Climate Change Blogs

Monday It Will be 80 degrees in Yellowknife

Published: Julio 13, 2014
Monday It Will be 80 degrees in Yellowknife

The forecast for Monday in Yellowknife in the Northwest Territories is for a high temperature of about 80 F. Pretty nice. Sunday it’s predicted to be 80 in Inuvik, here’s a link to the Inuvik Weblog: Saving lives above the Arctic Circle!

Of course the more important news is that “Temperatures could drop to sweatshirt weather by Tuesday, when an unseasonably cool pool of air is expected to reach the northern and northeastern U.S.” (In Washington Post, July 10 2014, many other press sources as well) This cool air will be coming with a nice animated name, The Polar Vortex. Actually that’s not quite true, it’ll be coming with a confused heritage. According to the Capital Weather Gang, “A memo was emailed from the NWS’ Central Region to local offices directing forecasters to cease use of the term [polar vortex] according to Chris Vaccaro, director of NWS public affairs.” Perhaps it will come with “Cool Temps but “no” Polar Vortex.”

It’s all too complicated for me. I’m going to stay in the easy west, go someplace like Inuvik (at end of Dempster Highway) where it will be nice and warm. It would be easier to get to Boise, Idaho where today’s (Saturday, July 12, 2014) high was 105 F, tomorrow 102 and Monday 103. Lytton, British Columbia is likely to be over 100 F. These temperatures, about 20 F above normal, must be a typical excursion, because, well, there’s no weather feature with an animated name.

Now it’s going to be pretty nice in Yellowknife, temperature wise, but they are having some trouble with air quality due to the forest fires. They aren’t helped by the nice weather, according to Judy McLinton, a spokeswoman for the Department of Environment and Natural Resources (Canada), who says, “It’s going to start heating up again and heat up during the weekend. And it’s going to be hot again even all the way to Inuvik and the Sahtu.” So far, however, the fire season has not been as bad as last year.

The polar vortex was pretty neat last winter. Even I wrote a whole series of blogs that talked about the polar vortex. I was trying to explain the vortex prior to it becoming a media event after cold air, uninteresting out west, moved to the east. Had I only been smart enough to call it “the polar vortex” in that blog. Let’s see, the polar vortex ended up in WUWT and the The Cato Institute as they attacked John Holdren’s Video on the Polar Vortex. Therefore, as a solidly political term, it’s a good idea to bring it back.

Enough. I am not secure in my satire. My tutorials and summaries on hot and cold, the Arctic oscillation and isolated polar air are linked at the bottom. I will, however, repeat a figure I used in the blog I posted on December 8, 2013.

Here is a figure from the European Center for Medium-Range Weather Forecasts (ECMWF), that I have marked up a bit. The colors are the temperatures at the 850 hecto-Pascal surface, which is about 1.5 kilometers above the surface. The 850 hecto-Pascal temperatures are a good indicator of where it is hot and cold at the surface.



Figure 1: This figure is from the point of view of someone looking down from above at the North Pole (NP). The contour lines on the figure are the height of the 500 hecto-Pascal surface, which is between 5 and 6 kilometers above the surface of the Earth. The colors are the temperatures at the 850 hecto-Pascal surface, which is about 1.5 kilometers above the surface. The 850 hecto-Pascal temperatures are a good indicator of where it is hot and cold at the surface. For completeness with my example, the big, black dashed line is the jet stream of air flowing around the pole. Figure from the European Center for Medium-Range Weather Forecasts (ECMWF)

Back in December, I drew a blue arrow showing that the cold air at the pole had wobbled off of the pole and was pushed towards Colorado. To the west there was warm air, red arrow, pushing up towards Alaska. So while it had been cold in Colorado, it had been quite warm in much of Alaska. I used this as a real-world example off the hot and cold contrast that is characteristic of wobbles in the jet stream. These wobbles have warm air poleward, displacing the cooler air from the pole, pushing it south.

Here is a similar figure valid for July 14, 2014. There is a complete description of the figure here. The jet is far weaker in summer, less continuous than in the winter (bold, dashed arrows). In fact, it is difficult to define a single “polar vortex.” A blue arrow shows the cool air that is pushed towards the Great Lakes. To the west there is hot air, red arrow, pushing into western Canada. Being summer, it is far warmer at the pole than in winter. Still the Arctic is a place of cool air compared to the middle latitudes.




Figure 2: This figure is from the point of view of someone looking down from above at the North Pole (NP). The contour lines on the figure are the height of the 500 hecto-Pascal surface, which is between 5 and 6 kilometers above the surface of the Earth. The colors are the temperatures at the 850 hecto-Pascal surface, which is about 1.5 kilometers above the surface. The 850 hecto-Pascal temperatures are a good indicator of where it is hot and cold at the surface. For completeness, the big, black dashed line identifies the jet stream. Figure from the European Center for Medium-Range Weather Forecasts (ECMWF)


This is an unusual pattern for the summer time. There are several intrusions of warm air towards the pole, and there are centers of cooler air, I count 5 of them, distributed around the middle latitudes. The cool air, which will be centered on the Great Lakes, is displacing hot air, which is present over much of the U.S. The predicted high in Dallas, Texas on Monday is 103 F. In fact, as we get towards Monday, the predicted high in Ann Arbor, Michigan is 78 F, which is not that cool. (Medium and long-range weather forecasts are less reliable in summer than winter.)

Is the weather story here, really how cool it is?

Is there purpose to this entry? Doing a news search of “polar vortex,” there is an indelible relic of an uncharacteristic cold spell related to the return of the polar vortex. This is followed by even more links to there being a cold spell, but it’s not the polar vortex, or it is some diminished personification of the polar vortex. The original focus on the polar vortex as an explanation of the cold (in eastern North America) was, perhaps, a well-intentioned simplification. Perhaps it was meant to grab readers, watchers, listeners and web-site traffic. As the polar vortex mutated through the media, it was recognized early as naïve, mocked by comedians, dismissed as scientifically imprecise and politicized. It then becomes a trigger, that supports the doubt that is the goal of the political argument to disrupt climate-change and energy policy. This is a case when the pursuit of simple metaphors and snappy descriptions of complex events fuels the rhetoric. It is a fundamentally flawed tactic of communication and a fundamentally robust way to capture attention and fuel disruption. We must do better.

r

Previous entries on hot and cold:

Cold and Snowy and Warm and Wet

Previous entries on Arctic Oscillation:

Climate Change and the Arctic Oscillation 2

Climate Change and the Arctic Oscillation 1

Wobbles in the Barriers

Barriers in the Atmosphere

Behavior

Definitions and Some Background

August Arctic Oscillation presentation

CPC Climate Glossary “The Arctic Oscillation is a pattern in which atmospheric pressure at polar and middle latitudes fluctuates between negative and positive phases.”

Sea-Level Variability: A Primer

Published: Julio 9, 2014
Sea-Level Variability: A Primer

The comments in the last blog helped me realize the complexities of sea-level rise. In this entry I am going to explore sea-level rise more rigorously. I will continue using the East Coast of the U.S. as a case study.

One of the most certain consequences of the warming planet is that sea level will rise and land will be flooded. My mantra is that the temperature of Earth’s surface will rise, ice will melt, sea level will rise and the weather will change. It is easy to think of the ocean as a big cup and we are adding more water, from the melting ice, and, therefore, the seas will rise relative to the land. When we look at an individual place, like Norfolk, Virginia in the previous blog, the evaluation of sea level rise takes on many local details. In fact, it is much like talking about a single weather event in the context of a changing climate.

I’ll start with thinking about the factors that contribute to changes in sea level. I will refer to the ideas in the tutorials on modeling that I wrote in 2012, and specifically the entry, Balancing the Budget. In words there is an equation, which is

sea level tomorrow = sea level today + sea level gained – sea level lost

What contributes to sea level gains and loses? For those who want to know more, here is a link to an article by John Church and co-authors, Understanding and Projecting Sea Level Change. The article on sea level in Wikipedia is pretty good as well.

1. Sea level changes due to changing the density of water. This can come from either temperature changes or changes in the amount of salt in the water. These changes are known as “steric.”

2. Sea level changes due to adding water to the sea. Water is added when glaciers and ice sheets (e.g. Greenland and Antarctica) melt. Water is added by river runoff.

3. Sea level changes due to diverting water from the sea. For example, there are estimates that the building of dams offset about 30 millimeters of sea level rise in the last half of the twentieth century (Chao et al., Science, 2008).

4. Sea level changes because the land rises and falls. This could be due to plate tectonics, the large-scale motion of the surface of the Earth. There might also be sinking of the land when ground water is pumped out. And to make it more complicated, when the ice sheets melt, mass is removed from the crust of the Earth, and the land can rise or fall as it adjusts. These changes are often measured by mapping the Earth’s gravitational field; the gravitational force is not constant.

5. Sea level changes because of ocean dynamics. This will be the focus of this blog.

6. Sea level changes because of changes in the atmosphere. Atmospheric pressure and storm surges cause variability in sea level. The stress of wind on the ocean surface causes water to pile up in certain regions.

7. Sea level changes due to tidal forces.


Now I introduce a set of figures that focus on the East Coast of North America and the western Atlantic. These figures are from the nice collection at the web site Ocean Surface Currents hosted at the Rosenstiel School at the University of Miami.

Figure 1 shows the average position of the Gulf Stream, which is colored white in the figure. The colors in the ocean represent temperature, with yellows being warmer than greens that are warmer than blues. The Gulf Stream carries warm water northward, just off of the coast of the U.S. The Gulf Stream starts to leave the coast at North Carolina, more or less at Cape Hatteras. From here, the Gulf Stream flows eastward and then splits into several currents in the North Atlantic.



Figure 1: The Gulf Stream as represented by the Mariano Global Surface Velocity Analysis (MGSVA). The Gulf Stream is the western boundary current in the North Atlantic. The Gulf Stream transports warm water (heat) northwards. The averaging of velocity data from a meandering current produces a wide mean picture of the flow. The core of the Gulf Stream current is about 90 kilometers wide and has peak velocities of greater than 2 meters per second (5 knots). From Ocean Surface Currents hosted at the Rosenstiel School at the University of Miami.

What causes the Gulf Stream? The Gulf Stream is a surface current in the ocean, and it is largely caused by the stress of wind on the ocean surface. The trade winds flow from east to west across the Atlantic in the subtropics and tropics. In this figure, the trade winds are between 20 and 30 degrees north. Up at 40 degrees north, the average wind is from west to east. The wind, therefore, blows water towards North America in the southern part of the figure. Water is blown away from North America in the middle and northern part of the figure. The water being blown towards the coast in the south has to go somewhere. The Earth’s rotation and the presence of continent turn the water northward and it is guided along the coast.

This blog is about sea level. The winds from east to west in the subtropics are persistent and pile up water. This increases sea level. Since pressure in the ocean is related to amount of water above a point in the ocean, as the wind moves water around at the surface the pressure in the ocean changes. These changes in pressure cause the motion that becomes the Gulf Stream. The pressure in the ocean is directly related to sea level, the amount of water above a particular point.

Geography is important to climate. In Figure 2 the blue colors in the ocean are the depth of the ocean. The light blue near the edge of the continent is shallower than the deep blue. The light blue is the continental shelf, and the edge of the shelf is steep. Comparing Figure 2 to Figure 1, the Gulf Stream follows the shelf. This reveals the importance of the oceanic edge of the continent in shaping the Gulf Stream. I have marked the Grand Banks in the northern part of the figure. The Grand Banks guide the Gulf Stream, and as the stream of water moves beyond the Grand Banks, the Gulf Stream splits into several splinters. Important to sea level, there is bulge in the water off of the East Coast of North America caused by the wind stress and the continental shelf. The bulge of water associated with the Gulf Stream is about a meter in height. One meter is about the amount of rise in sea level expected from warming and ice melting in the next 100 years.



Figure 2: Topography/bathymetry of eastern North American and the western Atlantic. Topography is the height of the features on land. Bathymetry is the depth of the ocean. The units are not provided on the original web site, but are consistent with feet. From Ocean Surface Currents hosted at the Rosenstiel School at the University of Miami.

Let’s start to bring this information together to explore sea level rise and variability on the East Coast. Globally, the sea-level rise observed in the previous century is attributed to change in temperature (steric, Item 1 in the list above) and to adding water from melting glaciers and ice sheets (Item 2).

In the last blog and more completely in the comments, it was pointed out that Norfolk experiences subsidence, that is, the elevation of the land is declining. Up to half of the change in sea level at Norfolk is attributed to subsidence (Item 4). The U.S. Atlantic Coast, including Norfolk, has often been called a “hot spot” in sea level rise (also, press release from U.S. Geological Survey). It is easy to look at the subsidence of the land and attribute this hot spot to subsidence – not climate change. However, examination of the rate of sea-level rise reveals that the rate and changes of the rate of increase are faster than associated subsidence. What is the explanation of this regional change?

The most likely explanation lies in ocean dynamics. These changes can be viewed as centered on the Gulf Stream, and more broadly, the role of the Gulf Stream in the global circulation. Above, I wrote about how the wind stress and the continental boundary pile up water in the western Atlantic. The bulge of water is not at the coast, but off the coast a bit. This bulge is nearer the coast in the Southeast of the U.S. It is straightforward to hypothesize that changes in the Gulf Stream might have significant effects on the U.S. Coast. This is the subject of Oceanic control of sea level rise patterns along the East Coast of the United States by Jianjun Yin and Paul B. Goddard. Yin and Goddard make a convincing argument that “In response to the 21st century climatic forcing, the rise (fall) of the dynamic sea level north (south) of Cape Hatteras is mainly induced by the significant decline of ocean density contrast across the Gulf Stream.” The density change is largely related to the temperature, hence, a regional impact of the steric effect. Interestingly, there is also a potential impact from the fresh water inflow from the melting ice sheets in Greenland. Fresh water is lower density than salt water.

Figure 3 helps to place this Gulf Stream effect into a more regional and global context. This figure shows the Labrador Current, which is a cold-water current from the north that strongly influences the sea surface temperature of the U.S. North East and the Canadian Maritime Provinces. I have also placed arrows on Figure 2 showing the positions of the Gulf Stream and the Labrador Current. The Labrador Current directly receives the fresh water from the melting ice. Hence, as the Gulf Stream and Labrador Currents (cool and warm water, fresh and salt water) interact, there are many mechanisms that define the regional behavior of sea level. In the near term, decades, these regional factors can dominate the global rise, due to adding more water to the ocean. They can also act on faster times than are typical of the land rising and falling.

Final question: How does climate change affect sea level? The usual suspects are listed as changing the temperature of the ocean and adding water to the oceans from melting ice. These are important and act globally. Climate change and climate variability are also realized in changes to ocean currents. Since these currents are often close to the coasts, there are potential large, rapid and localized changes to sea level. The changes in surface currents in the ocean are related to changes in the stress of winds on the surfaces; hence, there are changes related to atmosphere pressure patterns. There is local variability due to storms and storm surges. And as the ice melts, the land might rise, might fall, also an effect due to climate change. These sources of variability will be important to planning in the next decades, but on the time of a century or longer, adding water to the ocean from melting ice will dominate; there’s really nothing working against it.



Figure 3: Labrador current as represented by the Mariano Global Surface Velocity Analysis (MGSVA). The Labrador Current is southward flowing and transports cold waters (blue) into the warmer Gulf Stream region (green). From Ocean Surface Currents hosted at the Rosenstiel School at the University of Miami.

North Carolina's Friendly Mountain Breezes, Sandy Beaches and Sea-Level Rise

Published: Junio 30, 2014
North Carolina's Friendly Mountain Breezes, Sandy Beaches and Sea-Level Rise

In the last entry, I promised to write more about sea-level rise on the East Coast of the U.S. My motivation is, partially, the North Carolina General Assembly putting a moratorium on rules, plans and policies that were based on the projections of greater sea-level rise. The NC Coastal Resources Commission was directed to provide a sea-level projection to be used by planners. Time marches forward and that commission needs to make a report in 2016.

Another motivation for wanting to revisit North Carolina’s position on sea-level rise is a recent article in the Washington Post on Norfolk, Virginia. Norfolk is just north of the North Carolina border. Norfolk is the home of the Naval Shipyard. The Navy has long recognized the vulnerability of their facility to rising sea levels, and this concern reaches throughout the community and the region. (Also NPR story on Norfolk)

Let’s start with North Carolina. There are a growing number of news stories about the state’s approach to sea-level rise. At this point, many of the stories are about whom to place on the NC Coastal Resources Commission. Frank Gorman III has been appointed chairman of the commission. Gorman has so far been credited with bringing order to chaos. He works in the fossil fuel industry, lives on the coast and is widely viewed as taking knowledge-based positions. Of note, he has focused the mission of the commission on the next 30 years. With a focus on 30 years, he removes the arguments about the rate of climate change because it takes 30 years or more for the different projections to diverge. (2014 update of the North Carolina story)

Much of the controversy in North Carolina started when it defined a planning number of 39 inches (1 meter). Such a high number is in the middle of the range of projections in reports such as the technical report on sea-level rise for the National Climate Assessment, yet few if any other states had chosen such a high figure for planning. By limiting the time span for consideration to the next 30 years, the 8-inch projections fall into a credible range. At 30 years, current knowledge suggests that sea-level rise will be accelerating. Thirty years is a short planning horizon for towns and counties and states. Is it responsible or legal to put blinders on our knowledge? What about the precedent of legislatively prescribing that which is outside of the control of legislation? Thirty years is politically expedient, and perhaps the limited guideline allows discussion that is otherwise not possible, but if planning follows it limits strictly, decisions will be made in denial of likely reality.

Turning to Norfolk. In late 2012, a team led by Adam Parris published a report Global Sea Level Rise Scenarios or the United State National Climate Assessment. Citing the Parris et al. report as the most appropriate for planning, the Virginia Institute for Marine Sciences submitted the Recurrent Flooding Study for Tidewater Virginia to the Virginia General Assembly in January 2013. This report is full of maps investigating the impact of sea-level rise on communities on the Virginia coasts. The report concludes “Recurrent flooding is a significant issue in Virginia coastal localities and one that is predicted to become worse over reasonable planning horizons (20-50 years).” Further, “Review of global flood and sea level rise management strategies suggests that it is possible for Virginia to have an effective response to increasing flood issues BUT it takes time (20-30 years) to effectively plan and implement many of the adaptation strategies.”

Here is a figure from the report, which shows the increase in the number of hours per year that there is flooding at The Hague, a neighborhood on an inlet off of the Elizabeth River in Norfolk. There has been a steady increase since about 1980. Examination of the details of flooding reveals that there are factors other than sea-level rise at play, notably there is also some sinking of the land (subsidence). However, when the budget of all the factors that play into the level of water at the coastline are taken into account, there is little doubt that the rising sea is at the core of the changes. (Link to Sea Level Rise and Flooding Risk in Virginia, Sea Grant Law and Policy Journal, 2013)





Figure 1: Hours per year of flooding in Norfolk’s Hague neighborhood. From Recurrent Flooding Study for Tidewater Virginia

Returning to the article in the Washington Post on Norfolk, Virginia and sea-level rise, there are a number of adaptation decisions that have been made. Currently, as houses are being rebuilt after storms the foundations are being raised. The city requires foundations on new construction to be 3 feet above flood level (a number implicitly the 1 meter of the original North Carolina plan). There is increasing discussion of buying people out and moving roads. There are plans for floodgates to protect The Hague neighborhood. A plan from a Dutch consulting firm suggests a cost of one billion dollars to provide protection from a foot of sea-level rise. And, for this to be effective, there needs to be planning along the whole coast. Otherwise, the patchwork of planned and unplanned, protected and unprotected, places along the coast will make a policy and management nightmare.

The areas I have talked about here, the North Carolina and Virginia coasts, are areas where I have spent time. Much of my childhood was building and rebuilding home-contrived ways to protect our cabin on the Neuse River in North Carolina. One lesson you learn in this little world is that if you don’t have a plan up and down the shore, what you do is vulnerable to what your neighbors don’t do. They are vulnerable to what you do. One can’t adapt alone to 39 inches of sea-level rise. The scope of planning required, neighbors, cities, counties and states is daunting. Decisions will not be uniform. And to add to the challenge, if we plan for 30, 50 or 100 years, all of those plans have to anticipate that sea level will still be rising. Thinking of that meter of salty water in places I have lived and worked makes it crystal clear that we need to work for the best future rather than preservation of the past.

r

Presentation on Planning in Virginia Thanks to bappit.

Land Subsidence and Relative Sea-Level Rise in the Southern Chesapeake Bay Region Thanks to nymore

The Heat is on in Greenland: Support the Dark Snow Project

Published: Junio 25, 2014
The heat is on in Greenland, where the high temperature on Tuesday hit an unusually warm 67°F at Kangerlussuaq (Sønder Strømfjord) in southwestern Greenland. It's been a hot June at Kangerlussuaq, where the temperature peaked at 73°F on June 15. That's not far below the all-time hottest temperature ever recorded in Greenland of 78.6°F, set just last year on July 30 at nearby Maniitsoq Mittarfia, as documented at wunderground's extremes page. The unusual warmth this year melted nearly 40% of the Greenland Ice Sheet in mid-June, according to data from the National Snow and Ice Data Center--far above the usual 15% figure. The warm June temperatures could be setting the stage for a big Greenland melt season this summer, and scientists with the Dark Snow Project are on the ice, 48 miles east Kangerlussuaq, conducting a two-month field experiment on the causes and implications of Greenland ice melt.


Video 1. Glaciologist Dr. Jason Box and climate change filmmaker Peter Sinclair explain the 2013 results and 2014 mission of the Darksnow project.

The Dark Snow Project
In 2013, glaciologist Dr. Jason Box of the Geological Survey of Denmark and Greenland launched the first crowd-funded Arctic expedition: The Dark Snow Project. The field study succeeded in its scientific mission of landing a team deep within the Greenland sheet, sampling the 2012 melt layer, and returning those samples for analysis. The results, soon to be published, showed a pronounced spike in black carbon at the critical layer, and indicated the strong need for more research. The "burning question": How much does wildfire and industrial soot darken the ice, increasing melt? Was the record melt and record darkness of the ice sheet in 2012 a harbinger of the future? A darker ice sheet absorbs more solar energy, in a vicious cycle that raises temperatures, melts more ice, and further darkens the ice sheet. The amount of melting that was caused by soot from forest fires is important to know, since global warming is likely to increase the amount of forest fires in coming decades. However, the amount of forest fire soot landing on the Greenland Ice Sheet is almost completely unknown.


Figure 1. Smoke from a fire in Labrador, Canada wafts over the Greenland ice sheet on June 17, 2012, as seen in this cross-section view of aerosol particles taken by NASA's CALIPSO satellite. Image credit: Dr. Jason Box, Ohio State University.

Saving Greenland's Ice Sheet is Imperative
Human-caused global warming has set in motion an unstoppable slow-motion collapse of the glaciers in West Antarctica capable of raising global sea level by 4 feet (1.2 meters) in a few hundred years, said NASA in a May 2014 press release. What's more, one of the glaciers involved, the Thwaites Glacier, acts as a linchpin on the rest of the ice sheet, which contains enough ice to cause a total of 10 to 13 feet (3 to 4 meters) of global sea level rise over a period of centuries. This unstoppable collapse makes saving Greenland "absolutely essential", said glaciologist Richard Alley in a May 2014 interview in Mother Jones. Greenland's ice sheet holds enough water to raise global sea levels by 7.36 meters (24.15 feet) were it all to melt, and civilization would be hard-pressed to deal with 10 - 13 feet of sea level rise from West Antarctica, let alone another 20+ feet from Greenland. "If we've committed to 3.3 meters (10.8') from West Antarctica, we haven't committed to losing Greenland, we haven't committed to losing most of East Antarctica," said Alley. "Those are still out there for us. And if anything, this new news just makes our decisions more important, and more powerful." Unfortunately, the Greenland Ice Sheet is much more vulnerable to melting than previously thought, found a May 2014 study by Morlighem et al., Deeply incised submarine glacial valleys beneath the Greenland ice sheet. The researchers found that widespread ice-covered valleys extend much deeper below sea level and farther inland than previously thought, and would likely melt significantly from steadily warming waters lapping at Greenland's shores.


Figure 2. Monthly changes in the total mass (in Gigatonnes) of the Greenland ice sheet estimated from GRACE satellite measurements between March 2002 - July 2013. The blue and orange asterisks denote April and July values, respectively. Note that the decline in ice mass lost from Greenland is not a straight line--it is exponential, meaning that in general, more ice loss is lost each year than in the previous year. However, the mass loss during the 2013 summer melt season was probably smaller than during 2012, said the 2013 Arctic Report Card.

Support for the Dark Snow Hypothesis
Observational evidence for the Dark Snow project's hypothesis that upwind forest fires might darken the Greenland Ice Sheet and cause significant melting was provided by a May 2014 paper by Keegan et al., Climate change and forest fires synergistically drive widespread melt events of the Greenland Ice Sheet. Their ice core study found that black carbon from forest fires helped caused a rare, near-ice-sheet-wide surface melt event that melted 97% of Greenland's surface on July 11 - 12 2012, and a similar event in 1889. Since Arctic temperatures and the frequency of forest fires are both expected to rise with climate change, the results suggest that widespread melt events on the Greenland Ice Sheet may begin to occur almost annually by the end of century.

Another factor contributing to a darker Greenland Ice Sheet and more melting may be additional wind-blown dust landing on the ice, according to a June 2014 study, Contribution of light-absorbing impurities in snow to Greenland's darkening since 2009. In an interview with ClimateWire, lead author Marie Dumont of France’s meteorological agency said, "Our hypothesis is that now that seasonal snow cover in the Arctic is retreating earlier than before, and bare soil is available earlier in the Spring for dust transport."

Related Jeff Masters blog posts
Slow-Motion Collapse of West Antarctic Glaciers is Unstoppable, 2 New Studies Say (May 13, 2014)
Dark Snow Project: Crowd-Source Funded Science for Greenland (April 26, 2013)
Greenland experiences melting over 97% of its area in mid-July (July 25, 2012)
Record warmth at the top of the Greenland Ice Sheet (July 18, 2012)
Unprecedented May heat in Greenland; update on 2011 Greenland ice melt (May, 2012)
Greenland update for 2010: record melting and a massive calving event

The http://www.greenlandmelting.com/ website has good resources for following this year's melt progression in Greenland.


Video 2. In a follow-up video, Dark Snow Project communications director Peter Sinclair explains how the recent finding of unstoppable West Antarctic glacial melt makes the saving of Greenland's glaciers absolutely essential.

Support the Dark Snow Project
One of Dr. Box's collaborators, photographer James Balog, who created the amazing time-lapse Greenland glacier footage in the fantastic 2012 "Chasing Ice" movie, puts it like this: "Working in Greenland these past years has left me with a profound feeling of being in the middle of a decisive historic moment--the kind of moment, at least in geologic terms, that marks the grand tidal changes of history." On that note, I encourage you all to consider a tax-deductible donation to the Dark Snow Project. The project has already raised $30,000, and hopes to raise another $10,000. One of the major uses for the money will be to pay for the portable Internet satellite gear needed to do regular posting, messaging, and skyping from the ice during July and August. The June 22 update from Dr. Box, as posted in Peter Sinclair's blog: "We saw a water fountain on the horizon, spouting to 100 feet above the surface. I think it is either a lot of water trying to fall down a small moulin cavitating, or a river on the ice sheet taking a violent turn. The spout lasted at least 18 hours!"

The tropics are still quiet and expected to remain so over the next five days, so I'll have a new post on Friday.

Jeff Masters

Drought in Syria: a Major Cause of the Civil War?

Published: Junio 18, 2014
Syria's devastating civil war that began in March 2011 has killed over 200,000 people, displaced at least 4.5 million, and created 3 million refugees. While the causes of the war are complex, a key contributing factor was the nation's devastating 2006 - 2011 drought, one of the worst in the nation's history, according to new research accepted for publication in the journal Weather, Climate, and Society by water resources expert Dr. Peter Gleick of the Pacific Institute. The drought brought the Fertile Crescent's lowest 4-year rainfall amounts since 1940, and Syria's most severe set of crop failures in recorded history. The worst drought-affected regions were eastern Syria, northern Iraq, and Iran, the major grain-growing areas of the northern Fertile Crescent. In a press release that accompanied the release of the new paper, Dr. Gleick said that as a result of the drought, "the decrease in water availability, water mismanagement, agricultural failures, and related economic deterioration contributed to population dislocations and the migration of rural communities to nearby cities. These factors further contributed to urban unemployment, economic dislocations, food insecurity for more than a million people, and subsequent social unrest."


Figure 1. The highest level of drought, "Exceptional", was affecting much of Western Syria in April 2014, as measured by the one-year Standardized Precipitation Index (SPI). Image credit: NOAA's Global Drought Portal.

Human-caused climate change a major factor in more frequent Mediterranean droughts
The paper also assessed the role of climatic change in altering water availability. There is growing evidence that annual and seasonal drought frequency and intensity in the Levant/Eastern Mediterranean region have increased from historical climatic norms, with the number of dry days increasing during the winter rainy season. Similar findings were discussed in a NOAA press release that accompanied the release of a 2011 paper by Hoerling et al., "On the Increased Frequency of Mediterranean Drought." That paper found that human-caused emissions greenhouse gases were "a key attributable factor" in the drying up of wintertime precipitation in the Mediterranean region in recent decades.


Figure 2. Winter precipitation trends in the Mediterranean region for the period 1902 - 2010. In the 20 years ending in 2010, 10 of the driest 12 winters took place in the lands surrounding the Mediterranean Sea. Image credit: NOAA.

Future conflict over water in the Middle East
The potential for future conflict in the Middle East over water is significant. Researchers Heidi Cullen and Peter deMenocal discussed previous incidents in 1975 and 1990: Turkey, because it has the good fortune of being situated at the headwaters of the Tigris – Euphrates River system, can literally turn off the water supply of its downstream neighbors. When the Ataturk Dam was completed in 1990, Turkey stopped the flow of the Euphrates entirely for 1 month, leaving Iraq and Syria in considerable distress. Similarly, in 1975, when the Syrians began filling Lake Assad after completion of work on the Tabqa Dam, Iraq threatened to bomb the dam, alleging that it seriously reduced the river’s flow. Both countries amassed troops along the border.


Figure 3. Stele of Narâm-Sîn, king of the Akkadian Empire, celebrating his victory against the Lullubi from Zagros. Limestone, c. 2250 BCE, Louvre Museum. Image credit: Marie-Lan Nguyen

A great Syrian drought 4,200 years ago
Great civilization-threatening droughts have happened before in Syria. In a 2000 article published in Geology, "Climate change and the collapse of the Akkadian empire: Evidence from the deep sea", a team of researchers led by Heidi Cullen studied deposits of continental dust blown into the Gulf of Oman in the late 1990s. They discovered a large increase in dust 4,200 years ago that likely coincided with a 100-year drought that brought a 30% decline in precipitation to Syria. The drought, called the 4.2 kiloyear event, is thought to have been caused by cooler sea surface temperatures in the North Atlantic. The Akkadian Empire, which flourished in ancient Mesopotamia between 2334 BC - 2193 BC, also crashed at this time, giving credence to the idea that the drought may have been a key reason why. The 4.2 kiloyear event has also been linked to the collapse of the Old Kingdom in Egypt. The paper concluded, "Geochemical correlation of volcanic ash shards between the archeological site and marine sediment record establishes a direct temporal link between Mesopotamian aridification and social collapse, implicating a sudden shift to more arid conditions as a key factor contributing to the collapse of the Akkadian empire."

Commentary
People fear storms, and spectacular and devastating storms like Hurricane Sandy and Hurricane Katrina have stirred more debate in the U.S. about taking action against climate change than any other weather events. But I argue that the on-going Western U.S. mega-drought and Syrian drought should be louder wake-up calls. Drought is the greatest threat civilization faces from climate change, because drought takes away the two things necessary to sustain life--food and water. Drought experts Justin Sheffield and Eric Wood of Princeton, in their 2011 book, Drought, list more than ten civilizations and cultures that probably collapsed, in part, because of drought. Among them: The Mayans of 800 - 1000 AD. The Anasazi culture in the Southwest U.S. in the 11th - 12th centuries. The ancient Akkadian Empire in Mesopotamia. The Chinese Ming Dynasty of 1500 - 1730. When the rains stop and the soil dries up, cities die and civilizations collapse, as people abandon lands no longer able to supply them with the food and water they need to live. The fact that the most politically volatile region on the planet is already experiencing an increase in drought that research links to climate change should be a serious wake-up call about the need to manage water resources more wisely--and to work to forge an international agreement in Paris in 2015 to cut down on the amount of heat-trapping carbon dioxide humans are putting into the air. Dr. Gleick's paper concludes with sensible options for reducing the risks of water-related conflicts in the Middle East, including expansion of efficient irrigation technologies and practices, integrated management and monitoring of groundwater resources, and diplomatic and political efforts to improve the joint management of shared international watersheds and rivers.

References
Gleick, P., 2014, Water, Drought, Climate Change, and Conflict in Syria, accepted for publication in Weather, Climate, and Society

Cullen, H.M., and P.B. deMenocal, 2000, North Atlantic Influence on TIgris-Euphrates Streamflow, International Journal of Climatology, 20: 853-863.

Hoerling, Martin, Jon Eischeid, Judith Perlwitz, Xiaowei Quan, Tao Zhang, Philip Pegion, 2012, On the Increased Frequency of Mediterranean Drought, J. Climate, 25, 2146–2161, doi: http://dx.doi.org/10.1175/JCLI-D-11-00296.1

Kaniewski, D. et al., 2012, Drought is a recurring challenge in the Middle East, PNAS 109:10, 3862–3867, doi: 10.1073/pnas.1116304109

I'll have a new post on Friday.

Jeff Masters
About the Blogs
These blogs are a compilation of Dr. Jeff Masters,
Dr. Ricky Rood, and Angela Fritz on the topic of climate change, including science, events, politics and policy, and opinion.
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