darker surface absorbs more heat than a brighter one. Open water is darker than ice. The oceans will warm, melting the ice. It’s possible uncovered water will be cooler at night than previous years in winter if the ice recedes (ice also traps heat in the water under it), but day-time warming will more than offset that, especially in the summer time, when the Arctic receives more sunlight hours per day.

    Consequently, I expect winter temps to change little or maybe even get cooler in the Arctic if ice continues to recede for that period, and I expect the winter refreeze to cover a similar amount of area. But summertime temps will get hotter, as they have done over the the last couple of decades along with reduction of ice. The Arctic region has warmed more than any other large region on the globe over the last 30 years (at 4.7C per decade, according to the UAH satellite record). That’s year-round data, not just summertime. Observation doesn’t gel with the comments above.

  3. barry says:

    Sorry, that should be 0.47C per decade – 4.7C per century.

  4. barry says:

    One can compare Arctic temperature data with September sea ice coverage.

    http://moyhu.blogspot.com/2010/07/arctic-trends-using-gsod-temperature.html

    I didn’t expect the correlation to be quite so good, but if one looks at the peak temp years (1995, 2005, 2007), they match very well with the record sea ice minimums of those years. Other factors are in play, of course, and the match isn’t perfect, but this data doesn’t corroborate the thesis above.

  5. Rod says:

    Summertime temps have not gotten hotter over the past couple of decades at least during the period they spend above freezing. They’ve remained quite stable and this year they were actually cooler as measured by DMI. The year-round average is a different story.

    http://ocean.dmi.dk/arctic/meant80n.uk.php

  6. barry says:

    That’s a very odd data set. I notes it doesn’t measure in 10ths of degrees (it measures in 5K scale).

    From the same website, this is their sea surface temperature anomaly map.

    http://ocean.dmi.dk/arctic/satellite/index.uk.php – (Change the main parameter to ‘sea surface temp anomalies’)

    Summer time temps over the Arctic have increased. The anomaly map showing changes by as much as 4 and 5C + is for September, and greatly at odds with the data you showed from their other page – assuming I’m reading that page correctly. It’s not an intuitive graphic.

    It’s also *seems* to be at odds with many published studies:

    Click to access 2007GL029897.pdf


    Click to access tc-3-11-2009.pdf


    Click to access Steele_etal2007GL031651.pdf


    http://www.esajournals.org/doi/full/10.1890/06-0503.1

    … for example. All indicating a rapidly warming summertime Arctic over the last few decades.

    Has anyone contacted DMI to ask about those graphics and the data behind them? I may do so tomorrow. Good night.

  7. fishnski says:

    Hey Barry..I meant that the open water is able to feed Moisture into the surrounding landmasses which can cool faster producing more snow than if the arctic was solid ice. The increased area of White reflecting Snow helps the land area cool even faster & in turn can transfer that cold back over the Arctic which will drop the SST down to the point of freezing which works especially well after the arctic loses the solar energy.This is one reason why we can see great rebounds…Its just another guess on my part & it would not hurt my feelings if somebody shot my theory down in Flames!

  8. Bill Illis says:

    The Average Earth Albedo is 0.298 – 29.8% of the sunlight is reflected back to space without having an impact on Earth temperatures.

    The Albedo of solid snow-covered sea ice is usually about 0.65 – 65% of the sunligh is relfected. As the melt season continues, the snow melts and melt ponds appear and the Albedo of late season sea ice will fall to about 0.4.

    Open ocean water has an Albedo of 0.08 to about 0.2 – with ocean near the equator having the lower value and ocean at higher latitudes having the higher numbers (due to the lower solar incidence angle).

    There is also cloudiness to take into account. On average, there is about 65% cloud cover and the optical thickness (the actual amount of sunlight that does not get through the clouds) is about 28%. So, regardless of the sea surface conditions, the Albedo is going to start out at least 0.18.

    In July, open Arctic ocean water is going to have an Albedo (including clouds) of about 0.4. Sea ice covered regions will be about 0.6. So there is a calculable difference in the amount of solar energy being absorbed by the surface at this time of year (it is not a really big difference however).

    By the time the melt season really gets going in August and September, the solar incidence angle declines to 20 degrees, then 15 degrees and finally 0 degrees several days after the solstice on September 21 (and the amount of sunlight reflected rises exponentially as this angle declines for both sea ice and open water).

    When the sun gets down to about 10 degrees at 80N in late August, there is very little difference between open ocean water Albedo and sea ice covered Albedo, both are about 0.6 (and rise rapidly towards 0.95 for September 21st). So, by September, it makes no difference at all.

    One should also keep in mind that surface area represented by the Arctic ocean basin(above 75N for example) is only 1.7% of the total Earth surface so it is not going to make any difference to global temperatures – only local ones – especially when the Albedo difference (including clouds) between sea ice and open ocean is so small.

  9. barry says:

    I have contacted DMI and will update any response here, if they give permission.

    I note that the surface area covered at DMI is 80 degrees North, which spends most of the year covered with ice. How much of the area 80 degrees north has been open water at melt minimum the last few years?

    Other assessments of Arctic (summertime) temperature trends cover a broader area. I also noted that the DMI temperatures for October seem to have become warmer over the record.

    The October temperatures for the past few years have been among the highest in the temperature record at DMI, lending credence to the notion that less ice equals more heat near the record minimums of the last few years. But that’s a heavily qualified conclusion, of course.

    For the wider Arctic region, annual anomalies match fairly well with interannual sea ice coverage variability. There seems to be a correlation, particularly in the record-breaking years. Of course, other factors, like the surrounding land temperatures, and lateral heat transport through the atmosphere and oceans will have an impact, so I would not state anything here categorically. The same should apply, for the same reasons, to conclusions opposite to mine.

    Had I the time and skill, I would collect sea surface data from stationary locations most impacted by receding ice over the record (more open water for longer periods over the record), and attempt to find the trend specific to the topic from observations. A large number of coastal sea surface measurements, if possible.

  10. barry says:

    I finally got a reply from DMI. Below are parts of the email I received (I only edited out greetings and non-content stuff). Replies are in quotes and bolded.

    I have read quite a few studies on Arctic summertime temperatures indicating that the temperature trend for the region has been significantly positive over the last few decades. The University of Alabama satellite record maintained by Roy Spencer and John Christy has a trend of 0.47C/decade since 1979. I realize that the circle of the Arctic your graph covers a smaller area than many other assessments of Arctic temperatures.

    As your site is often referenced at various climate blogs, particularly the page above, would you be amenable to providing a brief reply? I plan to disseminate it responsibly, unless you state otherwise.

    1) It would appear at a glance that summer time temperatures have increased little over the past few decades going by the DMI graph set. Do you hold this to be the case?

    “From the link to WUWT, that you’ve attached below, it seems that a cooling temperature trend in the Arctic summer is present, throughout the past approximately 10 years. Where ‘summer’ is defined as the period where the +80N mean temperature is above 273K.

    However, I very much doubt that a simple conclusion can be drawn from that, as there are complicating aspects to that analysis, e.g.:

    1) The surface in the +80N area is more or less fully snow and ice covered all year, so the temperature is strongly controlled by the melting temperature of the surface. I.e. the +80N temperature is bound to be very close to the melt point of the surface snow and ice (273K) and the variability is therefore very small, less than 0.5K. I am sure you will find a much clearer warming trend in the same analysis applied to the winter period. The winter period is more crucial for the state of the Arctic sea ice, as this is the period where the ice is produced and the colder the winter the thicker and more robust the sea ice will become.

    2) The +80N temperature data after 2002 are based on the operational global deterministic models at ECMWF, at any given time. Before 2002 the ERA 40 reanalysis is used. I.e. the +80N temperatures are based on 4 different models, the model used for the ERA 40 data set and the operational models T511, T799 and T1279. The point is that there can be a temperature bias in one or more of the models, that can cause the lower temperature level since approximately 2002, where the shift between the ERA40 data and the operational model data occur in the WUWT-plot from the link below.”

    This was the link I gave in the email:

    http://wattsupwiththat.com/2010/08/05/dmi-polar-data-shows-cooler-arctic-temperature-since-1958/

    2) Can you help me understand what appears to be a discrepancy with other reports on Arctic temperature trends?

    “I do not think one can give a general comment on that – i.e. such discrepancies have to be discussed in a ‘case by case’ manner”

    3) Are there any published studies done by DMI researchers on Arctic temperature trends – for reference?

    “No – unfortunately, we have not had time to look deeper into this.”

    I already figured that the area DMI covers is almost completely ice-bound year round. It was good to have that confirmed. The summer temperatures in other data sets (studies I mentioned) cover a wider area, and observe increased summertime Arctic temps over the long-term.

    This doesn’t answer the question over whether an ice/albedo feedback has yet been observed, but it does put paid to the notion that DMI temps provide any insight. Until the sea ice at >80N has been significantly reduced, DMI data cover an area where the ice albedo has little changed over the satellite record. We must rely on data that from locations where summertime sea ice coverage has noticeably decreased over the long-term to see if there has been accelerated warming or not. One or a handful of locations won’t do. We need as many as possible to average out local dynamics and obtain a climate signal, if any.

  11. barry says:

    There might be a clue in Arctic ocean temperatures, which have increased by half a degree (centigrade) per decade over the satellite record.

    http://vortex.nsstc.uah.edu/public/msu/t2lt/uahncdc.lt – (trends along the bottom of the page for each region/decade)

    The Arctic ocean is the fastest warming place on Earth – faster the land Arctic and the entire Arctic region. Arctic waters are getting warmer faster than anywhere else.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s