Obesity and cancer third most important risk factor for cancer in the United States, just behind tobacco and diet (see Figure). Obesity is the source of about 15% of all preventable cancers. In 2018, Chinese researchers performed a systematic review and comprehensive quantitative meta‐analysis of cohort studies reporting body mass index (BMI) and the risk of 23 cancer types, providing epidemiological evidence supporting the association between BMI and cancer risk. The strongest positive association between BMI and cancer risk was found among patients in North America. The mechanisms by which obesity may increase the risk of cancer are not well understood, but it
Cool tropics paradox poleward heat transport by the oceans, and vegetational responses at high latitudes, were proposed, but these didn't fully explain behaviour in the southern hemisphere, and winter, respectively. Data from terrestrial proxies suggested that the equator may have reached 30 °C - however, this figure is based upon extrapolation of data found outside the tropics. This would imply that the foramaniferal proxies were wrong - the tests may perhaps have been overprinted by diagenesis. Researchers turned to shallow marine molluscs as it is easy to determine whether their shells had been altered by diagenesis. Many mollusc shells are constructed from aragonite,