This study estimates the predicted impact of climate change on levels of violence in a sample of 57 countries. We sample western and non-western countries and perform a multilevel ARFIMA regression to examine if warmer temperatures are associated with higher levels of homicide. Our results indicate that each degree Celsius increase in annual temperatures is associated with a nearly 6% average increase in homicides. Regional variation in this predicted effect is detected, for example, with no apparent effects in former Soviet countries and far stronger effects found in Africa. This variation indicates that climate change may acutely increase violence in areas that already are affected by higher levels of homicides and other social dislocations.

We investigated why a legislator would be willing to vote “yea” on final passage of a bill but would choose not to cosponsor that bill. We tested a series of hypotheses regarding the cosponsorship decisions of individual senators, using a dataset that includes every major initiative that was introduced and received a floor vote in the Senate between 1975 and 2000. We found that senators are more likely to cosponsor bills when their preferences diverge from the Senate median but are closer to those of the bill's sponsor. Also, senators are more likely to cosponsor bills when they sponsor a higher number of bills overall, when they become more connected with colleagues, and when their constituents increase demand for legislation within particular policy areas. Senators are less likely to cosponsor bills if they received a higher percentage of the general election vote in their most recent election.

College students politically participate through traditional mechanisms at lower rates than their elders. Yet, members of this group may participate by other means, like friending candidates and joining political groups through social networking websites. We argue that these online activities serve as a meaningful form of civic engagement by broadening who participates and encouraging other forms of participation. Using a survey of randomly chosen undergraduates at a large Midwestern university, we discover that important distinctions exist between those who friend or join these online social networks and those who participate in more traditional off-line political activities. While interest in politics is a precursor to off-line engagement, it does not predict friending or joining an online social network that is political in nature. However, friending candidates or joining such networks appears to mobilize college students to engage in other forms of political participation.

A growing body of research suggests a positive connection between climate change and crime, but few studies have explored the seasonal nature of that link. Here, we examine how the impact of climate change on crime may partly depend on specific times of the year as recent climatological research suggests that climate change may have a diverging impact during different times of the year. To do so, we utilize the largest, most current dataset of all main categories of reported crime by month and year in the United States—the Federal Bureau of Investigation’s (FBI) Uniform Crime Reports. We employ historical weather data collected by the Global Historical Climatology Network to measure climate change, and develop a procedure that weighs and connects these data to individual crime reporting agencies. We discover not only a positive association between climate change and crime but also substantial monthly variation in this association.

Popular and scholarly accounts argue that signing statements are important tools for presidents to shape the implementation of policy. Although signing statements might be important presidential tools, the legislative branch stands in the most immediate and direct competition with the executive for ultimate control of the bureaucracy. In this article, we assess whether congressional committees react to presidential signing statements with increased oversight. Using a data set that includes every oversight hearing held by the U.S. House between 1995 and 2007, we find evidence that congressional committees are sensitive to the number of objections raised by presidents in signing statements. As the president uses signing statements to object to a larger number of provisions in laws, the affected House committees respond with more oversight.