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Worldwide Carbon Dioxide Emissions Holding Constant

A recent article in the New York Times by Eduardo Porter (here) points out that if one considers only carbon dioxide emissions (CO2) from the combustion of fuels, then worldwide emissions have been flat for 3 years in a row.

Figure 1. Source: International Energy Agency, 2017b.

The finding comes from a news release issued by the International Energy Agency (IEA). Figure 1 shows the data. Between 1980 and 2014, global CO2 emissions from fuel combustion grew from 17.7 billion metric tons to 32.3 billion metric tons. However, in 2015 they stayed at 32.3 billion metric tons, and in 2016 emissions were 32.1 billion metric tons. (IEA 2017a, 2017b)

Since 2005, CO2 emissions from fuel combustion have declined in the OECD from 12.8 billion metric tons to 11.7 billion metric tons, a decline of 8.6%. In the United States, emissions declined from 6.71 billion metric tons to 5.00 metric tons (a decline of 25%). That’s good work, however it needs to be put in context. Compared to 1990, OECD emissions in 2016 were 6.4% higher, and USA emissions were 4.1% higher. (IEA 2017a)

I don’t have breakouts by country for 2016, but in 2015 the world’s largest emitter of CO2 from fuel combustion was the People’s Republic of China (mainland China), at 7.28 billion metric tons. Even China is reducing its emissions, however, by 1% in both 2015 and 2016. (IEA 2017a)

Emissions from fuel combustion may be the best estimate of worldwide emissions available. They constitute the largest percentage of emissions, and it is virtually impossible to inventory how much methane is being released by every bog or permafrost around the world, or how much nitrogen oxide from farm chemicals, etc.

Figure 2. Source: Earth Systems Research Laboratory, 2017.

In August I posted that the American Meteorological Society reported that in 2015 the concentration of CO2 in the atmosphere averaged above 400 ppm for the first time ever. It was my opinion that this was terrible news: 400 ppm was something akin to a threshold we needed not to cross in order to avoid the worst effects of climate change. We crossed it decades before anybody thought we would. Further, the concentration of greenhouse gases was continuing to increase, and the rate of increase seemed, if anything, to be growing over time. Figure 2 repeats the chart showing the trend over time.

How can one reconcile that post with the new findings? Imagine you are on the Titanic, and an hour ago the ship struck an iceberg. The ship’s crew happily reports that the amount of water getting into the ship is no longer increasing minute-by-minute. Well, that’s nice to hear, but water is still pouring into the ship, and unless you can stop the water getting in, the ship will still sink. The CO2 situation is similar, but in reverse. The rate at which the world is putting CO2 into the atmosphere may not be going up, but we are still putting billions of tons of it into the atmosphere every year. It is more than enough to cause climate change. We don’t need emissions to flatten, we need them to decrease to a fraction of what they are today.

So, it is good news that worldwide emissions have not grown over the last 3 years. Perhaps it even tends to validate the efforts we’ve been making: maybe moving away from fossil fuels, especially coal, has helped stabilize emissions. But we have a long way to go before we stop this vessel of ours from sinking.

UPDATE: The Global Carbon Project released a report published 11/13/2017 (after this post was written) that projects 2017 carbon emissions from combustion of fuels will increase 2% from 2016. If their estimates prove correct, then the period of flat emissions will be over, and emissions will have resumed their upward climb. (Global Carbon Project, 2017)

Sources:

Earth System Research Laboratory. 2017. Full Mauna Loa CO2 Record. Downloaded 2017-06-15 from https://www.esrl.noaa.gov/gmd/ccgg/trends.

Global Carbon Project. 2017. Global Carbon Budget: Summary Highlights. Viewed online 11/15/2017 at http://www.globalcarbonproject.org/carbonbudget/17/highlights.htm.

International Energy Agency. 2017a. CO2 Emissions from Fuel Combustion: Highlights. Downloaded 11/09/2017 from https://www.iea.org/publications/freepublications/publication/CO2EmissionsfromFuelCombustionHighlights2017.pdf

International Energy Agency. 2017b. IEA Finds CO2 Emissions Flat for Third Straight Year Even as Global Economy Grew in 2016. Downloaded 2017-11-09 from https://www.iea.org/newsroom/news/2017/march/iea-finds-co2-emissions-flat-for-third-straight-year-even-as-global-economy-grew.html.

California Ablaze: Nature’s Revenge?


Fires torch hundreds of thousands of acres in California.


Just a few short weeks ago I discussed the terrible hurricanes that affected Houston, the Caribbean Islands, and Florida this year. Now, the headlines are full of the wildfires that have been raging in California.

By late September, it had already been a heavy forest fire season in the western United States. Then, over the weekend of October 7-8, wildfires broke out in the area around the Napa and Sonoma Valleys. Fanned by hot, dry winds, they spread unbelievably quickly, burning 155,509 of acres (as of 10/17/2017), including prime wine producing vineyards, and thousands of homes (CALFIRE 2017b). Dozens were killed. Figure 1 shows the Coffee Park area of Santa Rosa in 2015. Figure 2 shows it after the fire. The gray areas are homes that have been burned – I mean burned to the ground, reduced to ashes. (City of Santa Rosa 2017)

Figure 1: Coffee Park Neighborhood, Santa Rosa CA, in 2015. Source: City of Santa Rosa.

Figure 2. Coffee Park Neighborhood, Santa Rosa CA, after the fire. Source: City of Santa Rosa.

 

 

 

 

 

 

 

 

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All totaled, as of 10/15/2017 CALFIRE lists 7,980 fires in California that have burned 1,046,995 acres (1,636 sq. mi.) (CALFIRE 2017b). Figure 3 shows a map of the fires. Maps such as this one tend not to be comprehensive, as they map the fires to which the specific agency has responded. (CALFIRE 2017a) Across the United States, as of 10/17/2017 there have been 51,435 wildfires that have burned 8,769,877 acres. That puts 2017 among the top 10 fire years ever, and compares to an average of 6,016,599 acres from 2006-2016. Figure 4 shows the data. Data collection methods changed after 1984, which is why I have used different colors for before and after that year. (National Interagency Fire Center)

Figure 3. Fires Responded to by CALFIRE in 2017. Source: CALFIRE, 2017.

Figure 4. Data source: National Interagency Fire Center, 2017.

 

 

 

 

 

 

 

 

 

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At a recent workshop of wildland fire experts, the consensus was that the United States was experiencing wildland fires that were behaving in aggressive, destructive ways that had never been experienced before. (National Academy of Sciences, Engineering, and Medicine 2017) What is going on?

In a series of posts last year, I explored the role that wildfire plays in western forests and showed that, though the number of fires did not seem to be trending higher, the number of acres burned per fire did. The result was that more acres per year were burning. There seemed to be 3 causes. One was that, while for decades fire was regarded as an unmitigated evil and suppressed as vigorously as possible, it was now regarded as a necessary part of forest ecology, and was allowed to burn without suppression efforts in some cases. A second reason was that decades of suppression had left western forests littered with dead and downed wood, perfect conditions for small fires to grow into huge raging crown fires that destroyed tens of thousands of acres. And a third reason was that climate change had raised summer temperatures, causing forests to dry out earlier in the season, turning small fires that would extinguish on their own into large, destructive fires.

Early fall is the driest time of year in the regions around the Napa and Sonoma Valleys. Typically, it has rained very little or not at all since March or April; the grasslands are brown and sere, the forests dry and brittle. Then, in October, the wind starts to blow: the Diablo Winds in Northern California, and the Santa Ana Winds in Southern California. Fueled by high pressure over the central United States and lower pressure over the coast, the winds rush over the Sierra Madre Mountains, down the passes and valleys, and through the lowlands. It happens every year. This year, when the fires started near the Napa and Sonoma Valleys, gusts were blowing at 79 m.p.h. Recent research suggests that the winds may be getting hotter and drier as a result of climate change. (Fountain, 2017)

Wildfire needs three things to grow, and it got all of them: warm temperatures, lots of dry fuel, and high winds that were hot and dry. The fires blew up into raging infernos. Blowing sparks along at 70+ m.p.h., the wind and the fire outraced the firefighters. In a span of only a few hours, tens of thousands of acres were reduced to ashes, whole neighborhoods were destroyed, and dozens were killed.

Hurricanes in the Atlantic, fires across the West, deluges and record heat in Australia, terrible floods in Asia, drought and desertification in some parts of Africa and floods in other parts: is Mother Nature mad at us? Is she exacting revenge for the way we have mistreated Her all these years? To borrow a thought from Abraham Lincoln: if we shall suppose that environmental destruction is an offense against Nature, and that humankind has caused that offense, and that suffering inevitably comes to those who commit such offenses, and if Nature now gives to us these terrible disasters as due to those who have caused the offenses, then shall we see in them anything but a judgment and a justice that is altogether true and righteous? “Woe unto the world because of offenses.” (Lincoln, 1865)

Sources:

CALFIRE. 2017a. Incident Information: Number of Fires and Acres. Viewed online 10/17/2017 at http://cdfdata.fire.ca.gov/incidents/incidents_stats?year=2017.

Cal Fire. 2017b. Statewide Fire Maps. Downloaded 2017-10-17 from http://www.fire.ca.gov/current_incidents.

City of Santa Rosa. 2017. Emergency Information Homepage: Fire Aerial Photo Comparison. Downloaded 2017-10-17 from https://www.srcity.org/2620/Emergency-Information.

Fountain, Henry. 2017. “California Winds are Fueling Fires. It May Be Getting Worse. New York Times, 10/11/2017. Viewed online 10/17/2017 at https://www.nytimes.com/2017/10/11/climate/caifornia-fires-wind.html?action=click&contentCollection=climate&region=rank&module=package&version=highlights&contentPlacement=1&pgtype=sectionfront.

Lincoln, Abraham. 1865. Second Inaugural Address. Viewed online 10/17/2017 at http://www.bartleby.com/124/pres32.html.

National Academies of Sciences, Engineering, and Medicine. 2017. A Century of Wildland Fire Research: Contributions to Long-term Approaches for Wildland Fire Manage- ment: Proceedings of a Workshop. Washington, DC: The National Academies Press. doi: https://doi. org/10.17226/24792. Downloaded 8/25/2017 from http://nap.edu/24792.
National Interagency Fire Center. Year-to-Date Statistics. Viewed online 10/17/2017 at https://www.nifc.gov/fireInfo/nfn.htm.

Damaging Weather Events in Missouri

Figure 1. Data source: Office of Climate, Water, and Weather Services.

Damage from sever weather in Missouri shows a different pattern than does damage nationwide. As Figure 1 shows, the cost of damage from hazardous weather events in Missouri spiked in 2007, then really spiked in 2011. Since then, it has returned to a comparatively low level. The bulk of the damage in 2011 was from 2 tornado outbreaks. One hit the St. Louis area, damaging Lamber Field. The second devastated Joplin, killing 158, injuring 1,150, and causing damage estimated at $2.8 billion. The damages in 2007 came primarily from two winter storms, one early in the year, one late. In both cases, hundreds of thousands were without power, and traffic accidents spiked.

In 2015 Missouri saw an increase in weather-related damage, primarily due to the flooding that struck between Christmas and New Years that year. There was similar flooding this year in April, so 2017 will likely see a similar increase.

Figure 2. Data source: Office of Climate, Water, and Weather Services.

Figure 2 shows deaths and injuries in Missouri from hazardous weather. Deaths are in blue and should be read on the left vertical axis. Injuries are in red and should be read on the right vertical axis. The large number of injuries and deaths in 2011 were primarily from the Joplin tornado. In 2006 and 2007, injuries spiked, but fatalities did not. The injuries mostly represented non-fatal auto accidents from winter ice storms. The fatalities in 1999 resulted from a tornado outbreak.

The Missouri data covers fewer years than the national data discussed in my previous post. It also covers all hazardous weather, in contrast to the national data, which covered billion dollar weather disasters.

While the national data shows a clear trend towards more big weather disasters, Missouri’s data does not. The Missouri data seems to reflect the kind of disaster that occurred and where it occurred. Tornadoes, if they hit developed areas, cause injuries, deaths, and lots of damage. Floods cause fewer injuries and deaths; damage can be significant, but it is limited to the floodplain of the river that flooded. Ice storms affect widespread areas; damages come mostly through loss of the electrical grid and car crashes, which cause many injuries, but fewer deaths.

Sources:

Office of Climate, Water, and Weather Services, National Weather Service. 2016. Natural Hazard Statistics. Data downloaded 9/11/2017 from http://www.nws.noaa.gov/om/hazstats.shtml#.

InflationData.com. 2016. Historical Consumer Price Index (CPI-U) Data. Data downloaded 2/10/16 from http://inflationdata.com/Inflation/Consumer_Price_Index/HistoricalCPI.aspx?reloaded=true.

Missouri State Emergency Management Agency. Declared Disasters in Missouri. Viewed online 9/12/2017 at https://sema.dps.mo.gov/maps_and_disasters/disasters.

Descriptions of specific weather events, if they are large and significant, can be found on the websites of the Federal Emergency Management Administration, the Missouri State Emergency Management Agency, and local weather forecast offices. However, in my experience, the best descriptions are often on Wikipedia.

Severe Storms on the Increase


The number of severe storms is increasing, and so is their intensity.


Figure 1. Source: NOAA National Centers for Environmental Information.

In the previous post I noted that Hurricane Harvey was one in a series of storms that have devastated Houston, and indeed, the country as a whole. I asked what is going on, and whether it has always been this way.

The National Centers for Environmental Information tracks weather disasters that cause over $1 billion in damages. Figure 1 shows how many there have been each year going back to 1980. The number varies from year-to-year, but over time there has been a significant increase – there weren’t any in 1987, but in 2011 there were 16. Through July 7, 2017, roughly half the year, there have been 9.

(Click on chart for larger view.)

In the chart, the colors represent different types of weather disasters. Storms are divided into 3 categories: winter storms, which involve ice and snow, tropical cyclones (like Hurricane Harvey or Tropical Storm Irene), and severe storms. This last category includes thunderstorms and tornadoes, as well as severe rain events like the ones that caused flooding in Missouri in December 2015 and April 2017. You can see that the increased number of billion-dollar disasters has come from an increase in the number of severe storms. It has not come from tropical storms or winter storms.

Figure 2. Data source: NOAA National Centers for Environmental Information.

Figure 2 shows the damage cost from billion-dollar weather disasters each year. The damage cost is adjusted for inflation. The chart shows that there are many years when the total cost is below $25 billion. However, there are also years where the amount of damage spikes. The year with the largest damage was 2005, when Hurricane Katrina devastated New Orleans and a wide swath of the Gulf Coast, and damage topped $213 billion. That’s quite a chunk of change. The second highest cost occurred in 2012, when Hurricane Sandy came ashore in New York. This year, 2017, only includes damage up to July 7, so it doesn’t include Hurricane Harvey or Irma. I have seen news stories that the cost of damage from Hurricane Harvey may reach $150 billion, and Irma will add billions more. By the time the year is done, the damage cost is likely to be the highest in history.

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Figure 3. Data source: NOAA, National Centers for Environmental Information.

Figure 3 shows the number of billion dollar weather disasters by type (through 7/7/2017). Since 1980, there have been a total of 212. Severe storms have accounted for 42% of the events.

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Figure 4. Data source: NOAA National Centers for Environmental Information.

Figure 4 shows the total costs of billion dollar weather disasters by type (through 7/7/2017). Since 1980 costs have totaled $1.24 trillion dollars, and tropical cyclones have accounted for about 47% of the total cost. Though they constitute the largest number of events, severe storms account for only 16% of the cost of damages. That is because such storms, while severe, affect relatively small areas. Tropical storms and droughts, on the other hand, affect much larger areas.

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Figure 5. Miami Beach in 1925. Source: Miami Design Preservation League.

All of the highest cost years have occurred since 2004. The data is inflation-adjusted, so that should not be the reason. One possible reason not related to the weather is that there are more people living in harms way – the population living along the coast has grown, and sprawl has caused more of the landscape to be covered with development, increasing the likelihood that a severe storm will hit something and damage it. For instance, in 1920 the population of Miami-Dade County (the location of the City of Miami) was 42,753 (that’s right, less than 50,000). But in 2010 it was 2,507,362. In 1992, when Hurricane Andrew devastated Homestead, a small community southwest of Miami, the area between Miami and Homestead was mostly open agricultural fields. Today, just 15 years later, it has filled-in, and is one continuous urban area. This story has been repeated all along the coasts of America, and in many inland areas as well. (See here.)

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Figure 6. Intensity of Tropical Storms. Source: Kossin et al, 2013.

But I think that’s only part of the story. The number of tropical storms striking the U.S. may not have increased, but their intensity has. Figure 6 shows the intensity of tropical storms in different regions of the world over time. LMI stands for the lifetime maximum intensity of the wind in a storm, in meters per second. The lines represent quantiles. The 0.9 line (pinkish-purple) means that 90% of all storms that year were less intense than that value. The 0.8 line (light blue) means that 80% of all storms were less intense than that value, and so on. The authors dropped trend lines on the chart for each quantile. In the North Atlantic, storms have increased in intensity a lot. Those are the storms that strike the East Coast and Gulf Coast of the United States.

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Figure 7. Source: GlobalChange.gov.

Other kinds of heavy precipitation events are also on the rise, as I reported here. Figure 7 repeats a chart from that post showing the trend over time.

Scientists project that climate change will cause an increase in storm intensity and in heavy rain events. It seems that this is not a prediction for the future, it is already happening. One cannot say that any individual storm is caused by climate change, but storms like Hurricane Harvey, Tropical Storm Irene, and the April storm in Missouri are already “more common,” and are likely to be even more “more common” in the future.

Sources:

GlobalChange.gov. Broadcase_Trends-in-heavy-precip_V2. National Climate Assessment 2014. Downloads, Graphics (Broadcast). Downloaded 11/13/2016 from http://nca2014.globalchange.gov/downloads.

Kossin, James, Timothy Olander, and Kenneth Knapp. 2013. Trend Analysis with a New Global Record of Tropical Cyclone Intensity. Journal of Climate, 26, 9960-9976.

Miami Design Preservation League. Collins Ave. at 63rd Street in 1925.Downloaded 9/8/2017 from https://www.pinterest.com/pin/189714203027788727.

NOAA National Centers for Environmental Information (NCEI). U.S. Billion-Dollar Weather and Climate Disasters (2017). https://www.ncdc.noaa.gov/billions.

Wikipedia. Miami-Dade County, Florida. Viewed online 9/8/2017 at https://en.wikipedia.org/wiki/Miami-Dade_County,_Florida#2010_U.S._Census.

Hurricane Harvey Devastates Houston


Hurricane Harvey caused record flooding in Houston. Those poor people!


Figure 1. Flooding in Port Arthur, TX, from Hurricane Harvey. Source: South Carolina National Guard, 2017.

Most of you know about the terrible disaster that Hurrican Harvey caused in Houston, TX. The disaster will inevitably be compared to Hurricane Katrina and the flood that struck New Orleans. In both cases, a major city was flooded by a hurricane. Houston, however, is a metropolitan area with a population of about 6.3 million people, while New Orleans is a metropolitan area with a population of about 1.3 million. That means that Houston is almost 5 times as large.

New Orleans flooded so catastrophically because much of the city is below sea level. The levies broke, the ocean poured through, and the low areas filled up with water just like a bathtub would. Coastal Texas is a flat, low-lying area, some of which was swamp or marshland before being developed. It is not below sea level, however. Houston flooded because Hurricane Harvey dumped prodigious amounts of rain on the city – more than 4 feet of rain in some areas. The water couldn’t run off fast enough, and flooding occurred. The tragedy has been well covered by all of the national news sources, so I have contented myself with a single photograph of the flooding in Port Arthur, a small city about 100 miles northeast of Houston. (Figure 1) This blog focuses not on individual events, but on trends and on the big picture.

(Click on photo for larger view.)

Figure 2. Flooding in Houston from Tropical Storm Allison in 2001. Source: Harris County Flood Control District.

Houston has been hit repeatedly by tropical storms and hurricanes. From 1836 to 1936, the city suffered through 16 major floods, with the water level reaching as high as 40 feet in one of them. Since 1935, there have been 8 more. In 2001, Tropical Storm Allison dumped up to 35 inches of rain on Houston over 5 days, resulting in flooding that damaged over 73,000 homes and caused $5 billion in property damage (see Figure 2). In 2008, Hurricane Ike passed directly over the city, breaking out windows in downtown skyscrapers and wiping out electricity to some customers for over a month. Over the Memorial Day Holiday in 2015, rain of up to 11 inches over 24 hours drenched Houston, flooding thousands of homes. In April 2016 (last year), a trough of rain parked over the city, and over 24 hours, 17 inches of rain fell. They had to rescue 1,800 people from the floods, but even so 8 died and 1,144 homes were inundated.

But flooding is not limited to Houston. In April of this year, flooding in Missouri and Arkansas caused $1.7 billion in damages. In February, flooding in California caused $1.5 billion in damages, including Oroville Dam (see here). In October, 2016, Hurricane Matthew churned along the Atlantic Coast causing damage. In August, 2016, Louisiana received 20-30 inches of rain from a stationary storm, causing $10.3 billion in damages. And a December 2015 storm brought record flooding to Missouri and tornadoes to Texas, causing 50 deaths and $2.5 billion in damages. The list goes on and on.

Figure 3. Hurricane Irma Devastated the Island of St. Maarten. Photo: Gerb van Es, Dutch Department of Defense.

UPDATE: As of 9/8/2017, three more tropical storms have formed in the Atlantic Ocean: Hurricane Irma, a Catagory 5 hurricane (the largest category), passed over several Caribbean islands causing terrible damage (see Figure 3). As I write, it is bearing down on Florida. How bad will it be? We don’t know; it has diminished to a Category 4 hurricane, but it is wider than the Florida Peninsula is, and it is currently forecast to travel south to north right up the entire peninsula. Tropical Storm Jose is gaining strength in the mid-Atlantic, threatening many of the same islands that were just devastated by Irma, though it is forecast to turn north. And Hurricane Katia has formed just north of the Yucatan Peninsula, and is expected to come ashore north of Veracruz, Mexico.

What is happening? Has it always been this way, or is there more very damaging weather than there used to be? The next post will look at the national trend, and the post after that will look at the trend in Missouri.

Sources:

Gerb van Es, Dutch Department of Defense. Aerial Photo Shows the Damage of hurrican Irma in Phillipsburg, on the Dutch portion of the Caribbean Island of Sint Maarten. Downloaded 9/8/2017 from https://www.caymancompass.com/2017/09/07/enormous-catastrophe-st-martin-reeling-from-hurricane-damage.

Harris County Flood Control District. Harris County’s Flooding History. Viewed online 8/30/2017 at https://www.hcfcd.org/flooding-floodplains/harris-countys-flooding-history.

Harris County Flood Control District. Tropical Storm Allison. Viewed online 8/30/2017 at https://www.hcfcd.org/storm-center/tropical-storm-allison-2001.

NOAA National Centers for Environmental Information (NCEI) U.S. Billion-Dollar Weather and Climate Disasters (2017). https://www.ncdc.noaa.gov/billions.

South Carolina National Guard. 8/31/2017. Image #170831-Z-AH923-081. Downloaded 9/8/2017 from https://commons.wikimedia.org/w/index.php?curid=62096178.

Wikipedia. April 2016 United States Storm Complex. Viewed online 8/30/2017 at https://www.hcfcd.org/storm-center/tropical-storm-allison-2001.

Wikipedia. Houston. Viewed online 8/30/2017 at https://en.wikipedia.org/wiki/Houston.

Wikipedia. New Orleans. Viewed online 8/30/2017 at https://en.wikipedia.org/wiki/Houston.

Why 543 ppm CO2e Matters

In the last post I reviewed a report from the World Meteorological Organization; it said that in 2015 the atmospheric concentration of carbon dioxide reached 400 ppm for the first time. The methane and nitric oxide concentrations were 1,845 ppb and 328 ppb. Combined, I calculated that the 3 gases had a radiative forcing equal to 543 ppm CO2e.

[Note: When first published, this post contained a typographical error: in the title and in the first paragraph, I reported the CO2e as ppb (parts per billion). Parts per million (ppm) is correct, and I have made the change.]

More recent data from the Mauna Loa Observatory indicates that, since 2015, the atmospheric concentration of carbon dioxide has climbed to 409.65, meaning that the combined radiative forcing is now even higher. But what do these numbers mean? I will try to explain.

Most scientists studying climate change have emphasized that it is already too late to avoid its effects entirely – they are already happening. My recent posts on the declining snowpack of the western United States are just one example. I’ve also published numerous posts documenting the increase in temperature in Missouri and other states, the USA as a whole, and the world as a whole.

Figure 1. Source: IPCC 2014.

Scientists have also emphasized that the effects of climate change will depend on how much the temperature increases. The more the temperature increases, the more severe the effects will be. Figure 1 illustrates the conceptualization. In the chart, each column represents a system that climate change will affect. The 2 y-axis scales represent temperature change, the scale on the left relative to the period from 1986-2000, the one on the right relative to 1850-1900. The color coding of the columns represents the degree of risk that is projected. White and yellow represent less risk, red and purple represent more. There are no cut-off points in this graph, but you can see that as the temperature increases more than 2°C (relative to 1986-2000), the risk grows from moderate to high or very high.

How much the temperature will actually increase depends on how high radiative forcing goes, which will depend on the atmospheric concentration of GHGs. Carbon dioxide is the principal GHG.

Figure 2. Data source: Earth Systems Research Laboratory 2017b.

Figure 2 shows the average annual carbon dioxide concentration measured at the Mauna Loa Observatory from 1959 through 2016 in blue. During the last 10 years, the concentration grew an average of 0.57% each year. In red, Figure 1 projects the carbon dioxide concentration through 2100, assuming that it continues to grow at that rate each year. By 2100, the carbon dioxide concentration will have reached 651 ppm.

The future atmospheric concentration of GHGs depends on how much we continue to emit. To study the possibilities, scientists use a series of scenarios that range from sharply reduced emissions, through a middle ground, to very high emissions. They have changed the names they give these scenarios, and now call them RCP2.6, RCP4.5, RCP6, and RCP8.5. RCP6 is associated with a carbon dioxide concentration in 2100 that is similar to the 651 ppm projection I calculated above. Thus, if emissions continue to grow at the same rate, the earth will approximate the RCP6 scenario.

Now, as I noted in the last post, the growth in the atmospheric concentration of carbon dioxide seems to be accelerating. Thus, there is some question regarding whether the earth really is following the RCP6 scenario or something worse. For now, I will stay with RCP6.

Figure 3. Projected Temperature Increase Under Four RCP Scenarios. Source: Collins et al, 2013.

Figure 3 shows the mean temperature increase that is projected to occur under each RCP scenario, with RCP6 in orange. By 2100, a temperature increase of about 2°C is projected to occur. (One additional thing to note about this chart: the temperature increase under RCP6 and RCP 8.5 does not stabilize by 2100 – the temperature will continue to increase thereafter.)

Okay, now we’ve got what we need to draw some simple conclusions. The atmospheric concentration of carbon dioxide is increasing at a rate that, if it continues, will approximate the RCP6 scenario. That scenario is associated with a temperature increase of about 2°C compared to 1986-2000, and an even higher temperature thereafter. At that temperature increase, unique and sensitive systems will already be experiencing severe risk. And at that temperature increase, the global aggregate risk will grow from medium to high.

Well, if you come away thinking it is all a bit complex and vague, if not downright mealy-mouthed, I wouldn’t blame you. Climate scientists used to speak more directly, but then they came under attack from those who wanted to destroy them, and those days are gone. If you want to think further about the implications of all this, then think about these questions:

  1. What does it mean for the health of the planet, and for the health of our species on this planet, that we are following a course that puts unique and vulnerable systems under high risk? It’s already happening, just look around.
  2. What does it mean that we are following a course that will cause moderate-to-high aggregate global risk? What will the impacts be, and how will human life be affected?
  3. What does it mean for the health of the planet, and for the health of our species on this planet, that the increase in the concentration of carbon dioxide is not decelerating, but continuing to accelerate? The Kyoto Protocol was signed 20 years ago, and it was 11 years ago that climate change burst into widespread consciousness with Al Gore’s An Inconvenient Truth. What does it mean that we have known for so long that we need to address this problem, yet atmospheric GHG concentration growth continues to accelerate?
  4. What does it mean that, in the face of these facts, we elected a President who is hostile to the idea of climate change, and he appointed an EPA Administrator who is, also.
  5. Even absent our current President and EPA Administrator, have we shown any sign of being willing or able to undertake and accomplish the large-scale changes that will be necessary to address these problems?

The reality we face is becoming more dire each day, dear readers. We are passing danger signs like they mean nothing. We will have to live with the consequences for a very long time.

Sources:

Collins, M., R. Knutti, J. Arblaster, J.-L. Dufresne, T. Fichefet, P. Friedlingstein, X. Gao, W.J. Gutowski, T. Johns, G. Krinner, M. Shongwe, C. Tebaldi, A.J. Weaver and M. Wehner, 2013: Long-term Climate Change: Projections, Com- mitments and Irreversibility. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Earth System Research Laboratory. 2017 b. Mauna Loa CO2 Annual Mean Data. Downloaded 2017-06-15 from https://www.esrl.noaa.gov/gmd/ccgg/trends.

IPCC, 2013: Summary for Policymakers. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

IPCC 2014: Summary for policymakers. In: Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Field, C.B., V.R. Barros, D.J. Dokken, K.J. Mach, M.D. Mastrandrea, T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 1-32.

World Meteorological Organization. 2016. WMO Greenhouse Gas Bulletin: The State of Greenhouse Gases in the Atmosphere Based on Global Observations through 2015. Number 12, 24 October 2016. Downloaded 6/15/2017 from http://www.wmo.int/pages/prog/arep/gaw/ghg/GHGbulletin.html.

World Carbon Dioxide Concentration Above 400 ppm. for the First Time Ever


In 2015 the concentration of carbon dioxide was 400 ppm, for the first time ever. The atmospheric concentration of carbon dioxide equivalent (CO2e) was 543 ppm.


Figure 1. Atmospheric Concentrations of GHGs in 2015 and Radiative Forcing from 1979-2015. Source: World Meteorological Organization.

In this post I will catch up with the Greenhouse Gas Bulletin published by the World Meteorological Society in October, 2016. It concerns atmospheric GHGs during 2015.

For the first time ever, the global concentration of carbon dioxide averaged 400 ppm, while the concentration of methane rose to 1,845 ppb, and the concentration of nitrous oxide rose to 328.0 ppb. These represent growth from 2014 of 0.58%, 0.60%, and 0.31%, respectively. The concentration of carbon dioxide is now 144% of what it was in 1750, while methane is 256% and nitrous oxide is 121%. The data are shown in Figure 1.

The report does not calculate the carbon dioxide equivalent of the three combined, but simply multiplying methane and nitrous oxide by their global warming potentials yields a combined carbon dioxide equivalent of 543 (using the 100-year global warming potentials published in the IPCC 4th AR).

Radiative forcing (the warming effect) of these GHGs was approximately 3.0 watts per meter in 2015 above 1750, compared to approximately 1.7 in1979.

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Figure 2. Source: Earth Systems Research Laboratory, 2017c.

Figure 2 shows the recent data on carbon dioxide concentration as measured at the Mauna Loa Observatory. The red line represents the actual measured value, and the black line represents the trend. This location is often taken as the best place to measure atmospheric carbon dioxide concentrations because it is in the middle of the Pacific Ocean, far away from large local sources of carbon dioxide, high in the atmosphere, and buffeted by almost constant trade winds. The chart shows that the concentration of carbon dioxide surges each winter, then ebbs each summer. This seasonal effect is due to the summer greening of the Northern Hemisphere, where the bulk of the world’s land mass is. Once it has greened, the vegetation absorbs carbon dioxide and converts it to oxygen as part of the process of photosynthesis, pulling it out of the atmosphere. After the vegetation goes dormant during the winter, it does not absorb carbon dioxide, and the concentration increases.

The reading for May, 2017 was 409.65 ppm.

Earth Systems Research Laboratory, 2017 a.

Figure 3 shows the same data going back to the late 1950s. Though the concentration of carbon dioxide surges and ebbs each year, you can see that the trend is irrevocably upward. The peak each winter is higher than the previous winter’s high, and the low point each summer is higher than the previous summer’s low. At no time has this trend ever reversed, in fact it has never even slowed. If anything, the trend is curving upward, meaning it is increasing faster.

In the next post I will discuss what these findings mean.

Sources:

Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland, 2007: Changes in Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Earth System Research Laboratory. 2017a. Full Mauna Loa CO2 Record. Downloaded 2017-06-15 from https://www.esrl.noaa.gov/gmd/ccgg/trends.

Earth System Research Laboratory. 2017b. Mauna Loa CO2 Annual Mean Data. Downloaded 2017-06-15 from https://www.esrl.noaa.gov/gmd/ccgg/trends.

Earth System Research Laboratory. 2017c. Recent Monthly Average Mauna Loa CO2. Downloaded 2017-06-15 from https://www.esrl.noaa.gov/gmd/ccgg/trends.

World Meteorological Organization. 2016. WMO Greenhouse Gas Bulletin: The State of Greenhouse Gases in the Atmosphere Based on Global Observations through 2015. Number 12, 24 October 2016. Downloaded 6/15/2017 from http://www.wmo.int/pages/prog/arep/gaw/ghg/GHGbulletin.html.

Will Climate Change Affect Water Supply on the Missouri River?


How climate change will affect water supply from the Missouri River is not yet known. Current problems with Missouri River water supply principally affect the barge transportation industry, and the agricultural and industrial clients that use it to transport their goods and supplies.


The Missouri River is important for Missouri. More than half of Missouri residents get their drinking water from the Missouri River or the alluvial aquifer it directly feeds. Not only that, the river’s water is used for agricultural irrigation, for industry, to support barge traffic along the Missouri and Mississippi Rivers, for recreation, and to support the ecosystems that depend on the river for their survival.

Figure 1. Dams and Other Locations Along the Missouri River. Source: Google Earth.

In the previous post, I reported that the snowpack in the western United States has declined by 23%, and it is forecast to decline more by 2038. The eastern border of the study area forms the western boundary of the Missouri River Basin. Will the changing western snowpack impact the Missouri River’s ability to supply Missouri’s needs?

The answer is complicated. Precipitation in the Upper Missouri River Basin has historically fallen mostly as snow, building a winter snowpack that slowly melts during the spring. The snowmelt is gathered into reservoirs created by 6 large dams along the Missouri River, plus more than 40 smaller ones on tributaries. The 6 large dams begin at the Gavin’s Point Dam on the Nebraska-South Dakota border, and extend upriver to the Ft. Peck Dam in Montana. (See Figure 1.) The result is that water flow below the reservoirs is largely controlled by man, not nature.

Figure 2. Data source: Wikipedia.

The annual water yield from the Missouri River is small compared to the size of its basin. The data is given in Figure 2, where the red columns represent the length of the rivers, and the blue line represents their average discharge. No other river in the USA serves such a large basin with so little water. In drought years it is already too small to fully meet all of the demands that are put on it, resulting in conflict over how to manage the river, and over which values to give priority. The conflict has primarily been between up-river interests, which would like to see water allocated to support irrigation, drinking water, and mitigation in their states during periods of drought, and down-river interests, which would like to see water released to support commercial navigation on the river.

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Figure 3. Source: Hansen Professional Services, Inc. 2011.

In 2004, the Army Corps of Engineers changed the rules by which the river is operated to reduce water releases during drought. During drought years, this better supports up-stream interests, but results in a shorter season during which the river can support barge traffic. The result has been a decrease in annual tonnage moved on the river (Figure 3).

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Figure 4. Well Drilling in Western North Dakota. Source: Vanosdall 2013.

In addition, development in the Upper Missouri Basin has increased water demand in that region. A prime example would be the development of the oil and gas reserves in North Dakota. Well drilling uses large quantities of water. (See Figure 4). Given that the water yield from the Missouri River is already too small to fully support all of the demands placed on it, any increase in demand is bound to constrain supply even further.

The constraints discussed above, however, are all man-made constraints. How will climate change and the declining western snowpack affect all of this?

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Source: National Centers for Environmental Information.

The snowpack decline has occurred because of increasing temperature, not decreasing precipitation. Figures 5 repeats a chart I published in January 2016, showing that precipitation has increased in the region over time.

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Figure 6. Source: Melillo 2014.

Figure 6 shows that the 2011 National Climate Assessment projects that the annual flow on the Missouri River will actually increase by about 15% by 2070. However, more precipitation will fall as rain instead of snow, and the snow that does fall will melt sooner. This means that more water will enter the reservoirs during winter and early spring, and less during late spring and summer. In addition, increased temperature will increase evaporation from the river and reservoirs, and it will increase water consumption by crops, leading to earlier and increased demand for water. There is a potential mismatch between when the water is available and when it is needed.

The question will be whether it will be possible to manage the reservoirs successfully under the new conditions. When looking at the water situation in California (here), we discovered that water authorities expected climate change to create reservoir management problems that would result in an increased water deficit during the summer and autumn. It is possible that the reservoirs along the Missouri will encounter similar problems, but it is not certain.

One potential difference is that California has multiple, relatively short rivers, leading to only one large reservoir per river, and perhaps one or two small feeder reservoirs. The Missouri River, however, is a single long river. It has 6 large reservoirs chained along it, plus at least 40 feeder reservoirs on tributaries. This may give managers flexibility in managing the river that is not possible in California.

Five separate water resource studies have been undertaken to determine how climate change will impact the ability of the Missouri River to meet the demands placed on it. Unfortunately, they have not all been completed, and I can find no comprehensive analysis.

For the time being, problems with water supply on the Missouri River involve human decisions about how to manage the river. To date, in the State of Missouri they have primarily impacted the barge industry, plus the farmers and industries that depend on the barge industry to transport their goods and supplies.

Sources:

Drew, John, and Karen Rouse. 2006. “Missouri Water in High Demand.” Missouri Resources, Winter, 2006. Downloaded 5/31/2017 from https://dnr.mo.gov/geology/wrc/docs/Water-InHighDemand.pdf?/env/wrc/docs/Water-InHighDemand.pdf.

Bureau of Reclamation. 2016. Basin Report: Missouri River. Downloaded 5/25/2017 from https://www.usbr.gov/climate/secure/docs/2016secure/factsheet/MissouriRiverBasinFactSheet.pdf.

Bureau of Reclamation. 2016. SECURE Water Act Section 9503(c) – Reclamation Climate Change and Water. Prepared for United States Congress. Denver, CO: Bureau of Reclamation, Policy and Administration. Downloaded 5/25/2017 from https://www.usbr.gov/climate/secure.

Hanson Professional Services, Inc. 2011. Missouri River Historic Timeline and Navigation Service Cycle. Missouri River Freight Corridor Assessment and Development Plan. Downloaded 5/31/2017 from https://library.modot.mo.gov/rdt/reports/tryy1018.

Melillo, Jerry M., Terese (T.C.) Richmond, and Gary W. Yohe, Eds., 2014: Climate Change Impacts in the United States: The Third National Climate Assessment. U.S. Global Change Research Program, 841 pp. doi:10.7930/J0Z31WJ2. Available online at http://nca2014.globalchange.gov.

Vanosdall, Tiffany. 2013. Missouri River Water Supply. US Army Corps of Engineers. Downloaded 6/1/2017 from https://denr.sd.gov/coewatersupply22Apr2013.pdf.

Wikipedia. List of U.S. Rivers by Discharge. Data retrieved online 5/31/2017 at https://en.wikipedia.org/wiki/List_of_U.S._rivers_by_discharge.

Declining Snowpack in the American West


The snowpack over the western United States has declined about 23% since 1981. It is projected to decline more in the future.


I have written a number of posts about the looming water deficit in California due to a projected decline in the snowpack on the Sierra Nevada mountains. Is something similar projected to occur throughout the entire western United States?

Figure 1. Change in Snow Water Equivalent at SNOTEL Stations, 1955-2016. Source: Mote and Sharp 2016, in Environmental Protection Agency, 2016.

Yes. Studies find that the water content of the snowpack throughout the West has already declined 23%, and it is expected to decline more, perhaps up to 30% by 2038.

This decline is not occurring via a decrease in precipitation. Indeed, to date precipitation across the West has actually increased slightly. The decline is occurring due to increased temperature. Some precipitation that used to fall as snow now falls as rain, and the snow that does fall melts more quickly.

Mote and Sharp studied the snow water equivalent* of the snowpack in April from 1955-2016 at SNOWTEL measuring stations operated by the U.S. Natural Resource Conservation Service. Figure 1 shows a map of the stations, with blue dots representing stations where the snowpack increased and orange dots representing stations where the snowpack declined. The size of the dots represent the magnitude of change.

It is easy to see that the vast majority showed declines in the snowpack, in many cases by as much as 80%. Overall, Mote and Sharp computed that there had been an average 23% decline in the western snowpack since 1955.

 

Figure 2. Observed and Modeled Change in Snowpack. Source: Fyfe, et al, 2017.

Fyfe and his colleagues conducted climate modeling to try to determine whether the decline in the snowpack was due to natural causes or human causes. Figure 2 shows the results in a rather complicated graph. Let’s unpack it. The computer models ran from 1950 to 2010. The dashed black line shows the observed trend in the snow water content. The solid blue line shows the projected snow water content if only natural climate causes are included in the model. It doesn’t fit the observed trend very well. The solid black line shows the projected snow water content if both natural and human climate causes are included in the model. It fits the observed data quite closely. (The pink and green lines show data from analyses using other sets of data and need not concern us here. The gray band and blue dotted lines show statistical confidence levels for the computer simulations, and also need not concern us here.)

The simulation that included both natural and human causes agreed with the observed data, but the one that included only natural causes did not. The authors concluded that natural causes could not explain the loss of snowpack in the West. A combination of human and natural causes could explain it.

Figure 3. Projected Short-Term Change in Snowpack. Source: Fyfe, et al, 2017.

Fyfe and his colleagues also conducted a suite of climate models to project snowpack loss into the future. The results are shown in Figure 3. In this graph, the y-axis represents the actual snow water content of the snowpack, not the change. The blue line represents the computer model that projected the least snowpack loss in 2030, and the red line represents the computer model that projected the most loss. It is common practice among climate modelers to run a suite of projections, and when this is done, the average of them is often also presented, and it is often taken as likely to be the most accurate. In Figure 3, the average of the projections is represented by the black line.

It is easy to see that the trend in all of the lines is down. There is considerable variation from point-to-point in the red and blue lines, indicating that the projections expect there to be considerable variability in the snowpack from year-to-year. The black line is pretty smooth, however, as might be expected from an average of several analyses, and it has a consistent downward trend. The losses in snowpack in some of the projections ran as high as 60%, though average loss across the suite of projections was about 30%.

A 30% decline in the snowpack does not sound so dire; after all the projections are for a 60% loss of snowpack in California (see here). However, that projection was for the end of the century. This projection is for 2038; that’s only 20 years from now.

Some may wonder about how little snow water equivalent is shown on the y-axis of Figure 3. In the 1990s, the snowpack maxed-out each year at only 6+ cm. of snow water equivalent. In thinking about this number, remember two things: first, a centimeter of water represents somewhere between 3 and 20 centimeters of snow, with an average value being somewhere around 10 cm. Thus, 6 cm. of snow water equivalent would roughly equal 60 cm. of snow, or 23.6 inches. Thus, the average depth of the snowpack was about 2 feet. Second, remember that the measurements were averaged across hundreds of locations; some were high and received a great deal of snow, but some were relatively low (low altitude means more rain, less snow), or were located in areas that don’t receive much precipitation of any kind.

Much of Missouri depends on the Missouri River as a water supply, including both Kansas City and St. Louis. The Missouri River gets much of its water from the western snowpack. A declining snowpack may, or may not, have implications for our water supply, depending on whether the reservoirs along the Missouri River can accommodate the shift toward earlier snowmelt and increased rain. I will look at this issue in the next post.

*   Snow water equivalent: Different types of snow hold different amounts of water. Thus, scientists don’t just measure how deep the snow is. Rather, at a given location they take a representative sample of the snowpack and melt it, thereby determining how much water it holds. This is the snowpack’s snow water equivalent at that given location. April is generally when the snowpack is at its maximum.

Sources:

Environmental Protection Agency. 2016. Climate Change Indicators in the United States: Snowpack. Retrieved online 5/22/2017 at https://www.epa.gov/sites/production/files/2016-08/documents/print_snowpack-2016.pdf.

Fyfe, John, Chris Kerksen, Lawrence Mudryk, Gregory Flato, Benjamin Santer, Neil Swart, Noah Molotch, Xuebin Zhang, Hui Wan, Vivek Arora, John Scinocca, and Yanjun Jiao. 2017. “Large Near-Term Projected Snowpack Loss Over the Western United States.” Nature Communications, DOI: 10.1038/ncomms14996. Retrieved online 5/14/2017 at https://www.nature.com/articles/ncomms14996.

California Continues to Face Future Water Supply Challenges


Despite the wet winter in 2017, climate change will pose severe challenges to California’s future water supply.


In the last post I reported that Gov. Brown has declared California’s drought emergency officially over. The state has plenty of water for the next year. This post explores the implications of this wet winter for California’s long-term water status.

I first looked at this topic in a 13-post series that ran during the summer of 2015. The series starts here. It contains a lot of information about California’s water supply and consumption. I concluded that at some point in the not-too-distant future California would experience a significant permanent water deficit. The #1 cause of the deficit would be climate change, which is projected to result in a significant reduction in the size of California’s snowcap. The #2 cause would be population increase. I performed the analysis myself because I could find no sources that did anything similar. I’m not going to repeat that analysis in this post. Rather, I’m going to report a couple of new reports that confirm the concerns I had in 2015.

Figure 1. Source: California Dept. of Water Resources.

Figure 1 illustrates the problem California faces. Almost all of California’s precipitation falls during the winter. Some of it gets temporarily “locked up” as snowpack on the Sierra Nevada mountains. Demand for water, however, peaks during the summer. California has many man-made reservoirs that release water during the summer and fall, and the state depends on the melting snowpack to recharge the man-made reservoirs as water is drawn from them. In Figure 1, the blue line represents runoff and the red line represents water demand. You can see that moving the date of maximum runoff earlier in the year increases the amount of water that cannot be captured into storage (yellow area). It has to be dumped; see the post on Oroville Dam to see what happens if the volume of water being dumped gets too high. It increases the amount of water that must be released from storage in the summer and fall. The amount released is now larger than the amount of inflow the reservoir receives, resulting in an increased water deficit (the blue area represents water received, the green area represents water discharged equal to the size of the blue area, and the red area represents the deficit). There is a water deficit in average years, but it is small, and a winter with slightly above average precipitation can make up the deficit. Moving maximum runoff earlier in the year increases the size of the deficit; now only a much wetter year can recharge the reservoirs.

Figure 2. Source: California Dept. of Water Resources.

Figure 2 includes two charts. The first chart shows the percentage of precipitation in California that occurred as rain from 1948-2012. If precipitation occurs as rain, it is not snow and can’t add to the snowpack. On the chart, the black horizontal line is the mean percentage across all years. Red columns represent years with above average percentage of rain, the blue columns below average. There is variation between years, but you can see that the red columns cluster to the right while blue columns cluster to the left. That means that on average an increasing percentage of precipitation is falling as rain. Thus, on average, unless annual precipitation undergoes a sustained increase (which hasn’t happened and is not projected), California’s snowpack will shrink, because what once was snow is now rain.

The second chart in Figure 2 shows runoff measured on the Sacramento River. The red line represents the 50-year period from 1906-1955, while the blue line represents the 52-year period from 1956-2007. This is the specific problem that was discussed conceptually in Figure 1. You can see that runoff has moved earlier in the year by about a month.

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Figure 3. Source: National Centers for Environmental Information.

Why is more precipitation falling as rain rather than snow, and why is melt occurring earlier? Because of increased temperature. Winter is when the snow falls in California, and it is when the state receives the bulk of its precipitation. Figure 3 shows that the average winter temperature (December – March) has increased more than 2°F. In addition, if you look at Figure 3 carefully, you can see that the rate of temperature increase accelerated somewhere around 1980. The runoff chart in Figure 2 chunks the data into only 2 groups, each about 50 years long. Because of the acceleration in the increase in temperature, I believe that if they had chunked the data into 3 groups, each about 33 years long, the change towards earlier snowmelt would have been even greater than the one shown.

How dire is the threat is to California’s snowpack? It depends on which climate projection is used. The projected effects of climate change depend very much on how humankind responds to the threat. If we greatly reduce our GHG emissions immediately, the climate will warm less; if we don’t, it will warm more.

Figure 4. Source: California Dept. of Water Resources.

Figure 4 shows the historical size of the California snowpack plus 2 projections. The middle map show the projected size of the snow pack if warming is less. The map on the right shows its size if warming is more. You can see that, even under the low warming scenario, a loss of 48% of the snowpack is projected. Under the high warming scenario, a 65% loss of the snowpack is projected. These projections are for the end of the century. In my original series, I estimated the loss of snowpack at 40% by mid-century. That is not too far off from the high warming scenario. And I have to say, the evidence suggests that so far the world is operating under the high warming scenario, possibly, even worse.

Surface water is not the only source on which California depends. California withdraws significant amounts of water from underground aquifers, especially in (but not limited to) the agricultural areas of the Central Valley. Aquifers can be compared to underground lakes, but don’t think of them as being like a big, hollow cave in which there is a concentrated, pure body of water. Rather, think of them as regions of porous ground, such as gravel or sand. In between the pieces of gravel or sand is space, and that space can hold water. Below and on the sides are rocks or clay that are impervious to water, which allow the water to be held in the aquifer.

So long as the aquifer is charged with water, this is a situation that can last for thousands of years. If, however, water is pumped out without being replaced, then nothing occupies the spaces between the pieces of gravel or sand. If that occurs, the weight of the ground over the aquifer can compress the aquifer, reducing the amount of space available between the pieces of sand and gravel, reducing the capacity of the aquifer to hold water. When this occurs, it sometimes shows up as subsidence on the surface. In California, it is primarily the snowpack that feeds the aquifers. If a significant amount of the snowpack is lost, it will be less able to recharge the aquifers, and they will undergo increased compaction.

Figure 5. Map of Permanent Subsidence. Source: Smith et al, 2016.

As noted in my original series, significant subsidence has already occurred over California’s aquifers. More seems to be occurring every year. A recent study attempted to quantify the amount of water storage capacity being lost to compaction. The study covered the years 2007-2010, so it didn’t even include the recent severe drought (2007, 2008, and 2009 were dry years, but 2010 was 9th wettest in the record). The study covered only a small portion of the south end of the Central Valley Aquifer, yet it found that during those 4 years significant permanent subsidence had occurred (see Figure 5), resulting in a total loss of 748 million cubic meters of water storage, an amount roughly equal to 9% of the groundwater pumping that occurs in the study area. If this ratio held going forward, it would mean that for every 44.4 gallons of water pumped out each year, about 1 gallon of aquifer storage would be lost.

During the recent drought many newspaper articles reported that there had been a sharp increase in the number of wells being drilled in the Central Valley, and that the depth of the wells had also significantly increased. This suggests an increase in the rate at which the water table is being lowered, which would lead to an increased rate of compaction. As the study notes, this is a loss that cannot be replenished; aquifer storage lost to compaction is gone forever.

Dry periods become more devastating when they occur during hot periods. One reason the recent drought in California was so devastating was because it was a hot drought. A recent study found that climate change has already raised the temperature in the state (as in Figure 3 above), and will continue to raise it further, to the point that every dry year is likely to be a hot drought. The report concludes that anthropogenic warming has substantially increased the risk of severe impacts on human and natural systems, such as reduced snowpack, increased wildfire risk, acute water shortages, critical groundwater overdraft, and species extinction.

The bottom line here is that we are talking about the effects of climate change. Climate means average patterns over long periods of time – 30 years at minimum. The current wet period represents only 1 winter. Just as one swallow doesn’t make a summer, so one wet winter doesn’t make a climate trend. For that matter, neither do 5 dry years. However, California’s increase in temperature is a long-term change that does make a climate trend, and every indication suggests it will only increase more.

My conclusion is that this wet winter not withstanding, the concerns I voiced in 2015 over California’s water supply remain valid. As time passes, California will face increasing challenges meeting the demand for water (see here). The state will be unable to secure large new sources of surface water or ground water (see here), and will have to construct large, expensive desalination plants (see here). There will be sufficient water to supply human consumption if it is properly allocated (see here), but water available to agriculture will be reduced, resulting in a decline in California’s agricultural economy (see here). That loss, plus the cost of the desalination plants, will impact California’s economy (see here), as well as the food supply for the entire country.

[In the above paragraph I have referenced several of the posts in my 2015 series Drought in California. If you are interested in the topic, you should read the series sequentially, beginning with Drought in California Part 1: Introduction.]

Sources:

California Department of Water Resources. 2015. California Climate Science and Data for Water Resources Management. Downloaded 4/6/2017 from http://www.water.ca.gov/climatechange/docs/CA_Climate_Science_and_Data_Final_Release_June_2015.pdf.

Diffenbaugh, Noah, Daniel Swain, and Danielle Touma. 2015. “Anthropogenic Warming Has Increased Drought Risk in California.” Proceedings of the National Academy of Sciences. Downloaded 3/30/2017 from http://www.pnas.org/content/112/13/3931.

National Centers for Environmental Information. “California, Average Temperature, December-March, 1896-2016” Graph generated and downloaded 4/13/2017 at https://www.ncdc.noaa.gov/cag/time-series/us.

Smith, R.G., R. Kinght, J. Chen, J.A. Reeves, H.A. Zebker, T. Farr, and Z. Liu. 2016. “Estimating the Permanent Loss of Groundwater Storage in the Southern San Joaquin Valley, California.” Water Resources Research, American Geophysical Union. 10.1002/2016WRO19861. Downloaded 3/30/2017 from http://onlinelibrary.wiley.com/doi/10.1002/2016WR019861/full.