In Episode 4 and Episode 5 of our brief history of the scientific evidence of global climate change, we saw how direct atmospheric CO2 measurements and measurements from air bubbles trapped in ancient ice provide us a record of the Earth’s atmospheric CO2 concentration since Biblical times. This record reveals a dramatic and accelerating increase in atmospheric CO2 beginning with the onset of our large scale combustion of fossil fuels during the Industrial Revolutions:
Publicly available Scripps ice core-merged data, downloaded and plotted by me. Green: Ice core data from Law Dome, 0 C.E. to 1957 (see references here and here). Blue circles: Average yearly data from atmospheric sampling at Mauna Loa and South Pole, 1958-2016. Blue square: Mauna Loa measurement made on March 30, 2017. Human experience milestones added by me.
A new graphic prepared by Climate Central uses NASA and NOAA temperature data to show how the monthly global average temperature for each month since 1880 has compared with the average temperature for that month during the “early industrial” years of 1881-1910, highlighted in red in the plot above. (Basically, how much cooler or warmer each month was compared with that month during the time period when Dr. Brown and Mr. Escombe were conducting their early CO2 measurements at the Royal Botanical Gardens.) Cooler months are blue and warmer months are red, with the saturation of the color indicating the departure from the average temperature for that month between 1881 and 1910:
March, 2017 was the second warmest March on record, 1.3 degrees Celsius (2.4 degrees Fahrenheit) above the average March that Dr. Brown and Mr. Escombe experienced around their time at the Royal Botanical Gardens. It also marked the 627th consecutive month of warmer-than-average temperatures since that time.
This is not “fancy scientific data” or computer models. Just readings from thermometers at meteorological stations. Do you generally believe thermometers?
If you were born after December, 1964 (look for that lonely blue box above), you have never experienced a “cool” month.
On March 22, 2017, my family and I joined tens of thousands of scientists and supporters of science in over 600 cities on 6 continents in a nonpartisan March for Science.
At the Minnesota State Capitol, it was a beautiful Spring day. Here are some of the signs we spotted in the crowd of more than 10,000:
But there is still much to do to make sure we hold our federal, state, and local governments accountable for implementing rational policies informed by scientific knowledge, particularly with regard to global climate change. As Americans, we owe it to our Alaskan neighbors. As the #1 cumulative national emitter of fossil carbon, we owe it to the rest of humanity. We owe it to the other species with whom we share the Earth. As the potential beneficiaries of technologies that are available now and can limit the future economic havoc of hotter temperatures and rising oceans, while providing us complete energy independence and putting lots of people to work developing a global leadership position in sustainable energy, we owe it to our economy. As fathers and mothers and grandmothers and grandfathers, we owe it to the children to whom we will leave our planet.
The federal budget proposal on the table, if implemented, would cut the EPA’s budget by 31%, eliminating the jobs of 19% of its workforce and terminating the Clean Power plan which is the primary current policy vehicle for meeting our commitments under the Paris Climate Agreement. This is to be accomplished under the “leadership” of the newly appointed EPA Administrator, Scott Pruitt, who recently said he “would not agree that [carbon dioxide] is a primary contributor to the global warming that we see.” (Um, it is. It definitely is.) The proposed budget would even terminate NASA’s missions designed to monitor the Earth’s climate.
In an official statement on the March for Science, President Trump said, “Rigorous science is critical to my Administration’s efforts to achieve the twin goals of economic growth and environmental protection.” He went on to say, “My Administration is committed to advancing scientific research that leads to a better understanding of our environment and environmental risks.”
These are very encouraging statements. If they are serious statements, that would suggest that the President will encourage his EPA Administrator to take the opportunity of talking with his own employees, who can explain to him the facts surrounding the known causal relationships between fossil fuel combustion, atmospheric CO2 concentration, and global warming. It would suggest that the President will begin championing infrastructure investments like this one, to create jobs, develop a leadership position in a sustainable energy economy, and protect the environment. I will be watching with excitement for signs of these developments.
But, just in case, let’s give our representatives in government some encouragement. The activities initiated with the March for Science continue. This week, we are encouraged to contact our representatives to motivate them on this issue. You can see the call to action on the March for Science website.
I’m providing my own letters (copy them if you want!) here, as well as some resources to help you write your own.
On the day before Earth Day and the March for Science, it’s worth watching this 4-minute video commentary by astrophysicist and science communicator, Neil deGrasse Tyson on “Science in America”:
Video credit: StarTalk Radio. 4-minute commentary by astrophysicist Neil deGrasse Tyson on the past and present state of “Science in America”. The science related to global climate change is prominently discussed.
In March, 2017, residents of the Hawaiian island of Kauai connected a 54,978-panel solar farm to giant battery packs provided by Tesla, creating the world’s largest photovoltaic-battery combination power plant. The batteries store electricity generated when the sun is up for use at night, enabling the 13 megawatt solar array to provide power around the clock.
This power plant has reduced Kauai’s fossil fuel consumption by 1.6 million gallons per year and brought the proportion of its power from renewables higher than 40%, well on the way to the island’s goals of 70% by 2030 and 100% by 2045.
Tesla has contracted with the Kauai Island Utility Cooperative to operate the solar plant, providing electricity to island residents at a guaranteed flat rate of 13.9 cents per kilowatt-hour for the next 20 years. This is well below the current Hawaiian average electricity rate of 28.3 cents per kW-h and competitive with the U.S. overall average rate of 12.2 cents per kW-h (source: U.S. Energy Information Administration).
Watch this short news report to learn more:
Video credit: CNNMoney. News report about the Kauai’s new 13 megawatt photovoltaic-battery combination power plant, the largest in the world, which came online in March, 2017.
This is the nature of renewable energy in 2017. It’s here now. It’s available. In many cases, it’s competitive in cost with fossil sources. (The installed price of solar photovoltaic systems has been falling year on year for decades.) It can provide complete, local-scale energy independence and insulation from the market forces that cause fossil fuel prices to vary. It has no greenhouse gas emissions. Its provision requires no miners to get black lung. With continued investment, it will only get better and better.
While many of us appreciate the seriousness of global climate change, I think many people may under-appreciate the rampant availability of the solutions.
When we are talking about choices between future scenarios, we are really talking about just that: choices. We have everything we need to make dramatic steps toward solving this problem and ensuring a livable future Earth for generations to come.
On the other hand, our President has vowed “massive infrastructure spending” to get Americans “off of welfare and back to work rebuilding our country.” I think that’s great. I can’t imagine a more impressive, job creating, value creating national infrastructure project than this one.
CNN reports in April, 2017 about the ongoing bleaching and death of two-thirds of the Great Barrier Reef due to elevated ocean temperatures that have been directly linked to global warming. (Watch short video; watch more detailed CNN report including interviews with scientists studying the changing reef.)
Her love rains down on me as easy as the breeze I listen to her breathing, it sounds like the waves on the sea I was thinking all about her, burning with rage and desire We were spinning into darkness; the Earth was on fire
She could take it back, she might take it back some day
So I spy on her, I lie to her, I make promises I cannot keep Then I hear her laughter rising, rising from the deep And I make her prove her love for me, I take all that I can take And I push her to the limit to see if she will break
She might take it back, she could take it back some day
Now I have seen the warnings, screaming from all sides It’s easy to ignore them and God knows I’ve tried All of this temptation, it turned my faith to lies Until I couldn’t see the danger or hear the rising tide
She could take it back, she can take it back some day
She can take it back, she will take it back some day
She will take it back, she will take it back some day
-Pink Floyd, 16 May 1994
Video credit: YouTube. Pink Floyd performs “Take It Back” on The Division Bell tour, 1994.
This is the 5th episode in a series recounting the history of measurements and data related to Global Climate Change. If you’re just joining, you can catch up on the previous episodes:
Episode 1: Beginnings (or two British scientists’ adventures with leaves and CO2 measurements)
Episode 2: First measurement of anthropogenic global warming
In Episode 4, we saw Dave Keeling and coworkers discover the atmospheric CO2 concentration has been on a marked upward sweep, from about 290 ppm in 1900 to over 400 ppm now, and accelerating. Well, is that unusual? Is that a big swing? Or, does the CO2 concentration vary a lot due to natural causes?
Since Dave Keeling only began our continuous, high-accuracy CO2 measurements in 1958, it would seem we would need a time machine to figure that out. In some of the loneliest places on Earth, it turns out, nature has been quietly making time capsules for us.
In parts of Greenland and Antarctica, the snow never melts. In between the snowflakes, tiny volumes of air are trapped. As the years go by, each layer of snow is compacted under new layers. The snow is eventually compacted into ice, and the air is entrapped in minute, isolated bubbles. Geologists in heavy coats prospect for those historical bubbles, little bits of past atmospheres. Good spots to prospect are where it snows very often, such that the snow and ice are deep and the annual layers thick. One such place is Law Dome, Antarctica, a coastal location of Antarctica where the snowfall is as much as 225 lbs of snow per square foot per year.
(A) Field tents at Law Dome, Antarctica (Australian Antarctic Division). Ice core drilling was conducted in the tent in the foreground. (B) Slice from an ice core showing entrapped, ancient air bubbles (Norwegian Polar Institute). (C) Section of an ice core showing visible seasonal layers (Wikimedia Commons). (D) A researcher selects ice cores for greenhouse gas analysis at an Australian ice core storage facility (Australian Antarctic Division).
Ice cores are drilled out using cylindrical drills. Layers in the ice are dated, sometimes visually (see image C above), most times using more sophisticated methods. For example, a rare, heavy isotope of oxygen, O-18, is present in the frozen H2O of Antarctic precipitation at a higher concentration in summer than in winter. Thus, the years in an ice core can be counted as summer stripes and winter stripes, through isotopic analysis of the oxygen in ice layers using a mass spectrometer.
Scientists in the 1980’s expended considerable effort developing accurate methods of harvesting and measuring the composition of the old atmospheric air trapped in ice core bubbles. Since CO2 is water soluble, it’s important not to allow any of the ice to melt while you’re getting the air out. The figure below, from a 1988 paper, shows a schematic diagram of an apparatus used to measure the CO2 concentrations in gas samples retrieved from Law Dome ice cores. This has become known as the “cheese grater” technique, and is still used for CO2 analysis of ice cores.
Figure 1 of Etheridge, Pearman & de Silvia, 1988. Schematic diagram of “cheese grater” and associated gas condensing equipment for harvesting ice core air samples for analysis.
In a cold room (to prevent any melting), an ice core section is inserted in a cylinder with raised cutting blades on the inside, like an inside-out cheese grater. This is put inside a vacuum flask and shaken on a machine, crushing the ice inside. The released gases are sucked by a vacuum pump over, first, a water vapor trap, cooled to -100 degrees Celsius, to condense and remove water vapor. The dry sample is then made to flow over a “cold finger,” cooled by liquid helium to a frigid -269 degrees Celsius, cold enough to condense to liquid all the gases in the air sample. Once all the gas has been sucked out of the sample, the cold finger is isolated and warmed, and the accumulated gas sample is sucked into a gas chromatograph, a standard piece of analytical equipment for separating the gas constituents from each other and measuring their concentrations.
Between 1987 and 1993, Australian and French scientists working at Law Dome drilled 3 separate ice cores to depths of as much as three quarters of a mile. Samples of these ice cores have been analyzed by various groups. Below, in green, is a plot of data from a 2006 study of CO2 concentration from these ice cores going back over 2000 years.
Publicly available Scripps ice core-merged data, downloaded and plotted by me. Green: Ice core data from Law Dome, 0 C.E. to 1957 (see references here and here). Blue circles: Average yearly data from atmospheric sampling at Mauna Loa and South Pole, 1958-2016. Blue square: Mauna Loa measurement made on March 30, 2017. Human experience milestones added by me.
The data is publicly available; anyone can download it here. While this is a single data set, it is in agreement with data sets obtained from multiple ice cores, stored in multiple locations, by multiple scientific groups using a variety of methods (for a discussion of agreement between the various data sets, see here). The ice core data overlaps, with a high degree of agreement, with the Keeling Curve of direct atmospheric CO2 measurements made since 1958, shown in blue in the plot above. (Note that the blue data in the above plot are yearly averages, so the seasonal variations we saw in Episode 4 have been “smoothed out.”) No reasonable, well-informed person refutes this data, which has now been replicated by a multitude of independently sponsored research groups and reviewed extensively for years.
The historical CO2 data tells a story of remarkable stability for 90% of human experience since Biblical times. In fact, until around 1850, the atmospheric CO2 concentration averaged 279 ppm and never strayed outside a narrow range between 272 ppm and 284 ppm (see black lines on the plot below):
Plot of Scripps ice core-merged data showing the pre-industrial average (black dashed line) and range (black solid lines) of CO2 concentrations going back to 0 AD.
Around the time of the First and Second Industrial Revolutions (attended by the advent of coal-fired steam engines and the petroleum industry, respectively), atmospheric CO2 began its relentless upward sweep that continues today. By the time Dr. Brown and Mr. Escombe were doing CO2 measurements at the Royal Botanical Gardens around the year 1900, and certainly by the time Guy Callendar and Dave Keeling were publishing their CO2 measurements and analyses starting in the late 1930’s, the atmospheric CO2 concentration had already departed significantly from the pre-industrial range. The March 30, 2017 direct measurement at Mauna Loa was 47% higher than the average CO2 concentration that had persisted, until very recently, since classical antiquity.
The rate of increase of the atmospheric CO2 level is also strongly accelerating. The graph below shows the rate of change of CO2 concentration over the past two millenia. (If you remember your pre-calculus, I obtained the graph below by taking the derivative of the graph above.)
Rate of change of atmospheric CO2 concentration in parts per million per year (ppm/year).
Prior to the Industrial Revolutions, the atmospheric CO2 concentration changed very little from year to year, and the rate of change hovered around zero. Following the Industrial Revolutions, the rate of change was positive much more often than it was negative; the CO2 concentration was increasing. Immediately following World War II commenced an unprecedented period of positive and increasing rate of change of the CO2 concentration. Some climatologists have labelled the time period between the end of World War II and today as the “Great Acceleration.” During this period, the global population doubled in just 50 years, while the size of the global economy grew by a factor of 15 (Steffen, Crutzen & McNeill, 2007). At the same time, the global CO2 concentration has not only increased to levels unprecedented in previous human experience, but the rate of that increase has sped up from year to year. In 2016 (the hottest global year on record), the rate of increase reached 2.24 ppm/year.
The question for us is, how high do we wish to allow the atmospheric CO2 concentration to go? For me, I have to say the data shown above is alarming. The fact that, in spite of the data above, we are still having discussions about “putting coal miners back to work” is terrifying.
In a future episode in this series, we will get into the details of how historical temperature records have been created and linked to the CO2 concentrations above. But there is already enough information on this website to show that our prodigious CO2 production, if unabated, will lead to prodigious warming. The physics of the greenhouse effect are well understood and have been refined by scientists since the effect was first proposed in 1824. It is a mathematical certainty that more CO2 in the atmosphere will cause warming. As we saw in Episode 3, physicist Gilbert Plass used this known math and some of the first computers to predict in 1956 that the combustion of fossil fuels would lead to a warming of about 1 degree Celsius by around the year 2000, and that has come to pass.
In a 2013 paper, respected climatologist, James Hansen, and co-workers calculated that the Earth’s fossil fuel reserves are sufficient to raise the average land surface temperature by 20 degrees Celsius (36 degrees Fahrenheit). Try adding that to the summer temperature where you live. Since humans require a wet bulb temperature less than 35 degrees Celsius (95 degrees Fahrenheit) to maintain body temperature, this temperature change would literally make most of the Earth uninhabitable for humans in the summer. As an engineer, it’s impossible for me to imagine a workable adaptation for this problem that could be accomplished on the short time scale over which this change is presently on track to occur. In fact, given the comfortable stability in CO2 concentration humans have “grown up” with, there is nothing to suggest our social systems are prepared to deal with many of the consequences of the rapid climate changes we would experience on the current trajectory. Our farm land will be moving toward the poles. (Will we then clear more carbon-absorbing forests as it moves?) Our most valuable coastal real estate will be submerged.
As for the consideration of jobs, I suspect it will always be plausible to make the argument that jobs in fossil fuel reliant sectors of our economy will be eliminated by shifting to more sustainable sources of energy. It seems to me that new jobs will be created making solar panels, solar concentrators, and wind turbines. With respect to energy independence, I would argue that the sun shines and wind blows in all regions of the Earth. In any case, given the conclusions of the last paragraph, it would seem the only reasonable conclusion is, yes, as much as it may pain us, we will need to leave much of our remaining fossil fuels in the ground.
Know anyone who remembers the Dust Bowl? Grapes of Wrath and all that? Our President’s recent executive order, which can only be called “business as usual” (or worse) with respect to carbon emissions, aims to bring it back. To stay.
Image credit: NASA’s Goddard Space Flight Center. Projected soil moisture in 2095 at 30-cm depth (as deviations from the 20th century average) for a “business as usual” CO2 emissions scenario. Under this scenario, the atmospheric CO2 concentration reaches 1,370 ppm in 2100.
This projection was not made by a bunch of hacks and conspiracy theorists. The lead author on the study is a NASA scientist, and the picture above results from analyses of 17 different climate models by a team of independent scientists from multiple institutions. I myself am a scientist who dreamed of working at NASA, but I don’t. Please trust me when I say it’s competitive. The climate models involve enhanced versions of the same math that enabled the physicist, Gilbert Plass, to predict in 1956 almost the exact temperature rise and environmental observations we see now. See the NASA press release here. See the technical paper here.
The image above is called “business as usual.” It assumes the Paris Climate Agreement is not honored (as our President has clearly signaled his intent that we not honor it), and all of us go on emitting carbon like we have been. In this scenario, the atmospheric CO2 concentration reaches 1,370 ppm by 2100. (This is not crazy but quite realistic; as we have seen, the CO2 level has risen from 290 ppm in 1900 to 410 ppm today and the rate of increase is strongly accelerating.) The darkest regions in the above image have soil moisture comparable to the 1930’s Dust Bowl. Farmers and grocery shoppers, take note.
The image below is a “moderate emissions” scenario, which assumes we constrain our CO2 emissions such that the atmospheric CO2 concentration in 2100 is 650 ppm. It’s still dry compared with the 20th century average and, make no mistake, this will be challenging. But it’s not a Dust Bowl.
Image credit: NASA’s Goddard Space Flight Center. Projected soil moisture in 2095 at 30-cm depth (as deviations from the 20th century average) for a “moderate emissions” CO2 emissions scenario. Under this scenario, the atmospheric CO2 concentration reaches 650 ppm in 2100.
The second image seems like a better choice, for sure. But it’s not the trajectory we Americans are on, under the conditions of our President’s recent executive order. Under those conditions, if we achieve the second choice, it will be thanks to the Chinese, India, Europe, Brazil, and the rest of the 194 other nations that signed the Paris Climate Agreement. And it will be in spite of our own irresponsible actions as the current 2nd largest carbon emitter, the #1 cumulative historical emitter, and the most wealthy nation on the planet. We should be ashamed.
Look, I have no ill will toward coal miners. They have helped bring us enormous human progress. But we now clearly understand that progress has had a price we can no longer afford (and have developed the technology to avoid) paying. Modern coal mining is a technical job. Much like building solar panels or wind turbines. I propose that coal miners could learn to do either one of those. I recognize it would be a hardship (which we could choose to ease, for example, through government-subsidized retraining programs). I believe some of them would end up enjoying and prospering from such a change. And new jobs of the future, not the past, would be created. And the United States would be more competitive in the future global economy, which will embrace sustainable energy sources to the extent that it survives.
And let’s be clear. We’re not talking about the fate of some distant human generations. The children living among us, our children, will experience the year 2095 that we are choosing right now.
We have real choices to make. Not made-for-TV choices. And the time for making them is now. (The Earth doesn’t watch TV.)
Watch a short NASA video about this study narrated by lead researcher Ben Cook, NASA Climate Scientist:
Source: NASA Climate Time Machine. Map of the Southeast US with 6 meters (20 feet) of sea level rise. Red shaded regions would be underwater. For context, satellite observations have indicated a thinning of parts of the Greenland ice sheet. If it were to melt completely, water from the Greenland ice sheet would raise the global sea level by 5-7 meters (16-23 feet).
Image credit: The bathroom wall of my friend, Marlys. Marlys has lived in the same region of the Upper Midwest for 89 winters. She testifies that the effects of Global Climate Change on those winters are unmistakable.
