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".

Friday, May 27, 2011

Energy Efficiency in Public Buildings: The “Low Hanging Fruit” of Mitigation

Summary.  A conference on energy efficiency in public buildings was held recently in Connecticut.  Energy efficiency retrofitting projects represent an accessible and achievable contribution to reducing the demand for energy used in heating, cooling and air conditioning.  Contrary to other public capital projects or infrastructure development, energy efficiency retrofits avoid the need for bond funding, since the savings from the energy not used provide a short payback period as well as a mechanism for alternative financing.  The savings can be as high as 25-30% per year, once a project is completed.

Introduction.  A conference entitled “Leading by Example: Creating Jobs & Reducing Costs through Energy Efficiency in Public Buildings Across Connecticut” was convened on May 26, 2011, sponsored by the Emily Hall Tremaine Foundation of Meriden, Connecticut.

The rationales for holding the conference included

·        Recognition of the fact that no national energy policy has been enacted in the U. S., so that a single, nation-wide framework of policy and practices is absent;

·        Understanding of the importance of reducing the dependence of the U. S. on foreign sources of fossil fuels; such fuels are major sources for heating and electricity generation whose consumption can be abated by implementing energy efficiency; and

·        Realizing that in a time of economic hardship, it is important and advantageous to undertake projects such as improving the energy efficiency of public buildings as a way to create new jobs among a group of workers severely affected by unemployment.

Background.  The American state of Connecticut contains 169 municipalities.  Across the state, about one-fifth of the building stock houses government functions involving state or municipal jurisdictions.  This represents a significant portion of the total space heating and cooling demand found in the state.  Clearly, other states, indeed governmental bodies in most other countries in the world, have similar numbers of buildings in their jurisdictions that house the offices for carrying out their governing duties.  Thus it is clear that efficiencies created in public buildings will have a significant impact on the energy economy of the jurisdiction.

Energy Efficiency: Retrofitting of Existing Buildings.  Existing public buildings span a wide range of ages, and incorporate a broad range of construction practices reflecting many “generations” of building codes.  An estimate was cited in the day’s presentations that, according to the consulting firm McKinsey and Co., about $550 billion worth of energy renovation work on public buildings can be found in the U. S.  Generally, it is understood that significant savings in energy usage can be realized as soon as a retrofitting project is finished, resulting in short payback periods for recovering the costs of the project.

The Role of Energy Service Companies in Retrofit Projects.  Energy service companies (ESCOs) encompass those that engage in installing insulation; renovating windows; updating heating, ventilation and air conditioning (HVAC); updating lighting with low-energy devices, energy management systems, and more.  According to the National Association of Energy Service Companies (NAESCO), savings obtainable from energy efficiency projects (see the following chart)

                        Schematic diagram of savings envisioned for energy efficiency projects.
                        Source: NAESCO.  Reproduced with permission.

are considerable and immediate, leading to recovery of the costs invested in undertaking the projects in relatively short time periods.  After the payback period, the savings accrue indefinitely.  The ESCO industry’s history can be summarized as follows:
l      $40 billion in projects since 1990;
l      Growth by 12-fold over 1990-2007, for an annualized growth rate of 16%;
l      $50 billion savings – guaranteed and verified (see below);
l      330,000 person-years of direct employment;
l      $25 billion of  infrastructure improvements; and
l      420 million tons of CO2 savings at no additional cost.

According to NAESCO, the background and opportunities in the state of Connecticut include:
l      $200 million in state energy expenditures;
l      More than $200 million in local government energy expenditures;
l      30-35% savings feasible (US EPA);
l      Corroborated by ISE studies of CT buildings; and
l      More than $120 million in savings are available
(where the dollar amounts are presumed to be annual amounts).

Using a compounded-cost savings calculator available on the internet through the U. S. Environmental Protection Agency’s Energy Star program, NAESCO estimated that, for an annual savings of $100 million, with a duration of 15 years and an assumed interest rate of 4.5%, 90% of the total accumulated savings is almost $1 billion.  These savings are guaranteed and verified (see below).  Over this time it is estimated that CO2 emissions are reduced by 10.5 million tons, again involving no net investment of public funds (see below).  Among other purposes, this amount could be reinvested in further energy efficiency, carbon emissions reductions, or other infrastructure projects without increasing the capital and operating budgets at the time of the original efficiency project.  Such projects produce 9,500 new jobs directly involved in the work, and an additional estimated 11,400 jobs indirectly stimulated.

Financing Energy Efficiency Projects: an Alternate Paradigm.  Typically a government entity intending to undertake a capital or infrastructure project must obtain bonding authority from the jurisdiction involved, creating an obligation by the entity to pay the interest and principal to maturity of the bonds.  Energy efficiency projects provided by ESCOs offer a second, highly advantageous funding mechanism that avoids the need for issuing bonds.

ESCOs commonly offer to work on a project under an Energy Service Performance Contract (ESPC).  There are two models for ESPCs, in both of which the ESCO undertaking the project participates directly in the funding and guarantees that the completed project will afford the savings stream envisioned at the outset.  In one, Guaranteed Savings Financing (see the diagram below) a lender and the ESCO

                       Source: NAESCO.  Reproduced with permission.

together assume the risk burdens of the project, with the ESCO assuming the performance risk with savings guarantees.  In the second, Shared Savings Financing (see the diagram below), the ESCO assumes both credit risk as well as the performance risk

                       Source: NAESCO.  Reproduced with permission.

and the project is undertaken under a lease arrangement rather than an ownership arrangement.  Shared savings financing is more expensive due to the higher risks incorporated in the financial structure.

“Leading by Example”.  The title of the conference, “Leading by Example”, reflects the fact that in the United States, there is no integrated policy of energy objectives and practices that address global warming.  Three regional greenhouse gas accords have been set up involving many American states and Canadian provinces: the Western Climate Initiative, the Midwest Greenhouse Gas Reduction Accord, and the New England and mid-Atlantic Regional Greenhouse Gas Initiative.  These programs have varying levels of coverage and differing terms duration.  Actual implementation requires that each participating state or province pass its own legislation in order to put the terms of the agreement in force.  These factors obviously render compliance complicated and regionally inconsistent.  Commercial and industrial activity is impeded by not having a single national policy covering the countries in question.

In the face of this situation, there is widespread recognition that improving energy efficiency offers an inexpensive and achievable way to begin efforts at mitigating the emission rate of greenhouse gases that produce global warming.  For example, the European Union’s Energy Roadmap for 2050 places considerable emphasis on energy efficiency as a component in achieving the Roadmap’s objectives.  The conference reviewed here is a state-level approach to accomplishing energy efficiency, and has the support of the governor of Connecticut.  In passing let us note that on May 26, 2011, Governor Chris Christie of New Jersey also promoted energy efficiency as one component of achieving reductions in greenhouse gas emissions, even as he announced withdrawing his state from participation in the 10-state Regional Greenhouse Gas Initiative.

Conclusion.  Energy efficiency retrofits in public buildings represent a feasible and achievable contribution to our efforts at reducing emissions of CO2 as a greenhouse gas.  The technology is available and does not require the development of new practices or devices.  The financial advantages are considerable, since significant savings are available, and they can be considered to accumulate with compound interest to provide additional assets for further climate mitigation projects.  The economic advantages are considerable, for new jobs are created that can be filled without requiring new training or skill development.  Efficiency projects in public buildings should be undertaken with existing policies.  They will additionally provide incentives to extend efficiency projects into the commercial and residential realms.
© 2011 Henry Auer

Thursday, May 19, 2011

America’s Climate Choices: The U. S. National Academies Report

Summary.  The U. S. National Academies has issued a report, America’s Climate Choices, assessing climate change and strongly recommending that steps be taken to address it.  These include a) substantially reducing greenhouse gas emissions with great urgency, b) beginning societal efforts to adapt to global warming already under way, c) supporting research in climate change, d) developing new information systems useful to inform the public about this issue, and to actively involve the public in policy development, and e) coordinating our global warming initiatives with other efforts worldwide.  The report urges that iterative risk management, a repetitive cycle of policy development and implementation, be employed in these efforts.  It is urgent to begin these measures right away in order to avert even more serious consequences than have already happened.

Introduction.  The global average temperature, measured over the long term, has been increasing since the beginning of the industrial revolution.  The trend has become more pronounced in recent decades, and is forecast to continue increasing even more strongly in the future because of humanity’s increasing demand for energy and a growing global population.  This increase in temperature correlates with, and is due to, the increased burning of fossil fuels for energy by mankind.  Fossil fuels, coal, oil and natural gas, are all carbon-based and emit carbon dioxide (CO2), a principal greenhouse gas, into the earth’s atmosphere in direct proportion to the amount of fuel that is burned.

The nations of the world have gathered, starting in the early 1990’s, to try to reach agreement on limiting emissions of greenhouse gases under the United Nations Framework Convention on Climate Change (UNFCCC).  The two most recent meetings, in Copenhagen in 2009, and Cancun in 2010, adopted the goal of limiting the atmospheric concentration of CO2 and other greenhouse gases to the level that would constrain the overall increase in global average temperature to 2ºC (3.6ºF) above the level that prevailed prior to the start of the industrial revolution.  The nations of the world, however, have not been able to agree on adopting the requisite measures that would result in achieving this goal.  The Kyoto Protocol of 1997 committed industrialized countries to reduce annual emission to at least 5 per cent below 1990 levels in the commitment period 2008 to 2012.  Developing countries were excluded from coverage under Kyoto.  Although many signatory nations agreed to the Protocol, the U. S., by refusal in the U. S. Senate, opted not to be bound by the Protocol.

Present World Status.  The European Union (EU), which had joined the Kyoto Protocol, recently issued its report Roadmap for moving to a competitive low carbon economy in 2050”.  The Roadmap expands on the EU’s previous goal of reducing its rate of  greenhouse gas emissions by 20% below the levels of 1990 by the year 2020.  The goal in the Roadmap is the stringent restriction of reducing the greenhouse gas emission rate by 80 to 95% from the emission rate of 1990, by 2050, as recommended by the Cancun Agreement.  The Roadmap details numerous pathways and practices to attain that goal.

The Great Britain is reported to be setting still more rigorous objectives for itself of reducing greenhouse gases emission rates to 50% of the amount emitted during 1990 by 2025.  This is a considerably deeper reduction than the EU has set, and is more stringent than that of any similar-sized country, such as Germany.

China’s 12th Five Year Plan, covering 2011-2015, envisions overall expansion of its production of energy and consumption of fossil fuels, especially coal.  Its emphasis is on increasing the efficiency of its use of energy, resulting in lower energy intensity, i.e., the amount of energy needed for a fixed amount of its economic output.  Renewable energy other than hydroelectric generation constitutes a very small part of China’s energy economy, but under the Plan this sector is intended to expand rapidly.

Present Status in the U. S. The United States is the only major emitter of greenhouse gases without a national energy and climate change policy in place.  Ever since the Senate’s rejection of the Kyoto Protocol, numerous legislative efforts have been made to establish a policy that addresses climate change, but have failed.  In the resulting vacuum at the national level, three regional greenhouse gas agreements have recently been adopted among various American states and Canadian provinces—the Western Climate Initiative, the Midwest Greenhouse Gas Reduction Accord, and the New England and mid-Atlantic Regional Greenhouse Gas Initiative.  These programs have varying levels of coverage and differing terms duration.  Being agreements between sovereign states and provinces, actual implementation requires that each participating state or province pass its own legislation in order to put the terms of the agreement in force.  These factors obviously render compliance complicated and regionally inconsistent.  Commercial and industrial activity is impeded by not having a single national policy covering the countries in question.

U. S. National Academies Report: America’s Climate Choices.  The National Research Council, a section of the National Academies, issued its report, America’s Climate Choices, on May 12 2011 (see Note 1).  The report is summarized here, and further details are presented below under the heading Details.

The Earth is warming, and will continue to do so.  The report summarizes known climate science and develops forecasts of future trends using three emissions “scenarios”.  Since the industrial revolution, the time trends of a) mankind’s burning of fossil fuels, b) increasing atmospheric concentrations of the greenhouse gas CO2, and c) increasing average global temperatures all follow similar, linked paths.  For these and other reasons global warming is understood to be due to the man-made emissions of greenhouse gases.  Using computation-based climate models and three scenarios of further emissions of greenhouse gases, the report predicts worsening trends of scenario-dependent increased global warming in the future, and its consequences for the earth and for us, its inhabitants.

Recommendations. The report makes several recommendations.  It emphasizes that, in view of the long time period involved in combating global warming, repetitive cycles of identifying problems, developing goals, creating policies and practices to achieve the goals, and assessing attainment of the goals, will necessarily be involved.  The report calls this process iterative risk management.  It is highly recommended by the report because many aspects of climate change, the models used for predicting future trends, and the models used to predict effects of policies and practices, are complex and imperfect, and are likely to improve with time.

First, the report recommends substantially reducing greenhouse gas emissions.  This is considered a matter of great urgency, to be begun without delay.

Second, the U. S. government in conjunction with other levels of government and members of the private realm should begin efforts for adapting to the effects of global warming now.  Its effects are already being felt.  Society should begin practices and development of infrastructure to deal with these and further adverse effects of warming, those that we already know about and those that remain to be identified.

Third, the U. S. government should invest in the science of climate change.   Research into understanding climate change and predicting its effects are needed to limit its progress and to adapt to its effects.

Fourth, the U. S. government should sponsor development of new information systems that promote informing the public as to the choices confronting us concerning measures and policies addressing climate change.

Fifth, in the U. S. the response mechanism should include widespread deliberations among the public in order to develop and implement public policies, and review them regularly.

Sixth, the report recognizes that the U. S. is not alone in dealing with global warming, but that it is in fact a planet-wide challenge requiring coordinated efforts around the world.  Therefore the U. S. should actively participate in world-wide responses to climate change.  These must address reducing greenhouse gas emissions, improving adaptation policies, and developing effective reporting modalities.

Seventh, it should be the role of the U. S. government to coordinate the development and implementation of America’s varied responses to global warming.  Presently several response mechanisms are being created at the municipal, state and regional levels.  These risk lacking cohesion and creating mixed, if not conflicting, response mechanisms.  The federal government has a leading role to play in this endeavor.

Conclusions.  America’s Climate Choices affirms the broad acceptance in the scientific community that global warming is due to atmospheric emissions of man-made greenhouse gases, predicts that warming and its effects will worsen in the future without action, and outlines broad policy recommendations to address this issue.  As noted by both supporters and opponents, the report does not make specific recommendations concerning the nature of policies to put in place and actions to take (see comment in the New York Times).  This cannot be considered a critical failing.  The report rather urges us to action, leaving the details of what actions to take up to us, the public and our elected representatives, and to America’s corporate citizens.

The report stresses the necessity to address global warming using the tools of risk assessment, since the computational climate models are probabilistic in nature, and other factors, including the nature of human and economic behavior, are poorly modeled in these terms.  The report points out that in our ordinary lives, we buy insurance (at some economic costs) to protect against a perceived risk that has a relatively low probability of coming to pass (providing some economic benefit). 

A pertinent example that comes to mind, at the time of this writing, is the flooding along the Mississippi river now happening.  This nation has invested major financial resources to “buy flood insurance” in the form of erecting the vast levee system along the river.  The levees are our insurance policy, countering the risk of major economic and societal disruptions from flooding were they not in place.

Finally, the report stresses the necessity of early and meaningful action.  Delay only makes the problems facing humanity in confronting global warming more critical on the short term, leading perhaps to greater expenditures and a greater possibility of being too late to avert major consequences.


Historical Climate and Energy Patterns are Closely Correlated.
The annual average values of global temperature have been increasing since the beginning of the industrial revolution, when humanity began burning fossil fuels in earnest to supply its energy.  This is seen in the following graphic which shows

Copyright © National Academy of Sciences; reproduced with permission.

year-by-year global average temperatures from 1880 to 2010 (black squares and lines), and smoothing obtained by averaging each year over a window of five years (red curve).  It is seen that global temperatures have increased about 0.8ºC (1.4ºF) over the 130 years shown and are increasing more rapidly as the curve approaches the present.  Most of this change, about  0.6ºC (1.0ºF), has occurred in the last 30 years.

The shape and duration of the temperature dependence on time mirror closely both the accumulated total of CO2 released by burning fossil fuels over this time period (navy blue curve and amounts on the right axis), as well as the measured increase in concentration of CO2 in the atmosphere (magenta curve and amounts on the left axis), seen in the following graphic. (Note that the curves are compressed toward the right, compared to FIGURE 2.1 because the time axis here extends from 1800 to 2010.)

Copyright © National Academy of Sciences; reproduced with permission.

The preponderance of the scientific evidence supports that the temperature increase is man-made, due largely to the use of fossil fuels.  According to the report, the atmospheric concentration of CO2 is now higher than at any time in at least the last 800,000 years (citing D. Lüthi, and coworkers, Nature 453:379-382, 2008).

In the U. S., the adverse effects of the warming already experienced have led to increased temperatures, increased overall precipitation by about 5%, rising sea levels that erode shorelines and damage wetlands, thawing of Alaskan permafrost, reductions in mountain snowpacks that affect water flow in rivers, altered precipitation patterns including increased intensity coupled elsewhere with increased aridity, and substantial increase in number and seasonal length of wildfires.

Climate Predictions for the U. S.  The report predicts future climate trends to 2100 using a variety of computational global climate models particularized to the U. S., and three greenhouse gas emission “scenarios” drawn from the U. N. Intergovernmental Panel on Climate Change.  Results are shown in the following graphic, for, bottom to top, the case of continuing emissions along a trajectory from the 20th century (green line); “lower emissions” (blue line); “higher emissions” (orange line); and “even higher emissions” (pink line).

Copyright © National Academy of Sciences; reproduced with permission.

The solid heavy black lines at the left are the actual historical data up to about 2008.

These images represent annual rates of adding CO2 from burning fossil fuels to the atmosphere (left panel), where for each year the height of a curve represents how much is added during that year only, and the cumulative amount of CO2 present in the atmosphere (right panel), where each year’s value on a curve represents the total amount added from the beginning of the model up to the year in question, added to the base level of CO2 at the beginning of the industrial revolution.

To help understand the left and right panels above, let’s imagine a bathtub filling with atmospheric CO2.  The left panel above can be considered the faucet, adding CO2 to the tub.  The right panel can be considered the bathtub, filling higher and higher with more and more CO2 with each year.  This is because the drain is mostly closed so that most of the CO2 is retained in the tub.

The effects of the predicted atmospheric CO2 concentrations (right panel) on predicted global temperature deviations from an average baseline over 1950-1970 is shown in the following graphic for, bottom to top, the “lower emissions scenario”, the “higher emissions scenario” and the “even higher emissions scenario”.

Copyright © National Academy of Sciences; reproduced with permission.

In the graphic above, the jagged black line from 1900 to 2010 shows the actual temperature deviation.  The green line shows a model simulation for the same time period, indicating that the model reproduces observed temperatures well.  This gives confidence in the use of the model.  The colored lines from 2010 to 2100 are the same scenarios as in FIGURE 2.3.  They show the results of modeled temperature increases for each case.  In none of the scenarios does the temperature stop increasing.  Additionally, no significant differences between the scenarios become apparent until about 20 years from now.  I.e., we in the U. S. will not be able to know until then whether adopting one or another of the scenarios will have serious consequences.  The report points out that this is a serious risk of continuing on a “business as usual” emissions trajectory.

The report also  points out that these various trajectories carry with them numerous known and unknown climatic risks due their impacts on life and the physical world.  A few examples of predicted changes include worse heat waves; global sea level rise; bleaching and loss of coral reefs; greater aridity in the Southwest; effects on agriculture due to higher photosynthetic activity, temperature, precipitation, and insect infestations; changes in forest species prevalence; and public health and economic risks including dangers from extreme weather events.

Managing Environmental Risk.  In addition to the above predictions, which can be modeled reasonably well, the report points out that many of the effects of global warming are less capable of being modeled or estimated.  As a result they need to be analyzed by methods of risk assessment, which ultimately needs to be done on a societal level, involving serious consideration in the scientific, political and public realms.  Costs and benefits of actions cannot easily be evaluated.  If we choose to implement certain actions to counter global warming, their costs are felt right away, but the intended benefit may not become evident for many years, and both aspects may affect future generations of people. 

Iterative Risk Management Approach.  For these and other reasons the report recommends following a cycle of trying particular measures, assessing whether and how effectively they work, and changing or reinforcing the measures depending on the outcome.  This is termed iterative risk management, and is illustrated using the following graphic.

Copyright © National Academy of Sciences; reproduced with permission.

We Need to Begin Acting Now. As shown in the report, climate change due to man-made emissions of greenhouse gases is already occurring.  Delaying efforts to reduce emissions means later measures would have to be more dramatic, immediate, and expensive.  Delay also increases the risk of being left with adverse effects that can’t be reversed.  Immediate action is necessary because the main greenhouse gas, CO2, persists in the atmosphere for centuries or longer so that its effects on global warming will persist.  The U. S. and the rest of the world are currently installing new energy facilities, many of which will continue to emit greenhouse gases, which risks making global warming worse.  All these considerations point to the need to begin reducing greenhouse gas emissions right away.

Note 1. The report is the result of a legal mandate enacted by Congress in 2008 and is to be delivered to it for its consideration.  Congress directed the National Academy of Sciences to “investigate and study the serious and sweeping issues relating to global climate change and make recommendations regarding what steps must be taken and what strategies must be adopted in response to global climate change”.  America’s Climate Choices summarizes and develops recommendations based on four preceding reports issued under this mandate that present aspects of this topic in greater detail.  These are:
Advancing the Science of Climate Change;
Limiting the Magnitude of Future Climate Change;
Adapting to the Impacts of Climate Change; and
Informing an Effective Response to Climate Change.
The reports were prepared by a large panel of experts drawn from the academic realm, nongovernmental organizations, governmental agencies, and the commercial world.  Each report, including America’s Climate Choices, was reviewed by several outside experts likewise drawn from these three areas of society, and finally approved by the National Research Council.

© 2011 Henry Auer

Tuesday, May 10, 2011

Decreased Worldwide Crop Yields Are Tied to Global Warming

[Note: This post is revised from the original version posted May 10, 2011 by the addition of the section on the article by Zhao and Running.]

.  Climate scientists model global climate trends showing varying regions of increased temperature in some regions, and increased rainfall or aridity in differing regions of the world.  Recently rigorous statistical analyses have shown that increased global temperatures are responsible for extreme rainfall and flooding events.  In May 2011 Lobell and coworkers showed that increased average global temperatures over the period 1980-2008 are responsible for decreased crop yields of the staple crops maize and wheat.  The resulting shortages lead to significant worldwide modeled increases in prices for these commodities.  This results in increased hardship for those populations of the world living at or near poverty.  This economic argument provides a strong incentive to develop new economic activity by investing in renewable, carbon-free sources of energy.

Introduction.  The global average temperature, measured over the face of the earth over year-long intervals, has been increasing since the beginning of the industrial revolution.  The trend has become more pronounced in recent decades, and is forecast to continue increasing even more strongly in the future in the absence of action to reverse the trend.  This increase in temperature correlates with, and is due to, the increased burning of fossil fuels for energy by the nations of the world.  Fossil fuels, coal, oil and natural gas, are all carbon-based and emit carbon dioxide (CO2), a greenhouse gas, into the earth’s atmosphere in direct proportion to the amount of fuel that is burned (although the different fuels yield differing amounts of CO2 on combustion). 

Global Warming and Extreme Weather. Climate scientists, on the basis of elaborate computational models of long-term climate trends covering the entire planet, predict varying degrees of temperature increases, and changes in rainfall and snowfall patterns, for different regions of the globe.  Some regions may become warmer and more arid, while others may experience more rainfall.  The phenomena are likely to produce extreme weather events, whose consequences can be very costly to the populations subjected to their damaging effects.  For this reason global warming has a strong potential for causing severe economic distress in ways that nations will not have prepared for.

Until recently we have only treated news reports of extreme weather events as anecdotes, without necessarily saying they might have been due to, or made worse by, global warming.  Examples that come to mind include drought and increased forest fire activity in the American west, increased incidence of strong hurricanes in the Caribbean region, the devastating monsoon flooding in Pakistan in the summer of 2010, and droughts in Russia and Siberia in recent summers leading to pronounced reductions in wheat harvests across the region.

Extreme Weather Is Directly Caused by Global Warming.  Recently climate scientists have conducted rigorous statistical analyses specifically to determine whether extreme events, whose probabilities of occurrence are necessarily very small, are correlated with global warming.  Two peer-reviewed reports that were published in the authoritative journal Nature in February 2011 were able to draw exactly such conclusions.  In one report (see Note 1), a decades-long study of temperature and precipitation patterns across the entire Northern hemisphere, from 1951 to 1999, concluded that long-term patterns of increased precipitation were statistically linked with the increase in global temperature caused by human activity. In the second report (see Note 1), a particular devastating flood in a region of England in October-November of 2000 likewise could be directly attributed to man-made global warming determined over the period 1957-1999 preceding the flood.  In a tutorial fashion, a post on this blog seeks to make understandable how changes in atmospheric temperature can contribute to changes in precipitation patterns, while acknowledging that other factors also enter into an understanding of these changed patterns.

In this post we present a new report concerning the role of global warming in reduced crop yields affecting the harvest of important staple foods around the world.

Global Warming Reduces Harvest Yields of Staple Crops.  The important journal Science published a peer-reviewed report by Lobell, Schlenker and Costa-Roberts online on May 5, 2011 (10.1126/science.1204531; see Note 2), in which the authors examined whether any correlation is found between temperature, rainfall amount and crop yields for the four staples maize (corn), wheat , soybeans and rice.  They analyzed temperature and rainfall patterns during the growing seasons locally at all places on Earth for which records of raising any of these crops exists, over the period 1980-2008, using data from 1960-2000 as a reference (see Note 3).  Models were created for this analysis that characterized the relationship between the weather-related variables and crop yields.  The authors found that, for all regions yielding these crops, except in the United States, the time-averaged global yields of maize and wheat declined, by 3.8% and 5.5%, respectively, compared to models that did not incorporate the time trends observed for temperature and rainfall.  The results for soybeans and rice had regions with increased yields and regions with decreased yields, which largely compensated one another over the globe, resulting in no clear trend.

Over the period 1980-2008 the measured concentration of CO2 in the atmosphere increased from 339 to 386 parts per million (ppm; volumes of CO2 per 1,000,000 volumes of air).  Experiments by other researchers suggest that this increase in CO2 could have produced a “CO2 fertilizer effect”, increasing yields by about 3% over the measured time period, because plants use the extra CO2 in the air to grow faster.  The results show that, if a positive CO2 fertilizer effect occurred, it was exceeded by the negative effect of the warming of the planet.  The authors also point out that the decreased yields prevailed over any improvements in agricultural technology that may have been implemented over the 28 year period examined.

The importance of global warming includes the adverse effects it inflicts on humanity, especially on economic activity.  The authors have estimated the impact of the decreased yields of maize and wheat, using worldwide economic models drawn from the published literature.  They estimate that average commodity prices would increase by about 19% if the CO2 fertilizer effect is not taken into consideration, and by about 6% if it is.

Details.  The surface of the earth was divided into grids having 5 deg of latitude and longitude on a side.  At the equator this corresponds to a grid plot about 5.8 miles (9.3 km) on a side.  For each of the four crops a grid location was included if the grid produced more than a minimum amount of the crop in question.  Temperature and rainfall records for the growing season in each grid were analyzed.  It was found that little difference existed for rainfall records between 1960-1980 and 1980-2008 for any of the crops, but that temperature increased significantly for all the crops between these two time periods.  On a projection of the earth, the temperature increased significantly in most regions depicted, but rainfall across the globe was increased modestly in some regions and decreased modestly in others.

The Supporting Online Material (Note 2) explains the mathematical modeling used in this report.

Crop trends are depicted for major country producers for each of the four staple crops.  For rice the major producers showed slight decreases but these were exceeded by 5-95% confidence limits, so that no trend was considered to be significant.  For soybeans the yields for the major producers were mostly negative, by 5-8%, but again the confidence limits were large and removed the results from significance.   The results for maize showed large, significant, decreases of about 3% to about 8% for China, Brazil and France, with narrow confidence limits.   For wheat, China, India, and France had decreased yields in the 2% to 6% range, and for Russia the decrease was about 14%, all with narrow confidence limits suggesting significance.  For maize, wheat and soybeans, the U. S. is a major producer but showed minimal change in crop yields for each. 

Global Warming Reduces Total Worldwide Use of Atmospheric Carbon Dioxide in Green Plants.  In a publication by Zhao and Running (Science Vol 329, pp. 940-943, 2010; see Note 1) the total amount of CO2 taken up by green plants, and converted into vegetable matter, was tracked globally by area grids from 2000 to 2009.  Over the decade, year-by-year, the changes in total CO2 taken up, while fluctuating, declined by about 1% of the total amount.  The pattern of year-by-year changes tracks remarkably precisely with the changes in atmospheric concentrations of CO2.  On a global projection map coded by the amount of change in total CO2 absorbed, most of the decrease, and the most dramatic decreases, occur in the Southern Hemisphere.  Comparing the Northern Hemisphere with the Southern Hemisphere year-by-year, the changes in total CO2 taken up and a standardized measure of the severity of droughts track each other closely in the Southern Hemisphere; the Northern Hemisphere shows less striking variations.  Significantly, in addition, the global total CO2 taken up decreases as the global temperature increases. 

This article is generally consistent with the results on crop yields described by Lobell and coworkers, above.

The authors conclude that the decrease in global total CO2 absorbed “potentially threatens global food security and future biofuel production and weakens” the ability of vegetated land areas to absorb additional CO2 that arises from burning fossil fuels.

.  Contrary to earlier unsubstantiated surmises that global warming may possibly be a cause for weather extremes, the recent published scientific reports described here and in earlier posts establish with statistical rigor that this in fact is occurring.  Extreme rainfall and flooding cause major economic harms, both in human effort involved in emergency response, and in recovery and reconstruction efforts.  And in those cases mentioned anecdotally in the introduction, even if statistical causation has not been established, one can reasonably attribute at least a fraction of the economic impacts, say 20-40% for sake of discussion, to the extreme character of the event brought on by global warming.

Regardless of one’s attitudes or beliefs concerning global warming due to humanity’s burning of carbon-containing fossil fuels, the adverse economic consequences of extreme weather events provide a strong incentive to undertake remedial actions as soon as we can.  It’s better to invest in alternative energy sources in order to decarbonize our energy economy than it is to have to spend emergency relief funds on about the same scale when an extreme event occurs.  Investments in renewable energy sources and their operation provide new job opportunities that promote a vibrant economy.  To the extent that such measures would contribute to lessening global warming and its adverse consequences, human misery around the world would be considerably diminished.

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Note 1. Abstract available online free, or the full article for a fee or through personal or institutional subscription.  Many public libraries, and university libraries open to the public, receive the journal.

Note 2.  Supporting Online Material, referred to in the text of the article, is available at 

Note 3.  A simple tutorial of the scientific method used in climate science is available here.

© 2011 Henry Auer

Thursday, May 5, 2011

Wind Energy: A Growing Source of Renewable Energy

Summary.  Wind energy plays a small but growing role in the world’s energy economy.  The European Union has the objective of reducing greenhouse gas emission by 80-95% by 2050.  China’s 12th Five Year Plan, covering 2011-2015, includes the goal of rapidly expanding its presently small wind generating capacity.  The United States, with no national energy policy currently in place, has several short term fiscal incentives to stimulate private development of renewable energy including wind energy.


The burning of fossil fuels is recognized as being a major contributor to the increase in man-made greenhouse gases accumulating in Earth’s atmosphere.  The United Nations-sponsored Intergovernmental Program on Climate Change and other organizations conclude that the increase in greenhouse gases leads to warming of the average global temperature, which is predicted to produce several adverse consequences impacting our life on the planet.

The world’s nations have gathered in conference to attempt unified responses to the threats posed by global warming.  The most recent was the Cancun conference in November 2010.  In response to the perceived problem, most nations have undertaken to slow the growth of atmospheric greenhouse gases, and even to achieve a leveling off of their concentration at a new, elevated, level.  This involves ambitious programs to reduce burning fossil fuels, and to substitute alternative sources of energy in their place.  One contribution to this endeavor is large scale development of wind power for generation of electricity.  Aside from the energy required to manufacture the wind turbines used and the transmission lines that carry the resulting electricity, wind power is deemed to have no emissions of greenhouse gases when operating.

In this post development of wind power is described in Europe, China and the U. S.

Wind World-wide

According to the Global Wind Energy Council, world-wide wind generating capacity for electricity is predicted to grow to a total of about 450 gigawatts (billion watts, GW; see Note 1) within 5 years, and to about 1,000 GW in 10 years (reported by BTM Consult ApS).   At present the world-wide generating capacity is almost 200 GW, which is 22.5% higher than in 2009.


The European Union (EU) has 27 member nations.  The European Commission, its executive body, issued its Roadmap for moving to a low carbon economy in 2050 (see the post) on March 8, 2011.  The goal set forth in the Roadmap is to reduce greenhouse gas emissions by 80 to 95% from the emission level of 1990, by 2050.  The Roadmap builds on an earlier EU initiative to reduce greenhouse gas emissions by 20% by 2020.  Achieving these objectives requires concrete policy decisions to be implemented in each of the member nations.  It envisions reductions in emissions of 1% per year until 2020, then 1.5% per year from 2020 to 2030, and finally 2% per year until 2050.  These should provide about 25% reduction in emissions by 2020, about 40% by 2030, and about 60% reduction by 2040.  This is shown in the following graphic.

Relative greenhouse gas emissions charted at 5 year intervals by economic sector.  Actual results shown through 2010; projected results thereafter.  The red line shows projected results using policies in place prior to the Roadmap.  The remaining projections include technologies and policies to be implemented under the Roadmap.  Source: European Commission, “A Roadmap for moving to a competitive low carbon economy in 2050” March 8, 2011

The Roadmap envisions major reductions in emissions coming from the electric power sector, by developing renewable sources including wind power.  Today all renewable sources for power generation in the European Union are already 45% of the total; the Roadmap envisions virtually 100% renewable power by 2050.
In the near term, the members of the EU have the goal of generating 21% of their electricity from renewable sources by 2010.  As seen in the graphic below, slightly less than half of non-hydro renewable electricity generation in 2005 was from wind energy.

Historical renewable electricity energy provided by sector in Europe, 1990-2005, Twh/yr (billion Kwh).
Purple, cross striped (narrow band at top): Offshore wind.
Purple, vertical stripes: On-shore wind.              Yellow: Solar photovoltaic cells.
Orange-brown cross striped: Geothermal electricity.
Gray cross striped: Biowaste.                 Green, dotted: Solid biomass.                Pink: Biogas.
Source: European Commission, Renewable Energy Road Map, 2007

Although most wind energy in Europe is land-based, off-shore wind energy projects are also being developed, mostly in the North and Baltic Seas.  A European transnational grid is being developed to connect these resources.


China recently released its 12th Five Year Plan, covering the years 2011-2015, including its plans for expanded energy production and use.   The five year plans are determined by the central government, and their implementation likewise is administered centrally. 

From 2010 to 2015, overall electric generating capacity will increase from about 1000 GW to about 1400 GW (see Note 1).  This increase includes a major and growing amount of generating capacity from coal, a very slight increase in hydroelectric generating capacity, and increases totaling about 1% of total capacity in 2010 to about 3% of total capacity in 2015, for renewable energy. 

According to a cited report from the Chinese Wind Energy Association, China is adding wind-generated electric power to its energy mix at a rapidly expanding pace, even as the share that wind generation contributes remains quite small.  At the present time, China’s total wind generating capacity is 45 GW.  It added 18.9 GW of new capacity in 2010, representing a 73% increase over the previous year.  Under the 12th five Year Plan covering 2011-2015, China plans to install 70 GW of new wind generating capacity by 2015, and for the following five year plan, 150 GW by 2020. 

Much of this new wind capacity is manufactured within the country.  Sinovel Wind Group Co. is a specialized enterprise that manufactures on-shore, off-shore and intertidal wind generators.  In 2010 it provided 4.4 GW of capacity, making it the largest wind manufacturer in China, and No. 2 in the world.  The company has subsidiaries placed in Spain, Australia, Canada, the U.S.A. and Brazil.

According to the International Energy Agency’s World Energy Outlook 2010, during the period 2008-2035 about 9% of newly added energy demand in China will be delivered by renewable sources other than hydroelectric, including wind.  However, as noted above, the majority of the increases remain fossil fuel-derived energy.

United States

The U. S. is the only major emitter of greenhouses in the world without a national energy policy in place.  The U. S. Environmental Protection Agency is in the process of preparing administrative rules governing emissions in an atmosphere of active political debate and concerted opposition from affected interests.   As of 2010 35 states and the District of Columbia have put renewable portfolio standards, mandates or goals in place, which would govern the role of renewable energy sources within their respective boundaries.  Since the various programs differ, and 15 states have no policy in place, this creates a disparate and confusing regulatory framework across the country.

As of 2009, the role of wind power in the generation of electricity (excluding transportation and building heating) is shown in the following graphic

It is seen that wind generation accounted for 1.7% of all electricity generation in the U. S., as of 2009.  (It is worth noting in passing that solar energy contributed a very small amount to electricity generation.)

According to the American Wind Energy Association, 35% of newly added generating capacity in the U. S. since 2007 is wind power.  The annual rate of increase in wind-based electricity generating capacity was 61% in 2008 and 28% in 2009.  The net summer electricity generating capacity in the U. S. is shown in blue in the following graphic.
Total wind energy generation (green line, left scale) and net summer generation capacity (blue bars, right scale) in the U. S. 1999-2009. Source: U. S. Energy Information Agency  

It is seen that installed power generating capacity (blue) and total energy generated from wind (green; see Note 1) are increasing rapidly.  Nevertheless, according to the U. S. Energy Information Agency (USEIA), wind generation constituted less than 1% of the total energy consumed in the U. S. in 2009.  Based on the average electricity usage per household in 2008, the total energy generated by wind in 2009, 73,700 million Kwh, would have been sufficient to supply the electricity needs of 6,700,000 households (see Note 2).  The wind energy generated in 2009 represents 5.4% of all residential electricity used
in the U.S. in 2009.

A projection by USEIA of generating capacity that may be installed in the coming years is shown below. 

Source: U. S. Energy Information Administration

Planned wind energy installations are shown in lavender.  It is seen that as of the date of preparation, 2009, wind facilities decrease significantly after 2011.  This may reflect the expiration of tax incentives explained below.  From the point of view of combating the emission of greenhouse gases, projected new installations fueled by fossil fuels (coal, red; and natural gas, orange) are much larger and highly significant.  Newly commissioned fossil fuel plants will continue in operation for several decades, making continued additions to the atmospheric burden of greenhouse gases each year.

The USEIA projects an increased role for renewable sources in the generation of electricity over the coming decades, increasing to 17% of overall electricity production by 2035 , up from 9% in 2008; wind power will be a major contributor to this growth.  A strong impetus for use of renewable sources is to contribute to the decarbonization of our energy economy.  This is viewed as a significant factor for minimizing the effects of global warming.  In general, the capital costs for installing renewable sources, including wind, are evaluated as being more costly than fossil fuel-driven sources.  Much of this cost comes from the fact that land areas in the U. S. that provide abundant sources of renewable energy, such as wind and solar power, are distant from the ultimate consumers, so that costly transmission lines must be built.  But balancing this initial outlay, the cost of operating the facilities is much lower once built, since no fuels need to be purchased.

These effects may be overcome by continuing to offer favorable tax credits for installing new renewable energy facilities.  The Federal Renewable Electricity Production Tax Credit has contributed to an eight-fold increase in wind energy production in the years  since 2001.  The Federal Energy Policy Act of 2005 provides interest-free financing to government entities intended for wind energy.  The USEIA projects that extending this credit beyond its expiry would have a significant favorable effect going forward.  Additional factors guiding installation of new renewable generation facilities are the Renewable Portfolio Standards or goals that many states have put in place, as well as marketable certificates for renewable energy that may be traded among providers.

The U. S. Energy Information Agency’s Annual Energy Outlook 2011 issued April 2011 presents a comprehensive analysis of U. S. Energy production and consumption foreseen through 2035.  Its Reference case is based on current policies and laws without assuming extension of provisions that expire at various points in time.  Its No Sunset case builds on the Reference case by assuming extension of favorable tax and other fiscal policies during the period of the analysis.  Its Extended Policies case includes the assumptions of the No Sunset case and adds to it the extension of current federal energy efficiency policies.

The following graphic presents historical and projected contributions to all forms of renewable energy other than hydroelectric power through 2035 under the Reference case.

Electricity generation from all renewable sources projected for the Reference case beyond 2009.
Source: U. S. Energy Information Agency: Annual Energy Outlook 2011

In the years immediately preceding and following the cutoff year 2009 the most significant increase occurs with wind-derived electricity generation (blue).  This sector then shows a sharp break at about 2012 and remains essentially constant thereafter.  This stark behavior is due to the fact that under the Reference case favorable tax credits expire at that time, as discussed above.

The following graphic shows projections for the total amount of renewable electricity generated under the Reference, No Sunset, and Extended Policies cases.  Beyond about

Total renewable electricity generation per year over 2005-2009 (historical data) and 2010-2035 (projection) under three cases.  The kilowatt-hours generated are higher than in the preceding graphic, presumably because hydroelectric power is included here.
Source: U. S. Energy Information Agency: Annual Energy Outlook 2011

2023 the No Sunset case, which includes extensions of favorable tax credits, leads to a significant increase in generation compared to the Reference case.  By 2035, considering electricity generation from all sources, the Reference case provides 14% whereas the No Sunset case provides 16%, displacing generation from fossil fuel-derived generation.  (The Extended Policies case falls below the No Sunset case because, it is proposed, its increased efficiencies lower the demand for electricity so that less needs to be  generated.)

On April 19, 2011 the U. S. Secretary of the Interior, Ken Salazar, approved construction of the first off-shore wind energy project in the U. S.  The project, by Cape Wind Associates, is to be installed in Nantucket Sound off the south coast of Massachusetts, and envisions 130 turbines arrayed across 25 square miles in the shallow waters of the Sound, generating up to 420 MW (0.42 GW) of power.  This should supply about 75% of the immediate region’s electricity needs. This project had previously gone through many years of environmental and permitting review at various levels of government.

Conclusion.  The perceived dangers accompanying increased atmospheric concentrations of greenhouse gases provide an impetus for the nations of the world to work toward an emissions-free energy economy.  The European Union, striving to attain 80-95% reductions by 2050, has significant wind energy installed, with plans to expand.  China, with a centralized economy, building on an initial small base, intends drastically to expand its wind energy generating capacity, while also expanding its fossil fuel-driven electricity generation.  The U. S., with no central energy policy in place, has short-term fiscal incentives to stimulate private development of wind energy; these incentives are not considered secure in the long term.  The disparate array of state renewable portfolio standards currently in place make it difficult for enterprises to plan and install new wind energy facilities.

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Note 1.  A watt is a unit of power, quantifying the rate at which energy is provided or consumed.  It is a small unit. 

A kilowatt (1,000 watts, Kw) is a more manageable unit of power.  10 100-watt light bulbs represent 1 Kw; an electric toaster would be 1-2 Kw.

Generating capacity is the rate at which an installation provides power, such as in millions of watts (megawatts, MW) or billions of watts (gigawatts, GW); please note these are watts, not kilowatts.

Energy is a measure of total work done, given by power x time and for electricity is watt-hours.  Again this is usually given in terms of kilowatt-hours, Kwh.  10 light bulbs burning for 1 hour would be 1 Kwh.

Note 2. According to the USEIA, in 2008 the average annual usage of electricity for a U. S. household was 11,040 kWh, with a state-by-state range of 6,200 (lowest) to 15,600 (highest).  The total residential electricity consumption in the U. S. in 2009 was 1,363 billion Kwh.  Commercial and industrial electricity usage is in addition to this amount.

© 2011 Henry Auer