One would think the latest reports documenting the lack of action regarding climate change, the continued and accelerating changes to the oceans and cryosphere, the deteriorating condition of the Great Barrier Reef, and the astonishing decline in avian populations along with the ongoing extinction of numerous other plant and animal species, should serve to focus global attention on planetary change in the Anthropocene. Unfortunately, it would appear that business as usual will be the most likely outcome of all these reports, despite much wringing of hands, gloomy predictions and opining of pundits, experts and the like.
A hallmark of the Anthropocene is the observably (much!) higher rate of change in many Earth system processes as compared to “background” rates determined from historical records. This acceleration has been well documented, but very poorly communicated to the general public and largely ignored by decision makers. Rising concentrations of carbon dioxide, increasing sea and land temperatures, accelerated melt rates of sea ice, permafrost and ice sheets, along with rising sea level, inform us that a critical fork in the road lies ahead. Ignore these signposts and there will be no opportunity to even make a choice as to which road we take—the decision will have been already made.
With this analogy in mind, I turn to three papers, one written in 1976, one in 2013, and another released this September. In 2013, James Hansen and 17 other scientists published “Assessing ‘Dangerous Climate Change’: Required Reduction of Carbon Emissions to Protect Young People, Future Generations and Nature.”( Dangerous climate change) Their paper documented the continued rise in atmospheric carbon dioxide from fossil fuel combustion, along with the various attendant impacts to Earth system processes, the environment and human health and well-being arising from this accumulation. The authors suggested that the inertia of the climate system causes it to respond “slowly to this man-made forcing,” complicating policy responses, as well as obscuring the potentiality for irreversible climate change due to slow feedbacks. Although the rapidity and scale of such changes; e.g., irreversible melting of Antarctic and/or Greenland ice sheets remains unclear, continued combustion of fossil fuels threatens to lock us into this future.
They argued that the implications of future climate change already “in the pipeline” are thus intergenerational, presenting young people of today with a future they will have had no hand in shaping. The authors suggested that “(a) scenario is conceivable in which growing evidence of climate change and recognition of implications for young people lead to massive public support for action” based on the expectation of “fairness and justice in a matter as essential as the condition of the planet they will inhabit.” This sounds remarkably like the argument underlying today’s campaign by young people for climate justice. The conclusions of the 2013 paper are stark: the opportunity to avoid climate disruptions and maintain global temperatures below 2oC will require “extraordinarily rapid emission reductions” and choosing an alternative energy pathway, a “fork in the road” from a carbon-rich energy path to one that is carbon-free.
The choice of a “hard energy path” as opposed to a “soft energy path” was outlined more than forty years ago, in Amory Lovin’s seminal October 1976 Foreign Affairs article “Energy Strategy: The Road Not Taken?” (Soft Energy Paths) in which he outlined the numerous benefits of shifting from a “hard path” of fossil fuels and nuclear power to a “soft path” of efficiency and renewable energy, focused on matching the quality of energy to its end use. Lovins’ deeply controversial and influential article showed a way forward to an energy future that today bears a remarkable similarity to his original description. However, despite rapid efficiency improvements, technological breakthroughs and movement along a soft energy path envisioned by Lovins, a key aspect of the soft energy path, deployment of renewables, lags approximately 25 years behind the 1976 projections. Deployment of renewables must therefore accelerate even more rapidly if we are to move towards an energy future that will avoid the irreversible climate change outlined by Hansen et al.
These choices are now before us, laid out in a September 2019 White Paper from the World Economic Forum, “The Speed of the Energy Transition—Gradual or Rapid Change?” (The speed of the energy transition) The paper poses the question “Will the global energy transition from fossil fuels to sustainable energy be gradual or rapid?” The authors suggest the choice of paths will be made this decade, that the two paths are mutually exclusive, and that the choice of business as usual “regrettably … means that the goals of the Paris Agreement will become increasingly unachievable.”
There are three “signposts” along the path to a Rapid global
energy transition by 2030 according to the White Paper:
(1) solar electricity
at $20-$30 per megawatt hour
(2) carbon taxes
implemented on around half of emissions at $20 per tonne
(3) three peaks to
take place in the 2020’s
a. peak demand for new internal combustion
b. peak demand for fossil fuels in electricity
c. peak demand for all fossil fuels
If we pass these, the Rapid transition is on track; failure to pass these leads to a future whose socioeconomic and Earth system dimensions will be dictated by processes humanity has set into irreversible motion. The chart from Hansen, et al hints at the potential long lags in the climate system’s response to fossil fuel emission cuts: it could take centuries before atmospheric carbon dioxide levels return to “safe” levels of 350 ppm.
The chart below from BerkelyEarth shows the path to 1.5oC is only a decade or so distant, if current trends continue. The chart shows a ten-year moving average of the Earth’s surface temperature, plotted relative to the average temperature from 1850-1900. At the current rate of increase, 1.5oC above the 1850-1900 average will be reached by 2035.
According to Hansen et al., warming will reach 1.5oC and “stay above 1.0oC until 2400 if emissions continue to increase until 2030.”
Perhaps Greta Thunberg said it best in her September 23
address to the United Nations:
“For more than 30 years, the science has been crystal clear. How dare you continue to look away and come here saying that you’re doing enough, when the politics and solutions needed are still nowhere in sight…The popular idea of cutting our emissions in half in 10 years only gives us a 50% chance of staying below 1.5 degrees [Celsius], and the risk of setting off irreversible chain reactions beyond human control…Fifty percent may be acceptable to you. But those numbers do not include tipping points, most feedback loops, additional warming hidden by toxic air pollution or the aspects of equity and climate justice…You are failing us. But the young people are starting to understand your betrayal. The eyes of all future generations are upon you. And if you choose to fail us, I say: We will never forgive you.
We will not let you get away with this. Right here, right now is where we draw the line. The world is waking up. And change is coming, whether you like it or not.” (Thunberg Transcript)
July was remarkably warm, in fact July’s average temperatures—for both land and sea–were the highest monthly temperatures ever recorded since 1850. This image from NOAA illustrates some of the more noteworthy records set last month.
I should also mention that Berkeley Earth (http://berkeleyearth.org), in their summary of 2018 global temperatures published early this year, estimated that 2019 would “…likely… be warmer than 2018, but unlikely to be warmer than the current record year, 2016. At present it appears that there is roughly a 50% likelihood that 2019 will become the 2nd warmest years since 1850.” As of August 15, they are now predicting a 90% probability of this occurring. This screenshot from Robert Rohde’s (BerkeleyEarth) Twitter feed illustrates long-term weather stations (those with at least 40 years of records) that have reported a daily, monthly or all-time record high temperature from May 1st to July 31st. Looks like a sea of red!
Some of the
more attention-grabbing aspects of the late July heat wave came from Greenland.
masses from Europe arrived over Greenland late in July and early August,
causing record-setting melting across about 90% of the ice sheet during a five-day
event. Melt area reached 154,500 square
miles, 18% larger than the 1988-2017 average. The record warmth established an
all-time high melt event for this monthly period, and total ice mass loss for
2019 is nearly equal to that of 2012, the year of highest loss for the
satellite-era. (National Snow and Ice
Data Center Greenland Today)
all about the records!
attention has been given to elevated Arctic temperatures, increased ice-sheet
melt and its contributions to sea-level rise, and low seasonal sea-ice coverage, but several
other issues attending warming air and sea temperatures warrant discussion as
well. Over the longer term—decades, not days,
warming temperatures are measurably impacting terrestrial and marine
ecosystems. These “slow” ecosystem
changes aren’t as attention-grabbing as all-time records of high temperature or
ice melt, but are one of the distinguishing characteristics of the Anthropocene.
(see “The Anthropocene” tab on the Home page).
Let’s look at a couple of examples, one from terrestrial ecosystems, and
one from marine ecosystems.
In a July 10 article (Hydrologic Intensity) the authors demonstrate in a more complete fashion than previous work, the linkage between rising air temperatures and acceleration of the hydrological cycle. Their model incorporates both the supply of water (precipitation) and demand (evapotranspiration) between the surface and the atmosphere. Reinforcing other research that suggests hydrologic intensification is occurring, the new research shows “widespread hydrologic intenstification from 1979-2017 across much of the global land surface, which is expected to continue into the future.” The findings add a little more support to the likelihood of a climate future where there is “increased precipitation intensity along with more days with low precipitation.” The temporal and spatial distribution of hydrologic intensification will have important consequences ranging from urban flood control to the management of agroecosystems—an issue of considerable importance as population rises this century.
Marine fisheries are also significant food sources for global populations. In an article published in March (Sciencehttps://science.sciencemag.org/content/363/6430/979) researchers looked at 235 marine fisheries (fish and invertebrates) from 38 ecoregions, representing one-third of reported global catch. They concluded that there has been a statistically significant decline in the maximum sustainable yield of 4.1% from 1930 to 2010 that is linked to warming oceans. Five of the ecoregions had losses of 15 to 35%. The authors conclude that “ocean warming has driven declines in marine fisheries productivity and the potential for sustainable fisheries catches.” These trends are exacerbated by overfishing, but sound management plans incorporating temperature-driven trends have the potential for remediating these changes.
Both examples suggest that temperature-driven changes to key provisioning services of terrestrial and marine ecosystems are of equal importance to the headline-grabbing temperature and ice-melt records of the last month. These changes are “slow-motion” impacts of a warming world; like rising sea-levels, ecosystem changes will have profound impacts, but are invisible over short-term news and policy cycles in which we appear to be ensnared.
The recently (Aug 7) released Special Report on Climate
Change and Land by the IPCC (https://www.ipcc.ch/srccl-report-download-page/)
offers a comprehensive review of the nexus between global warming/climate
change and land use change. As I have already
suggested in the “About this blog,” land use changes are a critical aspect of global
anthropogenic change; i.e. the Anthropocene. The new report stresses how a
changing climate (increased air temperatures, evapotranspiration, altered precipitation
regimes, etc.) impact soils and vegetation.
The latter underlie ecosystem health, including agroecosystems, as well
as intact “undisturbed” terrestrial ecosystems such as rainforests, peatland,
and coastal forests. These are critical
harbors of biodiversity, as well as essential elements in the provision of
ecosystem services upon which human well-being depends, such as carbon
sequestration and clean water.
Land use changes associated with agriculture, forestry, livestock,
road construction, and urbanization degrade these critical services, thereby
threatening our ability to sustainably provide food, fiber and other essential
goods and services to a continually growing, telecoupled global
population. Imprudent and ill-planned
(or adhoc) conversion of various terrestrial ecosystems in pursuit of food,
fiber and mineral resources has led to land degradation, desertification and
biodiversity loss at both a scale and speed that are without precedent.
The report emphasizes the urgent need to rein in these
unsustainable practices in order to both guarantee our ability to provide food
for the world, as well as provide a crucial sink for growing carbon
emissions. According to the report,
reducing forest deforestation and degradation are critical elements in
mitigating green house gas emissions.
Furthermore, transitioning the global population to a much more
plant-based diet from one that is significantly animal-sourced, will reduce
risks from climate change as well as help reduce agricultural
Only a wide-ranging and comprehensive approach to managing both our energy and land resources will provide sustainable, equitable and healthy outcomes for the global population. Immediate steps need to be taken, because the longer business as usual behaviors continue, our ability to deploy a wide variety of remedies will be increasingly foreclosed. Reducing green house emissions and altering detrimental land use practices are thus interconnected, inseparable and our failure to change both may lead to both irremediable impacts to ecosystems and the goods and services upon which humanity relies.
Greenland, Antarctica ice sheet mass loss (~1.1-1.3mm/yr)
~20-35% from other sources including mountain glacier and ice-cap loss, groundwater depletion, reservoir impoundment, and mass changes in other stores; e.g., lakes, soil, permafrost
the cumulative global groundwater depletion from 1900–2008 totaled ∼4,500 km3 from 1900–2008, equivalent to a sea‐level rise of 12.6 mm. As an identifiable, separate, semi‐independent hydrologic process, the volume and rate of estimated long‐term global groundwater depletion balances 6 to 7 percent of the observed SLR since 1900. (Konikow LF (2011) Contribution of global groundwater depletion since 1900 to sea-level rise. Geophys Res Lett 38(17), L17401. doi: 10.1029/2011gl048604)
Observed sea level since the start of the satellite altimeter record in 1993 (black line), plus independent estimates of the different contributions to sea level rise: thermal expansion (red) and added water, mostly due to glacier melt (blue). Added together (purple line), these separate estimates match the observed sea level very well. NOAA Climate.gov graphic, adapted from Figure 3.15a in State of the Climate in 2017.
Sea Level Tracked By Satellite Data 1993-Present
Sea Level Derived From Coastal Tide Gauge Data 1870-2000
Over the 1900 to present time span roughly 4.5 Million sq km of potential permafrost area has been lost.Berkeley Earth Permafrost
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)
Permafrost potential is declining…
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)
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
cryosphere as a whole has contributed around 45% of observed global sea level
rise since 1993.
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
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
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)
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
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
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
Visualizing Global Temperature Change: Ed Hawkins’ global temperature spiral
about the rise in global temperatures comes from multiple groups around the
Yearly global surface temperature from
1900–2017 compared to the 1981-2010 average (dashed line). The different colors
represent different research groups’ analysis of the historical temperature record. NOAA
Climate.gov graph adapted from State of the Climate in 2017.Details on the
datasets can be found in Table 2.1 and Figure 2.1 in the report.
At +1.7° C, the mean annual surface
air temperature (SAT) anomaly for October 2017-September 2018 for land stations
north of 60° N is the second highest value (after 2016) in the record starting
in 1900. Currently, the Arctic is
warming at more than twice the rate of global mean temperatures; a phenomenon
known as Arctic Amplification. Recorded
annual mean Arctic temperatures over the past five years (2014-18) all exceed
not just Berkeley Earth documenting global temperature…
Global temperatures have been trending upwards, above the long-term average for more than 40 years.
The period since 2015 has seen some of the warmest years since 1850. The probability distribution shown below clarifies this; note how 2016 was markedly warmer on average than earlier years.
Distribution of warming is uneven, but as in previous years, 2018 was characterized by very strong warming over the Arctic that significantly exceeds the Earth’s mean rate of warming.
Surface air temperature 2018: Concurrent heat events (see
Source: Vogel, M. M., Zscheischler, J., Wartenburger, R., Dee, D., & Seneviratne, S. I. (2019). Concurrent 2018 hot extremes across Northern Hemisphere due to human-induced climate change. Earth’s Future, 7. https://doi.org/10.1029/2019EF001189(See table below)
Twenty-two percent of populated and agricultural areas of the Northern Hemisphere concurrently experienced hot extremes between May and July 2018
Record-breaking temperatures occurred concurrently in multiple regions including North America, Europe, and Asia in late spring/summer 2018.
Europe experienced late
spring and summer temperatures that were more than 1◦C warmer than 1981–2010
The contiguous United States had the warmest May since 1895, and the hottest month ever observed was in July in Death Valley.
The 2018 hot temperatures are in line with an increase in
intensity and frequency of extreme heat events over many regions on land and in
the ocean in recent years.
It is virtually certainthat these 2018 north hemispheric concurrent heat events could not have occurred without human-induced climate change
We would experience a GCWH18-like event* nearly 2 out of 3 years at +1.5 ◦C and every year at +2 ◦C global warming
Results further reveal that the average high-exposure area projected to experience concurrent warm and hot spells in the Northern Hemisphere increases by about 16% per additional +1 ◦C of global warming.
*the temporal average between May and July 2018 as considered Global Concurrent Warm and Hot 2018 event, in short, GCWH18 extreme event.
Business As Usual Projections of Global Surface Temperature Will Push Global Temperatures Above 1.5 degrees C by 2035.
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.
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.
Radiative Forcing: 298 times that of CO2 over a 100 year period Residence time: 114 years
Agriculture (soil management—fertilizers, manure, burning of agricultural residues)
Growth of nitrous oxide
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
Flaring from oil gas extraction and processing
Transportation (diesel engines in on-and off-road vehicles, ships, generators)
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.
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)
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
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.
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.
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
CFC’s—100 years (CFC-12)
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
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
Matter (PM2.5) Air Quality
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
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
Get the Airvisual 2018 World Air Quality Report Here
pollution kills more people worldwide each year than does AIDS, malaria,
diabetes or tuberculosis.
the United States and Europe, air pollution is equivalent in detrimental health
effects to smoking 0.4 to 1.6 cigarettes per day.
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.
“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)