Nicole Ma

and 7 more

Many regions across the globe broke their surface temperature records in recent years, further sparking concerns about the impending arrival of “tipping points” later in the 21st century. This study analyzes observed global surface temperature trends in three target latitudinal regions: the Arctic Circle, the Tropics, and the Antarctic Circle. We show that global warming is accelerating unevenly across the planet, with the Arctic warming at approximately three times the average rate of our world. We further analyzed the reliability of latitude-dependent surface temperature simulations from a suite of Coupled Model Intercomparison Project Phase 6 models and their multi-model mean. We found that GISS-E2-1-G and FGOALS-g3 were the best-performing models based on their statistical abilities to reproduce observational, latitude-dependent data. Surface temperatures were projected from ensemble simulations of the Shared Socioeconomic Pathway 2-4.5 (SSP2-4.5). We estimate when the climate will warm by 1.5, 2.0, and 2.5 ℃ relative to the preindustrial period, globally and regionally. GISS-E2-1-G projects that global surface temperature anomalies would reach 1.5, 2.0, and 2.5 ℃ in 2024 (±1.34), 2039 (±2.83), and 2057 (±5.03) respectively, while FGOALS-g3 predicts these “tipping points” would arrive in 2024 (±2.50), 2054 (±7.90), and 2087 (±10.55) respectively. Our results reaffirm a dramatic, upward trend in projected climate warming acceleration, with upward concavity in 21st century projections of the Arctic, which could lead to catastrophic consequences across the Earth. Further studies are necessary to determine the most efficient solutions to reduce global warming acceleration and maintain a low SSP, both globally and regionally.

Jonathan Jiang

and 4 more

Clouds play a significant role in the Earth’s energy balance and hydrological cycle through their effects on radiation and precipitation, and therefore are crucial for life on Earth. Earth’s NexT‐generation ICE mission (ENTICE) is proposed to measure diurnally resolved global vertical profiles of cloud ice particle size, ice water content, and in-cloud humidity and temperature using multi-frequency sub-millimeter (sub-mm) microwave radiometers and a 94 GHz cloud radar from space. The scientific objective of ENTICE is to identify the important processes by which anvil clouds evolve and interact with ambient thermodynamic conditions to advance our fundamental understanding of clouds and reduce uncertainties in cloud climate feedback. Whether such an objective could be achieved depends on the orbital sampling characteristics of the mission. In this study, ENTICE sampling statistics are simulated using five different scanning methods in a 400 km altitude precession orbit with an inclination of 65°: nadir, forward pointing, side scanning, and conical scanning for the radiometers, and nadir pointing for the radar. Using the GEOS-5 Nature Run produced at 7-km and 30-min resolution, sampling statistics with respect to cloud types and local hours with enhancement from radar are calculated for ENTICE. The wide swath of ENTICE radiometers by conical and side scanning methods ensures ample high cloud samples gathered by ENTICE over its two-year mission for different types of clouds with sufficient sampling over the diurnal cycles. Sampling differences between radar and radiometers at nadir demonstrate that the combination of radar and radiometers will allow for measurements of cloud vertical profiles. Therefore, our results show that the designed orbit sampling of ENTICE is sufficient to fulfill the mission science goals.