Climate Change Impacts & Extreme Weather Events PDF

Toward More High-Resolution ENVR1150 [26 Sep] Climate Change Impacts & Extreme Weather Events IM, Eun-Soon Department of Civil and Environmental Engineering Division of Environment and Sustainability Review It is virtually...

Toward More High-Resolution ENVR1150 [26 Sep] Climate Change Impacts & Extreme Weather Events IM, Eun-Soon Department of Civil and Environmental Engineering Division of Environment and Sustainability Review It is virtually certain that increases in the frequency and intensity of heavy precipitation will occur in the 21st century. (True or False) It is very likely that there has been an overall decrease in the number of cold days and nights, and an overall increase in the number of warm days and nights since 1950 over most land areas. (True or False) Assessment of a human contribution to the increase in intensity of drought indicates low confidence, which means that no human impact occurred in drought. (True or False) A wealth of observations such as long-term measurement and satellite products can be helpful to enhance the confidence level of detection and attribution of climate change impacts. (True or False) Ice-albedo feedback contributes to the arctic warming amplification, which is an example of negative feedback. (True or False) A more refined representation of topography in the climate model can improve the accuracy to simulate Ice-albedo feedback. (True or False) The water-holding capacity of the atmosphere will increase by approximately 7% for each 1°C warming, which implies that the atmosphere is easily saturated under warmer climate conditions. (True or False) Review The sensitivity to different emission scenarios is larger in changes in precipitation than changes in temperature. (True or False) The emission scenarios are the main cause for the large uncertainty of global mean temperature projection at the end of the 21st century. (True or False) The confidence level of detection is generally lower than that of attribution. (True or False) James Balog, who is a professional nature photographer, described the ice as “the canary in the global coal mine” in his TED Talk entitled “Time-lapse proof of extreme ice loss”. What does it mean in the context of climate change? ➔ If dangerous gases such as carbon monoxide collected in the mine, the gases would kill the canary before killing the miners, thus providing a warning to exit the tunnels immediately. Similarly, ice loss can play a role in providing early warning signal for global warming. Changes in Extremes Under Global Warming Heat Waves ❖ How are future projections in extreme events under global warming ? Cold Waves ❖ What is the main mechanism leading to the Drought changes in extreme events under global warming? Wildfire ❖ What are determinants of risk caused by these extremes ? Floods Sea Level Rise Tropical Cyclone What Are Heat Waves? ❖ Definitions No formal heat wave definition exists. Definitions of “heat wave” vary among countries and even within a country. ❖ Characteristics Extreme heat may be one of the most underestimated and least understood of the deadly weather phenomena. Heat waves casualties In contrast to the visible, destructive and violent nature associated with severe weather events like floods, hurricanes, and typhoons, heat waves are “silent killer. It is very likely that global warming is brining more frequent and severe heat waves. [“Guidelines for Preparation of Action Plan Prevention and Management of Heat Wave” in India] Examples for Heat Waves Warning System ❖ Meteorological Service of Canada ❖ Korea Meteorological Administration The KMA has issued heatwave warnings if it occurs consecutively two days with maximum temperature exceeding 33°C. ❖ India Meteorological Department Heat Wave need not be considered till maximum temperature of a station reaches at least 40°C for Plains and at least 30°C for Hilly regions. When normal maximum temperature of a station is less than or equal to 40°C Heat Wave Departure from normal is 5°C to 6°C Severe Heat Wave Departure from normal is 7°C or more. When normal maximum temperature of a station is more than 40°C Heat Wave Departure from normal is 4°C to 5°C Severe Heat Wave Departure from normal is 6°C or more. Meteorological Condition Favorable for Heat Waves ❖ Typical meteorological condition favorable for heat waves High Pressure System : Sinking motion ( unfavorable for the formation of clouds and precipitation) Strong Incident Solar Radiation and Less Cloud Cover Atmospheric stagnation and Temperature Inversion : Less air movement. These factors are coupled and collectively contribute to severe heat waves Where Is the Hottest Location in the World? ❖ Spatial distribution of the maximum temperature climatology Do the region characterized by highest maximum temperature coincide with the region where the people suffer from the worst heat stress Maximum Wet-Bulb Temperature ❖ Yearly Maximum 3-hour WBT from ERA Interim Reanalysis (1979-2015) ❖ WBT can be a good indicator for quantifying mugginess during a heat wave Relationship T & RH & Moist Temp. (WBT) Saturation vapor pressure (hPa) Hot & Dry Hot & Wet es = 6.112*exp((17.67*T)/(T+243.5)) TW TW RH=70.7% RH=23.5% Td Tw Td Tw Wet-bulb temperature is particularly useful in human health applications associated with heat stress, because evaporation is the primary means by which bodies cool in hot environments; thus, when Tw is high, evaporative cooling is restricted and the body core temperature may rise (Davis et al. 2016). 35°C is the threshold value of WBT beyond which any exposure for more than 6-hour would likely be intolerable even for the fittest of humans resulting in hyperthermia. In current climate, TW rarely exceeds 31°C. NOAA Heat Index The heat index is a measure of how hot it feels when relative humidity is taken into account along with the actual air temperature. It is important to note that since heat index values were devised for shady, light wind conditions, exposure to full sunshine can increase heat index values by up to 15°F. HI = -42.379 + 2.04901523*T + 10.14333127*RH - 0.22475541*T*RH - 0.00683783*T*T- 0.05481717*RH*RH + 0.00122874*T*T*RH + 0.00085282*T*RH*RH - 0.00000199*T*T*RH*RH  No perfect single index Heat Stress Indices Combined effect of temperature and humidity Dc: dew point temperature in °C Tc: air temperature in °C H: relative humidity in °C [From Anderson et al. 2013 ] Factors Influencing Human Heat Stress ❖ Meteorological Factors Based on the principle of thermodynamics, diffusion of heat takes Temperature place between environment and human body. When sweat evaporates into vapor, heat will be transferred from Humidity the body to the environment by evaporation. Radiation directly applies heat to the body. Radiation The air movement around the body can influence the rate of heat flow Wind velocity away from the body. ❖ Physiological factors ❖ Sociological factors Break/rest regimes, use Heath / Age Occupational adaptation of cooling system, type of clothing. Labor Intensity Buildings & other structures Acclimatization to heat