Category Archives: Global Warming

Land-Fast Ice Cover off North Greenland: Will NASA bite?

Posted on May 17, 2013 by | 6 Comments

When a large outlet glacier of North Greenland (Petermann Gletscher) discharged an ice island four times the size of Manhattan in August of 2010, the United States’ Congress held formal inquiries on its cause within days of the event. Congressmen, scientists, and the global media speculated that this event and concurrent severe droughts in Russia and floods in Asia were tied to record-breaking air temperatures and global warming. Reviewing available data, Johnson et al. (2011) cautioned that most melting of floating ice shelves such as Petermann Gletscher is dominated by physical ocean processes below, not above the ice (Reeh, 2001, Rignot and Steffen, 2008). The National Journal asked me to write an essay to answer the question: “Is Climate Change Causing Wild Weather?” which I answered with a nerdy No, but …. Motivated by questions asked during the congressional hearing, I showed that waters in Petermann Fjord (a) originate from the Arctic Ocean to the north, (b) contain heat of Atlantic origin, and (c) have warmed significantly since 2003 (Muenchow et al., 2011).

Petermann Gletscher from MODIS Terra. Repeat NASA along-glacier flight tracks are shown in the left and middle panels. White line across the glacier are ICESat tracks. Thick black line across the glacier near y = 0 km is the grounding line location from Rignot and Steffen (2008). Dark areas within 2 km off the western wall are mountain shadows.

Petermann Gletscher from MODIS Terra. Repeat NASA along-glacier flight tracks are shown in the left and middle panels. White line across the glacier are ICESat tracks. Thick black line across the glacier near y = 0 km is the grounding line location from Rignot and Steffen (2008). Dark areas within 2 km off the western wall are mountain shadows.

When I reported here that the same glacier discharged yet another ice island in July 2012, this one “only” twice the size of Manhattan, I was not so sure anymore, that this was merely another extreme event caused by natural processes. Furthermore, only 4 weeks later I was aboard the CCGS Henry Larsen working in Petermann Fjord and Nares Strait to recover instruments that we had deployed in 2009. Witnessing dramatic change off North Greenland from my first visit in 2003 to my last in 2012, I will send NASA a proposal on monday. If suported, it would enable me to test the idea, that a changing sea ice cover off North Greenland over the last 30 years or so relates to the retreat and decay of glaciers north of 76 N latitude. Most of these glaciers connect the Greenland Ice Sheet to the ocean via floating ice shelves as does Petermann.

This is an image that shows land-fast ice in Nares Strait next to Petermann with the large ice-arch blocking all flow of ice to the south where we see open water or thin ice:

June-10, 2012 MODIS-Terra image showing location of moored array that was deployed in Aug. 2009 to be recovered in Aug. 2012.

June-10, 2012 MODIS-Terra image showing location of moored array that was deployed in Aug. 2009 and that we recovered in Aug. 2012.

Contrast the conditions in June 2012 above with in April of 2009 below. The southern ice-arch failed to form in 2009, there is much open water and loose, thin ice next to Petermann Fjord, but a northern ice-arch formed and prevented all flow of thick ice from the Arctic Ocean into Nares Strait or Petermann to glue it all together as it did in 2012 (or right now for that matter):

Largely ice-free Nares Strait on April 2009 with concurrent ocean velocity.

Largely ice-free Nares Strait on April 2009 with concurrent ocean velocity.

My main question is this: Has the changing sea ice cover next to glaciers anything to do with the break-up of many large glaciers all around North Greenland that we have observed the last few years? Is the removal of the summer sea ice from the many fjords of North Greenland a normal occurrence or is this a new regime that flushes many fjords free of ice in summer? Does the available record of air and ocean observations allow us to explain observed change? I believe that the public has all the data (MODIS, SSM/I, ICESat, etc) to answer these questions, but it will need a little work to actually provide quantifiable answers with error bars to pass academic peer review. Anyone is more than welcome to help and maybe even learn or apply skills for a graduate degree and well-paying jobs in physics or engineering.

ADDENDUM (16:33 EDT): As a result of Greenland losing so much mass and ice, the geographic North Pole started in 2005 to move abruptly towards Greenland. This was reported earlier this week by Nature after the research was accepted for publication at Geophys. Res. Let.

Johnson, H., Münchow, A., Falkner, K., & Melling, H. (2011). Ocean circulation and properties in Petermann Fjord, Greenland Journal of Geophysical Research, 116 (C1) DOI: 10.1029/2010JC006519

Münchow, A., Falkner, K., Melling, H., Rabe, B., & Johnson, H. (2011). Ocean Warming of Nares Strait Bottom Waters off Northwest Greenland, 2003–2009 Oceanography, 24 (3), 114-123 DOI: 10.5670/oceanog.2011.62

Reeh, N., H. H. Thomsen, A. K. Higgins, and A. Weidick (2001). Sea ice and the stability of north and northeast Greenland floating glaciers Annals of Glaciology, 33, 474-480

Rignot, E., & Steffen, K. (2008). Channelized bottom melting and stability of floating ice shelves Geophysical Research Letters, 35 (2) DOI: 10.1029/2007GL031765

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Melting Mountain Glaciers: Changing Planet Video

Posted on March 29, 2013 by | Leave a comment

A short video clip explains in stunning clarity how mountain glaciers change. The example is Mount Kilimanjaro in Tanzania, Africa. The video is produced professionally by NBC and NSF and contains actor Gregory Peck, writer Ernest Hemingway, as well glaciologists Lonnie Thompson and Douglas Hardy.

Lonnie Thompson has perhaps traveled the world for ice cores and published its science implications more extensively than anyone else. At a recent meeting in San Francisco I heart him deliver an engaging and fun presentation. His writing is most accessible in terms of clarity and context.

Thompson, L. (2002). Kilimanjaro Ice Core Records: Evidence of Holocene Climate Change in Tropical Africa Science, 298 (5593), 589-593 DOI: 10.1126/science.1073198

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Climate Change Negotiations, 18 years in 83 Seconds

Posted on November 27, 2012 by | Leave a comment

Cartoon alert: Several thousand delegates meet in Doha, Qatar all week to negotiate climate change actions and co-operation for the 18th time since 1995. Summing up 18 years of such negotiations, I just found an 83 second cartoon via Andrew Revkin’s DotEarth blog at the New York Times:

On a more serious note, Nature just published a commentary (.pdf) on how these international climate negotiations have evolved over time and perhaps lost their effectiveness. Their conclusion is that present United Nation structures hinder progress towards international co-operation to moderate climate change. Credit here goes to Roger Pielke’s blog where the original authors of the Nature Commentary give a brief summary of their findings.

ResearchBlogging.org

Schroeder, H., Boykoff, M., & Spiers, L. (2012). Equity and state representations in climate negotiations Nature Climate Change, 2 (12), 834-836 DOI: 10.1038/nclimate1742

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Storm Surges, Global Warming, and Delaware Beaches

Posted on November 4, 2012 by | 5 Comments

ADDENDUM (Nov.-7, 2012): Time lapse video from Delaware Sea Grant.

Rising seas and flood waters cause most of the damage during storms such as Sandy did last week. Tides, waves, and storms all contribute. We can debate how global warming impacts any of the above, but the arguments are involved. So lets assume, that neither tides, waves, nor storms are impacted by global warming, but that the globally averaged rise in sea level over the last 50 or 100 years is. This global warming induced sea level rise is about half a foot in 50 years (3 mm/year), but why would we care about global averages, when we live in Delaware? Furthermore, why worry about the whimpy surges we get ever 2-3 weeks. We don’t, we worry most about the most extreme events like Sandy and want to know how often they occur. Below I show a Sandy-like event to occur about once every 10 years. Furthermore, over time Delaware’s most extreme storm surges are rising twice as fast as global averages do. So, how much does the global warming impact our local flooding in Delaware?

Market Street on the beach in Lewes is in one of the lowest lying areas of town and takes its good old-time draining. This photograph looks northeastward toward the beach, just west of the intersection with Massachusetts Avenue. [Credit: Cape Gazette]

More than I initially thought: the largest storm surge that has hit Delaware was the Ash Wednesday storm on March 6, 1962 which added 5.8 feet to the regular tides and waves. I wrote about this yesterday using public NOAA data. This same storm today would add 6.8 feet to the regular tides and waves. For comparison, Sandy’s storm surge added 5.3 feet. So Sandy was a weak storm by comparison. If it had hit in 1962, it would have added only 4.3 feet. The difference of 1 foot in 50 years is due to steadily rising sea levels:

Largest storm surge at Lewes, Delaware each year from 1957 to present. The red line is a linear fit to the data. The slope indicates that the largest storm surge increase by almost 3 inches every 10 years.

On average each year has a larger largest surge than the year before. While this steady increase by 2.8 +/- 1.7 inches each 10 years is statistically significant (95% confidence), picking the extreme each year is perhaps not the best statistic as extremes do not happen often. Please note that a 95% confidence means that there is a 5% chance that the true increase is either smaller than 0.9 inches/decade or larger than 4.5 inches/decade.

What about the mean or average surge each year? From hourly data, I pick the middle surge, that is, half the surges each year are larger and half are smaller:

This increase of 1.4 +/- 0.2 inches per decade (95% confidence) is more in line of the global average. The uncertainty in this trend is smaller than that of the trend for the extreme, because the median sea level varies little from year to year, while the extreme value varies more from year to year. So, from these results we can conclude, that while the mean or median sea level at Lewes increases by perhaps 1.5 inches in 10 years, the extremes increase twice as fast. So, storm surges like Sandy will become more common than they are today mostly because of global warming.

Over the last 50 years we had at least 5 such events in 1962, 1968, 1996, 1998, and 2012. So, on average we have a Sandy-type storm surge greater than 5 feet every 10 years. This contradicts a Wilmington News Journal article today which quotes John Ramsey to describe “… Sandy as a 1-in-200-years storm, unlikely to be repeated anytime soon. That could give coastal communities time enough to deal with the real threats and realities of sea level rise and climate change.” There is no such time, as it is mis-leading to describe Sandy as a 1-in-200-year event when it has happened about every 10 years during the last 55 years. Instead of a 0.5% percent chance of a Sandy-like event to hit Lewes each year, I would raise this chance to be larger than 10%.

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Rising Seas, Storms, and Flooding

Posted on November 3, 2012 by | 2 Comments

Ocean waters are rising and flooding inland waters in Delaware and elsewhere. Some of this is perfectly regular and normal such as the up and down of the tides. Some of it is irregular and normal such as caused by storms, river discharges, waves, and weather. And some is caused by global warming as we continue to burn coal and oil to power our economies. Lets have a quick look at what all this looks like and try to put this into some perspective, but Sandy’s 5.3 feet surge last monday was second to the 5.5 feet surge that hit Lewes in 1962.

Cedar Street in Lewes flooded on Monday, October 29. (Photo by: Don Bland), as published by Cape Gazette.

The up and down of the tides each day is about 3 feet in Lewes, Delaware. This large change in sea level is so regular, normal, and predictable, that I remove it from all further discussion, because I want to know how extreme an event this week’s storm Sandy was. For this purpose I downloaded all the hourly tide gauge data from Lewes, Delaware from NOAA. The record starts in 1957 and is ongoing. Here is how the record looks for the last 4 weeks including the surge caused by Sandy last monday:

Sandy’s storm surge added 5.3 feet to the regular tide which is second-largest surge in the historical record. The largest surge at Lewes, DE was caused by the 1962 Ash Wednesday Storm that added 5.5 feet to the regular sea level:

So while Sandy was a very large surge, it was neither unprecedented nor a once in a century event. Furthermore, and this is where I come back to global warming, the 5.3 feet 2012 surge of Sandy includes the last 50 years of steady sea level rise which comes to about an inch every 10-15 years or about half a foot in the ~50 years between 1962 and 2012. So, a repeat of the 1962 storm system would cause a 6.0 feet and not the 5.5 feet surge that took place in 1962.

Furthermore, while the real size of the surge depends on where the center of the storm makes land-fall or where you are relative to the storm, the rising seas caused by global warming are much more uniform, that is, they are little different in Boston, New York, Lewes, Norfolk, or even San Francisco:

So, global warming and the rising seas it causes are both real and here to stay. Global warming provides the upward creeping background sea level to which larger tides, waves, and surges add. The combined effect of all these cause the coastal flooding. So 50 years from now, a rare, but perhaps perfectly natural freak storm like Sandy will cause a storm surge of 5.8 instead 5.3 feet on account of global warming. About 1/3 of this added sea level is caused by the oceans expanding as they warm, another 1/3 is caused by melting glaciers and ice sheets in Greenland and Antarctica, and the last 1/3 is caused by other processes. So, what happens on Greenland or China does not stay there, it impacts present and future sea level in Lewes, DE.

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Hurricane Sandy, Global Warming, and the Butterfly Effect

Posted on November 1, 2012 by | 3 Comments

I am stupid. I do not believe in Global Warming. No need to believe in what you know. And I know that globally averaged air temperatures increased for the last 150 years or so. I did the math myself using observations to conclude, that air temperatures around northern Greenland and Ellesmere Island increased 5 times the global average over the last 25 years (Greenland’s Warming, Melting, and Sliding to Sea). So, why am I stupid?

Cover of Bloomberg Businessweek, Nov.-5, 2012

I am stupid, because I totally disagree with what has just hit the news stand about Hurricane Sandy’s impact on the eastern seaboard of North America: It’s Global Warming, Stupid screams this week’s edition of Bloomberg Businessweek with a dramatic cover draped in red.

I do not deny that some element of global warming scenarios contributed in some way to this storm, but so did the butterfly I rescued earlier this year from my cat Zoe. The butterfly flapping her wings, I am convinced, contributed to the atmospheric turbulence and thus the weather we got, including Sandy. If this sounds crazy, it is, but so is the headline. We can argue all day, if Global Warming or my Butterfly Effect contributed more significantly to Sandy, but we will not come to a firm scientific conclusion.

The Businessweek article has some excellent points on page three with regard to climate change and policies that we can and should make to reduce carbon emissions, but it discredits these well-reasoned policies by using flood waters in Manhattan as the call for action with a screaming headline calling me stupid. If we make policies based on ill-informed drama, political manipulations, and without supporting good empirical evidence, then we do harm.

A shallow and short-term political victory does not address the deep and long-term social problems posed by climate change. Solutions to these problems such as carbon-trading, energy efficiency, smart growth, and adaptations are all endangered, if we chose to exploit emotions of the moment. This sets us up for an equally ill-informed and short-sighted political backlash. We ignore science at our own peril. This cuts both ways with regard to the political hackery and partisan politics on the issue of climate change. I can’t stand it, but then, I am stupid.

ADDENDUM Nov.-2: An excellent description of the storm’s evolution and relation to climate was published in Science Magazine.

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Arctic Sea Ice Cover and Extreme Weather Explained

Posted on September 19, 2012 by | Leave a comment

Addendum Sept.-24, 2012: A New Climate State, Arctic Sea Ice 2012 (video by Peter Sinclair).

I just discovered an outstanding interview that Dr. Jennifer Francis of Rutgers University gave to a non-profit community radio station out of Vancouver, British Columbia.

Jennifer Francis Interview 20120910

She connects and explains global warming, its much amplified signal in the Arctic, the extreme record minimal Arctic sea ice cover this summer, and how the warming Arctic and its disappearing sea ice impacts our weather in the northern hemisphere by slowing down the atmospheric jet stream separating polar from mid-latitude air masses. She explains all of this in non-technical language without loss of accuracy.

Dr. Jennifer Francis, Rutgers University [Photo Credit: ARCUS]

If this program piques your interest and you want to read more, Andrew Revkin of the New York time has led an informed discussion at his New York Times blog Dot Earth. And finally, Climate Central presented and illustrated Dr. Francis’ observations and ideas rather well with graphics and videos.

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Arctic Ice Cover and Petermann Fjord, Glacier, and Ice Island Video Footage

Posted on August 27, 2012 by | 2 Comments

The National Snow and Ice Data Center announced today, that the Arctic Ice Area Extent has reached an absolute minimum breaking the record minimum of 2007 with still several weeks of potential melting and retreat to go. This has been anticipated for many weeks now with perhaps the most extensive coverage and intelligent discussions over at Neven’s Arctic Sea Ice Blog.

The graph above shows Arctic sea ice extent as of August 26, 2012, along with daily ice extent data for 2007, the previous record low year, and 1980, the record high year. 2012 is shown in blue, 2007 in green, and 1980 in orange. The 1979 to 2000 average is in dark gray. The gray area around this average line shows the two standard deviation range of the data. The 1981 to 2010 average is in sky blue. Sea Ice Index data. [Credit: National Snow and Ice Data Center]

This is as big a deal, because an ice-covered ocean reflects much more sunlight back into space in summer than a black ocean does that absorbs more heat: a positive feedback. This is why people in hot climates wear white, not black clothes, they like to stay cool. Furthermore, this decline has been ongoing for the last 30 years and the climate models that policy makers rely on did not predict this level of ice cover to occur for another 20-30 years. So, the warming climate and the changes it caused are on an accelerated schedule with regard to the Arctic Sea Ice cover. Also, the remaining ice cover is thinner than it used to be, because the multi-year ice keeps leaving the Arctic faster than it can be formed inside the Arctic. Both the Fram Strait to the east of Greenland and Nares Strait to the west of Greenland export this old, hard, and thick ice that ultimately melts further south. The ice that is left in the Arctic Ocean has become both thinner, younger, and softer, making it easier to melt the next summer.

On somewhat related news from the University of Delaware (UDel), we put two videos together that show a tiny, if spectacular example of a different area that has never been ice-free for at least 150 years when people were looking: Petermann Fjord. On August 10/11, 2012 the Captain and crew of the Canadian Coast Ship Henry Larsen gave us unfettered 18 hours access to the newly ice-free waters of this large glacier that discharges about 6% of the Greenland ice sheet. The UDel press release has the video that is also posted at youtube. As a less professionally assembled version is my first introductory iMovie project, e.g.,

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Record Warming and Melting of Greenland

Posted on July 24, 2012 by | 10 Comments

These are admittedly daily data, and yes, it is warm in summer everywhere, and yes, when it is warm, snow and ice melt at the surface. Here is the latest image of Greenland’s warming and melting that I lifted (figure and caption) straight from today’s NASA release:

Extent of surface melt over Greenland’s ice sheet on July 8, 2012 (left) and July 12, 2012 (right). Measurements from three satellites showed that on July 8, about 40 percent of the ice sheet had undergone thawing at or near the surface. In just a few days, the melting had dramatically accelerated and an estimated 97 percent of the ice sheet surface had thawed by July 12. In the image, the areas classified as “probable melt” (light pink) correspond to those sites where at least one satellite detected surface melting. The areas classified as “melt” (dark pink) correspond to sites where two or three satellites detected surface melting. Image credit: Jesse Allen, NASA Earth Observatory and Nicolo E. DiGirolamo, SSAI and Cryospheric Sciences Laboratory


Continue reading →

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Greenland’s Warming, Melting, and Sliding to Sea

Posted on June 27, 2012 by | 10 Comments

Greenland is warming, Greenland’s warming is melting its ice, and Greenland melting ice is raising global sea level. All true, but it all has happened before during the last 100 years or so. Our technology to extract small signals buried deep in noise from both our backyard and remote Greenland is unprecedented. This skill should not fool us, that the large changes that we see in Greenland and elsewhere have not happened before. They have, but memory is a fickle thing, as “new” is exciting, while “old” is often forgotten and considered unimportant. Those who live in the past are doomed to miss the present, those who ignore the past, are doomed to repeat it. We need to learn from the past, live in the present, and prepare for the future.

Preparing for an expedition to Nares Strait between northern Greenland and Canada in about 5 weeks, I am exploring temperature data from land, satellites, and ocean sensors to get a feel for what has changed. I started with data from weather stations such as the U.S. Air Force Base Thule , Canada’s former spy station Alert, and Denmark’s Station Nord about 700-1000 miles from the North Pole. So, it is cold up there:

Annual cycle of air temperature (bottom panel) from south to north at Thule (red), Grise Fjord (green), Alert (blue), and Cap Morris Jesup. Data years (top panel) for each year day are degrees of freedom. For each place two temperature curves indicate upper and lower limits of the climatological mean temperature for that day at 95\% confidence.

Well, we knew that, but the real question is: Has anything changed? Has Global Warming reached Greenland? The plot above does not tell, but this one does:

Annual averages and trends of air temperature anomalies for the 1987-2010 period for (top to bottom) Station Nord (Greenland), Alert (Canada), Grise Fjord (Canada), and Thule (Greenland). Scales are identical. The trends are fitted to daily, not annual data. The annual averages are shown for display purposes only.

To some it screams: “Warming, melting, Greenland is surging to sea.” [It is, but it did so before.]

There is lots of fancy signal processing that goes into this (see Tamino or a class I teach) to make a firm statement:

The air around northern Greenland and Ellesmere Island has warmed by about 0.11 +/- 0.025 degrees Celsius per year since 1987. North-west Greenland and north-east Canada are warming more than five times faster than the rest of the world.

This must be huge (yes, it is), it must have an effect on the Greenland ice sheet (yes, it does), and this must raise sea level (yes, perhaps 10 cm or 3 inches in 100 years, Moon et al., 2012).

Now where is the catch?

The catch is that my records all start in 1987, because that is the period for which I have actual measurements from all those stations. My satellite record is even shorter: it starts in 2000, but with lots of work can be extended back to 1978. And my ocean record is shorter yet: it starts in 2003. There just are no other hard data available from north-west Greenland.

So, does this mean we are stuck with the gloom and doom of a short record?

No, but we have to leave the comforts of hard, modern data with which to do solid science. People have to stick out their necks a little by making larger scale interferences. Based on the 1987-2010 results shown above, I can now say that trends and year-to-year variations are all similar in Alert, Thule, Kap Morris Jesup, etc., etc., so I will use the 60 year Thule record to make statements that somewhat represent all of Nares Strait. I could also start looking for softer and older data. With soft data I mean sketchy ship logs kept by whalers, tense expedition reports of starving explorers (Lauge Koch, Knud Rasmussen, Peter Freuchen), and imperial expeditions (George Nares, Adolphus Greely).

Further south there are a few ports where government or trading authorities started records early. The current capital of Greenland, Nuuk (formerly Godthab) is such a place. The Nuuk record starts 1881. And what I find is that the current warming in Greenland has happened just as dramatic as it does now in the 1920ies and 1930ies [well, except for the 2010 spike, but that story is still ongoing]:

Data from Nuuk, southern Greenland, where the temperature record goes back to 1881 (monthly data from NASA/GISS). The dashed line indicates 1987.

The trend is statistically significant, about 0.008 +/- 0.03 degrees centigrade per year or about 10 times smaller than what it is for northern Greenland starting in 1987. So the devil of Greenland warming, melting, and sliding to sea is in the details or records that are too short. The Global Warming signal is in there, but how much, we do not know and perhaps cannot know. Furthermore, most of the globe of “Global Warming” is covered by water and the ocean warming we know little about. Recall, my ocean record off northern Greenland only starts in 2003 and ends in 2009 or 2012, if we recover computers, sensors, and data from the bottom of Nares Strait this summer.

Greenland’s data and physics of ice, ocean, and air are exciting and all show dramatic change. To me, this is a big and fun puzzle, but one has to be careful and humble to avoid making silly statements for political purposes that are not supported by data. Do I think Global Warming is happening? Absolutely, yes. Do I think it is man-made? Probably. What do I do about it? I ride my bicycle to and from work every day. And that’s what I do next … bicycle home.

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