Evidence increasingly suggests that as climate warms, some plant, animal and human populations may move to preserve their environmental temperature. The distances they must travel to do this depends on how much cooler nearby surfaces temperatures are. Because large-scale atmospheric dynamics constrain surface temperatures to be nearly uniform near the equator, these displacements can grow to extreme distances in the tropics, even under relatively mild warming scenarios. Here we show that in order to preserve their annual mean temperatures, tropical populations would have to travel distances greater than 1000 km over less than a century if global mean temperature rises by 2 °C over the same period. The disproportionately rapid evacuation of the tropics under such a scenario would cause migrants to concentrate in tropical margins and the subtropics, where population densities would increase 300% or more. These results may have critical consequences for ecosystem and human wellbeing in tropical contexts where alternatives to geographic displacement are limited.

In an era of significant disinvestment in public higher education by state governments, many public universities are moving toward a “progressive tuition model” that attempts to invest approximately one-third of tuition income into institutional financial aid for lower-income and middle-class students. The objective is to mitigate the cost of tuition and keep college affordable. But is this model as currently formulated working? What levels of financial stress are students of all income groups experiencing? And are they changing their behaviors? Utilizing data from the Student Experience in the Research University (SERU) Survey of undergraduates and other data sources, this study explores these issues by focusing on students at the University of California and ten AAU institutions that are members of the SERU Consortium. At least to date, the increase in tuition, and costs related to housing and other living expenses, have not had a negative impact on the number of lower-income students attending UC. Reflecting to some degree UC’s robust financial aid policies, and perhaps the growing number of lower-income families in California, there has been an actual increase in their number – a counterintuitive finding to the general perception that higher tuition equals less access to the economically vulnerable. At the same time, there is evidence of a “middle-class” squeeze, with a marginal drop in the number of students from this economic class. Students’ concerns for paying for higher education and accumulated student debt in the 2014 SERU are predictably higher among lower-income students, yet upper-middle income students (with annual family incomes from $80–125,000) are the least likely to agree that the cost of attendance is manageable. With these and other nuances and caveats briefly discussed in this study, the progressive tuition model appears to be working in terms of affordability and with only moderate indicators of increased financial stress and changed student behaviors. These results are not necessarily predictive of the future if tuition rates go up further. But they do indicate the higher tuition rates at highly selective public universities, if accompanied by robust federal, state and institutional financial aid, may be the best path for maintaining access to lower-income students, and for generating income needed for institutions to maintain or improve student-to-faculty ratios and other markers of quality. Freezing tuition, as currently demanded by state lawmakers in California, does not appear to be based on any clear analysis of the correlation of tuition and affordability. It appears more as a politically attractive way to appeal to voters while ignoring the financial consequences for public colleges and universities and the quality of the student experience.

Economists often use test scores to measure a student’s performance or an adult’s human capital. These scores reflect nontrivial decisions about how to measure and scale student achievement, with important implications for secondary analyses. For example, the scores computed in several major testing regimes, including the National Assessment of Educational Progress (NAEP), depend not only on the examinees’ responses to test items, but also on their background characteristics, including race and gender. As a consequence, if a black and white student respond identically to questions on the NAEP assessment, the reported ability for the black student will be lower than for the white student—reflecting the lower average performance of black students. This can bias many secondary analyses. Other assessments use different measurement models. This paper aims to familiarize applied economists with the construction and properties of common cognitive score measures and the implications for research using these measures.

The Great Recession was the longest and by some measures the most severe economic downturn in the postwar period. The experience revealed important weaknesses in the central cash welfare program for families with children in the United States, Temporary Assistance for Needy Families (TANF). First, TANF fails to reach a sizeable share of needy families, does little to reduce deep poverty, and is not targeted to the most needy. Second, in its current form the program does not automatically expand during economic downturns, when the need for the program is likely greatest and the additional consumer spending would be particularly welcome. To strengthen TANF, we propose reforms to expand its reach, improve its responsiveness to cyclical downturns, and enhance its transparency. Together these reforms would make the program more effective in protecting families from deep poverty.

To prepare for an urban influx of 2.5 billion people by 2050, it is critical to create cities that are lowcarbon, resilient, and livable. Cities not only contribute to global climate change by emitting the majority of anthropogenic greenhouse gases but also are particularly vulnerable to the effects of climate change and extreme weather.We explore options for establishing sustainable energy systems by reducing energy consumption, particularly in the buildings and transportation sectors, and providing robust, decentralized, and renewable energy sources. Through technical advancements in power density, city-integrated renewable energy will be better suited to satisfy the high-energy demands of growing urban areas. Several economic, technical, behavioral, and political challenges need to be overcome for innovation to improve urban sustainability.

We present an integrated model, SWITCHChina, of the Chinese power sector with which to analyze the economic and technological implications of a medium to longterm decarbonization scenario while accounting for very-shortterm renewable variability. On the basis of the model and assumptions used, we find that the announced 2030 carbon peak can be achieved with a carbon price of ∼$40/tCO2. Current trends in renewable energy price reductions alone are insufficient to replace coal; however, an 80% carbon emission reduction by 2050 is achievable in the Intergovernmental Panel on Climate Change Target Scenario with an optimal electricity mix in 2050 including nuclear (14%), wind (23%), solar (27%), hydro (6%), gas (1%), coal (3%), and carbon capture and sequestration coal energy (26%). The co-benefits of carbon-price strategy would offset 22% to 42% of the increased electricity costs if the true cost of coal and the social cost of carbon are incorporated. In such a scenario, aggressive attention to research and both technological and financial innovation mechanisms are crucial to enabling the transition at a reasonable cost, along with strong carbon policies.