Population-weighted degree-days: The global shift between heating and cooling.

Anthropogenic greenhouse gas emissions are driving global increases in temperature. This rise will likely lead to an increase in demand for cooling in the coming years. However, increasing temperatures are not the main explanatory factor for why the world is moving towards more cooling. This paper compares population and area-weighted cooling and heating degree-days derived using ERA5-Land reanalysis temperature, to show that population growth in warmer parts of the world drives cooling demand globally. The analysis shows that mean global area-weighted heating degree-days have fallen 8.46 °C days/year, whereas population-weighted heating degree-days have fallen by 12.5 °C days/year. At the same time, mean global area-weighted cooling degree-days have risen by 3.0 °C days/year, while population-weighted cooling degree-days have risen at 6.0 °C days/year. By using sub-country analysis, this paper shows that population-weighted degree-days can substantially differ from area-weighted degree-days. Finally, the findings highlight that the choice of heating and cooling degree-day base temperature is the most important parameter in the variability of degree-days and will need to be understood better in order to accurately account for future heating and cooling energy demand.

Observational evidence of the seasonal and demographic variation in experienced temperature from 77 743 UK Biobank participants.

BACKGROUND: Exposure to cold is known to be associated with severe health impacts. The primary epidemiological evidence for this is the seasonal variation in mortality. However, there is a paucity of directly measured data for personal cold temperature exposure. This paper develops the concept of experienced temperature, and reports how it varies with season, demographics and housing factors. METHODS: This study uses data from 77 743 UK Biobank participants. A novel method to directly measure participant's exposure to low temperatures using a thermistor in a wrist-worn activity monitor is described. These readings are combined with demographic and housing factor variables in a multiple regression model to understand underlying relationships. RESULTS: The study reveals a significant difference in experienced temperature of ~1.8°C between the periods of coldest and hottest external temperature. A number of demographic differences were also observed-such as people of Chinese ethnic background experiencing 0.65°C lower temperatures than other groups. CONCLUSIONS: This paper presents primary evidence for a seasonal variation in experienced temperature. This variation likely contributes to cold related mortality and morbidity. It is hypothesized that this relationship would be less strong in countries which suffer fewer impacts of cold winter temperatures.

International food trade contributes to dietary risks and mortality at global, regional and national levels.

Food trade is generally perceived to increase the availability and diversity of foods available to consumers, but there is little empirical evidence on its implications for human health. Here we show that a substantial proportion of dietary risks and diet-related mortality worldwide is attributable to international food trade and that whether the contributions of food trade are positive or negative depends on the types of food traded. Using bilateral trade data for 2019 and food-specific risk-disease relationships, we estimate that imports of fruits, vegetables, legumes and nuts improved dietary risks in the importing countries and were associated with a reduction in mortality from non-communicable diseases of ~1.4 million deaths globally. By contrast, imports of red meat aggravated dietary risks in the importing countries and were associated with an increase of ~150,000 deaths. The magnitude of our findings suggests that considering impacts on dietary risks will become an important aspect of health-sensitive trade and agriculture policies, and of policy responses to disruptions in food chains.