Posts tagged data
CU-NOAA study shows summer climate change, mostly warming
Nov 15th
“It is the first time that we show on a local scale that there are significant changes in summer temperatures,” said lead author CIRES scientist Irina Mahlstein. “This result shows us that we are experiencing a new summer climate regime in some regions.”
The technique, which reveals location-by-location temperature changes rather than global averages, could yield valuable insights into changes in ecosystems on a regional scale. Because the methodology relies on detecting temperatures outside the expected norm, it is more relevant to understand changes to the animal and plant life of a particular region, which scientists would expect to show sensitivity to changes that lie outside of normal variability.
“If the summers are actually significantly different from the way that they used to be, it could affect ecosystems,” said Mahlstein, who works in the Chemical Sciences Division of the National Oceanic and Atmospheric Administration’s Earth System Research Laboratory.
To identify potential temperature changes, the team used climate observations recorded from 1920 to 2010 from around the globe. The scientists termed the 30-year interval from 1920 to 1949 the “base period,” and then compared the base period to other 30-year test intervals starting every 10 years since 1930.
The comparison used statistics to assess whether the test interval differed from the base period beyond what would be expected due to yearly temperature variability for that geographical area.
Their analysis found that some changes began to appear as early as the 1960s, and the observed changes were more prevalent in tropical areas. In these regions, temperatures varied little throughout the years, so the scientists could more easily detect any changes that did occur, Mahlstein said.
The scientists found significant summer temperature changes in 40 percent of tropical areas and 20 percent of higher-latitude areas. In the majority of cases, the researchers observed warming summer temperatures, but in some cases they observed cooling summer temperatures.
“This study has applied a new approach to the question, ‘Has the temperature changed in local areas?’ ” Mahlstein said. The study is in press in the journal Geophysical Research Letters, a publication of the American Geophysical Union.
The study’s findings are consistent with other approaches used to answer the same question, such as modeling and analysis of trends, Mahlstein said. But this technique uses only observed data to come to the same result. “Looking at the graphs of our results, you can visibly see how things are changing,” she said.
In particular the scientists were able to look at the earlier time periods, note the temperature extremes, and observe that those values became more frequent in the later time periods. “You see how the extreme events of the past have become a normal event,” Mahlstein said.
The scientists used 90 years of data for their study, a little more than the average lifespan of a human being. So if inhabitants of those areas believe that summers have changed since they were younger, they can be confident it is not a figment of their imagination.
“We can actually say that these changes have happened in the lifetime of a person,” Mahlstein said.
Co-authors on the study were Gabriele Hegerl from the University of Edinburgh in Scotland and Susan Solomon from Massachusetts Institute of Technology.
CIRES is a joint institute of CU-Boulder and NOAA.
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CU Boulder study finds racial ‘hierarchy of bias’ drives decision to shoot armed, unarmed suspects
Oct 24th
Both the police and student subjects were most likely to shoot at blacks, then Hispanics, then whites and finally, in a case of what might be called a positive bias, Asians, researchers found.
In the first study of its kind, Joshua Correll, Bernadette Park and Charles M. Judd of CU-Boulder’s Department of Psychology and Neuroscience and Melody Sadler of San Diego State University examined how police and a group of undergraduate subjects decide whether to shoot or not to shoot “suspects” in a multi-ethnic environment.
“Most studies on the subject of stereotyping and prejudice look at two (ethnic) groups, usually in isolation. It’s always one group against another group,” said Correll, a CU graduate who joined the faculty in August after a stint at the University of Chicago.
“But as the country becomes more ethnically diverse, it’s more and more important to start thinking about how we process racial and ethnic cues in a multicultural environment,” he said.
As with previous studies into the question, data were gathered from subjects playing a “first person shooter” video game, in which figures of varying ethnicity — Caucasian, Asian, Hispanic and African-American — pop up, either “armed” with a weapon or another benign object, such as a cell phone.
Participants — 69 CU-Boulder undergraduates and 254 police officers — had to make quick decisions as to which figures posed a “threat” and shoot them. The police officers were recruited from two-day training seminars in Florida, New Mexico and Washington and represented numerous jurisdictions from 11 states.
The research demonstrates how persistent cultural stereotypes are, Correll said. Even students who displayed little bias when interviewed demonstrated otherwise when faced with a split-second decision.
“I may not believe it personally, but I am exposed to stereotypes constantly through media or social networks … (such as) the idea that young black men are dangerous,” he said. “Those associations can have an influence on my behavior even if I don’t believe them.”
The study found that police were considerably more accurate than students at correctly identifying a genuinely threatening suspect, as opposed to those brandishing a cell phone or wallet, perhaps a reflection of training. But officers were still influenced by the target’s race — an influence that may derive from the officers’ “contacts, attitudes and stereotypes,” Correll said.
For example, police who endorsed more violent stereotypes about Hispanics and those who overestimated the prevalence of violent crime in their districts demonstrated more bias to shoot Hispanic targets. That raises the question of whether police are responding to real-world threats — and whether that means some ethnic groups really are more likely to be armed and dangerous than others.
“That is a very sensitive question, whether or not (police officers’) reactions are based on some kind of truth. Is this police officers responding to reality on the ground? The short answer is, we don’t know,” Correll said. “But this research almost demands that we ask that question.”
The researchers’ recent findings were published in the Journal of Social Issues. The work was funded by a grant from the Russell Sage Foundation.
In 2007, Correll (then at the University of Chicago), Sadler (then at CU-Boulder), Park and Judd collaborated with the Denver Police Department on a widely cited study that found police officers were less influenced than the general public by racial bias and less likely than the general population to make a decision to shoot at African-American suspects wielding a benign object.
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CU team measures climate variability and conflict risk in East Africa
Oct 23rd
While a new study led by the University of Colorado Boulder shows the risk of human conflict in East Africa increases somewhat with hotter temperatures and drops a bit with higher precipitation, it concludes that socioeconomic, political and geographic factors play a much more substantial role than climate change.
According to CU-Boulder geography Professor John O’Loughlin, the new CU-Boulder study undertaken with the National Center for Atmospheric Research in Boulder is an attempt to clarify the often-contradictory debate on whether climate change is affecting armed conflicts in Africa. “We wanted to get beyond the specific idea and hype of climate wars,” he said. “The idea was to bring together a team perspective to see if changes in rainfall and temperature led to more conflict in vulnerable areas of East Africa.”
The research team examined extensive climate datasets from nine countries in East Africa, including the Horn of Africa, between 1990 and 2009: Burundi, Djibouti, Eritrea, Ethiopia, Kenya, Rwanda, Somalia, Tanzania and Uganda. The team also used a dataset containing more than 16,000 violent conflicts in those countries during that time period, parsing out more specific information on conflict location and under what type of political, social, economic and geographic conditions each incident took place.
The study, which included changes in precipitation and temperature over continuous six-month periods from 1949 to 2009, also showed there was no climate effect on East African conflicts during normal and drier precipitation periods or during periods of average and cooler temperatures, said O’Loughlin.
Moderate increases in temperature reduced the risk of conflict slightly after controlling for the influence of social and political conditions, but very hot temperatures increased the risk of conflict, said O’Loughlin. Unusually wet periods also reduced the risk of conflict, according to the new study.
“The relationship between climate change and conflict in East Africa is incredibly complex and varies hugely by country and time period,” he said. “The simplistic arguments we hear on both sides are not accurate, especially those by pessimists who talk about ‘climate wars’. Compared to social, economic and political factors, climate factors adding to conflict risk are really quite modest.”
The results are being published online Oct. 22 in the Proceedings of the National Academy of Sciences. Co-authors on the study include CU-Boulder Research Associate Frank Witmer and graduate student Andrew Linke as well as three scientists from the National Center for Atmospheric research — Arlene Laing, Andrew Gettelman and Jimy Dudhia. The National Science Foundation funded the study.
Much of the information on the 16,359 violent events in East Africa from 1990 to 2009 came from the Armed Conflict Location and Event Dataset, or ACLED, directed by Clionadh Raleigh of Trinity College in Dublin. The database covers individual conflicts from 1997 to 2009 in Africa, parts of Asia and Haiti – more than 60,000 violent incidents to date. Raleigh started the data collection while earning her doctorate at CU in 2007 under O’Loughlin.
In addition, more than a dozen CU-Boulder undergraduates spent thousands of hours combing online information sources like LexisNexis — a corporation that pioneered the electronic accessibility of legal and newspaper documents — in order to fill in details of individual violent conflicts by East African countries from 1990 to 1997. The student work was funded by the NSF’s Research Experiences for Undergraduates program.
The CU students coded each conflict event with very specific data, including geographic location coordinates, dates, people and descriptive classifications. The event information was then aggregated into months and into 100-kilometer grid cells that serve as the units of analysis for quantitative modeling.
Each conflict grid also was coded by socioeconomic and political characteristics like ethnic leadership, distance to an international border, capital city, local population size, well-being as measured by infant mortality, the extent of political rights, presidential election activity, road network density, the health of vegetation and crop conditions.
“The effects of climate variability on conflict risk is different in different countries,” O’Loughlin said. “Typically conflicts are very local and quite confined. The effects of climate on conflict in Ethiopia, for example, are different than those in Tanzania or Somalia. The idea that there is a general ‘African effect’ for conflict is wrong.”
The researchers used a variety of complex statistical calculations to assess the role of climate in violent conflict in East Africa, including regression models and a technique to uncover nonlinear influences and decrease “noise,” said O’Loughlin, also a faculty member at CU-Boulder’s Institute of Behavioral Science.
One component of the methods used by the team extracts predictions of individual instances of conflict from the statistical model and systematically compared them with the actual observations of conflict in the data, “a rigorous validity check,” he said.
Catastrophic conflicts like those in the “Great Lakes region” — Rwanda, Burundi, Uganda and the eastern Democratic Republic of the Congo — since the 1990s and the war with the Lord’s Resistance Army led by terrorist Joseph Kony that has been running since the late 1980s in northern Uganda and neighboring regions are marked with large red swaths on the maps.
Legacies of violence are extremely important for understanding and explaining unrest, he said. “Violence nearby and prior violence in the locality, especially for heavily populated areas, are the strongest predictors of conflict.”
Ongoing work is extending the study to all of sub-Saharan Africa since 1980 with a database of 63,000 violent events. Preliminary results from the work confirm the East African climate effects of higher than normal temperatures are increasing conflict risk.