GC170a1 1st EditionExam # 5 Study Guide Lectures: 18 - 222Lecture 18: Climate Change impacts: Droughts, Heat and Fire What is weather? - The state of the atmosphere at any given place or timeWhat are some examples of weather events? - Rainstorms- Tornadoes- Blizzards- Hurricanes- Heat waveWhat is climate? - The long-term average of weather in a given place o Refer to typical weather patterns  Monsoon rains in TucsonWhat is a drought? - Prolonged period of dry weather (lack of rainfall) that results in a serious water shortageHow are droughts defined? - Severity (how dry)- Length (# of years)- Special extent What are recent examples of droughts in the west? - California: currently in severe 3-4 year drought How does the jet stream pattern contribute to current drought in CA? - The jet stream ridge prevents storms from reaching California for several months and decreases rainfall for multiple yearsHow do these recent droughts compare to the 1930’s and 1950’s droughts? - Droughts were longer in the past and almost as severe- More widespread during the 1930’s and 50’sWhat is a global change type drought? - Global-Change type droughto A drought episode with warmer temperatures o Leads to more evaporation and drier soils o Regional droughtsWhat are the consequences of prolonged and severe drought (e.g., global change type drought)? - Loss of crops- Less water available - Forest Mortality- WildfiresWhat is a heat wave? And what are the consequences? - A period of very warm temperatures for a few days to weeks o Consequences:  Can lead to death in elderly or vulnerable populations Damage to crops and livestockWhat is happening with daily highs and lows in the past few decades (and what does that mean)? - Increases in record high temperatures- Increases in night-time temperaturesLecture #20: Wildfires (at end of Lecture #18 ppt) What happened with wildfire activity in 2002 and 2011? - 2002 severe drought across the intermountain westo Fire activity increased sharply in early 2002’so Colorado, Arizona- 2011 severe drought in Texas o Wallow Fire (Arizona) 841 square miles  Biggest wildfire in Arizona  6,000 people evacuated  32 homes destroyed  $109 million in fire fighting and damage costsIn Texas in 2011, what were the key factors that influenced the Bastrop county complex? - Exceptional drought that had been ongoing for months- Sparks from a powerline started the fire - Huge winds because of a nearby tropical storm- Consequences: o 2,000 homes in one weekend o 2 firefighters were killed o 3.4 billion in fire fighting costs, economic losses (timber, homes, infrastructure)How are the number of wildfires changing with warmer temperatures of the past 40 years? - Increase in the number of fires and warmer temperatures across the western US for the past 40 years - Warmer temperatures create a longer summer seasonLecture #19: Climate Change impacts: Extreme storms What is an extreme precipitation event and what are the consequences? - Extreme storms that brings lots of precipitation in a short period of timeo Consequences of heavy or extreme rainfall Flooding  Crop damage  Increased water pollutionWhat are two examples of extreme rainfall events? - Tucson July 2006o Persistent low-pressure system brought moisture to southern AZ for four days Brought 10 – 12 inches of rainfall to southern Arizona- Colorado (Sept 2013)o 17 inches of rainfall in four days o Annual amount of rainfall in 4 days o Extreme flooding throughout the Front Range (Boulder, Ft. Collins)Are extreme precipitation events changing in recent decades? - Increased occurrence of extreme one-day precipitation events over recent yearsRelated to sea surface temperatures, why are extreme precipitation events increasing? - Warmer sea surface temperatures increases evaporation - Warmer atmosphere can hold more moisture - Clouds move over land and more rainfall occursIs hurricane activity increasing with warming sea surface temperatures? - Hurricane activity (strength and duration): increasing in recent decades with increasing sea surface temperaturesWhat influences the strength or intensity of a hurricane? - Wind Shear:o High wind shear = large temperature gradient  Warm temperatures at the surface  Cool temperatures in the upper atmosphere - Intensifies a hurricane - Low wind shear = similar temperature throughout o Warm temperatures at the surface o Warm temperatures in the upper atmosphere  Causes a hurricane to weaken or break apartIs the number of hurricanes increasing over the 20th century (look at adjusted hurricane counts)? - It is NOT increasingWhat is the biggest concern with hurricanes in the future? - Concern that hurricanes will get more intense and have higher rainfall amountso Intensity relates to warmer sea surface temperatures leading to a stronger temperature gradient in the atmosphereo Higher rainfall amounts will result from warmer sea surface temperatures leadingto increased moisture in the atmosphereHow does sea-level rise influence the damage during hurricanes? - Storm Surgeo Water being pushed to shore by the storm winds  Sensitive to changes in storm intensity and direction Can be more destructive when sea level is higherLecture #20: C02 sources and emissions scenarios Where do the greenhouse gases come from? - CO2 o Burning of fossil fuels (coal, natural gas and oil)o Sectors that contribute most to CO2 emissions Industry Transportation Electricity generation- CH4 (Methane) & Nitrous Oxide (N2O)o Methane mostly comes from cattle and rice cultivation o N2O mostly comes from fertilizers o Increases in these have been modest in past few decadesWhat are the fossil fuels? - Coal, oil, natural gaso Plant matter buried and compressed into rocks millions of years agoo Oil and natural gas are liquids and stored within sedimentary rocks beneath surface o Coal is compressed plant matter that is solid rockWhy does our economy rely so much on fossil fuels? - The United States gets 81% of energy from fossil fuels, a little bit from renewable resourceso Cheapo Demand always increasingWhat is a global climate model (GCM)?- Global climate models (GCM) simulate future temperatures based on CO2 emissionsHow does it work? - Simulate the components of the energy budget and atmosphere- Change CO2 concentrations and surface propertieso = Predict temperaturesWhat do GCM’s predict for the future?- Temperature - Atmosphere and energy budgetHow do we know