Tag Archives: Oceans and Climate Change

Heat uptake, temperature increases in the ocean as a result of the heat uptake, sea level rise, changes in salinity, changes to global ocean circulation, and ocean acidification

General

Ocean Acidification 2021

Leave a comment

This is my fourth and final post on the 2021 report: Climate Change: The Physical Science Basis by the United Nations International Panel on Climate Change. I promised four posts covering ocean warming, sea level rise, salinity changes, and finally the subject of this post – ocean acidification. Acidification sounds scary doesn’t it? You might imagine a big rolling sea of water that can burn your skin off. It’s not that bad, but it’s still somewhat frightening. Now I don’t mean to scare people through my blog, that’s big media’s business. I want to inform people who don’t have the time to read thousands of pages of scientific documents about their contents. My blog posts are designed to provide you with a nuts and bolts synopsis of critical water issues plaguing the world today. But sometimes the data can be pretty worrisome.

So let’s get the scary bit out of the way shall we. The IPCC report points to the oceans absorption of carbon dioxide since the 1980s as being in the range of 20 to 30 percent of all human carbon emissions. As a consequence the pH of the ocean surface has declined 0.017 to 0.027 units per decade since the 1980s and subsurface pH up to a mile in depth have declined by 0.003 to 0.026. If you want to know more about how carbon dioxide impacts ocean pH you can find it here https://waterblogger.org/general-information/ocean-acidification-climate-change/ .

You may be asking yourself why such a small decline in pH is so scary. We have to do some chemistry to explain. As the ocean water absorbs carbon dioxide from the air a chemical exchange occurs, producing carbonic acid – H2CO3. The carbonic acid dissociates, generating HCO3 and H+. What this means is that carbonate ions (CO3) in the water are decreased and bicarbonate (HCO3) ions are increased. It basically changes the whole carbonate chemistry of the ocean. You might not care but all the little critters that make their shells from calcium and carbonate in the ocean’s water do.  Calcium carbonate saturation rates of seawater have been declining at rates of 0.07 to 0.12 per decade.

What I find particularly fascinating in the 2021 IPCC report though is the variation in pH decrease that has been measured in different parts of the ocean now, for example the tropical Pacific Ocean is decreasing in pH at a greater momentum than other ocean areas, while the western tropical Pacific Ocean (renowned for its warm pool of water) shows slower pH declines. Coastal areas are acidifying at a greater rate than elsewhere as waters there are supersaturated with carbon dioxide. What’s happening at depth is interesting too. The well known meridional overturning circulation zones, such as the one in the Atlantic Ocean characterized by the Gulf Stream, bring warm water from the lower latitudes into the Polar Regions where it cools and sinks thereby producing acidification in the deep ocean. Areas like the subpolar North Atlantic Ocean and the Southern Ocean have the highest acidification found at depths greater 2 miles.

Governments are busy trying to decrease carbon dioxide emissions. The results will reverse ocean acidification at the surface, but not at depth due to the long time scales of ocean turnover. This will result in a lasting legacy in the deep ocean and impact biological resources for thousands of years to come.

General

Ocean Salinty and Climate Change

Leave a comment

Ocean salinity is not a topic people often think about when it comes to climate change. After all why in the world would the salinity of the oceans change just because human produced greenhouse gases like carbon dioxide are accumulating in the atmosphere and the ocean? There’s a simple answer to this question though and I explained it in a detailed blog post about six years ago. You can read it at your leisure ( https://waterblogger.org/general-information/ocean-salinity-climate-change/  ). The short answer for the sake of brevity in this post is that greenhouse gases are causing the atmosphere to warm and warm air holds more moisture resulting in increased rainfall. If the amount of rain exceeds the amount of evaporation then a body of water becomes fresher and if there’s more evaporation than rain the water becomes more saline.

 This is all measurable and scientists have been measuring atmospheric water vapor since the 1970’s. It is raining more over the Pacific Ocean where there is already a lot of warmth with accompanying atmospheric moisture and it is raining less in the mid latitudes of the Atlantic Ocean. The Pacific Ocean is becoming less salty and the Atlantic Ocean saltier. Scientists in fact have been measuring the very dickens out of the oceans saline content. There are measurements through the Soil Moisture and Ocean Salinity (SMOS) satellite system and ARGO’s 2000 plus ocean based floating instruments. The latest 2021 International Panel on Climate Change report entitled Climate Change: The Physical Science Basis indicates that between 1950 and 2019 trends in near surface ocean waters have shown strengthening of the contrast between high and low salinity areas of the ocean. The report quantifies the increase in contrast as 0.14 parts per thousand. This is up slightly from the 0.13 parts per thousand reported in the 2013 IPCC report of the same name.

So what if some parts of the ocean are getting saltier and others are getting fresher? Who cares? Well scientists are concerned that changes in salinity will affect the density of ocean water as higher saline content results in denser water while fresher water is less dense. Ocean density is already being impacted by temperature changes. Cold water is denser than warm water. Certain deep water circulation patterns in the oceans are dependent on dense surface water sinking in the polar regions, for example the Atlantic Meridional Overturning Circulation (AMOC). AMOC brings warm surface water from the equatorial region of the Atlantic Ocean to the northern Atlantic where it cools, sinks and is transported back towards the equator. It’s like a big conveyor belt in the ocean. Scientists say that AMOC impacts the climate of the Northern Hemisphere but they seem quite uncertain as to how. They suspect it keeps conditions a lot warmer in the Northern Hemisphere than it would otherwise be. But all they really know is what is measurable and what is measurable is that AMOC is weakening. This makes sense if polar waters are warming and denser saline waters in the middle latitudes of the Atlantic are not being transported to the poles breaking the chain of the Atlantic Ocean circulation. If you live on the east coast of the United States you are probably familiar with AMOC as it includes the Gulf Stream which moves warm water from the Gulf of Mexico along the coast of the United States and Canada then on up to the Northern Scandinavian countries. Scientists are also uncertain as to what exactly is going to be the result of a weakening AMOC. There is of course a lot of speculation by researchers often based on what occurred in the geologic past when AMOC weakened. The IPCC report though does not take a position on the veracity of the various studies purporting to know exactly what happened when AMOC weakened in the past nor are they even a hundred percent sure if the weakening of AMOC is being caused by climate change. The IPCC report says that the record is too short to determine if weakening of AMOC is natural variability or driven by climate change. So I won’t speculate either, I’ll leave that to the popular press.

General

Sea Level Rise from Climate Change

Leave a comment
High water marks on a bulkhead

I read a story in the newspaper a few weeks ago about how the governor of Florida was visiting Miami in order to start the long process of providing protection from sea level rise to the low lying city. It was an interesting article; because in addressing the issues caused by sea level rise, like coastal inundation and flooding, he wouldn’t let the words climate change pass his lips even though the issues have expensive solutions like sea walls and drainage infrastructure. I’m not a political person but it seems strange to me that the guy won’t address the root cause of the problem and is only interested in temporary fixes. Sea level rise is becoming an acute problem all up and down the eastern seaboard of the U.S. wherever development has occurred along the coast. I live on an island where gauges to measure sea level have been installed to track the inevitable encroachment of the ocean. I’m afraid our community won’t exist in 50 years as no manner of temporary fixes will keep the island from disappearing.

Six years ago I wrote a blog post on the rising oceans (https://waterblogger.org/general-information/sea-level-rise-climate-change/ ). At the time scientists used satellite measurements to show there was a 0.03 inch yearly rise of sea level as the result of greenhouse gas emissions. Increased monitoring since then has produced a lot of new and better data, so let’s take a look at what the just released 2021 report from the United Nations International Panel on Climate Change Climate Change 2021: The Physical Science Basis has to say about sea level changes.

Here are the yearly sea level rises given in the 2021 report:

PeriodAverage Rate of Sea Level Rise in Inches per Year
1901 – 19710.05
1971 – 20060.075
2006 – 20180.15
Data from 2021 UN IPCC Climate Change 2021

What can we make of this new data? Simple math indicates that over the last 12 years of monitoring sea level has risen 1.8 inches and the total sea level rise from 1901 to 2018 is estimated at close to 7.9 inches. My last blog post based on the 2013 IPCC report on the physical science basis for climate change had an estimate of a 7.5 inch rise over the time period between 1901 and 2013. So we’re not talking about a huge increase in 8 years, but you can see from the table above that a continuous sea level rise is going on and that the rate of the rise is increasing on a yearly basis.

Why is sea level rising so quickly? Sure glaciers are melting and the Greenland Ice Sheet looks like swiss cheese because it has so many holes in it, but according to the 2021 IPCC report glacial melt has only caused about 41 % of the sea level rise between 1901 and 2018, although it is projected to increase as the loss of ice sheets is really beginning to take off and now accounts for 35 % of the sea level rise that has occurred between 2006 and 2018. The other reason for the sea level rising is simply good old fashioned thermal expansion. When you heat water, it expands. The 2021 IPCC report estimates thermal expansion is causing 38 % of sea level rise.

Other factors playing into higher sea levels are density and circulation changes in the ocean; however the 2021 IPCC report fails to quantify their contribution. I find it hard to believe because there are a multitude of other facts and figures given, but really the report just doesn’t say. There’s often a failure to communicate in the IPCC report caused chiefly by omissions like this one but also because so many different time periods and measurements are compared. It’s a hard slog to get through the whole report and garner any useful information. My literary critique aside, the changes caused by thermal expansion (thermosteric changes) and density changes from increased salinity (halosteric changes) are lumped together in the 2021 IPCC report as “steric sea level change.” These two changes actually should be working at cross purposes to each other, as greater density decreases volume whereas higher temperatures increase volume. I would take exception to how they are presented in the report, except in reality the halosteric changes are negligible.

So this is probably more complex than you ever thought and then to put even more of a spin on things (excuse the pun) sea level rise is not the same everywhere due to the earth’s rotation and gravity. In other words your sea level rise in Thailand is not going to be the same as it is in say New York City because water is sloshing around and mounding up differentially.

What is causing the sea level to rise is probably not as important as the projections in the 2021 IPCC report for future changes in sea level. The 2021 IPCC report provides two different calculations for future sea level rise: one projection is for the scenario of greenhouse gases being substantially reduced and the other is for a scenario where they continue to be emitted at high levels. Compared to the time period between 1995 and 2014 calculations show that in 2150 global mean sea level will rise by about 2 feet for the low emissions scenario and by 55 feet in the high emissions scenario. Unfortunately the world is now beyond the tipping point of totally eliminating sea level rise because heat in the surface of the ocean is slowly circulating into the deeper parts of the ocean and will be retained there, causing thermal expansion for thousands of years to come.

General

Ocean warming -climate change

Leave a comment

I wrote my first blog post on ocean warming in 2016 (https://waterblogger.org/general-information/increase-in-ocean-temperatures-climate-change/). Almost six years have passed so let’s take a look at the state of the science in determining how our planet’s oceans are responding to the additional heat being transferred to them from the atmosphere. Conveniently the latest report from the International Panel on Climate Change (IPCC) just came out in 2021. It is entitled Climate Change 2021: The Physical Science Basis and is written in a much different style than the last IPCC report of the same name issued in 2013, because the science of climate change has grown. There’s a lot more certainty among scientists about what green house gas emissions from human activities are doing to our planet because there has been substantial data collection from a global network of monitoring systems over the last decade. Even the climate models have been updated and the predictions are now more useful. The bulk of the 2021 IPCC report is geared toward risk. In other words what is going to happen to this planet if it continues to warm and more importantly to readers of this blog, what is going to happen to the oceans?

The report uses a period between 1850 and 1900 as a reference period for comparison to today’s temperatures. You may recall those years were the beginning of industrialization. Scientists can now say definitively that global surface temperatures in 2021 are 2.1 degrees Fahrenheit higher than the time between 1850 and 1900.    

I wrote about ARGO in my very first post on how warming is affecting the oceans (https://waterblogger.org/general-information/oceans-and-climate-change/  ). ARGO is a system of floating scientific instrumentation deployed in the oceans around the world. The instruments measure, among other things, ocean temperature. The array of monitors has helped scientists determine the ongoing increases in ocean heat content in at least the upper 6500 feet of the ocean where measurements are being taken. Below 6500 feet there’s just not much data. But in the upper 6500 feet things are really warming up because these are the ocean depths where the ocean is storing heat from the atmosphere. Back in 2013 studies estimated that 90 % of earth’s energy caused by global warming since the 1970s is being stored in the ocean. New calculations say 91 %. Not much change there, but ARGO has been able to further refine for climate scientists where among the various depths of the ocean heat storage is concentrated. As you can imagine the first 3000 feet of the ocean is taking the big brunt of the action with 61 % of the total. This is important to realize because mixing and transfer of heat among the ocean layers is very slow. Later on in this blog post I’ll tell you why this is so important, but first a few more facts and figures for you from the report.

As everyone knows by now the three main greenhouse gases that are drivers of climate change are carbon dioxide, methane, and nitrous oxide. Carbon dioxide, which is in large part responsible for warming temperatures, is being exchanged and buffered by the ocean. Buffering is when carbon dioxide interchanges chemically with the water at the ocean’s surface to form a new compound – a weak carbonic acid. The ocean is taking up not only most of the heat from the atmosphere but is at the same time storing and reducing the amount of carbon dioxide. Carbon dioxide increases have been measured to be about 1.56 ppm a year over the last 61 years. During this time the accumulation of carbon dioxide in the atmosphere has remained about the same – 44 %. Why? Because the carbon is being taken up by the oceans and by the plants and soils of the planet. The circulation within the ocean slowly moves the carbon from the surface into deeper parts of the ocean.   

Scientists measure carbon in PgC. One PgC is equal to a billion metric tons of carbon. That’s a lot. The calculation of the cumulative amount of carbon dioxide from human activities that has been stored in the ocean is about 105 PgC. Do the math. Total human emissions of carbon dioxide are estimated to be 450 PgC. So the ocean is taking up 23 %. The fascinating thing that has been calculated in the 2021 IPCC report is when exactly the ocean will lose its buffering capacity for carbon dioxide. This is a mere chemical calculation, nothing special. Here’s the result: the ocean should be able to uptake carbon dioxide from the atmosphere through 2100, but its capacity to buffer will start decreasing around 2050.

What does this mean? It means that more carbon dioxide will remain in the atmosphere. For decades half of carbon dioxide has been taken up by the ocean and terrestrial carbon sinks and has slowed warming of the atmosphere. In 2050 the atmospheric temperatures will start to rise. You think its hot now, just wait.

And for the oceans? Average ocean temperatures today have increased by 1.6 degrees Fahrenheit from the reference period of 1850 to 1900. Since the 1970s, heat transfer to the oceans has increased by 0.28 – 0.55 yotta joules. No that’s not lotta joules; it’s yotta joules. Although it seems like a lot of joules to me. This a very large number, greater even than my calculator can handle. Take 0.28 and add 24 zeroes behind it. The 2021 IPCC report estimates that in the future ocean heat is likely to increase by 2 to 4 times that amount and 83 % of the ocean surface will warm over the 21st century. And here is what I told you earlier that I’d reveal later in this post. Even if green house gas emissions are drastically cut back, ocean warming will continue until 2300 because of the slow circulation between the upper and lower ocean depths.

So there you have it, the dystopian future of the oceans is sealed.

General

First Contact: Climate Change

Leave a comment

I can envision the future when aliens first arrive in 2150 to contact humanity. Gyzzzzlbex and Azzterixx stop at the United Nations building in New York City for a meet and greet.

            Gyzzzzlbex looks around and says, “Hey Azzterixx I don’t remember all this water covering up the city. I know it’s been two hundred years since we last visited this planet, but I’m sure there wasn’t this much water here then.”

            Azzterixx replies, “And where are all the people? I didn’t see a soul when we were on the way down here in our space ship. This planet was heavily populated when we last visited.”

            “Maybe they killed themselves off with those nuclear bombs they were testing in the desert when we had that hard landing in Roswell, New Mexico.”

            “Nah,” says Azzterixx, “My monitor doesn’t show any radiation.”

            “Well maybe there’s something here in the United Nations headquarters that will tell us what happened.”

            The two aliens look around in the various rooms and find a library.

            Azzterixx picks up a weighty tome, browses through it, then says, “Well look here Gyzzzzlbex, this document says that it is unequivocal that humans have warmed the atmosphere, ocean and land of this planet through release of green house gases and that there have been widespread and rapid changes to the atmosphere, oceans, cryosphere and biosphere as a result.”

            Gyzzzzlbex walks over to where Azzterixx is standing and tries to read over his shoulder. “What is that big book you are quoting from?”

            Azzterixx says, “It’s called Climate Change 2021: The Physical Science Basis. It’s by some panel of experts here at the United Nations called the International Panel on Climate Change. And holy cow it is 4000 pages long.”

            Gyzzzzlbex says, “How about turning the page there Azzterixx.”

            Azzterixx does so and they both inhale sharply.

            “So that’s what killed them all,” says Gyzzzzlbex.

            “Yes and they calculated it all out in this report. Amazing. They knew if they didn’t drastically cut green house gas emissions that the global surface atmospheric temperature could rise by as much as 12 degrees Fahrenheit by 2100. How sad. Well I guess our mission here is done.”

            As the aliens turn to leave Gyzzzzlbex says, “I wonder why they did nothing to stop green house gas emissions, knowing what they did?”

            I wonder too. I read the news coverage of the recent United Nations Climate Summit in Scotland which reported of a consensus among scientists and environmental organizations that the agreement reached there by some 200 countries will not be enough to mitigate greenhouse gases impacts on our climate. It’s been since January 2016 that I’ve written anything on how climate change is impacting the oceans, so I thought I’d take a hard look at the scientific research presented by the IPCC report on Climate Change: The Physical Science Basis just issued in 2021 versus the report by the same name from 2014. I wrote four posts on climate change in 2016 that covered:  ocean temperature changes, sea level rise, and ocean salinity. So I’m going to follow that process again in this blog to let long time readers catch up with the current science. Here is a link to the first post I wrote in 2016 (https://waterblogger.org/general-information/oceans-and-climate-change/ ).

General

Ocean Acidification – Climate Change

Leave a comment

When I took my first graduate level physical chemistry class many years ago, I had a professor who spent several lectures demonstrating how the human emission of carbon dioxide through the burning of fossil fuel could not contribute to the accumulation of greenhouse gases in the atmosphere and cause atmospheric temperatures to rise. His chemical equations showed how ocean water reacts with carbon dioxide in the atmosphere and essentially removes it.  The chemical equations for this exchange are actually very simple and quite well known. Carbon dioxide, which is CO2 (carbon and oxygen), reacts with water, which we know is H2O (hydrogen and oxygen), to form carbonic acid (H2CO3). Carbonic acid then further reacts with ocean water to produce bicarbonate (HCO3) and free hydrogen ions.

You’re thinking, we’re saved! We don’t have to worry about those carbon dioxide emissions from power plants and cars anymore. Let’s pump more oil and gas out of the ground and to heck with driving a Prius. Where’s my Hummer?

Well not so fast. My physical chemistry professor forgot to explain to us what happens to the ocean after this chemical exchange. What do we remember about free hydrogen ions? They are a measure of acidity. Remember pH? It is a scale of measurement from 1 to 14 where 7 is neutral. Anything below 7 is acidic and anything above 7 is basic. The pH of a solution is simply a measure of free hydrogen ions. The more free hydrogen you have, the more acidic your solution. So when the ocean reacts with carbon dioxide from the atmosphere, it is becoming more acidic. This is what is known as ocean acidification.

The pH of the oceans range from 7.8 to 8.4. So right now seawater is mildly on the basic side. The pH of the oceans is something scientists have been measuring for a long time. The change in the pH of the ocean can also be calculated based on man’s carbon dioxide emissions. Scientists have made an inventory of greenhouse gas emissions dating as far back as the start of the industrial age. Such inventories are not your most accurate of measures, especially when you are looking at emissions from several hundred years ago, but if anything they are probably undercounting emissions. The International Panel on Climate Change in their 2013 Report “The Physical Science Basis” states that currently the amount of total carbon dioxide from human emissions being stored in the ocean is 30 %. According to calculations using such inventories there has been a 0.08 decrease in pH in the ocean’s surface water between 1765 and 1994.

Direct measurement of pH taken since 1991 in the North Atlantic and North Pacific have shown a steady decrease ranging between ‾0.0014 and ‾0.0024 per year. These numbers reflect regional variations in pH decreases. The IPCC report states the variability in the decline of pH is a reflection of high latitude oceans not as effectively absorbing carbon dioxide.

The pH decreases seem tiny don’t they? But think about this. Oceans cover almost three-fourths of our planet; that is a lot of water. The fact that carbon dioxide emissions can change the pH of the entire surface water of the ocean every year by even these tiny amounts is phenomenal. Say you took the mid-range of this yearly decrease (‾0.0019) and multiply it by 1000 years. You would be looking at almost a pH decrease of 2 by the year 3016. You would be going from slightly basic ocean water to slightly acidic ocean water, just from human carbon dioxide emissions.

On the short term there are a lot of scientific researchers who are studying the impacts that these slight yearly decreases may be causing. None other than the National Academy of Sciences has weighed into the impacts of ocean acidification by developing  “A National Strategy to Meet the Challenges of a Changing Ocean (2010).” Ocean Acidification is a big concern of scientists, after all humans are changing the very chemistry of the earth’s oceans.

General

Ocean Salinity – Climate Change

Leave a comment

Have you ever read the folktale “Why the Sea is Salt?” It’s a cute little story about a magic handmill spirited away from Satan himself by an unfortunate thief. While hiding behind the door to hell, the thief sees the devil order the handmill to produce all sorts of lavish food and objects. Once he gets his hands on the magic handmill, the thief escapes by boarding a boat and setting sail. The devil had directed the handmill by simply saying “handmill grind…,” so the thief proceeds to tell the magic handmill to grind gold. Unfortunately for the thief, only Satan can make the handmill grind luxuries. For everyone else, the magic handmill just grinds salt. Once the handmill starts grinding salt, the thief realizes he’s forgotten the words the devil used to get the handmill to stop. The salt from the handmill overloads the boat and it sinks to the bottom of the ocean where the handmill keeps on grinding out loads of salt even today.

It’s a nice legend, but in reality we all know the main mechanism causing the sea to be salty is the erosion of minerals from rocks and soils. The eroded minerals are flushed down rivers and streams and deposited in the oceans. There’s also some contribution of minerals to the oceans from volcanic eruptions both above and below sea level. (Yes there are volcanic eruptions from the ocean floor.) The minerals in the ocean are concentrated by evaporation of freshwater from the ocean’s surface. Some of these minerals like calcium and carbonate are used by organisms to form shells. Other minerals are used as nutrients. Only the minerals which are not actively used by organic life in vast amounts are left behind. As you might guess the largest component of the dissolved solids left in the oceans are chloride and sodium, the components of salt. Useful for seasoning French fries but not much else.

With all you’ve heard in the media about the melting glaciers and the polar ice sheets, you would think the ocean was getting less salty, right? After all, the freshwater from all this ice is going into the ocean and scientists say that at least half of sea level rise is being caused by melting ice. Surely this addition of freshwater is having an impact.  In reality though the contribution of melting glaciers to salinity changes in the oceans is not as great as you might think, because there are a whole lot of other things going on between the oceans and the atmosphere which are far more influential on how salty the water is. The International Panel on Climate Change (IPCC) in their 2013 report “The Physical Science Basis” states that the oceans are getting saltier in some locations and less salty in others. For example the Atlantic Ocean is becoming saltier and the Pacific Ocean is becoming fresher.  Interestingly enough, the Atlantic has always been saltier than the Pacific. Why? It is that old hydrologic cycle of evaporation and precipitation. It just rains more in the Pacific.  Low salinity is found in areas where precipitation exceeds evaporation and runoff from rivers and streams. High salinity is found where evaporation exceeds precipitation and runoff.

Increases in atmospheric temperature as part of climate change increases this overall hydrologic cycle. Think about it. Warmer air holds more moisture than dry air. The IPCC cites that the atmosphere can actually hold about 4 % more water vapor for each degree Fahrenheit the temperature increases. Scientists have been recording atmospheric vapor since the 1970s and the data show increases in atmospheric water vapor. So essentially, it is raining more in warm areas of the Pacific Ocean and raining less in mid latitude areas of the Atlantic Ocean. The IPCC report notes that surface salinity of the tropical Pacific Ocean has declined by 0.1 – 0.3 parts per thousand over 50 years in the western equatorial regions and by up to 0.6 – 0.75 in the intertropical and southern Pacific. The subtropical Atlantic is saltier by 0.1 – 0.3. Polar regions also get more precipitation in the form of both ice and snow, so the ocean water in the arctic regions is becoming fresher as well, although I didn’t see an exact number in the IPCC report.

Interesting right? But exactly how vital is the role of salinity in the oceans? Colder water is denser than warmer water. Denser water sinks. In the arctic, cold fresh water sinks and spreads toward the equator, supplying the deeper ocean with freshwater and reducing salinity. It is a process that impacts the oceans circulation and ocean circulation impacts our climate. Fresh water is less dense than salty water. Will the freshening of the waters in the arctic impact the movement of polar waters in some way? Will increasingly dense salty water in the subtropics result in changes to the composition of deeper water? Now we are entering the realm of speculation. Other scientists don’t hesitate to speculate on possibilities. No less an august organization as the National Science Foundation speculates that based on research they funded back in the early first decade of the 21st century  fresher water at the northern pole could impact ocean circulation in the North Atlantic, in particular the Gulf Stream, and consequently weather in the Northern Hemisphere.

The impact of the Gulf Stream on North Atlantic climate appears to be as much of a myth as the thief’s magic handmill, according to the Lamont Doherty Earth Observatory at Columbia University. Here is a link to an article on why the Observatory says it is a myth:

http://www.ldeo.columbia.edu/res/div/ocp/gs/.

So I will leave speculation about the impacts of changes in ocean salinity to earth’s climate for someone else.

General

Sea Level Rise – Climate Change

Leave a comment

Sea level rise is probably the most well known impact to oceans from climate change. For those of us who live in low lying coastal areas, it has become the daily dirge we hear from environmental groups, state environmental agencies, and the media: “prepare for inundation by the ocean, prepare for inundation by the ocean.”  Just last week there was yet another public talk in my town about preparing for sea level rise. It may be too late for my town; we get water in the streets every time there is a high tide. Many a time, I’ve had to wear rubber rain boots in order to get to stores and restaurants on the waterfront. It’s kind of like Venice, Italy, where residents keep their rubber boots by the door during “acqua alta.” However our problem is not simply caused by sea level rise from climate change. There are other problems accosting us, like subsidence of the whole area due to what is called isostatic rebound from former glaciers in the area. So we are getting the double whammy. We have seen almost a foot of sea level rise in the last hundred years. How do we know? Well people have been monitoring tide gauges for literally hundreds of years.

 

Scientists have estimated that global mean sea level has risen by 7.5 inches since 1901. They have based their estimate on records from tide gauges around the world and since 1993 on satellite data. Of course most of the tide gauge records are from Europe and North America. Did you know that the Europeans were installing and measuring tides in the 1700’s? The oldest tide gauge in the United States was installed in San Francisco Bay in 1854. There are long records of tide heights. The problem is sorting all the data so you are not seeing effects of isostatic rebound and other contributors to what scientists term “vertical land motion.” These contributors are well known in areas where there are tide gauges, and the best course of action is not to use data from areas where there is known earth movement causing the land there to rise or subside. Since the late 1990s scientists have installed global positioning receivers (i.e. GPS) near these tide gauges in order to detect the amount of vertical land motion. This will help make the data from the tide gauges useful in the future.

 

Very precise measurements of sea level rise have been made since the early 1990’s through the use of radar measurements from satellites orbiting the earth. Water in the oceans is constantly moving around as a result of tides, rotation of the earth, general ocean circulation, expansion and contraction from changes in temperature, the whole hydrologic cycle of evaporation, precipitation, and runoff, as well as glacier melting and formation. So sea level varies continuously. To measure the actual change in sea level rise based on the satellite data, scientists have had to build a geodetic reference frame for the earth from which the satellite radar measurements are compared. The reference frame always stays the same even if the water is moving up and down and all around. Since the measurements from the orbiting satellite are so precise, the data can be processed to determine the overall actual sea level rise versus temporary ocean changes.

 

So is sea level rising consistently? What is its rate of rise? According to the 2013 Intergovernmental Panel on Climate Changes (IPCC) report “The Physical Science Basis” global mean sea level has been rising at rate of .07 of an inch a year since 1901. The number is of course based on both satellite and tide gauge data over the time period. The very precise measurements from satellite data (available since 1993) show a greater rate for global mean sea level rise of .13 of an inch per year – almost double the rise calculated from the combined tide gauge and satellite data.

 

Sea level has been rising since the end of the last Ice Age about 14,000 years ago. There are many geologists who have made maps of the migration of the world’s coast lines over the last 14,000 years. In fact in the United States, sea level 14,000 years ago was about 300 feet lower than it is today and the coastline was nowhere near where it is now. There is a formula called “Bruns Rule” which gives you the amount of horizontal feet gained or lost per inches of sea level rise. Using the formula, I calculated that the coastline 14,000 years ago was about 5 miles from where it is now. That is a very rough estimate. There are many contributing factors that make the ratios in the Bruns Rule calculation different based on the locality. Mapping by scientists is a better way to determine exactly where the coastline was at the end of the last Ice Age. My calculation is just to give you a feel for how much distance can be covered by a change in sea level.

 

So what part of sea level rise is just the natural processes going on as a result of the continued interglacial epoch that we live in and what is the amount caused by humans emitting greenhouse gases? The IPCC has calculated the amount of increased heat in the upper ocean caused by human induced climate change since 1971. (See my post on temperature changes in the oceans https://waterblogger.org/general-information/increase-in-ocean-temperatures-climate-change/). Based on their calculations an average of 0.02 inches of sea level change a year has occurred as a result of the warming of the upper ocean (upper 2300 feet). Another .008 inch rise per year is a result of warming from 2300 feet to the bottom of the ocean. So roughly 0.03 inches per year of sea level rise can be attributed to greenhouse gas emissions.

Although the rate of sea level is small on a yearly basis, the rate is steady. It will eventually affect everyone who lives on the coast. And sea level rise is going to be a costly problem. I can see it happening already as my town reconstructs flood walls and puts in new drainage systems to prevent high water from flooding streets, parking lots, an

 

General

Increase in Ocean Temperatures – Climate Change

Leave a comment

Whenever I read the latest scientific research on climate, I marvel at how much we don’t know. Meteorology is kind of a Johnny-come-lately sort of science. Sure there are big wheels of climate science like Gilbert Walker who in the 1920’s came up with what is now called the Walker Oscillation. I suspect most people have never heard of the Walker Oscillation, but meteorologists blame El Nino on the reversal of the Walker Oscillation and I’m pretty sure everyone is familiar with El Nino. (Here’s a great link to a blogger at the National Oceanic and Atmospheric Administration who explains the connection between the Walker Oscillation and El Nino:  http://www.climate.gov/news-features/blogs/enso/walker-circulation-ensos-atmospheric-buddy). If you look at other sciences, their foundations are based on centuries of work. Everybody knows of Galileo and Isaac Newton. Chemistry has its Antoine Lavoisier and geology has its Charles Lyell. I suppose you could name a few founding meteorologist from the 19th century, like Luke Howard. Luke who? Well he gave the names to the cloud formations which we still use today. Remember cumulus, stratus, and cirrus? I’m sure you memorized those names in school at some point. But really the greats of meteorology are probably alive today. The people cited by textbooks in a hundred years as the scientific founders and inventors of modern meteorology are writing papers and publishing now.

 

Peer review journals are often good at winnowing out papers of questionable scientific merit, but it is even better when you have a board of scientists who are engaged in examining all of the scientific literature on a subject in order to determine its significance; especially when dealing with a global issue like climate change. Or you will end up with a lot of debatable science, like the “hollow earth” theory of the 19th century touted by such luminaries as John Leslie, who by the way did some of the early work (strangely enough) on heat transfer. Yes there was quite a debate in the early 19th century on the “hollow earth” theory and it captured the imagination of writers like Jules Verne who in his famous 1864 novel “Journey to the Center of the Earth” sent a German team of explorers down through a volcanic crater into a supposed vast subterranean interior. So a panel of super cautious scientists is what I like to depend on in looking at climate change data. The Intergovernmental Panel on Climate Change (IPCC) sponsored by the United Nations is just such a group. I took the time to read the IPCC report on Climate Change: The Physical Science Basis, which was published by the Cambridge University Press in 2013.

 

I hope it doesn’t come as a surprise to anyone that heat transfers from the atmosphere to the ocean and vice versa. So as the atmosphere has warmed, so have the oceans. Not by much, you don’t have to worry about burning your toes when walking in the surf. The IPCC estimates there has been about a 0.2 degree Fahrenheit increase per decade in the upper 250 feet of the ocean since 1971. That’s kind of a global average. Temperature increases are variable depending at what latitude and in which ocean you are. And just as heat is transferred from the atmosphere to the ocean, the warmer surface ocean transfers heat to the colder deeper ocean. The IPCC estimates during the same time period, the global average increase in temperature down to 2300 feet has been about 0.03 degrees Fahrenheit per decade.

 

The IPCC was not confident in using temperature data collected prior to 1971 to make any sort of interpretation of long term ocean temperature changes, because the mix of instruments and the sparcity and variability of sampling didn’t provide consistent enough data to sort out long term temperature changes from the regular variable temperature changes found over seasons, years, decades and centuries. As interest in climate change has increased, so has the extent and quality of temperature measurements in the ocean. The IPCC also reported on the variability in warming among the oceans. Data shows a greater warming in the Northern Hemisphere than elsewhere on the globe.

 

Climate scientists like to talk about energy inventories, energy storage and energy transfer. Where is all that energy trapped by the greenhouse gases in the atmosphere going? After all, it normally would be reflected back out into space. Now all this heat and energy is trapped in the earth’s atmosphere. These days, there are actually reported inventories of greenhouse gas emissions. So scientists can calculate the total amount of various greenhouse gases, produced in power plants and by other human activities, in the atmosphere on an annual basis.

 

Climate scientists also can calculate how much energy would be needed to raise the upper ocean temperatures by the 0.14 degrees Fahrenheit the IPCC estimates has occurred over the 40 year period between 1971 and 2010. However methodologies are variable and therefore estimates are variable. I would say, it is a lot of additional energy that must have been transferred to the oceans to raise the temperature in the upper ocean by that much. The IPCC report cites numerous calculations found in the scientific literature. These calculations show an increased heating rate, somewhere between 74 and 137 Terawatts, would have been needed to raise the temperature of the oceans by the amount observed between 1971 and 2010. Most people are familiar with watts. You know if you have a 40 watt or a 60 watt light bulb. The watt is a measurement of energy transfer. A terawatt is one trillion watts. If you turn on your 40 watt bulb in your lamp it is using 40 watts per hour. If you use a 60 watt bulb it is using 60 watts per hour. If you turn on your 137 Terawatt bulb, it is using 137 trillion watts per hour. (Yes I’m just kidding, there are no terawatt bulbs.) But remember this is over 40 years, so the amount of energy transferred to increase the oceans’ temperature to the amount observed would be 137 Terawatts per 40 years.

 

The IPCC also goes on to calculate the amount of increased energy storage on the Earth between 1971 and 2010 based on annual inventories of greenhouse gas emissions. From the energy storage, they further calculate the resulting increased heating rate for the earth’s total surface and then just for the oceans. Now as far as I’m concerned we’re getting into the realm of science factoid versus science fact with these kinds of calculations. So I’m going to paraphrase what the IPCC states: based on increased energy storage due to greenhouse gas emission, 0.55 watts per square meter of additional heat were applied continuously (24 hours a day, 7 days a week, 365 days a year) over the entire ocean surface between 1971 and 2010.That’s a lot of extra energy going into the oceans of the world.

 

The ocean is a warmer place. Warmer water has a lot of consequences: changes in ocean chemistry, including oxygen content; impacts on the creatures that live in the oceans; and potential changes in ocean circulation, wind and weather.

General

Oceans and Climate Change

Leave a comment

I thought I’d catch up on the latest science on how climate change is impacting oceans. What you say? Climate change is impacting oceans? You thought it was just raising air temperature because sunlight can’t escape the atmosphere with all those greenhouse gases clogging up the works? It’s true, climate change is impacting oceans but you don’t hear much about ocean impacts, mostly because people get their news about climate change from the newspapers. It is rare to see a newspaper article on the subject, but it was a newspaper account which prompted my interest in the current science. It was a ham-handed article on the transfer of heat energy to the oceans. The article compared the transfer of heat energy in the atmosphere to the oceans, using the equivalent of how many atomic bombs would need to be detonated in order to produce the same amount of energy.

 

Every time I see energy measured in nuclear bombs I groan. It’s like every time you hear a politician call another politician Hitler. People are scared of another Hitler, but they are even more scared of nuclear bombs; and with good reason. Nuclear bombs release energy in a single area where they are detonated, which then spreads out to envelope the surrounding area in what we have all seen on television and in movies as a gigantic mushroom cloud of heat and radiation decimating everything within sight. Heat energy being transferred to ocean water is spread out over the oceans, which by the way constitute 70% of the surface of this planet. It goes on everyday of our life. It has gone on every day that the earth has existed with an atmosphere and an ocean. Energy transfer from the atmosphere to the oceans is not the same as a nuclear bomb blast. But people like to use these comparisons I think in order to frighten people.

 

Anyway the newspaper article covered a recent paper in the journal Nature Climate Change, which was written by scientists from a Department of Energy Laboratory, the National Oceanic and Atmospheric Administration and Pennsylvania State University – an impressive lineup. It’s an interesting article, where these scientists have looked at the heat uptake at various depths in the ocean using measurements taken since 1865. Now most of these measurements are not continuous measurements. Many of them are from what climate scientists like to call transects, where a ship takes various measurements during its voyage. For the journal article, these scientists even used data from the Challenger expedition, an English scientific mission in the 1870s. The Challenger sailed around the world for about six years measuring the depth of the ocean. The folks on the Challenger also measured water temperature. Pretty amazing for those times. These days, there are whole systems of floating buoys in the oceans, measuring all sorts of things. The big system out there, measuring temperature and salinity, is ARGO. I know you thought ARGO was a movie with Ben Affleck. But before it became a movie, it was actually the name of the ship on which Jason sailed in search of the Golden Fleece. (Greek Myth, look it up). So researchers named the current system of scientific instrumentation floats bobbing around out there in all the oceans of the world after a ship used in a futile journey by an ancient mariner; strange choice. The measurement system is huge though and is really cool. The system was set up in 2000 and has about 3000 floating stations. ARGO was devised to complement sea level rise measurements being taken by a satellite, which is named (get this) Jason – those scientists what a funny bunch.

 

Anyway, the journal article is an analysis of all these various measurements taken over approximately the last 150 years and the results show over half of the steady increase in ocean heat uptake from the atmosphere during this time has occurred since 1997. Well that made me think, wow, I’ve really lost touch with what is going on in climate change research. I’m not a climatologist or an oceanographer, and I tend to keep to issues effecting water on terra firma, but frankly I get a lot of questions on climate change and other than saying to people, it is getting warmer and what don’t you understand about temperature measurements, I do not have a good handle on current research findings. So I am setting out to inform myself and you about the research scientists are conducting on ocean impacts of climate change and what they have been discovering.

 

There are six big topic areas for how climate change and greenhouse gases are affecting oceans. Of course there is heat uptake as I’ve just been discussing, but there are also temperature increases in the ocean as a result of the heat uptake, there’s sea level rise, there are the changes in salinity, there are the changes to global ocean circulation, and there is ocean acidification. I’m going to check in first with the International Panel on Climate Change. Never heard of them? Well they are the United Nations funded science group who examines current research on climate change. The panel consists of an impressive group of scientists. Their job is to examine current research data for evidence of the extent the earth’s environment is being altered by climate change.

 

Every few years they produce a report which catalogues research findings to date. Their fifth report came out in 2014. I’m embarrassed to admit, I have only read their first report. It was published in 1990. So I’m only 25 years behind. I look forward to reading the report and providing this blogs readers with an insightful review.