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We simulated Arctic climate using a high‐resolution implementation of WRF driven by HadGEM‐ES2 climate model outputs, following IPCC5 warming scenarios RCP 2.6, RCP 4.5 and RCP 8.5. The downscaled results indicate that, by the end‐of‐century, there are no significant changes in the average minimum central pressures or total number of winter Arctic cyclones. However, there are significant changes in the spatial patterns. For example, the frequency and vorticity of cyclones tend to increase over the western Arctic. Due to the poleward movement of the polar frontal zone and the increased low‐level tropospheric baroclinicity, more cyclones are expected to form within the Arctic Basin and migrate into the western‐central Arctic. We expect about 39% more cyclone tracks forming and dying in the Arctic Basin under RCP8.5, compared to present climate. On the other hand, with the reduced baroclinicity in the entire troposphere, there is a reduced genesis, frequency, and vorticity of cyclones over the Atlantic Arctic. Moreover, the depth of cyclones shows a robust decrease over the Arctic Basin, suggesting weakened eddy kinetic energy. With increasing greenhouse gases, the changes in cyclone vorticities and their depths tend to be stronger. In addition, the high resolution Polar WRF results demonstrate that changes in cyclone track density and intensities consistently become more pronounced with increasing radiative forcing. Plain Language Summary: We used advanced climate models to simulate how the Arctic climate might change in the future. We focused on the scenarios outlined by the Intergovernmental Panel on Climate Change (IPCC) and their effects on Arctic cyclones. Our results show that, by the end of the 21st century, the overall characteristics of winter Arctic cyclones do not experience significant changes. However, there are interesting regional variations. The frequency and vorticity (spinning) force of cyclones are projected to decrease over the Atlantic Arctic but increase over the western Arctic. Simultaneously, fewer cyclones are expected over the Atlantic Arctic. Furthermore, the depth of cyclones over the Arctic Basin is expected to decrease, suggesting a weakening in their strength. In IPCC scenarios with higher emissions, the changes in cyclone characteristics become more pronounced. Similar trends are also observed in results from the latest climate models. Key Points: The frequency and vorticity of cyclones tend to increase (decrease) over the western‐central (Atlantic) Arctic under climate scenariosThe decreasing cyclone depths in the Arctic Basin suggest a weakened eddy kinetic energy in warming climate scenariosThe poleward shift of the frontal zone and increased baroclinicity lead to 39% more cyclones forming and dying in the Arctic Basin under the warmest scenario [ABSTRACT FROM AUTHOR]

We show that the winter Beaufort High (BH) index defined by sea level pressure (SLP) has a robust negative trend under the scenarios SSP5‐8.5 and SSP2‐4.5, with a reduction by about 5 hPa and 2 hPa, respectively, by the end of the 21st century. The negative trends in the BH SLP are associated with the changes in the background SLP over the Arctic basin. However, the vorticity of the winter BH tends to intensify under SSP5‐8.5, but shows no robust increase under SSP2‐4.5. The intensification is associated with the enhanced ridge over the Western Arctic. Therefore, it is necessary to take into account the dynamic aspects of the BH, such as vorticity. Based on this assessment, under the most likely emissions scenario, the winter BH is likely to weaken through the 21st century, in terms of SLP, but shows no robust changes in term of vorticity. Plain Language Summary: We used the latest IPCC global climate model outputs to investigate the wintertime changes in the Beaufort High (BH). Under the climate change scenarios, during winter, the sea level pressure (SLP) over the BH region is expected to decrease. The SLP reduction is up to 5 hPa by the end‐of‐the‐century. Thus, the BH seems to become weaker. However, its vorticity tends to increase under SSP5‐8.5, mostly due to the intensification of the ridge over the western North America. Key Points: The Beaufort High (BH) index defined by sea level pressure (SLP) decreases under warming climate scenariosMeanwhile, the BH vorticity tends to intensify due to the change in the ridge over the Western ArcticBesides the SLP, impact studies of the BH on the Arctic Ocean need to consider its dynamics such as vorticity [ABSTRACT FROM AUTHOR]

The radiative impacts of the stratosphere in global warming simulations are investigated using abrupt CO quadrupling experiments of the Coupled Model Inter-comparison Project phase 5 (CMIP5), with a focus on stratospheric temperature and water vapor. It is found that the stratospheric temperature change has a robust bullhorn-like zonal-mean pattern due to a strengthening of the stratospheric overturning circulation. This temperature change modifies the zonal mean top-of-the-atmosphere energy balance, but the compensation of the regional effects leads to an insignificant global-mean radiative feedback (−0.02 ± 0.04 W m K). The stratospheric water vapor concentration generally increases, which leads to a weak positive global-mean radiative feedback (0.02 ± 0.01 W m K). The stratospheric moistening is related to mixing of elevated upper-tropospheric humidity, and, to a lesser extent, to change in tropical tropopause temperature. Our results indicate that the strength of the stratospheric water vapor feedback is noticeably larger in high-top models than in low-top ones. The results here indicate that although its radiative impact as a forcing adjustment is significant, the stratosphere makes a minor contribution to the overall climate feedback in CMIP5 models. [ABSTRACT FROM AUTHOR]