See the Tabbed Pages for links to video tutorials, and a linked list of post titles grouped by topic.

This blog is expressly directed to readers who do not have strong training or backgrounds in science, with the intent of helping them grasp the underpinnings of this important issue. I'm going to present an ongoing series of posts that will develop various aspects of the science of global warming, its causes and possible methods for minimizing its advance and overcoming at least partially its detrimental effects.

Each post will begin with a capsule summary. It will then proceed with captioned sections to amplify and justify the statements and conclusions of the summary. I'll present images and tables where helpful to develop a point, since "a picture is worth a thousand words".

Thursday, March 24, 2016

Representative Lamar Smith Wrongly Asserts Global Warming Has Halted

Representative Lamar Smith of Texas, in a speech in the U. S. House of Representatives, lamented the widespread press coverage of a scientific publication last year showing that global warming had not stopped since about 2000.  He then decried the lack of press coverage for a new article that he wrongly claims “refutes” the earlier work.

In truth, both articles find that warming has continued during this period, contrary to Rep. Smith’s characterization of this period as a “halt” in global warming.  The new article finds that the warming during this period is a “slowdown” (compared to predictions from climate models), but not a “halt”, and thoroughly analyzes the reasons for the slowdown.  An important contribution comes from the decades-long cyclical operation of the Interdecadal Pacific Oscillation.

Representative Smith is wrong in saying that global warming has halted.  The newest global annual average temperatures for 2014 and 2015 have resumed increasing; that for 2015 is a pronounced record high.  Warming continues unabated, even if Representative Smith won’t admit to this reality.


In a speech on the floor of the U. S. House of Representatives   on March 21, 2016, Representative Lamar Smith of Texas stated “Americans deserve all the facts that surround climate change, not just those that fit the view the national liberal media wants to promote.”   He disparaged the media for covering a scientific study by the National Oceanic and Atmospheric Administration (NOAA) last year (which he did not identify further) that refutes earlier work characterizing a recent decade-long period as showing what he called a “halt in global warming”.  Rep. Smith then cited a new “study published in the journal Nature [that] confirms the halt in global warming” (again not identified by author or title).  He stated “[a]ccording to one of the study’s lead authors it ‘essentially refutes NOAA’s study’”, and called out the media for not covering this new result.

This writer presumes that Rep. Smith was referring first to the publication by Thomas Karland coworkers at NOAA and other research institutions, published in the peer-reviewed journal Science in June 2015. Contrary to Rep. Smith’s claim that the “scientists altered global surface temperature data to try and refute the two decade halt in global warming” (emphases added), Karl and coworkers carried out a rigorous reanalysis of existing, freely available, temperature records going back to 1880, and included new data from 2012 to 2014 that had not been previously analyzed.  They concluded “based on our new analysis, the IPCC’s [Intergovernmental Panel on Climate Change] … statement of two years ago – that the global surface temperature ‘has shown a much smaller increasing linear trend over the past 15 years than over the past 30 to 60 years’ – is no longer valid.”  Rather, they found that the rate of warming of the world's atmosphere during 1998 to 2014 has continued unabated compared to the warming experienced in earlier decades.

It is important to note that Karl and coworkers did not “alter” temperature data in their reanalysis, but rather applied corrections to account for earlier systematic errors in certain of the datasets used.  Further, they were not trying to “refute the [so-called] halt in global warming”, contrary to the accusation of Rep. Smith.   

Rep. Smith states that a new study published in Nature refutes the earlier NOAA findings.  This writer presumes he was referring to the publication by Fyfe and coworkers (Nature Climate Change  6, 224–228 (2016); doi:10.1038/nclimate2938; Published online  24 February 2016).   Contrary to Rep. Smith’s assertion, Fyfe and coworkers do not “confirm the [so-called] halt in global warming”, nor do they “refute” Karl and coworkers.  Fyfe and coworkers not only reexamined the global mean surface temperature records available, they also examined potential drivers of the observed trends. 

  • They found that the data analysis carried out by Karl and coworkers, as well as by other groups, showed that a “warming slowdown is thus clear in observations; it is also clear that it has been a ‘slowdown’, not a ‘stop’.” (Emphases added)  That is, contrary to Rep. Smith, this new work does not “confirm the halt in global warming.” (Emphasis added)
  • Referring to the work of Karl and coworkers, Fyfe and coworkers write “[r]ecent research that has identified and corrected the errors and inhomogeneities in the surface air temperature record is of high scientific value.”  This appreciation of the work of Karl and coworkers contradicts Rep. Smith when he dismisses the validity of their work.
  • Fyfe and coworkers write that the issue of “[h]ow unusual a period of reduced warming is, depends strongly on its length.”  The actual rates of warming are highly sensitive to the choices made for the length of time considered, and for the starting points and end points of the warming interval.
  • Fyfe and coworkers call the recent period, 2001-2014, a “slowdown” largely because the observed temperature trends for this period fall below modeled predictions for the period made by extending assumptions made for earlier decades into the recent period.
  • The authors point out that man-made contributions to warming did not cease during the slowdown.  Rather they ascribe the slowdown largely to internal variations in factors that affect climate, including the large contribution arising from the operation of the cyclical decades-long Interdecadal Pacific Oscillation (IPO) (as well as certain other variations).  The IPO was in its thermally negative phase during the slowdown period.  This was sufficient to counterbalance part of the man-made warming always present.  Being cyclical, when the IPO reenters its positive phase, warming from the IPO will supplement man-made warming, leading to stronger increases in global average surface temperatures once again.

It is concluded that Rep. Smith’s characterization of the last 15 years of global temperature data as one in which global temperature increases have “halted” is oversimplified and mistaken.  We agree that, in his words, “Americans deserve all the facts that surround climate change.”

The global average atmospheric temperature continues to increase, reaching record levels.  The U. S. National Aeronautics and Space Administration reports that 2015 was the hottest year on record covering the 135 years from 1880.  The land-ocean average was 0.87ºC (1.57ºF) above an average baseline for about 1950 to 1975.   For 2014 that value was 0.74ºC (1.33ºF) above the average.

The Climate Research Unit of the University of East Anglia (UK) similarly finds that 2015 was the warmest on record for data going back to 1850. 

NOAA also reports that 2015 was the warmest year on record, advancing 0.16ºC (0.29ºF) from the previous year, which itself was a record.  NOAA’s graph of annual temperature differences from the 20th century average is shown here
Land and ocean average annual temperature deviations, for 1880 to 2015, from the reference, the average for the 20th century,.  Left vertical axis in ºC; right vertical axis in ºF.  Blue, annual temperature is below the reference average; red, annual temperature is above the reference average.

The image above shows that the land and ocean annual average temperature has been increasing consistently and dramatically since about 1950.  There clearly is no “halt in global warming”, contrary to the floor speech given by Rep. Smith.  Indeed, the rise from 2014 to 2015 is remarkably large.

Rep. Lamar Smith of Texas gave a speech on the floor of the U. S. House of Representatives that casts doubt on the continued, dramatic rise of global annual average temperatures.  This post shows unequivocally that the long-term global average temperature continues its long-term increase.  It is widely recognized that the rise in the global average temperature is caused by the increase in man-made greenhouse gases (GHGs), primarily carbon dioxide, emitted into the atmosphere. 

The increased atmospheric burden of carbon dioxide is critical, because once this gas enters the atmosphere it remains resident for centuries or longer (about one-third is absorbed by the waters of the oceans).  Although humanity strives to reduce the annual rate of further emissions of GHGs, such efforts cannot reduce the total amount of GHGs already present.  This means that the extent of warming we are already experiencing cannot be reversed.  The average global temperature will continue increasing until annual emission rates approach zero.  The efforts of those who seek to lull us into a false sense of climate security are for naught; the scientific truths embedded in the global warming issue cannot be reversed simply by willing them so.

© 2016 Henry Auer


Thursday, March 17, 2016

Attribution of Extreme Events to Global Warming

The public, when contemplating global warming, includes those who question whether warming underlies the occurrence of extreme weather and climate events.  The U.S. National Academies of Science, Engineering and Medicine recently issued a report, “Attribution of Extreme Weather Events in the Context of Climate Change”.  It emphasizes that the appropriate format for questions concerning this issue can be phrased in terms such as “Are events of this severity becoming more or less likely because of climate change?” 

The report emphasizes that because of rapid advances in data analysis and climate modeling the severity of many extreme events can be attributed to contributing factors arising from warming.  It includes a schematic image, shown here, characterizing how the increasing degree of understanding of various types of events leads to increasing confidence in the degree to which we can attribute severity to contributions from global warming.

This post concludes with a selection of examples from the climate literature where such analyses have been made, leading to affirmative statements of attribution such as considered here.

Recently weather news has reported on extreme events in many regions of the world. 

  • The American states of Texas and Louisiana, and their neighbors, had intense rain for over a week in early 2016, triggering record-breaking flooding in the area.    
  • The American West has suffered severe drought conditions for four years, straining water supplies and lowering yields of important crops. 
  • Perth, Australia had a heat wave four days long with temperatures over 40ºC (104ºF) in February 2016, and has had seven days over this temperature this season.  
  • Pakistan has had increasing numbers of serious flooding events over the last century, including 40 events in the last 15 years.  Most of these are accompanied by loss of life and social dislocation, and significant damage to structures and agricultural lands.
These few anecdotes are potentially significant indicators of the effect that global warming is having at regional and local levels around the world.  Indeed, increased rates of occurrence of such phenomena are predicted with high confidence in recent global warming reports.  But in discussing the role of warming at the scale of such geographically small areas it is important to evaluate whether each one in fact is related to warming.  For example, if few or none are, climate science would be hard pressed to persuade policymakers and the public to undertake efforts to minimize further warming and adapt to its effects.  On the other hand, if it can be shown that there is indeed a contribution from warming, then climate science is justified in actively pursuing appropriate policies such as those agreed to at the United Nations conference in Paris in December 2015.

Here we discuss the question of whether, and how, extreme events can be attributed to global warming.

The U. S. National Academies of Sciences, Engineering, and Medicine issued the report “Attribution of Extreme Weather Events in the Context of Climate Change” (2016); Washington, DC: The National Academies Press (the Report) on March 10, 2016.  The Report emphasizes that extreme events, just as all our weather every day, results from the interactions of many atmospheric forces and processes.  For this reason, it makes the very important point that we can not justifiably ask a question such as “Was this extreme event caused by [man-made] climate change, yes or no?”  Such a simplified black-or-white question overlooks the complexity in climate and weather. 

Rather the Report offers different questions phrased as “Are events of this severity becoming more or less likely because of climate change?”; or, for single events such as local storms, the question could be “To what extent was the storm intensified, or its precipitation increased, because of climate change?”  Note that the questions deemed appropriate seek expressions of likelihood, rather than the certainty demanded by the yes-or-no question.  To any viewer of a televised weather forecast this should hardly be surprising.  After all, these daily predictions always provide likelihoods for sunshine (clear, partly cloudy, mostly cloudy, etc.) as well as percent probabilities of rain, sleet or snow.  In the same way, and for the same reasons, the Report concludes that statements of attribution should be phrased in terms of the probability or likelihood that global warming was a climatic factor contributing to the occurrence of the extreme event.

The Report summarizes its detailed deliberations about attribution of events to known or understandable contributing factors with a simplified conceptual diagram, shown here
Schematic diagram showing how our confidence (vertical axis) in attributing different kinds of extreme events to man-made climate change depends on our understanding of the extent to which climate change affects the particular type of event (horizontal axis).  Different types of extreme events are shown by the differently colored labeled circles.  The dashed line represents where a particular type of extreme event would fall if we had an ideal ability to attribute how climate change affects it.  In reality all the circles fall below the dashed line because our ability to attribute the specific events to man-made climate change is less than perfect.  Note that the understanding/attribution level is high for temperature events (upper right), and that these become lower as we pass through extreme rainfall (near the center) to severe convective storms (e.g., thunderstorms and tornadoes; lower left).
Source: U. S. National Academies of Sciences, Engineering, and Medicine,  “Attribution of Extreme Weather Events in the Context of Climate Change” (2016); Washington, DC: The National Academies Press. doi: 10.17226/21852.
The Report identifies two ways to label an event as “extreme”.  We have to be able to distinguish a supposed extreme event, potentially caused in part by the effects of global warming, from normal behavior.  First, data characterizing the event could be shown to differ from comparable data for a reference period extending over a sufficiently long period of time, with a high level of statistical significance.  Alternatively, data characterizing the event could be successfully modeled in a climate model that includes man-made global warming factors, whereas it could not be modeled by a similar model run excluding those factors, again, with a high level of statistical significance.  An event that fulfils either of these conditions can then be labeled as an event to which global warming contributes to its extreme character.
Extreme events had already been attributed to global warming before this Report. 
  • Analysis of data over the 49 year period from 1951-1999 shows that global warming is responsible for extremes of rainfall over the Northern Hemisphere.  Min and coworkers (Nature, 2011, Vol. 470, pp. 378-381, doi:10.1038/nature09763) showed that “human-induced increases in greenhouse gases have contributed to the observed intensification of heavy precipitation events found over approximately two-thirds of … Northern Hemisphere land areas.”  This work is significant because it covers a period of time in which greenhouse gas levels, and global average temperatures, were much lower than at present.
  • Extreme rainfall and catastrophic flooding in England and Wales in 2000 was very likely due to human-induced global warming.  Pall and coworkers carried out a probabilistic analysis of weather patterns and likelihood of flooding in the region (Nature, 2011, Vol. 470, pp. 382-385, doi:10.1038/nature09762). During October and November 2000 England and Wales had the heaviest rainfall since records began in 1766, leading to severe flooding. The authors concluded “it is very likely that global [human-induced] greenhouse gas emissions [occurring during the twentieth century] substantially increased the risk of flood occurrence…in autumn 2000.”
  • Kelley and coworkers (Proc. Natl Acad. Sci., published online before print March 2, 2015) report on the worst drought in recorded history in Syria and neighboring countries just prior to the “Arab Spring”.  The drought was serious enough that large numbers of farmers left their villages and migrated to Syria’s cities.  This caused major social and political turmoil and is considered to be a contributing factor to Syria’s ongoing civil war.  The authors found that human-derived greenhouse gases contributed to the drought.
  • Moore and Lobell (Proc. Natl. Acad. Sci., vol. 112 no. 9, pp. 2670–2675, 2015) analyzed changes in crop yields and climate change across Europe between 1989 and 2009.  Large scale decreases in yields were found in many localized regions, which correlated with increased temperatures and decreased precipitation over the 20 year period studied.
  • Diffenbaugh and coworkers (Proc. Natl. Acad. Sci., published online before print March 2, 2015) examined the drought in California from December 2012 to September 2014, likely the worst in 1000 years.  By simulating the region’s climate in model calculations the authors found that the extra amount of greenhouse gases added by human activity likely resulted in higher temperatures and reduced precipitation in the region.  This factor also contributes to a high risk of continued severe droughts.
  • Williams and coworkers also conducted detailed analyses of climate-related data for California, from 1901 to 2014 (Geophys. Res. Let. 2015; DOI: 10.1002/2015GL064924).  From rigorous statistical analysis the authors estimated that global warming was responsible for 8-27% of the observed excess drought conditions for 2012-2014, and for 5-18% for 2014 alone.  These findings indicate that although drought conditions may originate from various climatic factors operating cyclically over many years, its full extreme extent in the current drought has been worsened by global warming, producing the current record conditions.
  • Cook and coworkers (Sci. Adv. 1, e1400082 (2015); published electronically 12 February 2015) assessed drought conditions in the American Southwest and Central Plains.  Assuming that unrestrained emission of greenhouse gases would continue, the risk of severe droughts in these regions is projected to be extremely high, by various measures between about 69% and 97% in the second half of this century.
The Report by the National Academies makes clear that climate science has advanced remarkably in the last decade, so that attributions of global warming as a contributing factor to extreme events can reliably be made after appropriate analysis.  This depends on use of one or both of the methods, either data based or model based, mentioned above.  The progress making this possible includes the availability of far more observational data, on the one hand, and constant improvements in climate models on the other.  As a result statements of attribution, when merited based on analysis, now authoritatively support the role of man-made global warming, due to humanity’s continued and increasing use of fossil fuels, in the increasing severity of various types of extreme climate and weather events.  We all, as citizens of countries around the world, must marshal our efforts to reduce emissions as aggressively as possible.  The goal should be achieving near zero annual emission rates within a few decades, say by mid-century.
© 2016 Henry Auer

Friday, March 4, 2016

The Centennial Commemoration of the 2015 Paris Climate Agreement. II.

A Fable

Paris is sparing no extravagance for the centennial celebration of the 2015 climate agreement, themed “Paris 2115”.  The Eiffel Tower is decked out with the newest efficient lighting fixtures, highlighting the sky blue of the United Nations flag, intermingled with the Tricouleur, the red, white and blue of the French flag.  Laser light shows projecting these colors playfully pierce the air around its spire.

The Étoile and Arc de Triomphe are adorned with exotic vegetation brought from far reaches of the planet, symbols of the preservation of the environment resulting from one hundred years of sustainable climate policies resulting from the agreement.

The most striking aspect of the celebration is that several hundred thousand people from all around the world have descended on The City of Light, to mark the centennial of the United Nations Framework Convention on Climate Change (UNFCCC) agreement limiting emissions of greenhouse gases.  The 2015 agreement enshrined the goal of keeping the increase in global average temperature to under 2ºC (3.6ºF) above the preindustrial temperature, i.e., the temperature before humans began burning fossil fuels.  The agreement also included the more stringent goal of keeping the rise below 1.5ºC as a more ambitious option. 

Just under 200 nations, all the U.N.’s members, joined the agreement.  Now the member nations are celebrating, for they had in fact summoned their resources and achieved the more stringent goal.  This required that restraint and discipline be applied by each nation, each independently of, but in concert with, the constraints developed by every other nation.  The 2015 agreement made these constraints voluntary, nation by nation.  It is remarkable that the member nations all accepted the responsibility of fulfilling their pledges, with records and validation open for all to see.  Indeed, since the original 2015 pledges were deemed inadequate to attain this goal, the nations repeatedly reconvened every five years, and intensified their efforts by developing ever more stringent reduction pledges.  The centennial we are now celebrating honors these pledge extensions.  Without these extra efforts we could not have kept the global temperature from increasing as little as it has today.

How did this come about?  After all, the energy needed for industrialization and raising living standards in developing countries, obtained almost entirely from burning fossil fuels, had underpinned their headlong rush to economic growth for more than a century.  The fossil fuel industry was a significant fraction of the world economy, and the fuel companies exerted their considerable political power to maintain the status quo, extracting ever more fossil fuels each year.  This path, called “business-as-usual”, would have brought the world to an average temperature rise of about 4ºC, a truly devastating result.

Governments the world over, working in collaboration with the fossil fuel companies and other segments of the economy, transformed the world’s energy sector.  Governments and company managements, realizing the dangers of continuing along a business-as-usual path, transformed their political frameworks and business models.  The companies came to realize that there was profit to be gained by developing and deploying renewable energy sources, and redirected their development budgets accordingly.  New research and great economies of scale made solar and wind energy, for example, economical yet highly profitable.  Energy storage was optimized with new battery compositions and physical storage modes.  People began to see new beauty in renewable energy installations.  In the meanwhile, biotechnology researchers developed genetically modified crop plants that withstand the stresses of heat and drought more effectively than the old wild strains.  Research ingenuity also optimized yields of biofuels to provide all the needs of the growing airline industry.

Our land transportation has also been revolutionized.  Self-driving vehicles now navigate e-highways, minimizing the need for extra weight to protect us from crashes.  They are powered by newly developed highly efficient renewable energy sources.

Sadly, several small island nations that signed on to the agreement in 2015 no longer exist, because their islands were swallowed up by rising seas over the intervening one hundred years.  Already by 2015 sea level had been rising because, averaged over the seasons of the year, more ice melted from polar ice masses into the ocean than was deposited by fresh snow and ice.  Rising seas were already locked in by then.  Indeed, by 2015 ice loss had been accelerating because temperatures over the ice masses were rising rapidly.  Now as we fete the centennial, many coastal regions around the world have been lost to ocean inundation.

Pingali, Richard and Hailong met each other last night at the Korean pavilion.  Paris 2115 is organized around these centers, representing each nation of the UNFCCC agreement, all around the city.  Each one displays highlights of the environmental and sustainability contributions they have made in the past hundred years that brought us to this week’s celebration.  The three new friends are circulating among the pavilions, trying to take in as many as they can, from countries large and small. 

The celebration reaches its peak tomorrow, as major personalities from the UNFCCC and various nations speak about the significance of this occasion, and the way forward.  Of course these speeches will be streamed live as holographic displays in all the pavilions, so that all the celebrants can experience the immediacy of the presentations.

                                      *        *        *        *

The Paris Agreement reached in December 2015 represents major progress on the path to controlling worldwide emissions of greenhouse gases.  All 197 U. N. member nations agreed to its terms.  This accomplishment is due in large part to departure from earlier attempts at negotiating a treaty involving imposing predetermined limits on emissions from each nation.  Instead the Paris Agreement solicits voluntary pledges from each which, once filed, are subject to review and verification by the U. N. 

Prior to the convening of the Paris meeting almost all nations had already submitted their pledges.  A scientific evaluation shows that those pledges are insufficiently ambitious to achieve the goal of keeping the global average temperature increase less than 2ºC during this century.  Climate model calculations by  Fawcett and coworkers (Science, 2015, Vol. 350, pp. 1168-1169) show that the current voluntary pledges will keep the annual


Actual (up to 2010) and projected annual rates of emission of CO2 from energy and major industrial sources from 1990 to 2100.  The heavy lines are summary representations for four emissions scenarios.  Top to bottom these are the reference case of no emissions reduction policy in place; no reduction policy up to 2030, then a 2% per year reduction in emissions; implementation of only the current voluntary pledges through 2030, continued unchanged to 2100 (curve labeled INDCs); and the current voluntary pledges to 2030, then further reduction by at least 5% per year to 2100.  The individual thin lines are actual modeling runs repeated many times.  IPCC, Intergovernmental Panel on Climate Change; AR5, Fifth Assessment Report issued 2013-4.
Source: Fawcett and coworkers, Science, 2015, Vol. 350, pp. 1168-1169; .


rate of CO2 emissions level at their present rates up to 2100 (curve labeled INDCs in the graphic above).  Since these are annual rates, the emissions will continue to raise the total accumulated CO2 level throughout this period, leading to a steady rise in global average temperature to 2100.  Only the lowest heavy blue curve shows a decreased rate of annual emissions after 2030, accomplished in the model by imposing a stringent reduction in annual emissions rate of 5% per year.  The accumulation of CO2 in the atmosphere continues, admittedly at lower rates, throughout this period.  As a result the global average temperature will still continue rising from its present (unprecedented high) value at a slow but measurable pace.

The Paris negotiators recognized this deficiency, and included the intention in the Agreement to reconvene in five years to assess progress and to encourage updated pledges including more ambitious emission reductions from the member nations.  It also mentions explicitly the more stringent goal that reductions should in fact be ambitious enough to keep the increase in global average temperature below 1.5ºC.

Some nations and provinces around the world have already undertaken efforts to lower greenhouse gas emissions. China’s pledge lays out increasing annual emissions until 2030, mainly from burning coal, then a reduction in that rate.  But the recent economic slowdown in that country appears already to be leading to lower emissions than anticipated.  As part of its pledge, China intends to expand pilot cap-and-trade limits on emissions in some of its cities to the nation as a whole.

Australia imposed a carbon pricing scheme in 2012, but it was repealed in 2014.  In addition Australia is now severely cutting back its spending on its respected government scientific research organization, including its climate science section.  This impedes the country’s and the world’s ability to track its greenhouse gases and temperatures.

The European Commission announced a plan in 2010 to reduce emissions by 80% below 1990 levels by 2050.  Europe implemented a cap-and-trade Emissions Trading Scheme (ETS) a decade ago as part of its participation in the Kyoto Protocol, the UNFCCC agreement preceding the Paris Agreement.  The ETS has had difficulties that are preventing it from achieving its full potential.

The U.S. federal government has been unable to enact laws to limit emissions because the majority party in one or both of the Congress’s chambers does not admit the need to address man-made global warming.  But President Obama has undertaken executive steps that will double fuel efficiency of the nation’s vehicles, and will increase the efficiency of electricity generation in electricity generation.  Independently, California and some other states have policies limiting emissions similar to the reduction intended by the European Commission.

In Canada, the province of British Columbia has had a revenue-neutral carbon tax in place since 2008.  Revenues collected from the tax are used to lower tax rates in other categories.  Use of fossil fuels has dropped with no effect on the province’s economy.


Implementation of the Paris Agreement of 2015 promises to turn our world from a warming disaster to a manageable, but palpably warmer, global environment.  But there are powerful political and commercial interests opposing the changes needed to stabilize the global climate.  Business models of large multinational energy companies need to change, such that they recognize that profits can be derived from producing renewable energy.  Deep-rooted psychological barriers also exist that resist our need to change our ways.  With good will and ambitious planning the fable represented by Paris 2115 may come to pass.
© 2015 Henry Auer