Category Archives: Climate Change

The 100th Meridian Is Moving East

North Dakota, riparian wildlife habitat (photo from USDA)

The 100th Meridian West is an imaginary line on the map that happens to mark the climate divide between the humid east and arid west in North America. Or rather, it used to. The rainfall divide is moving east.

Extending from the North to South Poles, the 100th runs longitudinally in the U.S. from North Dakota through Texas.

The 100th meridian is on the upright border of Oklahoma and Texas (image from Wikimedia Commons)

Its coincidence with the rainfall divide was first documented in 1877 by John Wesley Powell who found during his explorations in the Great Plains that the 100th was a visible boundary. Locations to the east of the 100th received 20+ inches of annual rainfall, the west received less.

20 inches is a key number for agriculture and human population. It determines what you can grow, whether you have to irrigate and, thus, how many people can live there. Powell saw the line and told Congress it had implications for settlement of the western plains. Congress didn’t heed him but …

This 2014 map of U.S. Population by County shows that it played out as Powell expected. You can see the rainfall divide in population density. People choose to live where there’s water.

U.S. population by county, 2014 (map from US Forest Service)

You can also see the line from outer space. I’ve marked the 100th (approximately) on this satellite photo of Nebraska. The landscape is deep green to the east though not uniform.

Satellite photo of Nebraska shows it is drier west of the 100th (photo from Wikimedia Commons)

Nowadays the 100th is no longer the rainfall divide.

A study by Columbia University meteorologists found that the aridity line has shifted 140 miles east and is now statistically located at the 98th meridian. Climate change will move it even further as warming evaporates moisture in the northern plains and alters rainfall in the south.

In a hundred years the aridity mark may be firmly inside Minnesota, Iowa and Missouri. Aridity decreases the amount of agriculture and will probably change the population. People choose to live where there’s water.

John Wesley Powell’s “100th meridian” is moving east.

This article was inspired by Yale Climate Connections. Read more here in Yale Environment 360, 11 April 2018.

(photos from USDA, USFS and Wikimedia Commons; click on the captions to see the originals)

How The Mighty Monongahela Lost Its Crown

This used to be the Monongahela River (photo by Kate St. John)

Two million years ago the Monongahela was a mighty river.  Instead of being a short tributary of the Ohio and draining to the Gulf of Mexico, it flowed north to where Lake Erie is today and then to the Atlantic.  This stretch of the Ohio River in Pittsburgh was not the Ohio at all. It was the Monongahela.

Here’s how the mighty Mon River lost its crown and the reason why the Ohio turns south at Beaver, Pennsylvania.

Before the Pleistocene era, the Monongahela River drained 75% of today’s Ohio, Allegheny and Monongahela watersheds as it flowed north from West Virginia to the Lake Erie area (roughly the red arrow path below). 

Back in those days the Ohio River was just a tributary whose northernmost point was in Pennsylvania where it joined the Mon.  The Beaver and Shenango Rivers did not exist as they do today.  Their valleys carried the Monongahela north. 

Approximate flow of historic Monongahela River (derived from river maps at geology.com)

But then the climate changed. The Great Ice Age began.

Glaciers blocked the Monongahela’s northward flow so the river backed up and formed Lake Monongahela.  The pale dashed lines show the paths of our rivers today bending away from the prehistoric glacier.  

Lake Monongahela (image from Wikimedia Commons)

Eventually Lake Monongahela rose so high that it breached the lowest barrier in the Ohio valley near present day New Martinsville, WV (see orange arrow).

The Ohio started flowing “backwards.” It cut the Ohio River valley deeper, orphaned the northern Monongahela and reversed its flow, creating the Shenango and Beaver Rivers.

All of this was helped by the huge volume of water joining the Mon from the re-formulated Allegheny River watershed.  The Upper and Middle Allegheny river systems used to flow north too, but were also blocked by glaciers. Their proglacial lakes overflowed and joined the Lower Allegheny River flowing into the Ohio watershed.

And so the Monongahela River became a lowly tributary of the Ohio.

Climate change is big stuff.  When it gets cold it changes major rivers.  When it gets hot … Well, we’ll find out.

UPDATE: See the comments!  And here’s a map of the ancient Erigan River drainage from Ohio DNR.

(photo by Kate St. John. Red-arrow map derived from OH & PA river maps at geology.com, map of Lake Monongahela from Wikimedia Commons, annotated map of Erigan River via CVNP; click on the captions to see the originals)

How Early Is Spring This Year?

Snow this morning in Pittsburgh, 2 April 2018, 7:30am (photo by Kate St. John)
Snow this morning in Pittsburgh, 2 April 2018, 7:30am (photo by Kate St. John)

How early is Spring this year? That’s a hard question to answer.

This morning we have snow again in Pittsburgh and heavy snow-cloud skies. Spring feels late and yet it was early at first.

The animated map below from the National Phenology Network (NPN) shows the emergence of leaves across the Lower 48 States. NPN uses honeysuckle leaves as their marker plant and so do I.  The blue color shows late emergence, red means early.  Our leaves were 20 days early in Pittsburgh.

USA National Phenology Network Spring Leaf Anomaly, 30 March 2018 (from usanpn.org)
USA National Phenology Network Spring Leaf Anomaly, 30 March 2018 (from usanpn.org)

Here’s proof from February 20, 2018.

Honeysuckle leaves open in the heat, 20 Feb 2018 (photo by Kate St. John)
Honeysuckle leaves open in the heat, 20 Feb 2018 (photo by Kate St. John)

Since then Nature did a 180-degree turn and handed us a series of cold snaps capped by snow.  Our wildflowers have not bloomed yet.  Last year they were two to three weeks early and had gone to seed by the end of March.

Fortunately NPN tracks first blooms as well, using lilacs as the marker plant.(*)  On the map below you can see the Southeast bloomed 20 days early.

USA NPN Spring Bloom Anomaly, March 30, 2018 (from usanpn.org)
USA NPN Spring Bloom Anomaly, March 30, 2018 (from usanpn.org)

But we aren’t on the bloom map yet.

When will our wildflowers bloom?  We’ll have to wait and see.

 

(photo by Kate St. John. Animated maps from usanpn.org)

* From the USA NPN website: These models were constructed using historical observations of the timing of first leaf and first bloom in a cloned lilac cultivar (Syringa x chinensis’Red Rothomagensis’) and two cloned honeysuckle cultivars (Lonicera tatarica ‘Arnold Red’ and L. korolkowii ‘Zabelii’).

Record Heat

Honeysuckle leaves open in the heat, 20 Feb 2018 (photo by Kate St. John)
Honeysuckle leaves open in the heat, 20 Feb 2018 (photo by Kate St. John)

Yesterday we put on our summer clothes and this honeysuckle bush put out new leaves.  It was summer in February.

At 78 degrees F the high temperature broke two Pittsburgh records:  a new high for February 20 (formerly 68 degrees in 1891) and a new high for the entire month of February.  It was 37 degrees above normal.

When you look at yesterday’s map you can see how it happened. The jet stream dipped across the Northern Rockies and Plains, then abruptly turned north over the Texas Panhandle.  It was only 3 degrees F in western Nebraska while we were nearly 80.  The narrow temperature gradient — that yellow line across the Midwest — continues to produce heavy rain.

U.S. high temperature forecast map for 20 Feb 2018 (from the National Weather Service)
U.S. high temperature forecast for 20 Feb 2018 (map from the National Weather Service)

Meanwhile, like a yo-yo, we’re headed back to normal tomorrow and will lose those 37 degrees.  Today’s our last chance for record heat.

 

(photo by Kate St.John. Temperature map from the National Weather Service; click on the image to see the latest map)

Turning and Turning In The Widening Gyre

Central Arctic ocean currents (map by Brn-Bld via Wikimedia Commons)
Central Arctic ocean currents (map by Brn-Bld via Wikimedia Commons)

“The Beaufort Gyre is acting strangely,” said the news at Yale Environment 360.  “Scientists say it could kick off a period of lower temperatures in Northern Europe.”

Here’s why.

The Beaufort Gyre is a wind-driven current in the Arctic Ocean. Traveling clockwise it keeps sea ice contained and moving so slowly that the ice thickens.

Every five to seven years the winds change direction and the gyre spins counter-clockwise, dumping icebergs and cold freshwater into the North Atlantic near Iceland.  Then the winds switch back.

But now the winds haven’t changed direction for a long time, arctic ice is melting, and freshwater from the continents is flooding the Beaufort Sea.  The surface now holds as much freshwater as the Great Lakes and the gyre is spinning faster, still clockwise.

What will happen next?  The past gives us a hint.

Thirty years ago, when the gyre reversed direction for an extra long time, its ice and cold freshwater caused the North Atlantic herring fisheries to collapse and plunged Northern Europe into a temporary deep freeze.

Will the Beaufort Gyre change direction soon? And how long it will spin counter-clockwise?  No one knows.  Will the change be benign? Probably not.

The globe is warming overall (hence it was called “Global Warming”) but the resulting climate change is both hot and cold, weird and unpredictable.

It’s a bit like watching chaos unfold.

Turning and turning in the widening gyre
The falcon cannot hear the falconer;
Things fall apart; the centre cannot hold;
Mere anarchy is loosed upon the world …
The Second Coming by W. B.Yeats

Read more about the Beaufort Gyre at Yale Environment 360.

(map of Arctic Ocean circulation by Zeimusu via Wikimedia Commons; click on the image to see the original)

Why Is It Warming So Fast?

  • Friday, 5 Jan 2018

Egads, it was cold last weekend!  Here in Pittsburgh it was -6 to 11 degrees F, but yesterday things turned around.  Sunday (7 Jan.) started at -6oF but warmed to a high of 30.  Today will be above freezing and by Thursday the high will be 64oF.  That’s a swing of 70 degrees in only four days!

The slideshow above shows this in color for January 5, 8, 11 and 12.

I’m not complaining that we’re out of the deep freeze but … this weather is really odd.  Why did it get so cold and why is it warming so fast?  Why don’t we have a moderate winter like we used to?

Crazy as it sounds, it’s because the arctic is warming faster than the rest of us.  When there’s not a big temperature difference between the North Pole and the mid-latitudes (us) the jetstream slows down.  When it’s sluggish, it wobbles in high amplitude loops that dip as far south as Florida(*).

The video below explains why.  I recommend watching it twice; you see more the second time.  (My end notes have info on millibars, etc.)

So when a cold loop settles over us, we’re really cold and when it moves on we’re really hot.  It happens quickly in both directions.

Don’t put away your winter clothes on Thursday.  The forecast says it’ll be 5 degrees on Saturday night.

 

(temperature forecast maps from NOAA; Jet stream explanation by Jennifer Francis on YouTube)

Definitions and notes:

  • A millibar (or mb) is a unit of air pressure.
  • The average air pressure at sea level is 1013.25 millibars = 14.7 pounds.
  • What’s the significance of 500 millibars?   The 500 millibar pressure zone is where air pressure is half what it was at sea level, halfway up in the atmosphere. Since air pressure varies as weather systems move above us, the 500mb map is a great diagram of what the weather systems are doing.    Here’s the air pressure map for Friday 5 Jan 2018 at 1200z (8am).  Notice that the pressure lines echo Friday’s temperature map above.
  • (*) I wrote above that the jetstream dips as far south as Florida.  Well, it dips even further than that.  In June 2016 the northern jetstream crossed the equator and joined the southern one!

At Cape Cod: Before and During the Storm

Before the storm: Icy blue ocean at West Dennis Beach, Mass. 3 Jan 2018 (photo by Barb Lambdin)
Before the storm: Icy blue ocean at West Dennis Beach, Mass. 3 Jan 2018 (photo by Barb Lambdin)

On the day before the “bomb cyclone” hit Massachusetts my sister-in-law, Barb Lambdin, sent me two photos of the frozen ocean at West Dennis Beach, Cape Cod.   Intrigued by the coming storm, I asked her to take more photos when it hit.

The photo locations are part of the story:

  1. Before the storm: West Dennis Beach on the ocean side.
  2. During the storm: Corporation Beach in the protected middle of the bay shore.

Map of Massachusetts showing 1: oceanside photos at West Dennis Beach, 2: bayside photos at Corporation Beach (from Wikimedia Commons, annotated)
Map of Massachusetts. 1: oceanside photos at West Dennis Beach, 2: bayside photos at Corporation Beach

 

BEFORE THE STORM:

Above, the ocean was so calm on 3 January 2018 that ice had formed in flat sheets and blue-green water ponded on top.

The waves were small and slushy (below).  Barb calls them Frozen Margarita waves.

Before the storm, slushy waves at W Dennis Beach, MA 3 Jan 2018 (photo by Barb Lambdin)
Before the storm, slushy waves at W Dennis Beach, MA 3 Jan 2018 (photo by Barb Lambdin)

 

DURING THE STORM:

On 4 January it was too windy and dangerous on the ocean side so Barb went to the bay side at Corporation Beach.  The two photos below were taken at high tide.

Keep in mind that this is the calm side of Cape Cod yet the waves are high and about to flood the parking lot.  I have never seen waves break at Corporation Beach!

During the storm: Corporation Beach at high tide, Dennis,Mass. 4 Jan 2018 (photo by Barb Lambdin)
During the storm: Corporation Beach at high tide. Dennis, MA 4 Jan 2018 (photo by Barb Lambdin)

This high tide set a record at Boston, 60 miles north across the bay.

During the storm: Corporation Beach at high tide, Dennis,Mass. 4 Jan 2018 (photo by Barb Lambdin)
During the storm: Corporation Beach at high tide. Dennis, MA 4 Jan 2018 (photo by Barb Lambdin)

For more information and cool graphics see The 10 best images of this week’s historic bomb cyclone in the Washington Post.

Is this the worst nor’easter we’ll see this winter? Who knows.

p.s. Why is it so cold?

Actually it’s extremely cold in the eastern U.S. but very warm in the West (click here for Departure From Normal Temperature graphic).

Four years ago we experienced the Polar Vortex of 2014 when the jet stream wobbled southward. It’s happening again. And it’s a feature of climate change.

Learn more at CBCnews: Why has it been so cold? Here’s what science says.

 

(photos by Barb Lambdin. Massachusetts map from Wikimedia Commons. Temperature map from the National Weather Service; click on the images to see the originals)

Crazy Warm

Barrow, Alaska as seen from the air, Aug 2007 (photo from Wikimedia Commons)
Barrow, Alaska as seen from the air, Aug 2007 (photo from Wikimedia Commons)

The computer said, “Those numbers are too high. They must be in error. Throw them out.”  And so Barrow, Alaska disappeared from the climate analysis database.

Fortunately a lot of people missed Barrow when it was gone. In fact they suspected it  might disappear some day because it’s so unusual.  The error was found quickly and the raw data will be restored.

What happened?

This month more than a year’s worth of temperature data for the northernmost point in the U.S. — Barrow, or Utqiávik, Alaska (see arrow) — automatically disappeared from the National Centers for Environmental Information temperature analysis system because it looked so out of whack.

Barrow, Alaska locator map (image from Wikimedia Commons; arrow added)
Barrow, Alaska locator map (image from Wikimedia Commons; arrow added)

Why would a computer throw away real data?

Computers that collect automated weather data have algorithms that test for wild abnormalities so that instrument errors are isolated (rejected) from the clean data calculations.  For instance, when a weather thermometer breaks or goes offline, the temperature is recorded as “zero.”  When this happens in July in Pittsburgh it’s so obviously incorrect that the software rejects it. Algorithms for climate analysis are even more stringent because a change to an instrument’s location can look like a trend even though it isn’t.

Here’s why Barrow looks crazy to a computer.  This graph by Derek Arndt at climate.gov shows circles for Barrow’s 1979-1999 average monthly temperatures, triangles for 2000-2017.  Notice that for most of the year those 20-year averages are pretty close but for October, November and December they’re widely different.  Computers don’t like that!

Average Monthly Temperature at Barrow in two eras 1979-1999 vs 2000-2017 (graph from NOAA)
Average Monthly Temperature at Barrow in two eras 1979-1999 vs 2000-2017 (graph from NOAA)

Barrow is experiencing rapid warming because there’s a lot less sea ice than there used to be.  When ice crowds the shore in the fall, Barrow gets cold, but now the ice recedes so far in the summer that it takes months longer to reach the town.

It’s crazy warm in Barrow.

 

A tip of the hat to Angela Fritz at the Washington Post for her 12 December article that brought this to my attention.  Read all about it at NOAA’s Beyond the Data blog: Alaskan North Slope climate change just outran one of our tools to measure it.

(photo and map of Barrow, Alaska from Wikimedia Commons. Graph from climate.gov. Click on the images to see the originals)

p.s. Barrow is now called by its native Alaskan name, Utqiávik.

Which Glaciers Will Flood Your City?

Map of glacial contribution to sea level rise in Miami (screenshot from NASA JPL)
Map of glacial contribution to sea level rise in Miami (screenshot from NASA JPL, pink circle added to highlight Miami)

Though the ocean will never flood Pittsburgh, I’m still fascinated by the rising sea.

Back in October I wrote about sea level fingerprints, the pattern of tiny elevation changes in sea level caused by uneven gravitational forces around the globe.  The highest ocean peaks are in the tropics, the deepest valleys are near melting glaciers.  As the land loses mass (ice) its gravitational pull decreases and it stops hugging the ocean to its shore.  The water has to go somewhere so it goes to the tropics.

This means that glacial melt affects sea level rise in two ways: 

  1. It adds water to the ocean that used to be sequestered on land and …
  2. It alters the sea level fingerprint, lowering the ocean nearby and raising it far away.

If you do the complicated math, you can find out how individual melting glaciers will affect sea level at specific locations.

Last month, scientists at NASA Jet Propulsion Lab did just that when they published a paper in Science Advances and an online tool that illustrates how glaciers will affect 293 coastal cities. 

Let’s take a look at Miami.

Almost half the sea level rise in Miami will be caused by glaciers (47.4% of total sea level rise) and almost half of that will be Greenland’s fault (20% of total sea level rise). That’s why Greenland is so red in the screenshot above.

The next highest glacial contributor in Miami will be Antarctica (12% of total sea level rise).  In the screenshot below you can see that South American glaciers help, too.

Map of Antarctic and South American glacial contribution to sea level rise in Miami (screenshot from NASA JPL)
Map of Antarctic and South American glacial contribution to sea level rise in Miami (screenshot from NASA JPL)

In fact, the entire northern hemisphere is endangered by Antarctica’s melting ice because it’s so far away.  Ironically the safest place to be is right next to a melting glacier.  Sea level will go down at those sites.

See the maps for yourself and try the online tool at NASA JPL.  Read more about it at These are the melting glaciers that might someday drown your city, according to NASA in the Washington Post.

(*) Pittsburgh’s Point is 711 feet above sea level. My immediate family lives 10 to 25 feet above sea level in Virginia and Florida.

(screenshots of glacial contribution to sea level rise in Miami from the online tool at NASA Jet Propulsion Lab.  On the first screenshot I added a pink circle to highlight Miami. Click on the images to use the online tool.)

Tornadoes in November

Damage in Williamsfield, Ohio from 5 Nov 2017 tornado (photo from National Weather Service, Cleveland)
Damage from 5 Nov 2017 tornado in Williamsfield, Ohio (photo from National Weather Service, Cleveland)

You know things are strange when there’s an outbreak of 15 tornadoes in Ohio and western Pennsylvania in November.

Just over a week ago, on Sunday November 5, 2017, a cold front passed over the southern Great Lakes and Ohio River Valley.  Before the front arrived it was humid and around 70 degrees — as much as 17 degrees above normal — so the front’s leading edge spawned 15 tornadoes.

The National Weather Service in Cleveland mapped 14 of them in their region.  I’ve added the EF-1 tornado in Calcutta, Ohio just west of Beaver County, PA reported by the National Weather Service in Pittsburgh.  Yes, 15 tornadoes!

Map of Nov 5, 2017 Tornado Outbreak in Ohio and northwestern PA (map from National Weather Service Cleveland. Added 1 tornado reported in NWS Pittsburgh region in Columbiana County, Ohio)
Map of Nov 5, 2017 Tornado Outbreak in Ohio and northwestern PA (map from National Weather Service Cleveland. I added 1 tornado reported by NWS Pittsburgh region in Columbiana County, Ohio)

The tornado in Williamsfield, Ashtabula County, Ohio was one of the strongest, an EF-2 with winds of 127 miles per hour.  It cut a swath 7 miles long ending at the western shore of Pymatuning Lake.  The damaged house shown above makes me glad I wasn’t there!

Calcutta, Ohio’s EF-1 tornado in the Pittsburgh Forecast Area blew down some trees and damaged the local YMCA.  And an EF-1 tornado blew through the city of Erie, PA for 2.4 miles, downing trees and crossing I-79 on its way.  Here’s its path through a very populated area.

Map of tornado path in Erie, PA on 5 Nov 2017 (map from National Weather Service, Cleveland)
Map of tornado path in Erie, PA on 5 Nov 2017 (map from National Weather Service, Cleveland)

Pittsburgh’s National Weather Service office points out how rare even one tornado is for our forecast area in November:

This [Calcutta, Ohio tornado] is the 14th confirmed tornado so far this year in our county warning area. On average, we see five tornadoes a year. This is the first November tornado since 2003 /14 years/ in New Philadelphia, Ohio. This is the 5th tornado in November for Columbiana county since 1950.

Experts say that climate change increases the frequency of severe weather.  I’d say that 15 tornadoes in November look like a good example.

 

(photo and maps from the National Weather Service in Cleveland. 14-tornado map altered to include the EF-1 tornado in Calcutta, Ohio reported by the National Weather Service in Pittsburgh. Click on the images to see the originals)

p.s. From Nov 5 to Nov 10, 2017 the temperature in New Philadelphia, Ohio went from 17 degrees above normal to 15 degrees below normal.  Yo-yo weather.