Ocean Acidification Planetary Boundary

“The global extent of ocean acidification, its complex social–ecological dynamics involving potential tipping points, the clear role of anthropogenic CO2 emissions to worsen it, the large uncertainties associated with most of its dimensions, and the potentially very large impacts, all together speak for a precautionary approach to address ocean acidification”

Source:  Jagers, S.C., Matti, S., Crépin, A.S., Langlet, D., Havenhand, J.N., Troell, M., Filipsson, H.L., Galaz, V.R. and Anderson, L.G., 2018. Societal causes of, and responses to, ocean acidification. Ambio, pp.1-15. Societal causes and responses to ocean acidification

pH has declined by about .11 units, equivalent to about a 28.8% increase in acidity, relative to pre-Industrial era baseline. (NOAA pH) (See the three figures below)

…(C)omputer re-creation of surface ocean pH from 1895 to the present and a forecast of ocean pH between now and 2100 under business as usual emission scenarios. Purple dots show cold-water coral reefs. Red dots show warm-water coral reefs. The pH scale is shown on the right. Increasing acidity is a relative shift in pH to a lower value. https://pmel.noaa.gov/co2/story/OA+Educational+Tools

1895 Estimated pH
2020 Estimated pH
2050 Estimated pH

CO2 And Seawater Chemistry:  “Ocean Acidification”

Fundamental changes in seawater chemistry are occurring throughout the world’s oceans. Since the beginning of the industrial revolution, the release of carbon dioxide (CO2) from humankind’s industrial and agricultural activities has increased the amount of CO2 in the atmosphere. The ocean absorbs about a quarter of the CO2 we release into the atmosphere every year, so as atmospheric CO2 levels increase, so do the levels in the ocean. Initially, many scientists focused on the benefits of the ocean removing this greenhouse gas from the atmosphere.  However, decades of ocean observations now show that there is also a downside — the CO2 absorbed by the ocean is changing the chemistry of the seawater, a process called OCEAN ACIDIFICATION.  NOAA Ocean Acidification

Significance:  Ocean acidification is expected to impact ocean species to varying degrees. Photosynthetic algae and seagrasses may benefit from higher CO2 conditions in the ocean, as they require COto live just like plants on land. On the other hand, studies have shown that lower environmental calcium carbonate saturation states can have a dramatic effect on some calcifying species, including oysters, clams, sea urchins, shallow water corals, deep sea corals, and calcareous plankton. Today, more than a billion people worldwide rely on food from the ocean as their primary source of protein. Thus, both jobs and food security in the U.S. and around the world depend on the fish and shellfish in our oceans. NOAA Ocean Acidification

Keeling Curve, pCO2 seawater, declining pH seawater 1988-2017

Source:  HOT_surface_CO2.txt Hawaii Ocean Time-series surface CO2 system data product Created 5 October 2009 by J.E. Dore Last updated 25 May 2019 by J.E. Dore”See HOT_surface_CO2_readme.pdf for explanatory material, metadata, and notes (http://hahana.soest.hawaii.edu/hot/products/products.html)” Adapted from:
Dore,J.E., Lukas, D.W.Sadler, M.J. Church, and D.M. Karl. 2009. Physical and biogeochemical modulation of ocean acidification in the central North Pacific. proc Natl Acad Sci USA 106:12235-12240

Novel Entities Planetary Boundary

Chemical pollution and the release of novel entities (Stockholm Planetary Boundaries)

“Emissions of toxic and long-lived substances such as synthetic organic pollutants, heavy metal compounds and radioactive materials (emphasis added) represent some of the key human-driven changes to the planetary environment. These compounds can have potentially irreversible effects on living organisms and on the physical environment (by affecting atmospheric processes and climate). Even when the uptake and bioaccumulation of chemical pollution is at sub-lethal levels for organisms, the effects of reduced fertility and the potential of permanent genetic damage can have severe effects on ecosystems far removed from the source of the pollution. For example, persistent organic compounds have caused dramatic reductions in bird populations and impaired reproduction and development in marine mammals. There are many examples of additive and synergic effects from these compounds, but these are still poorly understood scientifically. 

At present, we are unable to quantify a single chemical pollution boundary, although the risk of crossing Earth system thresholds is considered sufficiently well-defined for it to be included in the list as a priority for precautionary action and for further research.”

Biocide Planetary Boundary

In a recent paper (Nature Sustainability 1, 632-641 (2018) “Antibiotic and pesticide susceptibility and the Anthropocene operating space. 10.1038/s41893-018-0164-3)

The team defined and assessed the state of the planetary boundary for six types of resistance including: antibiotic resistance in Gram-negative and Gram-positive bacteria; general resistance to insecticides and herbicides and resistance to transgenic Bt-crops and glyphosate resistance in  herbicide resistant cropping systems. All six assessed boundaries are in zones of increasing risk and three out of six are in zones of high regional or global risk.”

State of the Anthropocene operating space of biocide susceptibility

Adapted from:  (2018). Antibiotic and pesticide susceptibility and the Anthropocene operating space. Nature Sustainability, 1(11), 632–641. doi:10.1038/s41893-018-0164-3 
  • Antibiotic susceptibility is globally surpassed for Gram-negative bacteria and in the uncertain zone for Gram-positive bacteria.
  • Pesticide susceptibility is generally assessed as being in the uncertain zone, but surpassed at the regional level in genetically engineered cropping systems owing to increasing resistance to foundational pesticides.
  • Insecticide resistance is assessed as being in the uncertain zone, given that multiple insecticide resistance is increasing in several pests.
  • In plants, multiple herbicide resistance is increasing and leads to an assessment of general herbicide use as being in the uncertain zone.
  • For Bt crops, the spread of resistance to regionally available Bt-crop toxins in the US mid-west and in India leads to an assessment of regionally surpassed.
  • For herbicide resistant crops, the increasing spread of glyphosate resistance leads to its assessment as regionally surpassed

Global Assessment:  for all major types of antibiotics and pesticides considered, we are today in a situation where resistance puts current practices at increasing risk

  Persistant Organic Pollutants (POPs)        

Source:  Stockholm Convention


Persistent Organic Pollutants (POPs) are organic chemical substances, that is, they are carbon-based. They possess a particular combination of physical and chemical properties such that, once released into the environment, they:

  • remain intact for exceptionally long periods of time (many years); 
  • become widely distributed throughout the environment as a result of natural processes involving soil, water and, most notably, air; 
  • accumulate in the fatty tissue of living organisms including humans, and are found at higher concentrations at higher levels in the food chain; and 
  • are toxic to both humans and wildlife.

As a result of releases to the environment over the past several decades due especially to human activities, POPs are now widely distributed over large regions (including those where POPs have never been used) and, in some cases, they are found around the globe. This extensive contamination of environmental media and living organisms includes many foodstuffs and has resulted in the sustained exposure of many species, including humans, for periods of time that span generations, resulting in both acute and chronic toxic effects.

In addition, POPs concentrate in living organisms through another process called bioaccumulation. Though not soluble in water, POPs are readily absorbed in fatty tissue, where concentrations can become magnified by up to 70,000 times the background levels. Fish, predatory birds, mammals, and humans are high up the food chain and so absorb the greatest concentrations*. When they travel, the POPs travel with them. As a result of these two processes, POPs can be found in people and animals living in regions such as the Arctic, thousands of kilometers from any major POPs source.

Specific effects of POPs can include cancer, allergies and hypersensitivity, damage to the central and peripheral nervous systems, reproductive disorders, and disruption of the immune system. Some POPs are also considered to be endocrine disrupters, which, by altering the hormonal system, can damage the reproductive and immune systems of exposed individuals as well as their offspring2; they can also have developmental and carcinogenic effects.

1.  POPs and bioaccumulation impacts in apex marine predators:  Jepson, Paul D., and Law, Robin J. 2016.  Persistant pollutants, persistent threats, Science 352,6292, pp. 1388-1389.  DOI:  10.1126/science.aaf9075

2.  For example, see a discussion of Michael Skinner’s work on transgenerational effects of exposure to epigenetic effects of exposure to DDT, permethrin, jet fuel, phthalates, bishphenol A, and dioxin:    Kaiser, Jocelyn, 2014.   The Epigenetics Heretic, Science, vol 343, 6169, pp361-363 DOI:  10.1126/science.343.6169.361

Climate Change: Cryosphere

Greenland Ocean Sunset  Photo by William Bossen on Unsplash

Arctic Regions: Permafrost, Sea Ice


Over the 1900 to present time span roughly 4.5 Million sq km of potential permafrost area has been lost. Berkeley Earth Permafrost

Map of estimated 0 to 3 m deep carbon inventory stored in the circum-Arctic permafrost region (Hugelius et al., 2014Kanevskiy et al., 2011Romanovskii, 1993). The eastern boundary of Canadian Yedoma areas is uncertain, indicated as a dotted line at the Alaskan/Yukon state border. The conceptual permafrost carbon climate feedback cycle is illustrated in the middle. The Yedoma domain marks the potential maximum occurrence of widespread Yedoma deposits but also includes other deposits that formed after degradation of Yedoma, such as thermokarst deposits. In West Siberia and the Russian Far East Yedoma occurs sporadically, e.g. in river valleys. (Deep Yedoma permafrost)

(Permafrost Carbon Network); Global carbon storage in soils and atmospheric carbon

Significance:  Approximately 1330-1580 Pg of soil carbon are estimated  to be stored in soils and permafrost of high latitude ecosystems, which is almost twice as much carbon as is currently contained in the atmosphere. In a warmer world permafrost thawing and decomposition of previously frozen organic carbon is one of the more likely positive feedbacks from terrestrial ecosystems to the atmosphere. Although ground temperature increases in permafrost regions are well documented there is a knowledge gap in the response of    permafrost carbon to climate change. (Permafrost Carbon Network)

Total estimated carbon storage is ~1300 Pg with an uncertainty range of between 1100 and 1500 Pg. Around 800 Pg carbon is perennially frozen, equivalent to all carbon dioxide currently in the Earth’s atmosphere. (Permafrost Carbon)

Global carbon storage in soils and atmospheric carbon

Permafrost potential is declining…

This figure shows the decline in permafrost potential over the 1850 to 2013 time period. The permafrost potential is defined by the decadal air temperature. If the annual average temperature over a 10 year period is 0C or below, then that area was regarded as permafrost. Over the 1900 to present time span roughly 4.5 Million sq km of potential permafrost area has been lost. Berkeley Earth Permafrost

Arctic Sea Ice

Average September (summer minimum) Extent Declining at -12.8%/decade (relative to 1981-2000 average

Ice Sheets: Antarctica, Greenland, The Third Pole

An ice sheet is a mass of glacial land ice extending more than 50,000 square kilometers (20,000 square miles). The two ice sheets on Earth today cover most of Greenland and Antarctica. During the last ice age, ice sheets also covered much of North America and Scandinavia.

Together, the Antarctic and Greenland ice sheets contain more than 99 percent of the freshwater ice on Earth. The Antarctic Ice Sheet extends almost 14 million square kilometers (5.4 million square miles), roughly the area of the contiguous United States and Mexico combined. The Antarctic Ice Sheet contains 30 million cubic kilometers (7.2 million cubic miles) of ice. TheGreenland Ice Sheet extends about 1.7 million square kilometers (656,000 square miles), covering most of the island of Greenland, three times the size of Texas.


-127.0 Gt per year +/- 39 (Mass variation since 2002)

Zodiac Cruising in Antarctica  Photo by James Eades on Unsplash
Ice mass measurements by NASA’s GRACE satellites

Source:  NASA Global Climate Change Ice Sheets

Elephant Island, Antarctica  Photo by Paul Carroll on Unsplash


  • Greenland ice sheet is a major contributor to sea level rise, adding on average 0.47mm +/- 0.23 mm/year to global mean sea level between 1991 and 2015
  • The cryosphere as a whole has contributed around 45% of observed global sea level rise since 1993. 
  • Observations show surface lowering across virtually all regions of the ice sheet and at some locations up to -2.65m/year between 1995 and 2017

Overall Greenland has lost 255+/- 15 Gt/year of ice over the period 2003-2016, compared to a rate loss of 83 +/- 63 Gt/year in the 1993-2003 period. 

Narsarsuaq, Greenland
Photo by Mahlersilvan on Unsplash

Greenland ice mass loss and melt extent

(a) Mass change time series for the entire Greenland ice sheet generated by DTU (red) and TUDR (blue). (b) Ice mass trends for 2007–2011 provided by DTU (left) and TUDR (right).
(TUDR  Technische Universitat Dresden; DTU Technical University of Denmark)
Source:  Greenland Ice Sheet Mass Balance

Source:  NSIDC Greenland Today

Melting ice sheets contribute to sea level rise

Source:  Denmark Polar Portal

Mass Change and Contribution to sea level rise 2003-2016

The map shows the latest changes in mass derived from data from the GRACE satellites.  The graph show the gain in the mass of ice when there is precipitation, and how much of this mass is lost when snow and ice melt and when icebergs break off from the ice sheet’s major outlet glaciers. The difference in these mass changes over a glaciological year (September-August) is called the total mass balance of the Greenland Ice Sheet.

The graph illustrates the month-by-month development in changes of mass measured in gigatonnes, Gt (1 Gt is 1 billion tonnes or 1 km3 of water). The left axis on the graph shows how this ice mass loss corresponds to sea level rise contribution. 100 Gt corresponds to 0.28 mm global sea level rise).  All changes are given relative to June 2006.

Based on this data, it can be seen that during the period 2003-2011 the Greenland Ice Sheet has lost 234 km3 of water per year, corresponding to an annual contribution to the mean increase in sea level of 0.65 mm 

This data shows that most of the loss of ice occurs along the edge of the ice sheet, where independent observations also indicate that the ice is thinning, that the glacier fronts are retreating in fjords and on land, and that there is a greater degree of melting from the surface of the ice.  (See map)

High on the central region of the ice sheet, however, the GRACE satellites show that there is a small increase in the mass of the ice. Other measurements suggest that this is due to a small increase in precipitation/snowfall.  (See map)

The Third Pole (Hindu-Kush and the Tibetan Plateau) (Source:  Science magazine Acceleration of ice loss)

Drekong Monastery, Tibet Autonomous Region, China  Photo by Evgeny Nelmin on Unsplash


  • Contains the largest volume of freshwater outside of the polar regions.
  • One-seventh of the world’s population depends on rivers flowing from these mountains for water to drink and to irrigate crops
  • Average ice loss during 2000-2016 (-0.43 +/- 0.14 meters water equivalent/year) is double compared to 1975-2000 (-0.22 +/- 0.13 meters water equivalent)
  • Acceleration of mass loss is consistent with warming temperatures recorded by meterological stations in the region

Glacier Mass Balance


Glacier Bay, Alaska  Photo by Michael Denning on Unsplash

Significance:  Today, many glaciologists are more concerned with predicting when various glaciers will disappear. In many parts of the world—including the western United States, South America, China, and India—glaciers are frozen reservoirs that provide a reliable water supply each summer to hundreds of millions of people and the natural ecosystems on which they depend. NOAA CLIMATE CHANGE GLACIER

  • 2018:  -0.72 meters water equivalent*   World Glacier Monitoring Service
  • Among the most dramatic evidence that Earth’s climate is warming is the dwindling and disappearance of mountain glaciers around the world. Based on preliminary data, 2017 is likely to be the 38th year in a row of mass loss of mountain glaciers worldwide. According to the State of the Climate in 2017

The cumulative mass balance loss from 1980 to 2016 is -19.9 meters, the equivalent of cutting a 22-meter-thick (72-foot-thick) slice off the top of the average glacier.

The graph shows cumulative mass loss in “*meters of water equivalent,” which is the depth of the meltwater spread out over the glacier’s surface area.

Melting of mountain glaciers has accelerated since 2000

Glacier mass balance (gray bars) from 1980–2017 for 37 worldwide glaciers with at least a 30-year monitoring history. Observations for 2017 are preliminary. Cumulative mass losses (orange line) have accelerated since 2000. As of 2016, the total loss was -19.9 meters, the equivalent of cutting a 22-meter- (72-foot-) thick slice off the top of the average glacier. NOAA Climate.gov graph adapted from State of the Climate in 2017.

Mer de Glace, Chamonix, France
Photo by Martin Adams on Unsplash

Climate Change: Greenhouse Gases

Carbon Dioxide

Global Temperature Change from 1850-2018. Graphics available for the globe and most countries. Ed Hawkins https://showyourstripes.info
Record high 414.71 ppm carbon dioxide reached June 13, 2019
No precedent for this level of carbon dioxide in over 800,000 years of ice core data

Click to access mlo_full_record.pdf

View of Mauna Kea and Mauna Loa from Haleakala
Photo by Ralph Howland on Unsplash
The Keeling Curve–the iconic documentation of carbon dioxide in the Earth’s atmosphere from 1958


The atmospheric abundance of CO2 has increased by an average of 1.83 ppm per year over the past 40 years (1979-2018). The CO2 increase is accelerating — while it averaged about 1.6 ppm per year in the 1980s and 1.5 ppm per year in the 1990s, the growth rate increased to 2.3 ppm per year during the last decade (2009-2018). The annual CO2 increase from 1 Jan 2018 to 1 Jan 2019 was 2.5 ± 0.1 ppm (see https://www.esrl.noaa.gov/gmd/ccgg/trends/global.html), which is slightly higher than the average of the previous decade, and much higher than the two decades before that.

NOAA Carbon Dioxide Radiative Forcing

The relentless rise of carbon  dioxide

Total Global CO2 Emissions

Photo by Martin Adams on Unsplash

Carbon dioxide emissions grew by 2.0% in 2018, the fastest growth for seven years; China (2.2% increase), India (7% increase) and the U.S.(2.6% increase) were responsible for around 69% of global emissions uptick (https://www.carbonbrief.org/in-depth-bp-data-reveals-record-CO2-emissions-in-2018-driven-by-surging-use-of-gas)

Total global carbon dioxide emissions in 2017: 41.2±2.8 GtCO2; 53% increase over 1990 (Source: Global Carbon Project)

  • Carbon dioxide emissions attributable to land-use change are highly uncertain, with no clear trend in the last decade
  • Land-use change was the dominant source of annual CO2 emissions until around 1950. In 1960 land-use change emissions accounted for 43% of emissions; between 2008-2017 they averaged 13%. In total, CO2 from land-use change accounts for 31% of cumulative emissions between 1870-2017.
  • Fossil CO2 emissions now dominate global changes: Coal (32%), Oil (25%), Gas (10%), Others (2%) account for 69% of cumulative emissions between 1870-2017.

Fate of anthropogenic CO2 emissions (2008-2017)

Source: Global Carbon Project Carbon Budget 2018 GCP Presentation
Source :  Figures from the Global Carbon Budget 2018 

Nitrous Oxide (N2O) (EPA N2O)

Shanghai, China  Photo by Holger Link on Unsplash

Radiative Forcing:  298 times that of CO2 over a 100 year period Residence time: 114 years


  • Anthropogenic (40%)
  • Agriculture (soil management—fertilizers, manure, burning of agricultural residues)
  • Fuel Combustion
  • Industry
  • Wastewater treatment

Growth of nitrous oxide

Red line is a linear fit to the global mean data demonstrating a fairly constant annual growth rate greater than 0.75 ppb/year

Global history of nitrous oxide as a function of latitude (y-axis) and time (x-axis).

Short-Lived Climate Pollutants

Black Carbon: 6600Gg (2015)

  • Radiative Forcing:    Black Carbon (BC) has a strong influence on radiative forcing, affecting the climate globally and regionally, and is responsible for a significant proportion of the global forcing to date.
    • Bond (2013)*  estimated that black carbon, with a total climate forcing of +1.1 W m-2, is the second most important human emission in terms of its climate-forcing in the present-day atmosphere; only carbon dioxide is estimated to have a greater forcing. For comparison, the radiative forcings including indirect effects from emissions of the two most significant long-lived greenhouse gases, carbon dioxide (CO2) and methane (CH4), in 2005 were +1.56 and +0.86 W m-2, respectively.
    • BC deposited on the cryosphere leads to enhanced melting rates and can affect the intensity and distribution of precipitation. Climate and Clean Air Coalition
    • Residence Time:  4–12 days

! ! Global emission estimates have uncertainties of about a factor of 2 (i.e., -50% to +100%) or even by a factor of 3 (See Climate and Clean Air Coalition)


  • Domestic biomass combustion (especially in traditional cookstoves)
  • Open-burning of municipal solid waste
  • Crop residue open-burning in the field
  • Traditional brick kilns
  • Forest fires and savanna burning
  • Traditional coke ovens
  • Charcoal making
  • Flaring from oil gas extraction and processing
  • Transportation (diesel engines in on-and off-road vehicles, ships, generators)

*Bond, T. C., Doherty, S. J., Fahey, D. W., Forster, P. M., Berntsen, T., DeAngelo, B. J., Flanner, M. G., Ghan, S., Kärcher, B., Koch, D., Kinne, S., Kondo, Y., Quinn, P. K., Sarofim, M. C., Schultz, M. G., Schul, M., Venkataraman, C., Zhang, H., Zhang, S., Bellouin, N., Guttikunda, S. K., Hopke, P. K., Jacobson, M. Z., Kaiser, J. W., Klimont, Z., Lohmann, U., Schwarz, J. P., Shindell, D., Storelvmo, T., Warren, S. G., and Zender, C. S.: Bounding the role of black carbon in the climate system: A scientific assessment, J. Geophys. Res.-Atmos., 118, 5380– 5552, https://doi.org/10.1002/jgrd.50171, 2013.

EPA Black Carbon

Global Methane: 1856.2 ppb (February 2018)

Source: NOAA methane trends

  • Radiative Forcing:  84 times stronger than CO2 per unit of mass in a 20 year period; 28 times greater over a 100 year period
  • Residence Time:  12 years
  • Key precursor to tropospheric ozone formation (see “Particulates and Ozone”)
  • Anthropogenic Sources (60% of global total emissions)
  • Livestock enteric fermentation (see note below chart)
  • Livestock manure
  • Rice cultivation
  • Miscellaneous agricultural sources
  • Waste treatment
  • Waste water treatment

Blue Arrow:  After a 7 year near-zero growth, methane emissions surged starting in 2007, and accelerated again in 2014.  Over half of all anthropogenic methane emissions are attributable to agriculture.  The recent surge in methane may be due in part (~50%) to an increase in ruminant emissions as well as a possible spike in tropical wetland emissions (Rising methane:  a new challenge). Rising methane emissions were not accounted for in IPCC projections of atmospheric temperature change; decreasing methane emissions were assumed.

Stratospheric Ozone Depletion

The abundances of the majority of Ozone Depleting Substances (ODSs) that were originally controlled under the Montreal Protocol are now declining, as their emissions are smaller than the rate at which they are destroyed. In contrast, the abundances of most of the replacement compounds, HCFCs and hydrofluorocarbons are increasing. (United Nations Scientific Assessment of Ozone Depletion 2018)

Linkages between stratospheric ozone depletion, UV radiation, and climate change, including environmental effects and potential consequences for human well-being, food and water security, and the sustainability of ecosystems (solid lines), with important feedback effects driven by human action (double-arrow solid lines) and other processes (dashed lines).

Source: Environmental Effects and Interactions of Stratospheric Ozone Depletion


  The ozone hole is not technically a “hole” where no ozone is present, but is actually a region of exceptionally depleted ozone in the stratosphere over the Antarctic that happens at the beginning of Southern Hemisphere spring (August–October). Satellite instruments provide us with daily images of ozone over the Antarctic region. The ozone hole image shows the very low values (blue and purple colored area) centered over Antarctica on 4 October 2004. From the historical record we know that total column ozone values of less than 220 Dobson Units were not observed prior to 1979. From an aircraft field mission over Antarctica we also know that a total column ozone level of less than 220 Dobson Units is a result of catalyzed ozone loss from chlorine and bromine compounds. For these reasons, we use 220 Dobson Units as the boundary of the region representing ozone loss. Using the daily snapshots of total column ozone, we can calculate the area on the Earth that is enclosed by a line with values of 220 Dobson Units (the white line in the figure).                     Source:  NASA Ozone Watch 

Antarctic Situation June 24 2019 Source: UK Met Ozone

  • The 2018 ozone hole:  The polar vortex began to form in early May and reached its maximum area in late September at around 34 million square kilometres.  It was a little larger than the decadal mean in size, and was generally of average or above average stability.  The ozone hole grew rapidly and by its maximum in late September was above the average size for the decade at 24.8 million square kilometres.  The area with ozone hole values had declined to zero by the end of November, later than in the last two years, but sooner than the decadal average.    NASA observations show that a minimum ozone amount of 102 DU was reached on October 11 and 12.  Although this is a low value it is not as low as around 1990 to 2000.  Ozone depletion would have been much worse this year without the protection of the Montreal Protocol.
  • Although the amount of ozone destroying substances in the atmosphere is going down, the inter-annual variation in the size and depth of the ozone hole is largely controlled by the meteorological conditions in the stratosphere. 
  • A simple extrapolation of the trend in minimum values gives the final year with ozone hole levels as 2073, though the error bars on this estimate are very large.  Models suggest that recovery may be more rapid after 2010. 
  • It is still too soon to say that we have had the worst ever ozone hole, particularly as there has been no major volcanic eruption in the Southern Hemisphere since 1992.  There has also been little cooling of the lower stratosphere since the mid 1990s. 

Chlorofluorocarbons (CFC’s)

Observations reported in Nature in May 2018 showed that the rate of decline of CFC-11, an ozone depleting substances in the atmosphere, which is also a greenhouse gas, had become slower than predicted.  This suggested that either something unusual was taking place in the atmosphere or that there were additional man-made emissions.  The paper suggested that the most likely reason was illegal manufacture and release from somewhere in eastern Asia.  Investigation by the EIA has found that production of polyurethene foam in China can explain the observed changes.  They encourage the Chinese government to take immediate action.  This became news again in May 2019 when another paper was published in Nature.

Source:  UK Met Ozone

Hydrofluorocarbons & Hydrochlorofluorocarbons (HCFCs) Source: HFC’s

HCFCs are growing at a rate of 8-15%/year

Radiative ForcingThe most abundant HFC is 1,430 times stronger than carbon dioxide per unit of mass

Source:  UK Met Ozone

            CFC’s—refrigerants; decompose in the upper atmosphere and catalyze the destruction of ozone.  Phased out according to the provisions of the 1990 Montreal Protocols of 1987, 1990.

            HFC’s and HCFC’s—Substitutes for CFC’s.  HCFC to be phased out by 2040 because they destroy ozone.  HFC’s targeted for emission reductions in the  Kyoto Protocol

Residence Time:

            CFC’s—100 years (CFC-12)

            HCFC’s—12 years

            HFC’s –13 years (e.g., HFC-134a); lifetime weighted by usage—15 years

Ozone Depleting Gas Index (ODGI) Source: NOAA ODGI

The ODGI is estimated directly from observations at Earth’s surface of the most abundant long-lived, chlorine and bromine containing gases regulated by the Montreal Protocol (15 individual chemicals). These ongoing, surface-based observations provide a direct measure of the total number of chlorine and bromine atoms in the lower atmosphere, or troposphere, contained in chemicals with lifetimes longer than approximately 0.5 yr. Because the lower atmosphere is quite well-mixed, these observations also provide an accurate estimate of the composition of air entering the stratosphere. The threat to stratospheric ozone from ODSs, however, is derived only after considering additional factors: the time it takes for air to be transported from the troposphere to different regions of the stratosphere, air mixing processes during that transport, and the rate at which ODSs photolytically degrade and liberate reactive forms of chlorine and bromine in the stratosphere.

ODGI “100” is defined as 100 at the peak in ozone depleting halogen abundance as determined by NOAA observations, and zero for the 1980 level, which corresponds to when recovery of the ozone layer might be expected based on observations in the past.
  • 2018 Antarctic ODGI 79; i.e., we have progressed 21% towards the 1980 benchmark
  • 2018 Mid-latitude ODGI 55; i.e., we have progressed 45% towards the 1980 benchmark

Particulates and Ozone

Atmospheric composition is determined by the mixture of emissions to the atmosphere, transport within the atmosphere, and UV-B radiation. The key interactions determining the composition includes (1) transport of ozone from the stratosphere, (2) emission of a wide range of substances from the ground, (3) transformation of material through the action of UV radiation (and particularly UV-B), and (4) mixing of the pollutants in the atmosphere. The resultant O3 and aerosols, in turn, have impacts on human health (5) and plants (6).
Environmental Effects and Interactions of Stratospheric Ozone Depletion (Chapter 6)

Particulate Matter (PM2.5) Air Quality

Mumbai, India            Photo by Abhay Singh on Unsplash

Particulate matter contains microscopic solids or liquid droplets that are so small that they can be inhaled and cause serious health problems. Some particles less than 10 micrometers in diameter can get deep into your lungs and some may even get into your bloodstream. Of these, particles less than 2.5 micrometers in diameter, also known as fine particles or PM2.5, pose the greatest risk to health.( EPA PM2.5) These particles are small enough to work their way deep into the lungs and into the bloodstream, where they trigger heart attack, stroke, lung cancer and asthma (Berkeley Earth Air Pollution)

Get the Airvisual 2018 World Air Quality Report Here

  • Air pollution kills more people worldwide each year than does AIDS, malaria, diabetes or tuberculosis.
  • For the United States and Europe, air pollution is equivalent in detrimental health effects to smoking 0.4 to 1.6 cigarettes per day.
  • In China the numbers are far worse; on bad days the health effects of air pollution are comparable to the harm done smoking three packs per day (60 cigarettes) by every man, woman, and child.
  • Air pollution is arguably the greatest environmental catastrophe in the world today. (Berkeley Earth Air Pollution)
2018 Ten Most Polluted Countries (Airvisual)

Unhealthy: The following groups should avoid prolonged or heavy exertion.

  • People with heart or lung disease
  • Children and older adults

Unhealthy for Sensitive Groups: The following groups should reduce prolonged or heavy exertion

  • People with heart or lung disease
  • Children and older adults

Changes (1990 to 2015) in the aerosol column optical depth at 550 nm, computed as the mean of six global models Environmental Effects and Interactions of Stratospheric Ozone Depletion (Chapter 6)

Carbon Dioxide Radiative Forcing

The annual greenhouse gas index (AGGI) for 2018 was 1.43—a 43% increase in radiative forcing since 1990

Radiative forcing, relative to 1750 due to carbon dioxide alone since 1979. The percent change from January 1, 1990 in this forcing is shown on the right axis.
Source: NOAA Carbon Dioxide Radiative Forcing

Radiative forcing, relative to 1750, of all the long-lived greenhouse gases. The NOAA Annual Greenhouse Gas Index (AGGI), which is indexed to 1 for the year 1990, is shown on the right axis.  1990 is the year of the Montreal Protocol, which regulated ozone depleting gases.  The annual greenhouse gas index (AGGI) for 2018 was 1.43—a 43% increase in radiative forcing since 1990
NOAA Annual Greenhouse Gas Index

Pre-1978 changes in the CO2-equivalent abundance and AGGI based on the ongoing measurements of all greenhouse gases
NOAA Annual Greenhouse Gas Index

(Left vertical axis) The heating imbalance in watts per square meter relative to the year 1750 caused by all major human-produced greenhouse gases: carbon dioxide, methane, nitrous oxide, chlorofluorocarbons 11 and 12, and a group of 15 other minor contributors. Source: NOAA Climate.gov graph, based on data from NOAA ESRL.
Today’s atmosphere absorbs about 3 extra watts of incoming solar energy over each square meter of Earth’s surface. According to NOAA’s Annual Greenhouse Gas Index (right axis) the combined heating influence of all major greenhouse gases has increased by 41% relative to 1990.  Annual Greenhouse Gas Index

Uncertainties in Emissions Inventories Source: Climate and Clean Air Coalition

“Studies of emission inventories show that, of the major pollutants, the lowest uncertainties are associated with CO2 and SO2,which depend primarily on the quality of fossil fuel statistical data and fuel properties. Studies estimate globally an 8% uncertainty (90% confidence interval) for emissions of CO2 (Andres et al., 2012; IPCC, 2014) and 8–14% uncertainty for SO2, for a roughly 5–95% confidence interval (Smith et al., 2011). However, uncertainty for certain sectors can be much larger, for example 50% for global estimates of CO2 emissions from the combined Agriculture, Forestry and Other Land Use sector (IPCC, 2014). Similarly, uncertainty can be larger in certain regions (e.g. China) due to uncertainties in the level of coal consumption, emission factor for coal and the actual implementation and efficiency of control technology (Guan et al., 2012; Liu et al., 2015; Olivier et al., 2015; Xu et al., 2009; Zhang et al., 2012). Uncertainties for global inventories of GHGs other than CO2 are much higher, being estimated by IPCC (2014) at ±20% for CH4 and ±60% for N2O (both expressed as the 90% confidence interval). Again, uncertainties for some sectors are much higher, for example, for CH4 emissions from rice paddy fields, livestock enteric fermentation and landfill.

Emissions of PM, including BC and primary OC, are more uncertain, as these pollutants usually form under poor combustion conditions in small, inefficient installations burning poor-quality fuels, which are difficult to account for, resulting in large emission variability (Bond et al., 2004; Klimont et al., 2017; Hoesly et al., 2018). Considering local data and knowledge about emission sources and their emission factors could significantly reduce these uncertainties (Zhang et al., 2009). Inconsistencies in measurements of PM emissions (e.g. in-stack or directly after stack for industry; laboratory versus real- world measurements for cookstoves) in different countries contribute to overall global inventory uncertainties. Uncertainty can also be large for activity data of relevance to PM emissions – such as poor-quality fuels (e.g. biomass) in cook stoves or brick kilns (Klimont et al 2017) or even size and composition of local vehicle fleets.

Bond et al. (2004) estimated total uncertainties of about a factor of 2 (i.e. -50% to +100%) in their global estimates of BC and OC emissions for 1996 from contained combustion (excluding open-burning of vegetation and crop residues). More recent work (Bond et al., 2013) estimated larger uncertainties for a global BC inventory for the year 2000; of around a factor of 3 for energy-related emissions and >3 when open-burning is included. Advances in emission characterization for small residential, industrial, and mobile sources will be required to reduce the scale of these uncertainties. Uncertainties in national scale BC emission estimates are likely to be less than for the global inventories described above. For example, emission uncertainties are considered to be in the order of 1.5 to 2-fold for national BC inventories recently prepared by EU countries for CLRTAP.”   (Emphasis added)

Ecological Footprint

Unlike these imprints in the sand that can be washed away by wind or water, the global footprint of humanity is leaving deeper and more permanent changes to our planet.

Earth Overshoot Day 2019 was July 29, the earliest ever

Our data show that we use as much from nature as if we lived on 1.75 Earths, yet we only have one.” 

  • As of 2016, 86% of the world’s population lives in a country with an ecological deficit.
  • 71% of the world’s population lives in a country with an ecological deficit and below world-average income
How many Earth’s does your country require?
Ecological Footprint–2019 Number of Earths
1.75 Earths for all of us…

Ecological Footprint vs Per Capita Biocapacity (global hectares per person)
Ecological Footprint vs. Biocapacity (global hectares)

Visit the Footprint Network (see link above) for a wealth of information regarding footprint analysis.

Calculate your footprint here:



Source Unless Otherwise Noted: Carbon Brief Global Emissions Summary

How much carbon dioxide is produced when different fuels are burned?

Pounds of CO2 emitted per million British thermal units (Btu) of energy for various fuels

Coal (anthracite) 228.6
Coal (bituminous) 205.7
Coal (lignite) 215.4
Coal (subbituminous) 214.3
Diesel fuel and heating oil 161.3
Gasoline (without ethanol) 157.2
Propane 139.0
Natural gas 117.0

Source: CO2 emissions from fossil fuels

2018  Global Energy Summary 

  • Energy use grew at a rate of 2.9%, the largest since 2010
    • China, the U.S. and India accounted for 2/3 of global energy-use growth
    • U.S. consumed more energy than ever before, expanding at the fastest rate in 30 years
    • The Middle East, Africa, and Asia now drive nearly all global energy consumption growth
Source: U.S. Energy Information Administration, International Energy Statistics


  • Wind and solar growth slowed modestly in 2018
  • Non-hydro renewables grew by 14.5%; represent 4% of global energy use
  • Hydro generation grew by 3%
  • All renewables represent 15% of global energy use


  • Natural gas was the single largest contributor to global energy-use growth
    • Natural gas use has increased by 31% since 2009
  • Oil consumption grew by 1.5%; U.S. and China accounting for 85% of this growth
    • Oil use has increased by 14% since 2009
  • Coal consumption grew at the fastest rate since 2013 (1.4%)
    • Global coal use has increased by 10% since 2009
    • Coal use increased by 1% in China, reversing 4 four years of reduction (or near-zero growth)
  • India was the largest single driver of global coal growth (45%)

Global coal use between 1965-2018, broken down by key consumers, millions of tonnes of oil equivalent
Matthew Henry on Unsplash
Nebraska, U.S. American Public Power Association on Unsplash


  • Total number of people globally without electricity now below 1 billion
  • Global electricity generation rose by 3.7%, led by China, India*, and the U.S.
    • *India:  A vast rural electrification program has brought electricity to 95% of Indian households, leaving only 11 million homes without electricity.  The International Energy Agency describes this programs as one of the greatest success stories of 2018 ( The Economic Times Rural Electrification )
  • Electricity sources
    • Renewables were the single largest contributor to the increase in global electricity use
    • April, 2019–U.S. renewables electricity exceed coal (21.6%) for the first time FERC  (see below)
    • Fossil fuels still account for 64% of global electricity
      • Electricity generated from coal set a new record in 2018—38%
      • Natural gas accounted for 23% of global electricity generation
    • Nuclear
      • Generation grew by 2.4%; China accounted for 75% of this growth
Doel, Beveren (Belgium) Nuclear Powerplant Photo by Frederic Paulussen on Unsplash

U.S. Energy Trends

In 2018, the United States consumed more energy than ever before; the increase was the largest since 2010.

  • Coal, natural gas, and petroleum accounted for 80% of total U.S. energy consumption

U.S. Generating Capacity 2019

U.S. electricity production from renewables surpassed coal in April, 2019
Source:  https://www.ferc.gov/legal/staff-reports/2019/apr-energy-infrastructure.pdf

Introduce Yourself (Example Post)

This is an example post, originally published as part of Blogging University. Enroll in one of our ten programs, and start your blog right.

You’re going to publish a post today. Don’t worry about how your blog looks. Don’t worry if you haven’t given it a name yet, or you’re feeling overwhelmed. Just click the “New Post” button, and tell us why you’re here.

Why do this?

  • Because it gives new readers context. What are you about? Why should they read your blog?
  • Because it will help you focus you own ideas about your blog and what you’d like to do with it.

The post can be short or long, a personal intro to your life or a bloggy mission statement, a manifesto for the future or a simple outline of your the types of things you hope to publish.

To help you get started, here are a few questions:

  • Why are you blogging publicly, rather than keeping a personal journal?
  • What topics do you think you’ll write about?
  • Who would you love to connect with via your blog?
  • If you blog successfully throughout the next year, what would you hope to have accomplished?

You’re not locked into any of this; one of the wonderful things about blogs is how they constantly evolve as we learn, grow, and interact with one another — but it’s good to know where and why you started, and articulating your goals may just give you a few other post ideas.

Can’t think how to get started? Just write the first thing that pops into your head. Anne Lamott, author of a book on writing we love, says that you need to give yourself permission to write a “crappy first draft”. Anne makes a great point — just start writing, and worry about editing it later.

When you’re ready to publish, give your post three to five tags that describe your blog’s focus — writing, photography, fiction, parenting, food, cars, movies, sports, whatever. These tags will help others who care about your topics find you in the Reader. Make sure one of the tags is “zerotohero,” so other new bloggers can find you, too.