In 2011, a series of violent severe storms swept across the Plains and Southeast U.S., bringing an astonishing six billion-dollar disasters in a three-month period. The epic tornado onslaught killed 552 people, caused $25 billion in damage, and brought three of the five largest tornado outbreaks since record keeping began in 1950. In May 2011, the Joplin, Missouri tornado did $3 billion in damage--the most expensive tornado in world history--and killed 158 people, the largest death toll from a U.S. tornado since 1947. An astounding 1050 EF-1 and stronger tornadoes ripped though the U.S. for the one-year period ending that month. This was the greatest 12-month total for these stronger tornadoes in the historical record, and an event so rare that we might expect it to occur only once every 62,500 years. Fast forward now to May 2012 - April 2013. Top-ten coldest temperatures on record across the Midwest during March and April of 2013, coming after a summer of near-record heat and drought in 2012, brought about a remarkable reversal in our tornado tally--the lowest 12-month total of EF-1 and stronger tornadoes on record--just 197. This was an event so rare we might expect it to occur only once every 3,000 - 4,000 years. And now, in May 2013, after another shattering EF-5 tornado in Moore, Oklahoma, residents of the Midwest must be wondering, are we back to the 2011 pattern? Which of these extremes is climate change most likely to bring about? Is climate change already affecting these storms? These are hugely important questions, but ones we don't have good answers for. Climate change is significantly impacting the environment that storms form in, giving them more moisture and energy to draw upon, and altering large-scale jet stream patterns. We should expect that this will potentially cause major changes in tornadoes and severe thunderstorms. Unfortunately, tornadoes and severe thunderstorms are the extreme weather phenomena we have the least understanding on with respect to climate change. We don't have a good enough database to determine how tornadoes may have changed in recent decades, and our computer models are currently not able to tell us if tornadoes are more likely to increase or decrease in a future warmer climate.
Video 1. Remarkable video of the tornado that hit Tuscaloosa, Alabama on April 27, 2011, part of the largest and most expensive tornado outbreak in U.S. history--the $10.2 billion dollar Southeast U.S. Super Outbreak of April 25 - 28, 2011. With damage estimated at $2.2 billion, the Tuscaloosa tornado was the 2nd most expensive tornado in world history, behind the 2011 Joplin, Missouri tornado. Fast forward to minute four to see the worst of the storm.
Figure 1. Will climate change increase the incidence of these sorts of frightening radar images? Multiple hook echoes from at least ten supercell thunderstorms cover Mississippi, Alabama, and Tennessee in this radar image taken during the height of the April 27, 2011 Super Outbreak, the largest and most expensive tornado outbreak in U.S. history. A multi-hour animation is available here.
Changes in past tornado activity difficult to assess due to a poor database It's tough to tell if tornadoes may have changed due to a changing climate, since the tornado database is of poor quality for climate research. We cannot measure the wind speeds of a tornado directly, except in very rare cases when researchers happen to be present with sophisticated research equipment. A tornado has to run over a building and cause damage before an intensity rating can be assigned. The National Weather Service did not begin doing systematic tornado damage surveys until 1976, so all tornadoes from 1950 - 1975 were assigned a rating on the Fujita Scale (F-scale) based on old newspaper accounts and photos. An improved Enhanced Fujita (EF) scale to rate tornadoes was adopted in 2007. The transition to the new EF scale still allows valid comparisons of tornadoes rated, for example, EF-5 on the new scale and F5 on the old scale, but does create some problems for tornado researchers studying long-term changes in tornado activity. More problematic is the major changes in the Fujita-scale rating process that occurred in the mid-1970s (when damage surveys began), and again in 2001, when scientists began rating tornadoes lower because of engineering concerns and unintended consequences of National Weather Service policy changes. According to Brooks (2013), "Tornadoes in the early part of the official National Weather Service record (1950 - approximately 1975) are rated with higher ratings than the 1975 - 2000 period, which, in turn, had higher ratings than 2001 - 2007." All of these factors cause considerable uncertainty when attempting to assess if tornadoes are changing over time. At a first glance, it appears that tornado frequency has increased in recent decades (Figure 2). However, this increase may be entirely caused by factors unrelated to climate change:
1) Population growth has resulted in more tornadoes being reported. Heightened awareness of tornadoes has also helped; the 1996 Hollywood blockbuster movie Twister "played no small part" in a boom in reported tornadoes, according to tornado scientist Dr. Nikolai Dotzek.
2) Advances in weather radar, particularly the deployment of about 100 Doppler radars across the U.S. in the mid-1990s, has resulted in a much higher tornado detection rate.
3) Tornado damage surveys have grown more sophisticated over the years. For example, we now commonly classify multiple tornadoes along a damage path that might have been attributed to just one twister in the past.
Figure 2. The total number of U.S. tornadoes since 1950 has shown a substantial increase. Image credit: NOAA/NCDC.
Figure 3. The number of EF-0 (blue line) and EF-1 and stronger tornadoes (maroon squares) reported in the U.S. since 1950. The rise in number of tornadoes in recent decades is seen to be primarily in the weakest EF-0 twisters. As far as we can tell (which isn't very well, since the historical database of tornadoes is of poor quality), there is not a decades-long increasing trend in the numbers of tornadoes stronger than EF-0. Since these stronger tornadoes are the ones most likely to be detected, this implies that climate change, as yet, is not having a noticeable impact on U.S. tornadoes. Image credit: Kunkel, Kenneth E., et al., 2013, "Monitoring and Understanding Trends in Extreme Storms: State of Knowledge," Bull. Amer. Meteor. Soc., 94, 499–514, doi: http://dx.doi.org/10.1175/BAMS-D-11-00262.1
Figure 4. Insured damage losses in the U.S. due to thunderstorms and tornadoes, as compiled by Munich Re. Damages have increased sharply in the past decade, but not enough to say that an increase in tornadoes and severe thunderstorms may be to blame.
Stronger tornadoes do not appear to be increasing Tornadoes stronger than EF-0 on the Enhanced Fujita Scale (or F0 on the pre-2007 Fujita Scale) are more likely to get counted, since they tend to cause significant damage along a long track. Thus, the climatology of these tornadoes may offer a clue as to how climate change may be affecting severe weather. If the number of strong tornadoes has actually remained constant over the years, we should expect to see some increase in these twisters over the decades, since more buildings have been erected in the paths of tornadoes. However, if we look at the statistics of U.S. tornadoes stronger than EF-0 or F-0 since 1950, there does not appear to be any increase in their number (Figure 3.) Damages from thunderstorms and tornadoes have shown a significant increase in recent decades (Figure 4), but looking at damages is a poor way to determine if climate change is affecting severe weather, since there are so many human factors involved. A study in Environmental Hazards (Simmons et al., 2012) found no increase in tornado damages from 1950 - 2011, after normalizing the data for increases in wealth and property. Also, Bouwer (BAMS, 2010) reviewed 22 disaster loss studies world-wide, published 2001 - 2010; in all 22 studies, increases in wealth and population were the "most important drivers for growing disaster losses." His conclusion: human-caused climate change "so far has not had a significant impact on losses from natural disasters." Studies that normalize disaster data are prone to error, as revealed by a 2012 study looking at storm surge heights and damages. Given the high amount of uncertainty in the tornado and tornado damage databases, the conclusion of the "official word" on climate science, the 2007 United Nations IPCC report, pretty much sums things up: "There is insufficient evidence to determine whether trends exist in small scale phenomena such as tornadoes, hail, lighting, and dust storms." Until a technology is developed that can reliably detect all tornadoes, there is no hope of determining how tornadoes might be changing in response to a changing climate. According to Doswell (2007): "I see no near-term solution to the problem of detecting detailed spatial and temporal trends in the occurrence of tornadoes by using the observed data in its current form or in any form likely to evolve in the near future."
Figure 5. Wind shear from the surface to 6 km altitude in May on days with days with higher risk conditions for severe weather (upper-10% instability and wind shear) over the South Central U.S. has shown no significant change between 1950 - 2010. Image credit: Brooks, 2013, "The spatial distribution of severe thunderstorm and tornado environments from global reanalysis data", Atmospheric Research Volumes 67-68, July-September 2003, Pages 73-94.
Figure 6. Six-hourly periods per year with environments supportive of significant severe thunderstorms in the U.S. east of the Rocky Mountains. The line is a local least-squares regression fit to the series, and shows no significant change in environments supportive of significant severe thunderstorms in recent decades. Image credit: Brooks, H.E., and N. Dotek, 2008, "The spatial distribution of severe convective storms and an analysis of their secular changes", Climate Extremes and Society
How are the background conditions that spawn tornadoes changing? An alternate technique to study how climate change may be affecting tornadoes is look at how the large-scale environmental conditions favorable for tornado formation have changed through time. Moisture, instability, lift, and wind shear are needed for tornadic thunderstorms to form. The exact mix required varies considerably depending upon the situation, and is not well understood. However, Brooks (2003) attempted to develop a climatology of weather conditions conducive for tornado formation by looking at atmospheric instability (as measured by the Convective Available Potential Energy, or CAPE), and the amount of wind shear between the surface and 6 km altitude. High values of CAPE and surface to 6 km wind shear are conducive to formation of tornadic thunderstorms. The regions they analyzed with high CAPE and high shear for the period 1997-1999 did correspond pretty well with regions where significant (F2 and stronger) tornadoes occurred. Riemann-Campe et al. (2009) found that globally, CAPE increased significantly between 1958 - 2001. However, little change in CAPE was found over the Central and Eastern U.S. during spring and summer during the most recent period they studied, 1979 - 2001. Brooks (2013) found no significant trends in wind shear over the U.S. from 1950 - 2010 (Figure 5.) A preliminary report issued by NOAA’s Climate Attribution Rapid Response Team in July 2011 found no trends in CAPE or wind shear over the lower Mississippi Valley over the past 30 years.
Figure 7. Change in the number of days per year with a high severe thunderstorm potential as predicted by the climate model (A2 scenario) of Trapp et al. 2007, due to predicted changes in wind shear and Convective Available Potential Energy (CAPE). Most of the U.S. east of the Rocky Mountains is expected to see 1 - 2 additional days per year with the potential for severe thunderstorms. The greatest increase in potential severe thunderstorm days (three) is expected along the North and South Carolina coast. Image credit: NASA.
How will tornadoes and severe thunderstorms change in the future? Using a high-resolution regional climate model (25 km grid size) zoomed in on the U.S., Trapp et al. (2007) and Trapp et al. (2009) found that the decrease in 0-6 km wind shear in the late 21st century would more than be made up for by an increase in instability (CAPE). Their model predicted an increase in the number of days with high severe storm potential for most of the U.S. by the end of the 21st century, particularly for locations east of the Rocky Mountains (Figure 7.) Brooks (2013) also found that severe thunderstorms would likely increase over the U.S. by the end of the century, but theorized that the severe thunderstorms of the future might have a higher proportion causing straight-line wind damage, and slightly lower proportion spawning tornadoes and large hail. For example, a plausible typical future severe thunderstorm day many decades from now might have wind shear lower by 1 m/s, but a 2 m/s increase in maximum thunderstorm updraft speed. This might cause a 5% reduction in the fraction of severe thunderstorms spawning tornadoes, but a 5% increase in the fraction of severe thunderstorms with damaging straight-line winds. He comments: "However, if the number of overall favorable environments increases, there may be little change, if any, in the number of tornadoes or hailstorms in the US, even if the relative fraction decreases. The signals in the climate models and our physical understanding of the details of storm-scale processes are sufficiently limited to make it extremely hazardous to make predictions of large changes or to focus on small regions. Projected changes would be well within error estimates."
Figure 8. From 1995 (the first year we have wind death data) through 2012, deaths from high winds associated with severe thunderstorms accounted for 8% of all U.S. weather fatalities, while tornadoes accounted for 13%. Data from NOAA.
Severe thunderstorms are capable of killing more people than tornadoes If the future climate does cause fewer tornadoes but more severe thunderstorms, this may not end up reducing the overall deaths and damages from these dangerous weather phenomena. In 2012, the warmest year in U.S. history, the death toll from severe thunderstorms hit 104--higher than the 70 people killed by tornadoes that year. Severe thunderstorms occur preferentially during the hottest months of the year, June July and August, and are energized by record heat. For example, wunderground weather historian Christopher C. Burt called the number of all-time heat records set on June 29, 2012 “especially extraordinary,” and on that day, an organized thunderstorm complex called a derecho swept across a 700-mile swath of the Ohio Valley and Mid-Atlantic, killing thirteen people and causing more than $1 billion in damage. The amount of energy available to the derecho was extreme, due to the record heat. The derecho knocked out power to 4 million people for up to a week, in areas where the record heat wave was causing high heat stress. Heat claimed 34 lives in areas without power in the week following the derecho. Excessive heat has been the number one cause of weather-related deaths in the U.S since 1995, killing more than twice as many people as tornadoes have. Climate models are not detailed enough to predict how organized severe thunderstorm events such as derechos might change in a future warmer climate. But a warmer atmosphere certainly contributed to the intensity of the 2012 derecho, and we will be seeing a lot more summers like 2012 in coming decades. A future with sharply increased damages and deaths due to more intense severe thunderstorms and derechos is one nasty climate change surprise that may lurk ahead.
Figure 9. Lightning over Tucson, Arizona on August 14, 2012. A modeling study by Del Genio et al.(2007) predicts that lighting will increase by 6% by the end of the century, potentially leading to an increase in lightning-triggered wildfires. Image credit: wunderphotographer ChandlerMike.
Lightning may increase in a warmer climate Del Genio et al.(2007) used a climate model with doubled CO2 to show that a warming climate would make the atmosphere more unstable (higher CAPE) and thus prone to more severe weather. However, decreases in wind shear offset this effect, resulting in little change in the amount of severe weather in the Central and Eastern U.S. late this century. However, they found that there would likely be an increase in the very strongest thunderstorms. The speed of updrafts in thunderstorms over land increased by about 1 m/s in their simulation, since upward moving air needed to travel 50 - 70 mb higher to reach the freezing level, resulting in stronger thunderstorms. In the Western U.S., the simulation showed that drying led lead to fewer thunderstorms overall, but the strongest thunderstorms increased in number by 26%, leading to a 6% increase in the total amount of lighting hitting the ground each year. If these results are correct, we might expect more lightning-caused fires in the Western U.S. late this century, due to increased drying and more lightning. Only 12% of U.S. wildfires are ignited by natural causes, but these account for 52% of the acres burned (U.S. Fire Administration, 2000). So, even a small change in lightning flash rate has important consequences. Lightning is also a major killer, as an average of 52 people per year were killed by lightning strikes over the 30-year period ending in 2012, accounting for 6% of all U.S. weather-related fatalities.
Summary We currently do not know how tornadoes and severe thunderstorms may be changing due to climate change, nor is there hope that we will be able to do so in the foreseeable future. It does not appear that there has been an increase in U.S. tornadoes stronger than EF-0 in recent decades, but climate change appears to be causing more extreme years--both high and low--of late. Tornado researcher Dr. Harold Brooks of the National Severe Storms Laboratory in Norman, Oklahoma said in a 2013 interview on Andrew Revkin's New York Times dotearth blog: "there’s evidence to suggest that we have seen an increase in the variability of tornado occurrence in the U.S." Preliminary research using climate models suggests that we may see an increase in the number of severe thunderstorms capable of producing tornadoes over the U.S. late this century, but these thunderstorms will be more likely to produce damaging straight-line winds, and less likely to produce tornadoes and large hail. This will not necessarily result in a reduction in deaths and damages, though, since severe thunderstorms can be just as dangerous and deadly as tornadoes--especially when they knock out power to areas suffering high-stress heat waves. Research into climate change impacts on severe weather is just beginning, and much more study is needed.
Video 2. Dr. Harold Brooks of the National Severe Storms Laboratory in Norman, Okla., gave a video interview at a tornado and climate research conference held at Columbia University earlier this year. He discusses why we don't issue seasonal tornado forecasts, but doesn't discuss climate change.
References Brooks, H.E., 2013, "Severe thunderstorms and climate change," Atmospheric Research, Volume 123, 1 April 2013, Pages 129–138, http://dx.doi.org/10.1016/j.atmosres.2012.04.002.
The scientific agreement that climate change is happening, and that it's caused by human activity, is significant and growing, according to a new study published Thursday. The research, which is the most comprehensive analysis of climate research to date, found that 97.1% of the studies published between 1991 to 2011 that expressed a position on manmade climate change agreed that it was happening, and that it was due to human activity.
The study looked at peer reviewed research that mentioned climate change or global warming. Peer review is the way that scientific journals approve research papers that are submitted. In peer review, group of scientists that weren't involved in the study, but who are experts in the field, look at the research being submitted and have approved that it meets scientific process standards, and the standards of that journal.
In 2011, 521 of those peer reviewed papers agreed that climate change is real, and that human activity is the cause. Nine papers in 2011 disagreed.
John Cook, founder of skepticalscience.com and the lead author on the study, said the motivation for the analysis was the importance of scientific consensus in shaping public opinion, and therefore policy. "When people understand that climate scientists agree on human-caused global warming, they're more likely to support climate policy," Cook said. "But when the public are asked how many climate scientists agree that humans are causing global warming, the average answer is around 50%."
This "consensus gap" is what Cook and the research team is trying to close. "Raising awareness of the scientific consensus is a key step towards meaningful climate action," Cook said.
This study is not the first to examine the overwhelming agreement among climate scientists. Surveys of actively publishing climate scientists as well as analyses of climate change papers have shown similar results.
In 2004 Naomi Oreskes, Professor of History and Science Studies at the University of California San Diego, published what many scientists consider the seminal study on climate change consensus. She also co-authored the book Merchants of Doubt, which identifies and examines the similarities between today's climate change conversation and previous controversies over tobacco smoking, acid rain, and the hole in the ozone layer.
Oreskes believes that the public isn't aware of the consensus because of deliberate efforts to cause confusion. "There has been a systematic attempt to create the impression that scientists did not have a consensus, as part of a broader strategy to prevent federal government action," Oreskes said. "The public have been confused because people have been trying to confuse us."
The study published Thursday is the first to take so many papers and authors into account. Doing a search on the popular science article website Web of Science for "climate change" or "global warming" produces over 12,000 results. Of these, 4,014 papers were identified to state a position on climate change. Among those, 3,896, or 97.1% endorsed the consensus that climate change was happening and that it was caused by human activity.
In an interesting result, Cook and his team found that over time, scientists tend to express a position on climate change less and less in their research papers. This is likely a result of consensus -- that if a scientific conclusion has been reached, there's no need to continue to state that conclusion in new research. "Scientists tend to take the consensus for granted," says Cook, "perhaps not realizing that the public still think it's a 50:50 debate."
Magical Mystery Tour: Unicorns, Yeti and the Loch Ness Monster
I am taking a hiatus from my “What Can I Do Series.” This blog will focus on three stories in the press in the past few months that have been flaring up. They have been smoldering for years and I expect they will smolder for a few more years.
As background, more than a year ago I wrote a piece entitled Form of Argument: Adventures in Rhetoric. In that blog I named a number of items to look for in politically motivated articles on climate change. One of the most common forms of argument is to look at one item of information and to ignore other information. Once this information is put at the center of the argument, a set of yes or no questions or statements that suggest contradictory knowledge follow it. This form of argument produces doubt, amplifies uncertainty and effectively disrupts a societal or governmental response to climate change. Also in that original blog, I warned of emotional appeals that suggested dishonesty and disreputable behavior. In the following examples, these elements of argument appear (see also Changing the Media Discussion and Lemos and Rood on the Uncertainty Fallacy).
All of the items that I discuss below are items that have been addressed in this blog previously. A reason that I am writing about them this week is that recently other writers have put together excellent discussions of the scientific knowledge and the communication of that knowledge. Also I refer to the web site Skeptical Science which has an ongoing collection of arguments against climate change science and their counters.
From a scientist - citizen perspective, the Economist article is a good article and it demonstrates some of the perils of communication and science driven by public dialogue. For example, the surface global temperature plots were in the 1990s highly touted as a communication tool to provide the story to policy makers and the people. However, it is known to be too simplistic, and the models were never built as predictive models.
From a scientist perspective, the global surface temperature record is not a singular or robust measure of planetary warming. There is heat going into oceans and melting sea ice and melting ice sheets and melting permafrost. I think an interesting tension is that there is a growing literature that the Earth is heating faster than predicted, when all of these other measures of heating are considered.
Judith Curry has a recent post on the warming pause in which she summarizes David Appell’s article W[h]ither Global Warming: Has it slowed down?. In great detail the reasons why the surface temperature record is not a singular measure of planetary warming are discussed. As we search for the heat and find it, largely in the ocean, all observations suggest that the planet is warming, and that the dominant cause is human-generated greenhouse gases from burning fossil fuels.
It has been a cold spring in the U.S.: The 2013 spring has been one of the most peculiar in my life. This follows 2012, which was just stunningly hot. 2013 has had a lot of record cold in the U.S. There has also been a lot of variability, record cold followed by record warm. Marshall Shepherd brought the article Cooler Spring Weather Does Not Equal a Cooling Climate to my attention. This article makes reference to a video from Climate.gov entitled Pockets of Cold on a Warming Planet. All I have to say here is the U.S. is not the world, globally March 2013 was the tenth warmest ever and for the past 337 months the global temperature has been higher than the twentieth century average. April will be number 338. Here is one of my old links on this subject Warm Cold Warm Cold.
Carbon Dioxide Increase is Good for the Plants and not Correlated with Temperature: There was an article in the Wall Street Journal, Defending Carbon Dioxide. I note that it was an opinion piece. It was full of opining with no cohesive basis in fact and isolated misrepresentation of fragments of knowledge. It misrepresents both climate knowledge and ecological knowledge. It was released to coincide with the atmospheric carbon dioxide crossing 400 parts per million. All I have to say about this is that carbon dioxide is a waste product and I can name numerous waste products that are good for plants. We choose to manage our sewage.
r
A note or two: I am glad to see in the various articles I reference here scientists becoming more circumspect about how we communicate about climate change. We see a number of places where attempts to make communication simple contributes to perpetuation of disruptive political arguments. We set up the isolated piece of information that falls prey to the yes-no questions that generate doubt.
And as for 400 parts per million of carbon dioxide – “never before experienced by humans.” That was true for 399, 398, 397 … and it will be true for 401, 402, 403 ... Silly.
From Skeptical Science which has an on going collection of arguments against climate change science and their counters.
Moderation of comments: I have been getting more and more complaints about what is going on in the comments. WU and I will be addressing this. To start, here is a modified version of Dr. Master’s Blog Contents Rules.
Rood's Rules of the Road
1. Please do not carry on personal disputes. 2. Keep it civil. Personal attacks, bickering, flaming and general trollish behavior will not be tolerated. Disagreements are fine, but keep them civil. 3. No spam. 4. Stay on the topic of climate change or the entry topic. 5. Foul language is not allowed. 6. Please avoid topics that would be considered adults only. Many children come to this site looking for information. 7. Threats and intimidation, especially that which extends into the real world will be dealt with accordingly. 8. Do not circumvent a ban. Most bans last 24 hours or less; please accept the ban. If you create a new username to circumvent a ban, you will be blocked from the site completely.
This is the continuation of a series in response to the question, “What can I do about climate change?” Links to the previous entries are listed at the end.
Last week rather than taking the conventional view of looking at greenhouse gas emissions from the burning of fossil fuels, I presented an accounting of the emissions associated with agriculture. My primary points were that agriculture was a major emitter of greenhouse gases, and, therefore, the choices we make individually and collectively about what we eat have large environmental consequences.
I want to explore more the impact of agriculture, particularly livestock. First, however, I want to remind folks of the series on calculating budgets. Last summer I did a series where I compared the basic methods of climate science to keeping a budget – just like a checking and savings accounts. One of the entries in that series looked specifically at complexity. The idea being that despite the fact that maintaining a budget is a relatively simple matter of addition and subtraction, if you consider all of the ways we get and spend money, then it can become remarkably complex.
I implied the complexity of accounting for the greenhouse gas emissions of agriculture in the previous entry. The amount of emissions from the direct use of fossil fuels is relatively small. Big sources of emissions come from removing trees and changing forests to agricultural lands and soil management. Many aspects of soil management influence how much carbon and nitrogen is stored in the soil. There is also the need to consider greenhouse gases other than carbon dioxide: for example, methane associated with ruminates and solid waste from livestock and nitrous oxide associated with fertilizer. Emissions also depend on:
- what crops are grown and what animals are raised
- agricultural practice, for example, whether the land is plowed or no-till methods are used
- policy, for example, renewable energy policy provides incentives and disincentives on what to grow
- biological processes that are different from field to field, region to region, year to year, and that are not highly quantified
The calculation of the budget of emissions from agriculture is a difficult problem. We can say with certainty the emissions are large and they change based on many factors. We can also say that the impact of agriculture on the environment is more far reaching than climate change. Anecdotally, most people think of the impacts of pesticides and herbicides, the issues of genetically modified organisms, soil erosion and water quality before they think of how agriculture and climate change play together. Agriculture is also a major focus of those who think about sustainability.
I ended the previous entry with a relatively weak statement that what we chose to eat or not eat does make a difference. I stated that at the top of the list, perhaps, the easiest decision is to eat less meat. The issue of eating meat, of course, steps into a set of the more controversial subjects of our society. For example, there are the issues of personal choice and intrusion into individual's lives. Also, there are those who place high value on the ethics of raising and slaughtering animals. There is no doubt, however, that livestock production uses immense resources.
“Livestock’s contribution to environmental problems is on a massive scale and its potential contribution to their solution is equally large. The impact is so significant that it needs to be addressed with urgency. Major reduction in impact could be achieved at reasonable cost.”
As strong as this statement is, there is a school of thought that Livestock’s Long Shadow is a significant underestimation of the emissions due to livestock. Most notably is an analysis by Robert Goodland and Jeff Anhang, Livestock and Climate Change, which does a different accounting of the budget of emissions of greenhouse gases. In Livestock and Climate Change it is maintained that there is significant undercounting and misallocation in the United Nations budget calculation. A point that is particularly important is that the proliferation of livestock production is human-made just as much as any building, road or power plant. Therefore, for example, the carbon dioxide of respiration of the animals needs to be considered in the budget calculation. Taking all of the budget changes in Livestock and Climate Change, the conclusion is that livestock is responsible for 51 percent of the total emissions. With this number, a far larger intervention is needed than “eat less meat.”
In December 2009, I took a group of students to the 15th Conference of the Parties in Copenhagen. When I got off the subway at the conference center, there were two loud groups of advocates. One was People for the Ethical Treatment of Animals, who had gone around Copenhagen and placed markers on utility poles and in trees where sea level would be if the Greenland ice sheet melted. Another group claimed that if we were all vegetarian, then we could reduce global warming by 70 percent.
The numbers in Livestock and Climate Change follow from a well-reasoned argument in the calculation of the budget of the emissions due to livestock. However, they are not without controversy. This controversy can be found in a number of places on the web: Columbia Journalism Review and Lifting Livestock's Long Shadow, Nature Climate Change and Measuring Livestock's Long Shadow, NYTimes. At the center of the controversy is another accounting of the impact of livestock, Cleaning the Air: Livestock's Contribution to Climate Change by Maurice Pitesky and others. This paper takes a vastly different accounting and concludes that impact of livestock is much smaller than in the United Nations Report, Livestock’s Long Shadow. An interesting aspect of its argument is that “The fact that land-use changes associated with livestock (i.e., forested land converted to pasture or cropland used for feed production) are a significant source of anthropogenic GHGs in Latin America and other parts of the developing world is apparent. However, it is likely that any kind of land-use change from the original forestland will lead to great increases in global warming.” The argument being that development in countries with growing population will lead to deforestation. Their argument is carried further “The United States and most other developed countries have not experienced significant land-use change practices around livestock production within the last few decades. Instead, over the last 25 years forestland has increased by approximately 25 percent in the United States and livestock production has been intensified (concentrated geographically), thus reducing its geographical footprint.”
In this food niche of strategies to mitigate climate change, we see the same arguments emerge as in the discussion of fossil fuels. We could be more efficient in our use of resources. With efficiency, however, in the face of a growing population and growing consumption, we are still faced with a growth of emissions of greenhouse gases. Therefore, if climate-change and broader environmental issues are given priority, then we must consume less of those products that are responsible for our largest greenhouse emissions. We can conceive of sources of renewable energy that are free of carbon dioxide emissions. However, it is more difficult to imagine how we raise livestock without the methane and nitrous oxide emissions, and these greenhouse gases cannot be dismissed.
My original list topper on diet was eat less meat. If we take the high emissions scenario as correct, then a climate priority calls for an intervention into our dietary practices that is comparable to the intervention required for reducing fossil fuels. This is a change in diet that I assert will be more difficult than the change in our energy system. Therefore, back to the original question, “What can I do about climate change?” – eat (a lot) less meat. Vegetarianism is good for the planet. This from a man who does eat a lot less meat than he used to, but has been, I maintain, overidentified with BBQ.
r
Some dietary resources: I have not checked these out too closely!
Setting Up the Discussion Deciding to do something, definition of mitigation and adaptation, and a cost-benefit anchored framework for thinking about mitigation
The Complete List Eight categories of things we can do to reduce greenhouse gases
We Are What We Eat Counting agriculture and its emissions of greenhouse gases
Moderation of comments: I have been getting more and more complaints about what is going on in the comments. WU and I will be addressing this. To start, here is a modified version of Dr. Master’s Blog Contents Rules.
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Two studies done in 2009 and 2010 found that 97% of actively publishing climate scientists agree that humans cause global warming. But what would a larger sample of the scientific literature show, extended all the way up to 2011? You're invited to help find out, by participating in an anonymous 10-minute survey where you will be reading the abstracts (summaries) of ten randomly selected technical papers on Earth's climate published between 1991 and 2011. The survey was created by physicist John Cook of The Global Change Institute at Australia's University of Queensland. Mr. Cook is the creator of one of my favorite climate change websites, skepticalscience.com. He authored one of our special Earth Day 2013 essays, Closing the Consensus Gap on Climate Change, from which I have pulled Figure 1 below. Mr. Cook is lead author on a new paper called "Quantifying the consensus on anthropogenic global warming in the scientific literature," to be published in the next month or so in Environmental Research Letters. The paper analyzes the same papers included in the survey you're asked to participate in, and the researchers plan to compare the results. Each of these 11,944 papers written by 29,083 authors and published in 1,980 journals included the keywords "global warming" or "global climate change" in their listing in the ISI Web of Science database. After reading each abstract, you will be asked to rate the level of endorsement within the abstract for the proposition that human activity (i.e., anthropogenic greenhouse gases) is causing global warming. There will be these choices available on a drop-down menu for you to choose from:
1. Explicit Endorsement with Quantification: abstract explicitly states that humans are causing more than half of global warming. 2. Explicit Endorsement without Quantification: abstract explicitly states humans are causing global warming or refers to anthropogenic global warming/climate change as a given fact. 3. Implicit Endorsement: abstract implies humans are causing global warming. E.g., research assumes greenhouse gases cause warming without explicitly stating humans are the cause. 4. Neutral: abstract doesn't address or mention issue of what's causing global warming. 5. Implicit Rejection: abstract implies humans have had a minimal impact on global warming without saying so explicitly. E.g., proposing a natural mechanism is the main cause of global warming. 6. Explicit Rejection without Quantification: abstract explicitly minimizes or rejects that humans are causing global warming. 7. Explicit Rejection with Quantification: abstract explicitly states that humans are causing less than half of global warming. 8. Don't know.
When you are all done, the survey will let you know how your average score for the ten papers compares to the rating given by the authors. The survey took me about 8 minutes to complete, and it was interesting to see the tremendous diversity of research being done on global warming in my random sample. I'll post about Mr. Cook's results when his paper is published in the next few months.
Figure 1. Two recent studies have sought to measure the level of agreement in the scientific community in different ways and arrived at strikingly consistent results. A 2009 study led by Peter Doran surveyed over 3,000 Earth scientists and found that as the scientists' expertise in climate change grew, so did the level of agreement about human-caused global warming. For the most qualified experts, climate scientists actively publishing peer-reviewed research, there was 97% agreement. Alternatively, a 2010 analysis led by William Anderegg compiled a database of scientists from public declarations on climate change, both supporting and rejecting the consensus. Among scientists who had published peer-reviewed climate research, there was 97% agreement. However, it is worth pointing out that science is not decided by majority vote. This is articulated concisely by John Reisman who says: "Science is not a democracy. It is a dictatorship. It is evidence that does the dictating." Figure and text taken from Mr. John Cook's special Earth Day essay, Closing the Consensus Gap on Climate Change.
These blogs are a compilation of Dr. Jeff Masters, Dr. Ricky Rood, and Angela Fritz on the topic of climate change, including science, events, politics and policy, and opinion.
