We diagnose climate model-simulated changes in the hottest summertime daily maximum temperatures under global warming and identify the regions where increases in these extreme temperatures are most amplified relative to warming in the mean state. We find that extreme summertime temperatures rise with global warming about 20% faster than mean temperature across much of the low and mid-latitude continental areas, a phenomenon we refer to as “warming warms the warmest worst” (WWWW). Our results suggest that WWWW applies particularly to land regions with relatively moist surface conditions in the current climate. We examine the potential mechanisms behind the emergence of these patterns. Several lines of evidence indicate that the affected regions experience WWWW because of suppressed evapotranspiration and the resulting higher Bowen ratios. We suggest that this mechanism may link WWWW to increased episodicity of precipitation.
Beyond this, I will also briefly talk about my main PhD project, on the utility (or futility) of using stable water isotopes to constrain tropical convective simulation. I will introduce how water isotopes are regarded as promising candidates for revealing sub-grid convective processes, and why I conclude they unfortunately do not usefully provide new constraints to the mean convective entrainment rate or precipitation efficiency, two critical convective processes which we lack observations and theories for. I hope to communicate my thoughts on using tracers as proxies for physics that we cannot directly measure.