In My View

In their article “Arctic Security Considerations and the U.S. Navy’s Roadmap for the Arctic” (Spring 2010, pp. 35–48), Rear Admiral David W. Titley and Courtney C. St. John make the claim that “the prevailing and well established scientific view attributes this [Earth] temperature change to anthropogenic emissions of ‘greenhouse’ gases” (page 35), based on the Intergovernmental Panel on Climate Change report AR4, 2007

Calibration: Clark Kent or Superman?

Biography: Dr. Titley is a nationally known expert in the field of climate, the Arctic, and National Security. He served as a naval officer for 32 years and rose to the rank of Rear Admiral. Dr. Titley’s career included duties as Oceanographer and Navigator of the Navy and Deputy Assistant Chief of Naval Operations for Information Dominance. While serving in the Pentagon, Dr. Titley initiated and led the US Navy’s Task Force on Climate Change. After retiring from the Navy, Dr. Titley served as the Deputy Undersecretary of Commerce for Operations, the Chief Operating Officer position at the National Oceanic and Atmospheric Administration. Dr. Titley has spoken across the country and throughout the world on the importance of climate change as it relates to National Security. He was invited to present on behalf of the Department of Defense at both Congressional Hearings and the Intergovernmental Panel on Climate Change (IPCC) meetings from 2009 to 2011. He has presented a TEDx talk on climate change and speaks regularly on this topic at Universities across the country. He currently serves on the Advisory Board of the Center of Climate and Security based in Washington DC. He is currently a Senior Scientist in the Department of Meteorology at the Pennsylvania State University, and founding Director of Penn State’s Center for Solutions to Weather and Climate Risk. The Center will help organizations and citizens prosper and succeed in today\u27s and tomorrow\u27s weather and climate environment by taking advantage of all the skill in weather and climate forecasts. Dr. Titley holds a Bachelor of Science in meteorology from the Pennsylvania State University. From the Naval Postgraduate School, he earned a Master of Science in meteorology and physical oceanography, and a Ph.D. in meteorology. He was elected a Fellow of the American Meteorological Society in 2009 and holds an honorary Doctorate from the University of Alaska, Fairbanks

Extreme Rainfall and Flooding over Central Kenya Including Nairobi City during the Long-Rains Season 2018: Causes, Predictability, and Potential for Early Warning and Actions

The Long-Rains wet season of March–May (MAM) over Kenya in 2018 was one of the wettest on record. This paper examines the nature, causes, impacts, and predictability of the rainfall events, and considers the implications for flood risk management. The exceptionally high monthly rainfall totals in March and April resulted from several multi-day heavy rainfall episodes, rather than from distinct extreme daily events. Three intra-seasonal rainfall events in particular resulted in extensive flooding with the loss of lives and livelihoods, a significant displacement of people, major disruption to essential services, and damage to infrastructure. The rainfall events appear to be associated with the combined effects of active Madden–Julian Oscillation (MJO) events in MJO phases 2–4, and at shorter timescales, tropical cyclone events over the southwest Indian Ocean. These combine to drive an anomalous westerly low-level circulation over Kenya and the surrounding region, which likely leads to moisture convergence and enhanced convection. We assessed how predictable such events over a range of forecast lead times. Long-lead seasonal forecast products for MAM 2018 showed little indication of an enhanced likelihood of heavy rain over most of Kenya, which is consistent with the low predictability of MAM Long-Rains at seasonal lead times. At shorter lead times of a few weeks, the seasonal and extended-range forecasts provided a clear signal of extreme rainfall, which is likely associated with skill in MJO prediction. Short lead weather forecasts from multiple models also highlighted enhanced risk. The flood response actions during the MAM 2018 events are reviewed. Implications of our results for forecasting and flood preparedness systems include: (i) Potential exists for the integration of sub-seasonal and short-term weather prediction to support flood risk management and preparedness action in Kenya, notwithstanding the particular challenge of forecasting at small scales. (ii) We suggest that forecasting agencies provide greater clarity on the difference in potentially useful forecast lead times between the two wet seasons in Kenya and East Africa. For the MAM Long-Rains, the utility of sub-seasonal to short-term forecasts should be emphasized; while at seasonal timescales, skill is currently low, and there is the challenge of exploiting new research identifying the primary drivers of variability. In contrast, greater seasonal predictability of the Short-Rains in the October–December season means that greater potential exists for early warning and preparedness over longer lead times. (iii) There is a need for well-developed and functional forecast-based action systems for heavy rain and flood risk management in Kenya, especially with the relatively short windows for anticipatory action during MAM