Extreme weather and climate change: the connections and impacts

Is there a connection between extreme weather events (rain, cold, heat, droughts, hail, hurricanes, tornadoes, and more) and climate change?

Yes.

Are extreme weather events becoming stronger and happening more frequently?

Yes.

Are these extreme weather events having a greater impact–economic losses, human migration, loss of plant and animal species and even extinction, worsening human health, and more.

Yes, again.

See the research …

Quick bibliography: the connection between extreme weather events and climate change.

*Cohen, J., Pfeiffer, K., & Francis, J. A. (2018). Warm arctic episodes linked with increased frequency of extreme winter weather in the United States. Nature Communications, 9(1), 869. [PDF] [Cited by]

“Recent boreal winters have exhibited a large-scale seesaw temperature pattern characterized by an unusually warm Arctic and cold continents. Whether there is any physical link between Arctic variability and Northern Hemisphere (NH) extreme weather is an active area of research. Using a recently developed index of severe winter weather, we show that the occurrence of severe winter weather in the United States is significantly related to anomalies in pan-Arctic geopotential heights and temperatures. As the Arctic transitions from a relatively cold state to a warmer one, the frequency of severe winter weather in mid-latitudes increases through the transition. However, this relationship is strongest in the eastern US and mixed to even opposite along the western US. We also show that during mid-winter to late-winter of recent decades, when the Arctic warming trend is greatest and extends into the upper troposphere and lower stratosphere, severe winter weather—including both cold spells and heavy snows—became more frequent in the eastern United States.”

*Kretschmer, M., Coumou, D., Agel, L., Barlow, M., Tziperman, E., & Cohen, J. (2018). More-persistent weak stratospheric polar vortex states linked to cold extremes. Bulletin of the American Meteorological Society, 99(1), 49-60. [PDF] [Cited by]

The extratropical stratosphere in boreal winter is characterized by a strong circumpolar westerly jet, confining the coldest temperatures at high latitudes. The jet, referred to as the stratospheric polar vortex, is predominantly zonal and centered around the pole; however, it does exhibit large variability in wind speed and location. Previous studies showed that a weak stratospheric polar vortex can lead to cold-air outbreaks in the midlatitudes, but the exact relationships and mechanisms are unclear. Particularly, it is unclear whether stratospheric variability has contributed to the observed anomalous cooling trends in midlatitude Eurasia. Using hierarchical clustering, we show that over the last 37 years, the frequency of weak vortex states in mid- to late winter (January and February) has increased, which was accompanied by subsequent cold extremes in midlatitude Eurasia. For this region, 60% of the observed cooling in the era of Arctic amplification, that is, since 1990, can be explained by the increased frequency of weak stratospheric polar vortex states, a number that increases to almost 80% when El Niño–Southern Oscillation (ENSO) variability is included as well.”

*Pendergrass, A. G., & Knutti, R. (2018). The uneven nature of daily precipitation and its change. Geophysical Research Letters, 45(21), 11,980-11,988. [PDF] [Cited by]

“Rain falls unevenly in time, which can lead to floods and droughts. A few days with heavy rain contribute disproportionately to total precipitation, while many days with light drizzle contribute much less. What is not appreciated is just how asymmetric this distribution is in time, and the even more asymmetric nature of trends due to climate change. We diagnose the temporal asymmetry in models and observations. Half of annual precipitation falls in the wettest 12 days each year in the median across observing stations worldwide. Climate models project changes in precipitation that are even more uneven than present-day precipitation. In a scenario with high greenhouse-gas emissions, one fifth of the projected increase in rain falls in the wettest 2 days of the year and 70% in the wettest 2 weeks. Adjusting modeled unevenness to match present-day unevenness at stations, half of precipitation increase occurs in the wettest 6 days each year. Rather than assuming more rain in general, society needs to take measures to deal with little change most of the time and a handful of events with much more rain.”

*Pokharel, B., S-Y, S. W., Meyer, J., Gillies, R., & Yen-Heng, L. (2019). Climate of the weakly-forced yet high-impact convective storms throughout the Ohio river valley and mid-Atlantic United States. Climate Dynamics, 52(9-10), 5709-5721. [PDF] [Cited by]

“The 1-in-1000-year precipitation event in late June 2016 over West Virginia caused tremendous flooding damage. Like the 2012 mid-Atlantic derecho that blacked out much of the DC area, similar events can be traced to small, mid-tropospheric perturbations (MPs) embedded in the large-scale ridge pattern. Under this “weakly-forced” pattern, severe weather outbreaks commonly occur alongside eastward propagating MPs acting as a triggering mechanism for progressive mesoscale convective systems, which move across the central and eastern US. Forecasting of such weakly-forced yet severe weather events is difficult in both weather and climate timescales. The present diagnostic analysis of the MP climatology is the first step toward developing metrics that can identify and evaluate weakly-forced severe weather outbreaks in multi-model projections. We report a discernable, potentially pronounced subseasonal change in the MP climatology associated with the changing climate of North America. Both sea surface temperatures within the Gulf of Mexico and mid-level high pressure over the central US were found to exhibit strong correlations with MPs. Analysis of regional climate downscaling indicates a projected increase in MP frequency and the associated convective precipitation through the mid twenty-first century.”

*Prein, A. F., Liu, C., Ikeda, K., Trier, S. B., Rasmussen, R. M., Holland, G. J., & Clark, M. P. (2017). Increased rainfall volume from future convective storms in the US. Nature Climate Change, 7(12), 880-884. [Cited by]

Mesoscale convective system (MCS)-organized convective storms with a size of ~100 km have increased in frequency and intensity in the USA over the past 35 years, causing fatalities and economic losses. However, their poor representation in traditional climate models hampers the understanding of their change in the future. Here, a North American-scale convection-permitting model which is able to realistically simulate MSCs is used to investigate their change by the end-of-century under RCP8.5. A storm-tracking algorithm indicates that intense summertime MCS frequency will more than triple in North America. Furthermore, the combined effect of a 15–40% increase in maximum precipitation rates and a significant spreading of regions impacted by heavy precipitation results in up to 80% increases in the total MCS precipitation volume, focused in a 40 km radius around the storm center. These typically neglected increases substantially raise future flood risk. Current investments in long-lived infrastructures, such as flood protection and water management systems, need to take these changes into account to improve climate-adaptation practices.”

*Rahmani, V., Hutchinson, S. L., Harrington,John A.,,Jr, & Hutchinson, J. M. S. (2016). Analysis of frequency and magnitude of extreme rainfall events with potential impacts on flooding: A case study from the central United States. International Journal of Climatology, 36(10), 3578-3587. [Cited by]

“Climate variability and change can impact rainfall by varying time, location, magnitude, and frequency of precipitation events. Fluctuations in heavy rainfall events can impact flooding and drought events and water management systems. This research addresses temporal and spatial distributions of extreme daily and monthly rainfall in Kansas using daily rainfall data from 23 stations for the period 1890–2013. The Mann–Kendall non‐parametric method was used in trend analysis. Results indicate an increasing trend in the annual daily maximum rainfall, and an increase in the annual number of rainfall events above the 90th, 95th, and 99th percentile thresholds at a majority of stations since 1890. The most recent 30‐year climate normal period (1981–2010) was selected to assess contemporary change compared to the entire period (1890–2013). Most stations have a steeper positive slope for all extreme rainfall parameters for 1981–2010. Generally, western Kansas receives smaller and fewer extreme storms than eastern Kansas with respect to both magnitude and frequency.

Since 1890, June has been the month that receives the greatest amount of rain in each year at a majority of stations (18 of 23). Stations in eastern Kansas tend to experience earlier maximum rainfall on a monthly basis than central and western stations. Earlier annual maximum monthly rains can affect soil moisture and runoff generation. Timely maintenance and improvement in water, soil, and flood management systems are necessary in order to increase preparedness of the society to flash floods and protect them from water management systems failures.”

Questions? Please let me know (engelk@grinnell.edu).

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