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Contribution of air conditioning adoption to future energy use under global warming Lucas W. Davis a,b,1 and Paul J. Gertler a,b,1 a Haas School of Business, University of California, Berkeley, CA 94720; and b National Bureau of Economic Research, Cambridge, MA 02138 Edited by B. L. Turner, Arizona State University, Tempe, AZ, and approved March 27, 2015 (received for review December 9, 2014) As household incomes rise around the world and global temperatures go up, the use of air conditioning is poised to increase dramatically. Air conditioning growth is expected to be particularly strong in middle- income countries, but direct empirical evidence is scarce. In this paper we use high-quality microdata from Mexico to describe the relationship between temperature, income, and air conditioning. We describe both how electricity consumption increases with temperature given cur- rent levels of air conditioning, and how climate and income drive air conditioning adoption decisions. We then combine these estimates with predicted end-of-century temperature changes to forecast future energy consumption. Under conservative assumptions about house- hold income, our model predicts near-universal saturation of air conditioning in all warm areas within just a few decades. Temperature increases contribute to this surge in adoption, but income growth by itself explains most of the increase. What this will mean for electricity consumption and carbon dioxide emissions depends on the pace of technological change. Continued advances in energy efficiency or the development of new cooling technologies could reduce the energy consumption impacts. Similarly, growth in low-carbon electricity generation could mitigate the increases in carbon dioxide emissions. However, the paper illustrates the enormous potential impacts in this sector, highlighting the importance of future research on adaptation and underscoring the urgent need for global action on climate change. air conditioning | energy demand | climate change | adaptation | energy efficiency S ales of air conditioners have exploded worldwide over the last few years. The growth is not driven by high-income countries like the United States, where almost 90% of homes already have air conditioning (1). The growth is driven by middle-income coun- tries where households and businesses are buying air conditioners at alarming rates. The prime example is China, where sales of air conditioners have nearly doubled over the last 5 y. In 2013 alone there were 64 million units sold, more than eight times as many as were sold in the United States (2). The scope for increased demand for air conditioning is stag- gering. Take India, for example. Compared with the United States, India has four times the population, but also more than three times as many cooling degree days (CDDs) per person (3). Thus, India’s total potential demand for cooling is 12+ times that of the United States. Air conditioning is still relatively uncommon in India and other low-income countries, but this is poised to change dramati- cally as incomes rise around the world. Air conditioning will bring relief to the more than three billion people who live in the tropics and subtropics. However, meeting the increased demand for electricity will be an enormous challenge. Trillions of dollars of investments will be required in electricity generation and transmission infrastructure, and even the most robust markets will be threatened by shortages and price spikes. In addition, most electricity worldwide continues to be generated using fossil fuels, so this growth in air conditioning means billions of tons of increased carbon dioxide emissions. In this paper we use high-quality microdata from Mexico between 2009 and 2012 to characterize empirically the relationship between temperature, income, and residential air conditioning. Our data and modeling approach allow us to carefully distinguish between the intensive margin (i.e., how electricity consumption increases with temperature given today’s equipment stock) and the extensive margin (i.e., how income and climate drive air conditioning adoption decisions).* Focusing first on the intensive margin, we use electric billing data to estimate semiparametrically the relationship between tempera- ture and residential electricity consumption. The estimates show large increases in electricity consumption on hot days. For example we find that, relative to a 65–70 °F day, each additional day with a mean temperature exceeding 90 °F increases monthly electricity consumption by 3.2%. Moreover, the results show that the tem- perature–response function is significantly steeper for households living in states where air conditioning is more prevalent. For the extensive margin, we use detailed microdata to measure the empirical relationship between climate, income, and air condi- tioner adoption. We find that what matters most is the interaction between climate and income. In cool areas, air conditioner satura- tion is near zero for all income levels. In warm areas, however, we find a close relationship between household income and air con- ditioner adoption, with ownership increasing 2.7 percentage points per $1,000 of annual household income. The relationship is pre- cisely estimated and similar across alternative specifications. Finally we combine both sets of estimates with predicted end- of-century temperature changes from a set of state-of-the-art climate models. Considering the intensive margin alone, our estimates imply that temperature increases as predicted under the Representative Concentration Pathway (RCP) 8.5 emissions scenario would lead to a 15.4% increase in residential electricity consumption by end of century. This is similar to existing esti- mates for the United States (6), despite much higher levels of air conditioning saturation in the United States. Significance The use of air conditioning is poised to increase dramatically over the next several decades as global temperatures go up and incomes rise around the world. In this paper, we use high- quality microdata from Mexico to characterize empirically the relationship between temperature, income, and air condition- ing. We describe both how electricity consumption increases with temperature given current levels of air conditioning, and how climate and income drive air conditioning adoption de- cisions. We then combine these estimates with predicted end- of-century temperature changes to forecast future energy consumption. Overall, our results point to air conditioning im- pacts being considerably larger than previously believed. Author contributions: L.W.D. and P.J.G. designed research, performed research, analyzed data, and wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. 1 To whom correspondence may be addressed. Email: [email protected] or gertler@ haas.berkeley.edu. This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10. 1073/pnas.1423558112/-/DCSupplemental. *Energy demand studies have long made this distinction between the intensive and extensive margins (4, 5). 5962–5967 | PNAS | May 12, 2015 | vol. 112 | no. 19 www.pnas.org/cgi/doi/10.1073/pnas.1423558112 Downloaded by guest on September 29, 2020
Transcript of The Menstrual Cycle and Endometriosis : Treatments Using ... · endometriosis. After the first 2...
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The Menstrual Cycle and Endometriosis: Treatments Using Hormones
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About the Menstrual Cycle:The ovaries play a very important part in women’s lives. They are found in the lower part of the pelvis near the ends of the fallopian tubes. They contain thousands of eggs, also known as ova. Each egg is held within a structure called a follicle.
Just as a period is ending, an area of the brain produces a hormone that travels through the blood stream. (Hormones are chemicals produced by the body. They control or regulate the actions of certain cells or organs). This hormone causes the ovaries to start preparing an egg for ovulation. As the egg matures, its follicle produces another hormone called estrogen. Estrogen causes the lining of the uterus (endometrium) to become thicker.
When the egg is mature and the amount of estrogen has reached a certain level, another hormone sent from the brain causes the egg to be released from the ovary. This is called ovulation. It occurs about 14 days before the next period begins.
The cells remaining in the follicle form the corpus luteum. The corpus luteum produces estrogen and another hormone, progesterone, over the next 2 weeks. The hormones cause the lining of the uterus to become thicker and rich with blood vessels to support a pregnancy. This is called the pre-menstrual phase of the cycle.
If there are sperm in the fallopian tubes, the egg may become fertilized. The fertilized egg then moves through the tube to the uterus. If it implants, a pregnancy has been started.
If no pregnancy occurs, the corpus luteum will break down and stop producing hormones. This causes the lining of the uterus to be shed, and is known as the menstrual period.
The menstrual cycle is counted from Day 1 of a menstrual period until Day 1 of the next period and is an average of 28 days long (between 25 and 35 days is considered to be normal).
Uterus
Fallopian Tube
Endometriosis Lesions
About the Menstrual Cycle and Pelvic Pain:
Many women have some cramps or discomfort before or during their menstrual periods. In women with endometriosis the pain can be very severe. It may occur throughout the menstrual cycle. It is often much worse during the menstrual period.
Endometriosis is a condition in which the tissue that lines the uterus (the endometrium) is also present in areas within the pelvis and outside of the uterus. During each menstrual cycle the endometrial tissue outside of the uterus responds to hormone signals in the same way that the endometrium inside the uterus does. It builds up and then breaks down, causing the release of Prostaglandin (a hormone that causes muscles to cramp) along with areas of inflammation and pain.
Endometriosis also causes the lining of the uterus (the endometrium) to act differently. It produces a higher level of hormones such as prostaglandins that cause severe cramping and pain. These hormones also sometimes cause abnormal bleeding (heavy periods or spotting between periods).
Hormonal Treatments for Endometriosis and Pelvic Pain
There are four levels of treatment that can be used to stop (suppress) the natural menstrual cycle in order to control pelvic pain:
Ovulation suppression using the Birth Control Pill, Birth Control Patch, or Vaginal Ring
Most birth control pills (BCP), the contraceptive patch (Evra®) and contraceptive ring (NuvaRing®) contain a combination of two hormones, estrogen and progesterone. If taken or used for 21 days, starting from the first day of the menstrual cycle with no breaks, the levels of these hormones in the woman’s body do not rise and fall. The ovary is not signalled to prepare an egg, and ovulation does not happen. The lining of the uterus (endometrium) does not build up as much as it usually does.
When the woman stops taking the two hormones (usually after 21 days), she experiences a withdrawal bleed. This is the shedding of the small amount of endometrium that grew while she was taking the hormones.
Some BCP packages contain 28 pills, 21 of which contain hormones. The last 7 pills contain no hormones. The withdrawal bleed happens during the week the woman takes the last 7 pills.
The Ortho Evra® Patch and NuvaRing® also contain estrogen and progesterone and are used for the first 21 days of the menstrual cycle. The withdrawal bleed happens during the following 7 days. The patch and the ring are very helpful for women who may not always remember to take a daily pill.
Known benefits of using a combination of estrogen and progesterone for ovulation suppression:
• Reducesmenstrualcrampsandpainthroughoutthe cycle
• Conditionssuchasexcesshairgrowth,acne,oilyskin and pre-menstrual symptoms are improved
• Lowerstheriskofanemia,pelvicinfection,tubalpregnancy, and painful ovarian cysts
• Givesaprotectiveeffectagainstendometrialandovarian cancer (in long term users).
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Step One:
One of the treatments for endometriosis uses hormones that stop the menstrual cycle. This reduces the activity of endometrial tissue and results in less pain and bleeding.
• Providescontraception.Fertilityreturnsquicklyfor most women when pregnancy is desired and the medication is stopped.
Possible Side effects include:• Breasttenderness• Nausea• Moodandweightchanges(visitwww.
contraceptiononline.com for more details).• Headaches• Changesinlibido(sexualdesire)• Bloodclotsinthelegsorlungs(thrombosis)(a
risk for a small number of women)• Highbloodpressure,heartattackandstroke(very
rare in healthy women)• Possibleslightassociationwithbreastandcervical
cancer (not proven)
The side effects usually get better by the end of the 3rd month. They all go away when the pill, patch or ring is stopped. Women who have side effects that do not go away may find a different brand of BCP to be helpful.
The use of combined estrogen and progesterone is not recommended for women who have the following conditions:• Problemswithbloodcirculationsuchashigh
blood pressure, blood clots, heart attack, stroke• Certaintypesofcancers• Undiagnoseduterinebleeding• Liver,gallbladder,chronicrenaldisease,or
uncontrolled diabetes• Smokersafterage35• Suspectedpregnancy• Certaintypesofmigraines• Epilepsy• Areclosetothetimeofplanned(elective)surgery
Suppression of Menstruation through continuous Use of the Birth Control Pill, Birth Control Patch, Vaginal Ring, or Levonorgestrel IUD (intrauterine device)
If Step One does not help, the BCP, Ortho Evra® Patch or NuvaRing® can be used daily to try to avoid a withdrawal bleed. This is a more effective way to control pelvic pain. Studies have shown that it is very safe.
The only problem with this approach is called “break through bleeding” (BTB). This is dark coloured, black or red spotting, or it may be a light blood flow that happens on and off during the month. This occurs because the lining of the uterus (endometrium) has become thin but has grown small veins that bleed easily. It is not dangerous, but can be very annoying. It may also be painful for some women.
This can be solved by stopping the hormone medication for 5 or 6 days. This allows the lining to be cleared out. During the time without the hormones, the bleeding and pain might be worse, but will stop as soon as a new cycle of medication is started. This way, the woman can control her bleeding pattern.
The Levonorgestrel (Mirena®) IUDThelevonorgestrel(Mirena®)IUDisinsertedintotheuterus. It releases a steady dose of Progestin which affects the uterus but is present at a very low level. Ovulation still occurs for most women. Placing the Mirena at the time of surgery increases the effect and the duration of pain relief after surgery.
If you choose this option, you will need to buy the IUDataPharmacy(approximately$350.00.).ItworksbesttoinserttheIUDduringamenstrualperiodtominimize abnormal bleeding.
Mild Estrogen Suppression using continuous Progesterone (progestin)
Progestins (synthetic progesterone) are drugs that are taken as a pill or by injection on a regular (daily or weekly) basis. Progestins act to suppress or stop ovulation and lower estrogen levels in the body. They are called second line treatment and are much more effective than BCP in controlling pelvic pain. This is because they have an anti-inflammatory effect on the endometrium. -3-
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Step Three:
Examples of progestin medications used to lower estrogen levels are Depo Provera®, Visanne®, Norluten® and Megace®. The main side effects of these medications are breakthrough bleeding and weight gain.
Fortyto50percentofwomenexperiencesomeformofbreakthroughbleeding.Formostwomen,thisimproves over several months of the treatment.
Weight gain is usually caused by changes to the metabolism that affect how the body deals with carbohydrates. Some women have a greater tendency for this effect. A healthy diet that is low in carbohydrates from breads, pasta, sugars and processed foods can help avoid these changes. A regular exercise program can also promote both physical and emotional health.
A small number of women experience mood changes that may include depression or irritability, and some women experience vaginal dryness and hot flushes if their estrogen levels get very low.
Progestins also lower bone mineral density and can affect cholesterol levels. These effects are not considered important in healthy women in the reproductive age group. If progestins are well tolerated, they can be used for many years until fertility is desired. With the use of oral progestins, fertility returns when the medications are stopped. The delay may be a few months after stopping progestins given by injection.
Another possible treatment is the use of a synthetic androgen (male) hormone called Danazol®. It is given vaginally to have a local effect on nearby endometriosis, but is present at very low levels in the rest of the body and does not stop ovulation. The side effects are similar to those of progestins but can also include excess hair growth, acne and oily skin. These sideeffectsareinfrequentwhenDanazolisgivenvaginally. The side effects go away after the use of Danazol is stopped.
Deeper Estrogen Suppression using GnRh (Gonadotropic Releasing Hormone) Agonists
TheseincludeLupron®(givenbyinjection)andSynarel® (given by nasal spray). They are the most effective drugs for stopping estrogen production and menstrual cycles and decreasing the symptoms of endometriosis. After the first 2 weeks of use, 95% of women have no bleeding of any kind.
The side effects include hot flushes, insomnia, vaginal dryness and loss of bone density. A small number of women experience unstable moods, depression, irritability, intrusive thoughts and anxiety. There is no weight gain due to these medications.
Side effects can be eliminated using “add back” treatment. This involves a small amount of estrogen and progesterone or progesterone alone to prevent hotflushesandboneloss.UsingthisapproachdoesnotlowertheeffectsoftheGnRhagonistsonendometriosis, so “add back” is usually recommended. This combination can be continued for long periods of time, but is expensive.
More information can be found at: www.endometriosis.org
Developed by the BC Women’s Centre for Pelvic Pain & Endometriosis http://www.womenspelvicpainendo.com/
BCW919 © 2012 (11) BC Women's Hospital & Health Centre-4-
Step Four:
