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What Causes Oxygen to be Used Up In Deep Waters?

by February 26, 2012

ANSWER (CURRENTLY UNDER REVIEW): Bacteria use up the oxygen in the process of breaking down organic matter, like the waste from tiny animals and dead algae. This answer is focused on coastal ocean waters, but generally applies to deep waters in estuaries, ponds, lakes, and slow-moving stretches of rivers.
 

Q001 how oxygen is used up in deep waters v04

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From Toilet to Treatment to Treatment to Tap in San Diego

by February 10, 2012

dog-drinking-from-toilet_sm2 My first reaction to hearing at the breakfast table about today’s piece in the NY Times about water reuse in San Diego was that it isn’t all that different from what we have been doing for years: discharging treated waste water into streams and rivers and then drawing out drinking water downstream, counting on bacterial decomposition, dilution, and other processes to treat further the discharged water. I was pleased to see that this point was discussed in the article.

Drinking water that recently was flushed down a neighbor’s drain is a tough concept, pardon the pun, to swallow. However, as the piece in the Times correctly points out, we are headed into times in which resources like water are likely to be scarcer. To my mind, this community is a shining example of people—who rightly had very strong feelings on an issue—being willing to accept what the science community had to offer. Jerry Sanders, the mayor of this San Diego community, put it this way: “If science is behind you and you can prove that, I think people are willing to listen.” Here, here!

Image in post from Climate Watch. Thumbnail image on home page from the NY Times article.

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EarthQ Core Business Model: Where Is the Sweet Spot?

by February 1, 2012

Recently, we have been working to launch a project dubbed EarthQ. The goal has been to shepherd good questions and cultivate good answers by bringing the right mix of experts to Quora, as is described in this post about bringing the carbon cycle to Quora. This work continues, but so far, my attempts to draw in a few experts to help with answers have come up dry. The Quora team thinks it is okay for those who pose a question to answer it, so that will likely be my next step. Perhaps with a solid answer to the first question, What are the compartments in which carbon is stored on Earth?, I can then start to draw in some colleagues to endorse the answer by up-voting it… (more…)

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Tracking the Mood About Gas Prices on Twitter: A Case Study

by January 25, 2012

As another test of our strategy for teasing out public opinion from social media, we explored measuring mood about gas prices on Twitter. This post summarizes the findings from this case study. Incidentally, we are set up to measure mood from Twitter on an ongoing basis, although we would need to find a partner to help defray the ongoing costs of crowdsourcing the sentiment judgments. (See this post to read more about our decision to examine the discussion about gas prices on Twitter.)

The sentiment we mapped was culled from tweets gathered from four weeks’ worth of data starting on May 22nd, 2011. This time period was chosen to coincide with Memorial Day, a holiday during which many Americans travel by car. Our team was curious to see whether there would be an uptick in either the volume of tweets about gas prices during this period or a noticeable change in sentiment about these prices. (more…)

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Monitoring Will Be Key As Minnesota Takes A Leadership Role in Managing Nutrient Runoff

by January 18, 2012

5223892647_2a55e1b7c2 Yesterday I had the opportunity to hear EPA Administrator Lisa Jackson speak at the University of Minnesota, who was in town to launch a new program along with Minnesota’s Governor Mark Dayton and USDA secretary Tom Vilsack. The new initiative, Minnesota Agricultural Water Quality Certification Program, has a goal of reducing the introduction of nutrients and soils to waterways via runoff, a process known as “non-point source pollution” (a point source is a pipe, a sewage treatment plant, etc.).

I was drawn to the talk specifically to hear what Administrator Jackson would say about the new program, which I had read about in the morning’s Minneapolis StarTribune. She did not disappoint, although the bit about this new program occurred just as the questioning period came to a close. It was clear that she has a good deal of enthusiasm about this new program and its prospects for helping to reduce pollution, such as the introduction of nitrogen into the Mississippi that can lead to low-oxygen conditions in the Gulf of Mexico. (more…)

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A Billion Dollars Flowing Down the Mississippi Annually

by December 20, 2011

In a recent post, I did a bit of research to update the picture of nutrient flows down the Mississippi due to runoff and other sources in its watershed. There’s been an ongoing debate about the source of the nutrients in the river that are directly linked to low-oxygen conditions in the Gulf of Mexico.

For a taste of the debate, check out the controversy a year ago surrounding the premier of Troubled Waters, A Mississippi River Story (link to view on Twin Cities Public TV). Among other activity, there was a heated back-and-forth on the opinion pages of the Minneapolis Star Tribune (first piece arguing that research for film was dubious, counter piece by producers about the research behind the film). The flare up nearly squelched the premier, although it ultimately took place.

Personally, I experienced how difficult it can be to establish a “consensus view” of how to describe nitrogen flows for the report on ecosystem indicators described in my previous post. There was a constant tension throughout the report process to “tell readers what to do with the information” rather than just “giving them the facts.” I believe we ultimately struck a good balance, however, we nearly had resignations of participants when we unintentionally pushed the line on the indicator dealing with the movement of nitrogen and got too close to pointing fingers. (more…)

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Anything New in the Story of Nitrogen Moving into the Gulf of Mexico?

by December 14, 2011

Dialogue Earth has roots in a broad, stakeholder-based national report on the condition and use of U.S. ecosystems published by the Heinz Center in Washington, D.C. (the report is available in hard-copy from Island Press). Curiosity about the ongoing relevance of these indicators has led me to dive in and see what, if anything, can be said about trends since the release of the report in 2008.

The first indicator in the spotlight is one that describes the movement of nitrogen (N) into major waterways, through run-off as well as point discharges such as sewage treatment facilities (here’s a link to download a pdf of the indicator). Why is this an important indicator of the state of U.S. ecosystems? Our explanation in the report does a good job of answering this question:

Nitrogen is an important plant nutrient and is essential to all life. Nitrogen is an abundant component of the earth’s atmosphere, but it is unavailable to most life in gaseous form. In order to be used by plants and other organisms, nitrogen gas must be “fixed,” or converted to a “reactive” form, that plants can use, such as nitrate. Nitrogen is fixed and accumulates in ecosystems through natural processes, such as the growth of nitrogen-fixing plants like clover and soybeans. However, human activity has greatly increased the amount of reactive nitrogen added to ecosystems. The largest human-caused input of nitrogen to ecosystems comes from the conversion of atmospheric nitrogen gas into fertilizers. Additional reactive nitrogen gas is produced by the combustion of fossil fuels. Reactive nitrogen from all these sources can ultimately enter streams and rivers. Excess nitrogen transported to coastal waters by rivers can lead to low oxygen conditions, threaten fish and animal life, and degrade coastal water quality. (more…)

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Bringing the Global Carbon Cycle to Quora

by December 3, 2011

In a recent post about building a knowledge base for general consumption on the topic of ocean acidification, I suggested that it would be wise to step back and address questions-and-answers about the carbon cycle. This is a cross-posting of a post I just put up on Quora: The Carbon Cycle, Starting in.

And, the first question is also up on Quora: What are the compartments in which carbon is stored on Earth? Do you have the credentials to answer this, or do you know someone who does? Please help out—I believe it will be a rewarding way to bridge the gap between the science community and the rest of society. Also, keep in mind that “upvoting,” adding comments for the author, or suggesting edits,  as soon as there is one or more answers will be a really great way to participate.

For anyone new to Quora, I’d encourage you to take a look at a new infographic and video that helps explain how to have a winning strategy within the Quora community.

Any and all feedback is welcome!

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How Do I Go About Answering A Question on Quora?

by December 3, 2011

As a follow-up to a first infographic designed to help newcomers make sense of Quora, a relatively new question-and-answer site on the Web, this new infographic targets those who are new and want to dive in and begin answering questions. It is posted as an answer to How do you answer a question on Quora? There already are some great resources on Quora for those who are getting started, such as Lucretia Pruitt’s post “Welcome to Quora. Do Yourself a Favor & Slow Down” (1663 upvotes, and counting) and What are the basic rules around using Quora?

As an experiment, I created a short (3 min) video that walks you through the infographic. Note that there are a bunch of links to Quora questions throughout the video—ensure annotations are turned on to see them. Feedback welcome!

And, the infographic…

new-answerer-infographic-sketch-v02

 

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So You’re On Quora, Now What?

by October 16, 2011

As we gear up to tackle some basic questions and answers on Quora about the carbon cycle as part of our EarthQ project, with a goal of soon being able to tackle issues like ocean acidification and global warming, it seemed that a roadmap to Quora would be key for collaborators who might never have hear of it. Hence, the idea of a Quora Infographic emerged late this past week. Here’s version 0.1 that I’m throwing out for feedback. What do you think? Helpful? Silly? Gaping holes?

infographic-sketch-v02_small

UPDATE: Now showing version 0.2, thanks to a comment from friend Mike Troiano to highlight the start arrow. Keep the comments coming!

Version 0.1
infographic-sketch-v01_small

See this also on my post on Quora. I’d appreciate you up-voting it there if you like the idea.

Creative Commons License
So you’re on Quora, now what? by Dialogue Earth is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License. Permissions beyond the scope of this license should be submitted here.

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Building A Knowledge Base About Ocean Acidification on Quora

by October 13, 2011

Some months ago, we did a proof-of-concept video contest on the subject of ocean acidification. Here’s the winning video, about a snail that doesn’t have a shell, goes to learn why, and then forms a band to spread the word about this phenomenon.

Our overall vision is that we’d only initiate video, or other multimedia, projects once we’d nailed down the “science behind the story.” Furthermore, to us, nailing down the story means that we’ve ferreted out those key points for which we can get widespread agreement from experts drawn from across society–those from industry, NGOs, government, as well as academics.

To be blunt, we skipped this (huge) step for ocean acidification for two reasons. We were trying to proof out a crowd-based process for creating videos that conveyed science points fairly. Also, I had a good bit of background on the issue from my graduate work in oceanography.

102__0x0_quora-picture Now that we’re aiming to cultivate Q&As on Quora on topics related to the environment, it seems only logical to revisit the topic of ocean acidification. We’re dubbing this Quora-based project EarthQ (see also this post about putting candidates on the spot about global warming). For reference, see this post I did on the science behind the story of ocean acidification.

The goal of EarthQ will be to identify the top questions about various issues people are likely to ask about ocean acidification–assuming we can shepherd solid answers that are endorsed by a wide spectrum of experts. Taking this approach ties into Anticipating Questions People Will Ask About a Topic. Of course, if we’re successful, we will have created a great network of experts ready to jump to assistance as new questions emerge organically on Quora.

I’m a big advocate of working with building blocks on an issue. Having given this a good deal of thought recently, it is clear to me that step one will be to develop Q&A that fully explain the carbon cycle. Then, we can move on to the topic of ocean acidification. Then we should have worked out enough of the kinks to take on the topic of global warming. Onward!

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Putting Candidates and Others on the Spot About Global Warming

by September 29, 2011

This opinion piece, written in response to a recent Star Tribune op-ed, was published on Yale’s Forum for Climate Change and the Media on September 29, 2011.

The presence, or perhaps more so the absence, of serious climate change dialogue in the run-up to the presidential elections could make the issue a volatile unknown: Few politicians in the national spotlight want to be caught holding strong opinions in favor of aggressive policies to slow, curb, or reverse anticipated climate change.

James Lenfestey, a former Star Tribune editorial writer on climate and education, recently argued in Minneapolis Star Tribune (op-ed 9/17) that journalists should drill presidential candidates on six questions related to climate change, presumably to highlight those who are silent, or openly hostile, toward taking action in the face of this global threat.

Commentary

The media clearly can do a better job in raising serious issues like global warming with those leading, or aspiring to lead, our country. BUT putting candidates on the spot is unlikely to yield what our country desperately needs: a serious, ongoing dialogue about this global issue, which has connections to nearly every aspect of our society. Such a dialogue MUST be built on a foundation of trust and respect for political and ideological differences, as well as different scientific backgrounds.

Lenfestey’s six questions can be boiled down to these two: Do you believe global warming is occurring? And, do you believe we should have aggressive policies to counter this threat?

Lumping together opinions about how persuaded one is by the underlying science with questions about the appropriateness of a policy response is a recipe for an unproductive dialogue. Having spent a number of years working with experts drawn from across society to describe the condition and use of our ecosystems, I learned that it is essential to separate these aspects of the conversation—especially for the more contentious issues. In other words, we collectively need to find some common ground before arguing about appropriate policy responses.

We need to build an initiative that is viewed as trustworthy to all of us, no matter our ideological and political positions, or our understanding of science. WE can do that. We can run a transparent process—open to full scrutiny and input from anyone—that develops a series of questions and broadly accepted answers relevant to the issue of climate change. Not 100 questions, but rather more like 10. Each answer would be endorsed by experts drawn from across society and viewed as trustworthy by citizens and politicians from across the spectrum, both politically and ideologically.

As an example, these answers would undoubtedly include:

  • Carbon dioxide, a colorless gas present in tiny concentrations in the atmosphere, can trap radiation from the Earth that would otherwise dissipate into space.
  • There is strong evidence of a marked increase in carbon dioxide directly linked with the growth of industrialized societies across the globe.
  • Our “fingerprints” are detectable in the altered chemical nature of atmospheric carbon dioxide.
  • Long-term temperature trends indicate significant increases in recent decades.

These would be the first building blocks to a serious national dialogue.

Let’s take on this challenge. Let’s develop a robust, multimedia Web presence that brings to life the science behind the questions-and-answers for general audiences. Ideally, this effort would have its foundation on a public Q&A site, like Quora (http://quora.com).

Circling back to Lenfestey’s questions, let’s ask each candidate if he or she would support such an open, transparent process to create robust common ground across society. Global warming, which has the potential to irreversibly alter our world, demands a serious dialogue, and now is the time for to initiate it. Time is short, and there is a lot to do. Let’s make it happen.

Kent Cavender-Bares is an environmental scientist and the founder of Dialogue Earth, a nonprofit media project that has received major seed funding from the University of Minnesota’s Institute on the Environment and the Foundation for Environmental Research. The views represented are his alone and do not represent those of the University of Minnesota.

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Capturing Mood About Daily Weather From Twitter Posts

by September 29, 2011

After considerable preparation, we’ve just launched a version of our interactive tool, Pulse. Using Pulse, users can explore feelings about the weather as expressed on Twitter.

We began the process by choosing a topic that would yield a substantial volume of discussion on Twitter as well as be of general interest. Once we settled on weather, we wrote a survey designed to gauge Twitter users’ sentiments about the topic. With the help of workers from the “crowd” accessed through CrowdFlower, we had tens of thousands of relevant tweets coded as to the expressed emotion about the weather. These results were then used to create an “instance” of the Pulse tool, which manifests as a map of the United States that at a glance reveals Twitter users’ sentiments about the weather in their region on a given day. (You can read more about the coding process here and our choice of weather as a topic here.)

For our launch of Pulse for weather, we chose to feature tweets published over a month beginning in late April, 2011, a period in which many extreme weather events occurred—the devastating tornado in Joplin, MO; widespread drought throughout the South; and flooding of the Mississippi River, among others. The image below is from May 25, three days following the Joplin tornado (jump to the interactive map here).

may-25-pulse

We gathered tweets from all 50 states as well as for about 50 metro areas. Here you can see a zoom up on several states centered on Missouri.

zoom-may-25-pulse

The interactive map tells part of the story, namely a state’s or city’s overall sentiment about the weather, while the content under the “Analysis” and “Events” tabs reveal some of the “why” behind this sentiment: what were some of the most notable weather events occurring on a given day? [Note: our "events" feature has a bug in it and is currently turned off. In the future, icons will show up on the map to highlight out-of-the-ordinary weather events, like outbreaks of tornadoes, persistent flooding or drought, etc.] To what extent did the weather deviate from normal conditions? Why were tweets from, say, the South, uniformly negative during a certain time? What was happening when we saw a single positive state amidst a region that was otherwise negative?

We hope that weather is just the beginning. We envision using the Pulse tool to visualize nationwide sentiments about more complex, nuanced topics in the future—a sample of emotions about gas prices is just around the corner, and see our preliminary work on opinions about global warming. For now, you can explore the Pulse tool here, and let us know what you think!

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Message From the Bubble: A Concept for Periodic Videos About the Environment From A Roving Earth Bubble

by September 23, 2011

Brace yourselves, this is not high-production value material. Rather, this is a video that I produced in about 15 minutes, start-of-script-to-exporting-video-from-iMovie. It is the product of a brainstorming session during a great workshop put on by Liz Neeley of the COMPASS team at the U of MN’s Institute on the Environment.

Here’s the concept. I build an “Earth Bubble” that would be a moveable “studio.” Each week, or so, I plan and shoot a new video of the flavor of the one below. Aside from hopefully being a fun and engaging style, the final bit would be to zoom out and show where the Bubble is this week. Hanging from a tree, by a river… You get it.

Thoughts?

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World Food Production: Don’t Delude Yourself; Population Will Grow

by August 31, 2011

The following letter-to-the-Editor, a follow-up to my post about global population growth that is essentially a foregone conclusion, appeared in the Aug. 31, 2011 issue of the Minneapolis St. Paul Star Tribune:

In response to Prof. Allen Levine’s commentary about world hunger (“It’s world hunger (and it’s our world,)” Aug. 21), one letter writer and several readers who commented online argue for population control as an essential part of the equation.

In reality, fertility rates have dropped markedly over past decades. Demographers understand that, even at today’s relatively low rates, today’s children will have children of their own faster than older generations will die off.

An aggressive program to lower fertility rates will not alter that reality.

For those concerned about feeding, clothing and fueling the world’s population, accepting that we will have another 3 billion residents on the planet by 2050 is essential.

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Population Control Should Not Be A Priority Issue for Those Concerned About the Global Food Challenge

by August 29, 2011

In a letter-to-the-editor in today’s Star Tribune, a reader took issue with U of Minnesota Prof. Allen Levine’s recent opinion piece about the challenges facing our global agricultural system. Specifically, the writer asks why Prof. Levine apparently ducked the issue of “population control”:

Prof. Allen Levine makes a number of compelling points about combating world hunger (“It’s world hunger (and it’s our world),” Aug. 21). However, he neglects a key point — because it is our world. He does not mention population control. The fewer people there are, the fewer resources will be used, even with a growing middle class. Why is it anathema these days to talk about population control?

Prof. Levine’s piece raises a number of interesting points and sparked a number of online comments, including several others addressing population control:

  • NO mention of population control in this article? Sure, it’s a thorny issue – but if we don’t find a way to slow population growth, nature will do it for us, as horrific famines! The April, 2011 issue of Wired magazine has a great article about an Indian scientist who has come up with a male birth control method. It’s an inexpensive, easily reversible, safe kind of vasectomy, with zero side effects. The Bill and Melinda Gates Foundation has given this scientist a small grant to pursue this potentially huge solution, so please go to www.wired.com and read about this exciting development!
  • If we don’t find a way to slow population growth, nature will do it for us” Starvation in Africa is an example that it is already occurring.
  • Simple answer: Population control. Remember the 70′s. With less people we will need less fuel, less food, less of everything. Of course that would require responsibility by large population groups. Let’s see which groups responded to this crisis over 40 years ago. Ah! The European and North American groups self regulated their population successfully. The Chinese started later and used coercion. The others…nothing. Time to pull up the drawbridge and stop saving the overpopulators.

As discussed in a previous post chronicling a talk by Hans Rosling, a professor of global health at Sweden’s Karolinska Institute, there’s a lot of momentum in global population trends, and there is really very little that can be done to influence population trends over the next 40-50 years. Baring some unforeseen calamity, demographers predict that the World’s population will reach 9 billion by 2050, a statistic cited by Prof. Levine. The reason is that today’s children will have their own children faster than older generations will die off. This is true even with the low fertility rates existing across most of the planet. (more…)

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GPM Sheds Light On Why Hybrid Cars Are Tough To Justify On Fuel Savings Alone

by August 23, 2011

Hybrid car parking only

Photo credit, Chris Bloke on Flickr

Have you ever considered buying a hybrid car and gone through the calculations to compare the fuel cost savings to the higher price over comparable non-hybrid models? Chances are good that the math is not on the side of purchasing a hybrid, as pointed out in this USA Today opinion piece questioning the recently-announced, aggressive fuel efficiency standards. Most likely, it is our choice of metrics for evaluating fuel efficiency that help to make such calculations turn out to be less intuitive than we might expect, as discussed in this previous post on fuel economy metrics.

Hybrid cars are those that combine a large battery with an engine that generally runs on gasoline, although diesel hybrids are possible. In city driving with lots of starts and stops, the energy normally lost through braking is used to incrementally charge the battery—through a technology known as regenerative braking. If you’re looking for a 2-minute diversion, check out this video below featuring Maxwell von Stein, whose video was featured on Science Friday last week. He created a bike that uses a flywheel to store energy from braking to provide a boost literally down-the-road. He sees this as a great test case for creating a new type of hybrid car…

Because we need to brake less on highways, hybrids lose much of their advantage during highway driving. You can check out the EPA city/highway ratings for hybrids and compare them to non-hybrids side-by-side at fueleconomy.gov.

Following up on the previous post on MPG v. GPM (that is, miles per gallon v. gallons per mile), here are some quick calculations showing the fuel savings for two models from Toyota (Camry) and Ford (Fusion) that are available as hybrids. As in the previous post, the orange bar shows the fuel savings in gallons for 5000 miles of city driving.

thought_experiment_hybrid

The Fusion Hybrid driver could anticipate saving about $1000 on fuel over three years if she/he drove 5000 city miles, and the Camry Hybrid driver could expect about $700 in savings for three years of 5000 city miles—these calculations assume a gas price of $3.50 per gallon.

Grabbing some rough prices from Motor Trend’s site, it would cost about $6800 more for a Fusion Hybrid and about $4400 for a Camry Hybrid (these comparisons are very rough and are based on models that are one step up from the base offering for the non-hybrids; they also do not include any applicable rebates, deals, etc.).

Baring any government subsidy to help offset the purchase price, we immediately see the quandary facing a potential purchaser of a hybrid car: it is very tough to imagine recovering the extra purchase price through fuel cost savings. Plus, as mentioned above, if the hybrid was to be used for a good bit of highway driving, the potential fuel savings would diminish considerably.

I argued in the aforementioned post that GPM is a better way to get an intuitive feel for fuel savings. Interestingly the fueleconomy.gov site offers vehicle stats in GPM rather than MPG. I have to wonder if many people click on that option. Here are the side-by-side comparisons of the hybrid and non-hybrid Fusion and Camry models. First, using MPG as the comparison point, then with gallons per hundred miles (GPM). The cost savings tables at the bottom provide the same type of thought experiment as described above, though it is a bit more complex blending highway and city mileage.

fueleconomy_gov_mpg fueleconomy_gov_gpm

It would be a little like getting a nation to think metric, but one gets a sense that the second comparison provides information that is more instructive about cost savings from fuel usage.

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How Would Smiley Faces Change My Driving Behavior?

by August 12, 2011

xcelenergyreport1 Having just spent a bunch of time working on a pre-proposal for the National Science Foundation, I’m excited about an idea to create more feedback for drivers about their energy use. This project concept is motivated by recent research that many of us have a tough time judging the relative energy savings from a variety of behavior changes.

For example, the researchers found that many Americans estimate that a central air conditioning system uses about the same amount of energy as a window unit, when in fact a window unit typically uses several times less energy (link to abstract of article by Shahzeen Z. Attari and colleagues in the Proceedings of the National Academy of Sciences here).

Perhaps you are an Xcel Energy customer, or you’re with another utility that is taking advantage of OPOWER’s innovative approach to giving feedback to utility customers. As a residential customer of Xcel’s, we receive a monthly statement showing our use of energy compared to similarly-sized homes in our neighborhood. Thus, we receive a chart with our use of electricity and natural gas over the past 12 months, comparing our usage to that of our “efficient neighbors” and “all neighbors.” Here is our household usage over the past year from Xcel’s Energy Report website, which provides all of the data digitally after registering. (more…)

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Do Electric Cars and Nuclear Power Really Have Zero Carbon Emissions?

by August 8, 2011

The Nissan Leaf

Photo credit, Tom Raftery on Flickr

A piece about incentives to promote electric cars in Europe published in the Star Tribune a few days caught my eye. The author, who actually wrote the piece for the New York Times, discusses how the size of incentives are linked with reductions in carbon emissions and stated “Logically, electric cars with zero carbon emissions qualify for the largest incentives.”

Unless the electric vehicle (EV) was manufactured in world that uses no carbon-based fuels and the electricity that charges the EV’s batteries is devoid of carbon emissions, then this is not possible.

My guess is that the author confused direct and indirect emissions from EVs. Yes, there are no carbon emissions from EVs directly. However, electricity is needed to charge an EV’s battery, and even wind and solar have small carbon emissions. Electric vehicles also need to be manufactured and maintained, both of which will contribute to lifecycle emissions of carbon. Here’s one recent study that digs into the the energy use, cost, and carbon dioxide emissions of electric cars.

The statement about EVs reminded me of similar statements I’ve heard recently on the radio about nuclear energy. True, the plume that is characteristic of a nuclear plant’s cooling towers is water vapor. Yet, there are considerable lifecycle emissions of carbon connected to facility construction, uranium mining and processing, and waste disposal. Here’s a recent paper that evaluates the lifecycle emissions associated with nuclear energy, including estimates of how nuclear compares to other energy sources—on average about twice that of solar photovoltaic (PV) and about seven times less than natural gas.

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Sentiment Analysis Milestone: More Than One Million Human Judgments

by June 27, 2011

judgment-shot We have developed a process, dubbed Pulse, to extract nuanced sentiment from social media, like Twitter. We recognized early on that tools weren’t available to adequately answer specific questions, such as: “What’s the mood about today’s weather?” or “What portion of Twitter authors who discuss global warming believe that it is occurring?” or “Did Apple or Google have a more favorable buzz during this year’s South-by-Southwest Interactive?” Specifically, we concluded that it was necessary to get humans involved in the process—especially for Twitter posts, or tweets, which are often cryptic and have meaning that might be missed by a computer algorithm.

So, we turned to crowdsourcing.

However, successfully leveraging the power of the crowd for our sentiment analyses required cultivating the crowd, which we have achieved by working with partner CrowdFlower. In short, CrowdFlower offers an approach where we can access various work channels (we have relied mostly on Amazon’s Mechanical Turk), yet do so by layering on a quality control filter. Specifically, we intersperse within jobs what CrowdFlower terms “gold” units—in our case, tweets for which we already know the sentiment.  Workers build trustworthiness scores by getting the gold units correct. If they miss a gold unit, they get some feedback from us that has been tailored to that unit, such as “This person is happy that their garden is getting rain, so this should be marked as a positive emotion about the weather.”

We have been running a lot of jobs through CrowdFlower, but only recently did I step back and add up the tweets processed. For more than 200,000 individual tweets, we have received more than 1,000,000 trusted, human judgments from the CrowdFlower workforce! I know our research team, who had to do a bunch of judgments early on as we worked out a viable strategy, are grateful that we could get help from the crowd.

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