The sun shines on the middle of the continent while the coasts face the wrath of ocean storms

Quite the day out in weather world, although you wouldn’t know it from looking outside here in the land of the corn. Beautiful day, although still waiting for the leaves to make an appearance. Soon enough, but the sun shines bright overhead. Calming and peaceful for a walk later.

Outside my favorite coffee shop in Lincoln. 52 degrees F and very light wind. Your normal late March day in all its glory.

After a winter which was tumultuous with big temperature swings (sometimes 50 degrees F within days), it’s nice to have a little stability for some days. Looking near or mildly above normal temperatures the next several days with periods of rain showers. Our winter in this region was less than 0.5 C below normal relative to 1981-2010, but running 0.5-1 C above normal relative to 1881-1910 when factoring the effect of climate change. And temperatures from anthropogenic climate change began rising globally after the mid-1700s, so late-19th century values are still conservative on the changes which have occurred here. People around here were complaining about how cold it was this winter. It could’ve been a lot worse as we had a few 60 and 70 degree temperatures in February mixed with the 10s and 20s for highs in January and February! Just wild.


Global temps relative to the late-20th century vs. the late-19th century (the latter showing the effect of anthropogenic climate change very obvious). The Arctic is getting “hot” (for the survival of sea ice) fast with major effects on the region and world for further global warming.

Actually reminds me of a story in the coffee shop of a mother and adult daughter discussing this past winter. The daughter saying how “normal” it was to have these huge swings in temperature and crazy weather (snow then short-sleeve weather). Mother saying “Well I remember when I was young, it would be more consistently cold with a lot more snow, not like now”. What’s normal has changed with time in a lot of world, but you wouldn’t know it unless the different generations notice and chit chat about it.

Our chances of snow appear to be over. Never say never, as the East Coast seems to be getting blasted by these cold storms, but when you start seeing these consistent mild conditions finally, it’s usually a sign of the seasonal transition…finally.

I do have some concern over this Spring’s tornado season I must say. La Nina periods in the El Nino Southern Oscillation tend to be known for quite intense tornado outbreaks. Trying to get a science paper reading in about it this week if I can. The Gulf of Mexico waters are running above normal for moisture, the South has been quite warm overall with record warm days and months this winter. And jet stream dynamics continue to be favorable for bringing periodic shear profiles for significant severe weather. The atmosphere put on quite a show this weekend in the Deep South where it is climatologically favorable for tornado activity. Reminds me to prep an emergency kit. We do have a weather radio, but with things like tornadoes and urban flooding, you never know when you will need a little more to get through a few days of darkness and no refrigeration.

While, it’s quiet here, the West and East Coasts are being battered by major winter storms to start Spring. Very strong upper-level trough over the eastern third of the country and another over the Eastern Pacific means the 4th nor’easter of the month in the East and huge atmospheric river event in Southern California. Heavy snow or flooding/mudslides?

Middle atmosphere wave pattern showing deep trough generating significant coastal storm with snow over the mid-Atlantic/Northeast. Atmospheric river from SW flow over California.
Strong east coast storm. You can also see how dead quiet it is over the center of country from prominent high pressure overhead.
Moderate to heavy snow falling over New Jersey and New York City/Long Island.
Strong West Coast storm impacting California with heavy rain.
Moderate to heavy rainfall impacting parts of Southern California. Problems with flooding and mudslides/debris flows likely. (radar as of 1 pm PDT).

Good mid-week to all and stay safe in these stormy areas!

–Meteorologist Nick Humphrey


High Amplitude Jet Stream Pattern To Lead to Extremely Abnormal Temps for Central/Eastern US; “Blow Torch” Heat to Arctic.

The US will be a land of extremes as a high amplitude jet stream…the story of this winter continues to impact the US as very abnormally cold temperatures impact the Central US and (later) the Great Lakes region, with very abnormal heat spreading northward into the Eastern third of the country mid-week. Sunday, much of the Great Plains were experiencing temperatures 20-25 degrees F above normal (~10-12 degrees C). As the week progresses, the jet stream amplitude over North America will intensify and bring highs of 30 degrees F (15+ C) or greater above normal mid-week to the Ohio and Tennessee Valleys into the mid-Atlantic and New England states. This means mid-Spring highs on the East Coast and a resumption of well below freezing temps over the Central and Northern Plains.

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In addition to the abnormal temperatures, another major story will be potentially heavy rainfall across a wide swath of the Midwest and Deep South ahead of the accompanying cold front which will push eastward mid-week. Abundant moisture from the Gulf of Mexico will aid in the generation of rainfall, some of which will help short term drought conditions, but could also produce flash flooding.

Moderate risk of flash flooding over portion of Texas, Oklahoma, much of Arkansas and southern Missouri Tuesday.
Tuesday evening forecast surface map showing widespread moderate to heavy rainfall likely from Texas to Michigan.

The Arctic Ocean has been experiencing an extraordinarily warm winter with consistent high heat to the region (relative to regional norms). As a result, sea ice has been suffering severely as the combination of high amplitude high pressure ridging and ocean cyclones push heat, wave action and wind into the sea ice sheet, along with very abnormal sea surface temperature right up against the sea ice (9-18 degrees F/5-10 degrees C above normal). Sea ice extent is currently running at the lowest on record in the history of human civilization, rapid melting already in progress in the northern Bering Sea, and 2017 annual sea ice volume was the lowest on record. The current max extent this season occurred on February 6th. The current earliest maximum peak extent is February 25th in 2015. The current record year for record minimum peak extent is 2017…2018 is currently beating that record and has the 2nd lowest year-to-date volume as well.


The sea ice is showing some signs of refreezing after its early February peak. However, more extreme heat is to come as more storms from both the Bering Sea and the North Atlantic advance heat and moisture into the Arctic Ocean this week. One storm will move over far Eastern Siberia and into the Chukchi Sea on Tuesday. Wednesday, another, stronger storm will approach Greenland, moving over the Canadian Archipelago Thursday, slowly shifting toward the Beaufort Sea Friday.


Note the last two sea level pressure images for 2/23 and 2/24. Not only the strength of the cyclone (in blue) but the tightly packed lines of equal pressure (isobars) between the low pressure system and the strong high pressure system over the Barents Sea, north of Scandinavia. These tightly packed isobars represent a very strong pressure gradient which will result in very strong southerly wind gusts (near hurricane-force) and intense wave action striking the sea ice sheet of the Arctic Ocean mid to late week. This in combination with the very warm, moist air moving into the region will make for a “blow torch” of heat from the Atlantic, eroding the cold conditions of the Arctic, stunting the freeze season further. This will likely lead to further ceasing or recession of sea ice as well.

GFS forecast high temperature for Thursday, showing above freezing temperatures penetrating into the deep Arctic. This may continue into Friday. Today through Tuesday will feature near or above freezing temperatures moving out of the Bering Sea into the southern Chukchi Sea as well.

I’ve been tracking the Arctic all season and there has been a shocking level of persistent warmth in the region with 2-3 degrees C above normal temps (for the region) being quite common many more extreme day higher than that. The Arctic Ocean basin may experience, as a region, anomalous temperatures of an incredible 6-8 degrees C above normal Tuesday-Saturday. This is relative to the 1981-2010 average. However, as climate change is abruptly warming the Arctic region, leading to rapid sea ice loss compared to the past, relative to the late 19th and mid 18th centuries (in the early era of human generated climate change), the anomalies are likely 0.7 or 1  degree C higher than that, respectively.

GFS Anomalous temperature forecasts for the Arctic region valid 00 UTC Feb 23rd. Extreme heat by regional standards over the Arctic for much of the week.

The implications for the collapse of sea ice are quite serious. The sea ice sheet regulates the jet stream by making the Arctic region permanently cold across a wide area. As long it it remains permanent with only modest seasonal melt, it can behave much like a continental ice sheet would behave on the atmosphere (like in Antarctica). The jet stream exists because the Arctic atmosphere is cold throughout the vertical column. The strong temperature gradient with the mid-latitudes is what makes it exist. But with abrupt warming of the Arctic caused by the collapsing ice sheet (which feeds back on accelerating such a collapse), this weakens the jet stream and has been causing it to become wavier with increasingly more extreme and frequent high amplitude patterns (which feedback and melt the Arctic more). Such research has been conducted by scientists such as Dr. Jennifer Francis of Rutgers University and others, showing the jet stream slowing and becoming higher in amplitude since the 1960s. Such abrupt warming also leads events such as “sudden stratospheric warming” and “splitting” of the polar vortex, supporting Arctic blasts to the south and abundant heat transport to the Arctic.

If the ice sheet collapses completely (no more in summer, low to little meaningful extent in the polar night), you get even more abrupt warming of the sea surface from below and above through collapse of the ocean thermocline (persistently cold water “cap” atop somewhat warmer water) and air temperature inversion (warmer air atop cold surface air) as well as from the much reduced albedo (white, reflective surface). The warming atmospheric column with height further reduces the temperature gradient with the mid-latitudes, weakening the jet further and causing more extreme “wave action”, greater blocking patterns as you get these big waves and little eastward progression of systems and the polar jet actually retreats farther north. This can dramatically shift precipitation patterns northward could cause much hotter, drier conditions in the mid-latitudes. It’s been a major concern for a long time in in climate change science, but a process thought to be of concern in the “high emissions” scenarios of the mid to late 21st century as increasing aridity across the mid-latitudes would destroy forests and not allow crops to be grown where they are currently grown because of increasing extreme heat (or storms). So this would have impacts not only in the Arctic, but also in the mid-latitudes. Unfortunately, a recent phrase has been increasing use the past few years. “Faster than expected”. Some prominent researchers openly admit an ice-free Arctic may be possible before 2020. See also HERE.

I’ll have more on the situation in the Arctic this week as well as the heavy rainfall in the US. Also, keep an eye on Tropical Storm Gita approaching New Zealand to start the week!

–Meteorologist Nick Humphrey

Effect of Sun-Mon Arctic Ocean Storm on Sea Ice

You may remember I posted last Friday about the major North Atlantic storm which was expected to move into the Arctic Ocean Sunday and Monday producing hurricane-force winds, 30 ft+ waves and temperatures over 40 degrees F above normal (near or even above freezing in places). Well that storm advanced through the Arctic and now noticeable effects can be seen (via satellite analysis) on sea ice concentration (amount of ice vs. open water in a given area) and on sea ice sheet growth and resulting extent.

North Atlantic Surface Analysis valid at 06 UTC February 5th (midnight CST) showing the 958 millibar low pressure system off shore northeast Greenland entering the Arctic Ocean from the North Atlantic basin. (US National Weather Service)
Global Forecast System model analysis valid 12 UTC February 5th (6 am CST). This shows the very strong sustained winds and (by Arctic standards north of 80N) extremely warm temperatures during the height of the storm. This was thanks to very strong warm air advection from the Atlantic Ocean. The system had a sub-tropical connection with heat and moisture originating from the subtropical western Atlantic. Average temperatures in many places should be -30 to -15 F (-34 to -26 C). (

Included are two images of the sea ice concentration…one I saved from the February 3rd, another just posted for February 6th. Lighter blues are for 90-95% concentration, with yellows and reds being for 75-90%.

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Extent growth basically stopped between February 3-6 (near 13,300,000 sq km for four days).

2018 year-to-date extent (currently at record lows) vs 2016 extent (previous daily record lows for this time of year) and the 1980s average. Sea ice extent and volume collapse is underway in the Arctic Ocean because of Anthropogenic Climate Change caused by abrupt warming in the Arctic (notable since the 1980s, accelerating since the 2000s). 

More very above normal temperatures will hit the Arctic this weekend as a powerful blocking high pressure system over the Pacific (sound familiar…) raises temps once again across Alaska and allows storm tracks to head for the Bering Strait and Chukchi Sea once again. Meanwhile, the Atlantic side will continue to remain “open” with another storm also moving into the region this weekend. No storm appears to be nearly as powerful as the Sunday-Monday event, but the litany of systems bringing at least some wind, wave action and temps not far below the freezing point of salt water is no good for the Arctic.

Temperature anomaly (degrees above or below average) forecast by the GFS model for the Arctic region valid 18 UTC February 10th (noon CST). Normal is based on 1981-2010 baseline. To approximate the major effect of anthropogenic climate change since the end of the 18th century add +0.9 degrees C (K).
GFS maximum temperature forecast valid 18 UTC February 10th (noon CST). Very warm air temperatures on both the Atlantic and Pacific entrances to the Arctic Ocean.

Arctic sea ice is extremely important for everything from Arctic regional ecology, marine biology to effects on overall warming of the Arctic Ocean and surrounding land areas (and permafrost). There is also evidence that the rapid warming of the Arctic because of anthropogenic climate change is altering the polar jet stream circulation which may be leading to an increased frequency and magnitude of extreme weather events. 

Sea ice thickness and thickness anomalies in January 2018. (Zach Labe)

–Meteorologist Nick Humphrey



Wild Ride – More Cold Intrusions into North America/Europe, Powerful Warm Storm Headed for Arctic Ocean Monday

This winter has been a fascinating one to say the least. Wild oscillations between very abnormally warm and very abnormally cold while other places are are just consistently very warm. Or perhaps just very dry. Much of this has been thanks to the current La Nina pattern in place over the Tropical Pacific. The atmospheric pattern leading to abnormally cooler waters over the eastern tropical region also lead to the promotion of strong high pressure systems over the Central North Pacific with unusually higher amplitude jet streams. This favors a polar jet aiming for the Pacific Northwest, northern tier and into the northeastern third of the country while the Southwest and Sunbelt see drier conditions.


Conditions of at least “Abnormally Dry” cover over 67% of the Continental US. It is the most coverage in abnormally dry conditions since February 5, 2013. It is, interestingly, the 49th greatest extent of at least Abnormally Dry conditions on record out of 944 recorded weekly updates (over 18 years now). Conditions of at least D1 “Moderate Drought” coverage over 38% of the Continental US. It is the most coverage in D1 conditions since April 22, 2014.

Of note with this pattern regime has been the, at times, extreme nature of the jet stream amplitudes. They have driven very warm temperatures into the Arctic with record low sea ice across the Arctic Ocean, the warmest December on record across the state of Alaska, and record high temperatures in portions of the Southwest US in January with the aforementioned persistent drying and intensifying drought concerns. 

Meanwhile, significant Arctic intrusions have been impacting the US, particularly in January and more appear likely in February as “teleconnections”…patterns in global circulation which give clues toward a general weather regime for a region of the world…show signs of further intense extreme jet stream amplitudes with very strong upper-level high pressure systems blocking storm tracks over the north Pacific and Bering Sea, which downstream will mean a cross polar flow in the upper atmosphere of very cold air upper troughs and surface Arctic fronts and high pressure systems over northern Plains/Midwest into the Northeast US. The Deep South should escape as warmer air from the subtropics attempts to advance north and may keep the Arctic air at bay. Europe looks to also have periods of similar cold (and interior Siberia of course! Check out the incredible cold they had last month).

Temperature Anomalies in the US (Sunday, Thursday) and in Europe (Monday). Widespread temps below freezing during the day in parts of central and Eastern US and central and eastern Europe during these cold periods. Very persistent warmth with highs in the 60-80s in the Southwest US.


Powerful Arctic Ocean Storm Sunday-Tuesday

While the mid-latitudes get hit with Arctic cold, the Arctic is being pounded by significant amounts of mid-latitude heat. And now the computer models are pointing towards a major North Atlantic storm developing early this weekend, moving over Greenland and then into the middle of the Arctic Ocean Sunday night-Monday. This storm will be very powerful…as strong as any classic North Atlantic ocean winter storm, and will bring significant amounts of high winds, battering waves and high “heat” to the Arctic. How warm? Perhaps as warm as 50-60 degrees F above normal temperatures over much of the Arctic Ocean. This will mean highs near or just above freezing up to the North Pole!

Temperature forecast by the Global Forecast System model for noon CST Monday showing near or above freezing temperature penetrating deep into the interior Arctic as a result of intense warm air advection.
A significant sector of the Arctic Ocean will have air temperatures over 40 degrees F above normal (or higher) during the day Monday.

This storm is forecast to initially form southwest of the tip of Greenland and east of Quebec Friday and will beginning moving over Greenland Saturday. Sunday, the system will begin to impact the Arctic, with warm and moisture transport from the North Atlantic (all the way from the Azores!) increasing abruptly late-Sunday. By Monday morning, models indicate waves moving up the Fram Strait toward the Arctic may be as high as 30 ft in strong south-southwesterly flow. Over the sea ice sheet, the low pressure system will be intense as it emerges from Greenland…possibly sub-960 millibars with widespread wind gusts of up to hurricane-force likely over much of the interior Arctic Ocean east and south of the low on the Atlantic side.

GFS depiction of the powerful low pressure system over the central Arctic Ocean on Monday. The European model has a similar strength low. Winds up to hurricane-force wind gusts and battering waves are likely conditions for the tenuous sea ice.
Forecast significant wave heights for early Monday with the worst of it in the Fram Strait.

Why this storm is so significant is because the Arctic sea ice is continuing to undergo collapse because of anthropogenic climate change. If the Arctic climate warms to the point that it simply cannot support sea ice in the warm season, with the Arctic Ocean warming as a result of very low albedo (reflectivity to visible light which would otherwise limit warming) compared to white ice (or latent heat of melting/freezing, instead of heat going into warming the ocean directly), this will have dramatic effects on not only regional climate but global climate (I can go into greater details in this in the comments or provide resources). Generally this was something expected much later in the future, but may occur earlier than expected, although it is difficult to predict when exactly this will occur as it would be nonlinear and abrupt. However, as mentioned, ice volume and extent for ice are running at record or near record lows across the Arctic Basin. Some of these effects on albedo and heating have already begun to be felt over the past several years on the marginal seas which are beginning to become increasingly ice free during the warm season (Chukchi Sea, Beaufort Sea, Eastern Siberian Sea), but it’s important to not have the interior Arctic Ocean lose significant ice. Particularly in the winter, but it has been struggling just to freeze this winter! For more on recent sea ice developments see these videos by Paul Beckwith (M.Sc, PhD candidate; HERE and HERE).

In the meantime, while we have year to year variability…various teleconnection patterns, anthropogenic forcing (CO2, other gasses) is the most dominant regime on our climate and so even while I must emphasize weather is not climate…I must also emphasize that climate is a statistical distribution of weather events; and so extreme weather events which are increasing in frequency and magnitude are a sign of our climate shifting to more extreme conditions and in sensitive places (particularly cold climates like the Arctic), those shifts are incredibly noticeable.

–Meteorologist Nick Humphrey

The Science Behind “Atmospheric Bomb” Cyclones

The first full week of January featured a powerful winter storm – known as a nor’easter – intensify off the east coast of the United States causing snowfall from the North Florida to Maine into Atlantic Canada, along with widespread power outages from strong winds as well as storm surge flooding and battering waves.

Powerful nor’easter offshore Long Island Thursday afternoon.
Vehicles navigate Monument Square on Sunday in North Adams, Massachusetts, which was under a snow emergency. Gillian Jones / AP

The storm underwent rapid intensification known in meteorological slang as “bombogenesis”. An “atmospheric bomb” occurs when a developing cyclone’s low pressure center intensifies explosively…defined as at least 1 millibar or 1 hectopascal drop per hour on average during a 24 hr period. This system had a pressure drop of 54 millibars in 24 hrs (1004 to 950 millibars). This bombogenesis phase can occur in both frontal cyclones seen in the mid-latitudes such as with this week’s storm or with tropical cyclones. A famous example would be Hurricane Patricia in the Eastern Pacific in 2015 which experienced a minimum central pressure drop of 95 millibars during a 24 hr period (967 to 872 millibars).


Bombogenesis in mid-latitude cyclones occurs when there are favorable jet stream dynamics which allow for strong vertical motion, to force air up and away from a developing surface low. These include very strong upper-level winds and diverging flow. This allows for a high rate of decrease in surface pressure, intensifies the pressure gradients, reinforces the “conveyor belts” of warm, moist air flowing into the cyclone for clouds, releases latent heat and producing precipitation, which further strengthens the storm.


For frontal cyclones, the most intense atmospheric “bombs” occur when you have a merging or “phasing” of the northern and southern jet streams (basically the polar jet with much colder air to its north and the subtropical jet with far richer moisture sources to its south). This “phasing” of jet streams occurred with the most recent nor’easter.

Upper-atmospheric air flow maps from Wed-Thurs morning showing the phasing of the polar and sub-tropical branches of the jet stream, which intensified the massive East Coast nor’easter.


“Bomb” cyclones are nothing new. Unfortunately for us who have to live and deal with their impacts, human-induced climate change has forced our world to retain a significant amount of heat energy. These major changes on climate in just the past 20-30 years have caused statistical changes in observed weather. And one of those changes is in rapid intensification of cyclones. With tropical cyclones, there is evidence that a warming ocean and lower atmosphere (with greater moisture/latent heat release) is playing a role in increasing the frequency of rapidly intensifying tropical cyclones (here’s a paper by Kishtawal et al. on the topic). With mid-latitude cyclones, there is ongoing debate on the issue. However, there ongoing research suggests that in addition to thermodynamic roles, the increasing “waviness” of the polar jet stream theorized to occur in a warming world may have impacts on mid-latitude weather and long-term climate patterns. High amplitude jet streams produce greater mixing of air masses at lower levels of the atmosphere between the polar regions and sub-tropics (a process known as temperature advection). The increase in jet stream amplitude acts as a feedback to further amplify Arctic warming rapidly relative to the mid-latitudes as much warmer air advects into the far north (jet slows slightly with less temperature gradient, but becomes much more amplified, enhancing warming further). While the effect of the mid-latitudes circulation patterns on the Arctic seems more well-established because of the rapid changes in the far north, climate scientists are in much higher disagreement on the effects of feedbacks back on the mid-latitudes. Dr. Jennifer Francis (Rutgers University; see short webinar on possible connection between Arctic warming and mid-latitude extreme weather), among other scientists continue to do research actively on jet stream dynamics in the mid-latitudes with regards to climate change. But such a combination of warming energy sources and amplified jet stream patterns could further the development “bomb” cyclones in the future as the world continues to warm, at least while there remains strong temperature gradients between air masses to fuel mid-latitude storms (mid-latitude cyclones may be weaker and/or found much farther north in a much warmer planet). And there has already been a statistically detectable shift northward in winter storm tracks in the Northern Hemisphere and an increase in the severity (intensity of cyclones and precipitation rates) and frequency of “atmospheric river” events in the Eastern Pacific toward North America since the 1950s (see Key Finding #4-5/Chapter 9 of US Climate Report).

What “bomb” means as far as hazardous impacts will depend on the specific storm, but when it comes to ocean storms, like what was witnessed this week, obviously, damaging winds, heavy surf, storm surge flooding and heavy precipitation which can cause dangerous disruptions are what are all possible. In this case, much of it was all snow and ice. In the warm season, it can be flooding rainfall. But human-induced forcing (retaining of heat in Earth’s system) is now known to play a role in the attribution of the intensification of these large-scale weather systems within the changing climate regime.

–Meteorologist Nick Humphrey

Five Year Anniversary of Landfall of Superstorm Sandy

Five years ago today (October 29, 2012), the post-tropical remnants of what was Hurricane Sandy made landfall on the New Jersey coastline as a hurricane-force windstorm, causing destructive straight-line winds and historic, damaging surge from the North Atlantic extending from the Jersey coast north into the New York City Metro Area, with historic flooding of lower Manhattan.

Image of extremely large Hurricane Sandy by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite on October 28, 2012. Sandy would become the largest tropical cyclone on record in the North Atlantic Basin.
Sandy produced widespread wind gusts of 75-90 mph across portions of New York and New Jersey with heavy rainfall totals of 7-10 inches across parts of New Jersey, Delaware, and Maryland. Storm surge was Sandy’s main cause of significant damage, with wind damage and flooding rainfall additional impacts. The post-tropical “superstorm” caused a 10-13 ft storm surge which damaged and destroyed homes and businesses along the Jersey Shore and Hudson Waterfront, with a record 13.88 ft water rise reported at Battery Park in Lower Manhattan.

Damage by Super Storm Sandy in Brooklyn, NY (“Proud Novice” on Wikipedia).
Super Storm Sandy damage in Mantoloking, NJ taken on October 30, 2012. (US Air Force).
The flooded Brooklyn-Battery subway tunnel in NYC on October 30, 2012 (“vcohen” on Wikipedia).
Sandy’s expansive storm surge was more intense by multiple factors. As it came poleward, it grew significantly in size, a typical phenomenon for tropical cyclones moving into the mid-latitudes. However, Sandy’s weakening and mid-latitude interactions caused it become the largest North Atlantic tropical cyclone on record, producing a huge fetch (extensive wind over long stretch of open water). This fetch allowed for the building of significant ocean waves and piling up of water toward the shallow continental shelf of the Atlantic coast of the US. And although Sandy weakened somewhat and became “non-tropical”, this did not matter as the very large wind field remained and forward momentum of the very heavy ocean could not settle down in time before pounding the coastline with destructive surge.

In addition, Sandy made landfall at high tide, enhancing the storm’s ability to flood dry land areas and cause direct damage with battering waves. I will also note that this “flood reach” was even greater because of climate change-induced sea level rise. Global sea levels have risen 9 inches since 1880 and while the Intergovernmental Panel on Climate Change (UN) continues to indicate a likely sea level rise of up to 3.2 ft by 2100, many other reputable scientists have suggested the possibility of multi-foot sea level rise occurring this century as the result of exponential glacial melt feedbacks in Greenland and Antarctica. Perhaps as high as 6.5-16.5 feet by 2100 (see references #1-2 below). This, of course would be catastrophic for vulnerable coastal cities for both livability but initially for any places already exposed to storm surges. New York City is one most at risk.

Sea level rise has also been locally enhanced along the Northeast US Coast because of abnormally warm waters building offshore for years, leading to increased thermal expansion of the water surface upward. This may also be a result of climate change-induced weakening (#3) of the Atlantic Meridional Overturning Circulation (AMOC). While Superstorm Sandy wasn’t “caused” by climate change, it was part of an increasing regime of more extreme weather events (and events with with more extreme hazard variables) and a prelude to what will be far more frequent in the coming decades.

Sandy was retired after the 2012 Hurricane Season, causing 233 deaths from the Caribbean to the United States and producing an incredible $75 billion in damages (only 2nd to Hurricane Katrina). An incredible and devastating meteorological event which we can hope we continue to recover from and our country will be better prepared to mitigate against next time.

Surface analysis at 5 pm EDT October 29, 2012 showing Superstorm Sandy just offshore the coast of New Jersey pounding the Mid-Atlantic to New England. The intense pressure gradient (shown by the isobars) caused areas of gale and storm force winds over the Great Lakes because of the expanse of the storm.
Scientific References (for the nerds like me!):

1- Hansen et al. 2016. (scientific technical)

2- New science suggests the ocean could rise more — and faster — than we thought (Washington Post/Oct 17)

3. Youtube video of conference presentation (2016) by Dr. Stefan Rahmstorf on weakening AMOC. Can also refer to (#1) on this issue as it relates to potential effect on ice sheet dynamics.

WxClimoEd Series, Post #1, Part 2: Understanding Global Climate Change Indicators

Hello Weather & Climate News readers! This post will be the first (Part II) in what will be my ongoing education article series WxClimoEd. I hope to write educational posts on various topics related to weather and climate to help enhance your understanding of various phenomena and their impact on the environment, individuals and society. These posts will present key ideas and concepts and provide occasional linked sources to further, more detailed information.

Understanding Global Climate Change (Indicators)

In Part 2 of this article series on Global Climate Change, I’ll discuss the indicators of climate change in progress on  Earth. Even without the global measurements of temperature, there are plenty of signs in the climate system that change toward a warmer world is in progress.


Earth Undergoing Abrupt Climate Change

While global warming is considered to be detectable since the First Industrial Revolution (after 1750), since the latter half of the 20th century, the environment has begun to exhibit what could be considered “abrupt” changes. Among scientists who study natural abrupt change in the paleoclimate records have had some common thought on what “abrupt” means: 1) Changes in climate which can be witnessed within a human lifetime and 2) the change is very nonlinear; it far exceeds the mechanism which initiated the change in the first place (See this video presentation by Dr. White at the American Geophysical Union Annual Meeting discussing past abrupt climate change in the paleoclimate record). In the past, abrupt change usually occurred as a result of the advance or recession of ice sheets, leading to rapid change in local temperature or regional circulations (or even global distributions of precipitation or temperature patterns). Today, abrupt change is being increasingly witnessed as a result of an already unnaturally fast mechanism (rapid rise in carbon dioxide concentration, resulting in rapid rise in global temperatures relative to natural variability…multi-decadal to centennial  scales vs. multi-millennial).

Here are just some of  the abrupt changes resulting from the changing climate happening now:

  1. Decline in sea ice over the Arctic Ocean

Arctic Sea Ice Volume since 1979. Note gradual and accelerating collapse of sea ice volume. Arctic may fall below 1,000 cubic kilometers at some point in the month of September in as early as several years to a decade or so. This will begin the process toward widespread open ocean in the Arctic for a time in September.
2. Rapid increase in air temperature of the Arctic.

The Arctic (64-90N) has warmed around 3-4 degrees C since the 1881-1910 period (based on NASA data). 2-3 degrees C of warming has occurred just since the 1951-1980 period with notable warming since the year 2000. This has led to not only the rapid decline in Arctic sea ice, but the beginning the melting of land permafrost.

Average air temperatures (over land and ocean) in the Arctic region, relative to 1951-1980 average. Shown is 1984 (year I was born) to 2016. Red box show rapid warming of Arctic since 2000 compared to previous decades. “315” = +3.15 degrees C anomaly. (NASA GISS)
Addendum: The rise in the average temperature of Earth as a whole can count as abrupt, as seen in the earlier graph (farther back up). Most warming has occurred since the 1970s. The top ten warmest years on record going back to 1880 have occurred since 1998 (with 1998 now the last year in the top ten from the 20th century). 2017 is expected to be the 2nd warmest year on record just slightly behind 2016.

3. Increase in Sea Surface Temperatures and Oceanic Heat Content of Global Ocean.

The average sea-surface temperature of the global ocean from 60S-60N has risen around one degree C since the 1881-1910 period. 0.5 degrees C warming has occurred since 1980. Like the global air temperature, SSTs have been most of their record warm years since the turn of the 21st century, with an accelerated pace of warming since 2000 (1.62 degrees C/century currently, compared to 1 degree C/century 1950-2000). 2017 sea surface temperatures are currently running the 2nd warmest on record (NOAA data).

Sea surface temperature anomalies 1880-2016 for various sectors of global ocean. Values on graph are in degrees F. Oceans have warmed roughly 2 degrees F/1 degree C.
As far as oceanic heat content, the oceans have accumulated over 100 zetajoules (1 x 10^23 joules) of heat energy in the upper 700 meters of the global ocean since 1993. An incredible amount of energy, with increasingly accelerated warming in the deep ocean below 700 meters since 1993.

4. Acidification of the Global Ocean.

Earth’s seawater is slightly basic (basic is ph > 7). The global average ph of the oceans has decreased from 8.25 to 8.069 since the 1750s (ph was 8.104 in the 1990s). This is caused by the oceans dissolving carbon dioxide (30-40% of carbon dioxide released by humans dissolves in the oceans). This interaction forms carbonic acid, with further chemical reactions leading to increasing concentrations of the hydronium ion (H+). This leads to a lowering of the ph. The rate of acidifcation is faster than at anytime in the past 300 million years! The rapid acidification has been more pronounced in the Arctic Ocean because of very cold water (colder water can absorb more dissolved gases). When ph falls under 8 in the coming decades (assuming no mitigation), marine life which depend on carbonate structures (shellfish, sea snails, corals, some types of plankton, etc) begin to suffer from the corrosive effects of less basic waters.

5. Sea Level Rise


Sea levels are rising as a result of meltwater from land and thermal expansion as oceans warm. As the atmosphere and oceans continue to warm and weaken the Arctic and Antarctic Ice Sheets, sea levels will continue to rise, with possible nonlinear positive feedbacks accelerating it. It has already accelerated since the end of the 20th century. “King Tides” have become an increasing problem because of sea level rise in the 21st century.

6. Increase in Extreme Weather and Climate Events

The end of the 20th century into the early 21st century has featured a statistical increase in extreme weather events. Climatologists usually classify “extreme” as being 4-5+ standard deviations from the mean of all events. Such increase in extreme events over the course of years means that natural variability is being dominated by global warming, and causing a continuously shifting climate pattern.

The shift in the range of meteorological variables across the bell curve because of climate change. The curve represents the normal distribution of events with natural variability (climate teleconnections and seasonal). The small shift of the mean by climate change causes a significant increase in less common events at one tail as well as an increase in truly extreme events not previously observed in the reference climate regime. (Presentation slide by Erick Fernandes, 2015).
Extreme events include heat, flooding, rainfall rates, drought, and wildfires. All of these occurrences have been increasing the frequency and severity around the world because of climate change. In addition, there is evidence that because of the high rate of warming of the Arctic, the mid-latitude jet stream has become weaker with increased amplitude extremes, leading to short-term and longer-term patterns favorable for extreme conditions at the surface. For example, high amplitude ridges of high pressure which do not move much or reform constantly can lead to extended periods of drought and extreme heat (while other areas downstream may receive cooler temps but heavy rainfall and flooding. This is actually something that is observable on meteorological timescales. Dr. Stefan Rahmstorf discusses the increases in extreme events from climate change in a lecture HERE.

One thing I must emphasize with understanding the impacts of global climate change is that it is impacting the environments of our world now and continue to accelerate in the coming years and decades (assuming no major changes are done). Global warming…the primary force of climate change, caused by our immense release of greenhouse gasses from fossil fuels…is the dominate force behind the rate of change in climate behavior. According to the Intergovernmental Panel on Climate Change in their 5th assessment, the world should actually be experiencing anomalous COOLING right now, but instead we have warmed Earth above and beyond natural long term global temperature variability. So when people ask “Did global warming cause (insert extreme weather event)?”, it is the wrong question. Climate looks at a collection of events for a trend. What is clear is that global warming is NOW causing a statistically significant increase in extreme events and will continue to do so. There is no “new normal” but only a continuous “ramping up” of the Earth’s natural variability toward greater extremes relative to the beginning of the Industrial Revolution, with greater impacts as humanity leaves the stable global climate in existence since the beginning of civilization.

This may be something many do not appreciate, but it is factual. Human civilization has changed Earth’s climate system to the point that we as humans are turning up the “thermostat” and started a multi-centennial experiment in geoengineering. Heat, drought, flooding, rainfall rates, wildfire events, and jet stream amplitudes, as a result, have all increased significantly in just the past 30 yrs.

If the climate were a piece of music…think of Earth’s relatively short-term natural cycles as the melody and global warming as the dominating background harmony from which the melody plays over. If the harmony changes keys, the melody will respond and shift accordingly.

In Part 3, I’ll discuss the projected future impacts of climate change being actively researched (and some already happening) such as food security, human health and living space.