Evidence of Climate Change in Orlando, Florida Josh Gray, Andrew Chin, Philip Womble, Sean Weyrich, Holly Padgett 04/21/2009

Precipitation: Overview and Context Average annual precipitation is ~48 inches Higher precipitation in summer months Dominated by frontal systems in the fall and winter, and convective events in the summer and spring ENSO variability Extreme events: tropical storms Data from Orlando Int. AP (ID: ) (28.43,-81.33) Period of record: 1952-current

Precipitation: Monthly Variability The climate record for Orlando indicates that summer months have elevated precipitation Summer means are ~7 inches compared with winter means of ~2.5 inches

Precipitation: Annual Variability 5 driest years: 2000, 1990, 1955, 1961, wettest years: 1994, 2002, 1959, 1997, 1991 Slight increase in annual precipitation over the period of record; not stat. sig. at 5% confidence level Qualitatively, annual precipitation appears to be increasingly variable

Precipitation: ENSO MEI: multivariate ENSO index: weighted average of the main ENSO components: sea level pressure, surface wind, SST, surface air temp, and cloudiness Positive values are associated with El Nino and negative values with La Nina The Orlando record indicates a strong correlation with MEI

Climate Change: IPCC Warmer temperatures lead to increased water vapor Increased precipitation in intertropical convergence zones, decrease in subtropics (likely), and increase in subpolar and polar regions (very likely) High amount of geographic and temporal uncertainty Less than 66% of models agree about the sign of the precipitation change in Florida Complex interaction with ET leads to high uncertainty as it relates to net hydrological fluxes for a region

Climate Change: ENSO and Tropical Storms Timmerman 1997: Increased frequency of ENSO like events with warming SST Observational evidence for increase in tropical cyclones in the N. Atlantic since 1970 Emanuel 2007: Tropical storms are likely to increase in intensity Increased intensity is strongly correlated with increasing SST

Precipitation: Conclusions The seasonal pattern of precipitation in Florida is characterized by wet summers Strong ENSO influence on temporal precipitation patterns Climate change is likely to increase ENSO like events and the intensity of tropical cyclones Climate change models have a high degree of uncertainty when it comes to the geographic variability in future precipitation There are implications for tourism and agriculture, the states two most important economic sectors, as well as hazard mitigation and response

Cooling Degree Days CDD= Avg. Temp. – 65°F CDD must be greater than or equal to 0 Linear Regression line shows increase of about 4 CDD/year

Heating Degree Days HDD= 65°F – Avg. Temp. HDD must be greater than or equal to 0 Linear regression line shows a decrease of about 3.4 HDD/year –Actually means avg. temps. for this period are increasing over time

Growing Degree Days GDD= Avg. Temp. - 65°F GDD must be greater than or equal to 0 Linear regression line shows increase of about 4.8 GDD/year

Implications The increase in CDD will mean that residents/businesses will use more air conditioning –Increases energy demand  increase in C02 emissions Decrease in HDD will equate to less heating during the winter season –Decrease in energy demand Due to Orlando being relatively warmer than the base temp of 65°F, it is likely that if these trends continue the energy demand will have a net increase Increase in GDD could have variable effects –Effects depend on the type of crops being grown and the season they are being grown in –If GDD continue to rise crops grown in other parts of the SE might be replaced with more subtropical crops more indicative of South Florida region

Data from Orlando Int’l Airport present Gap from filled with Orlando Exec. Airport Site comparison with Sanford, FL (~20 miles NNE) Typical annual mean between F Overall warming trend evident; also during last 16 years Seasonal definitions: winter 12/21- 3/21, spring 3/22-6/20, summer 6/21- 9/22, fall 9/23-12/20 Mean Temperatures

Summer Entire record Last 16 years Orlando °F/yr °F/yr. Sanford °F/yr °F/yr. 5 hottest years- 1987, 2005, 1990, 1998, hottest years- 2005, 2007, 2004, 2000, 2006

Winter Entire record Last 16 years Orlando °F/yr °F/yr. Sanford °F/yr °F/yr. 5 hottest years- 1971, 1988, 1974, 1981, hottest years- 1973, 1956, 1949, 1971, 1988

Entire record Orlando days/yr. Sanford days/yr. Days >85°F

Days <50 °F Entire record Orlando days/yr. Sanford days/yr.

Observations General heating trend, more evident in summer months Less distinct winter trend Top 5 highest slope values in Sanford in last 16 years Notable cooling trends- last 16 years in January at both sites, Orlando Fall and Spring last 16 years Reasoning Loss of wetlands, forests due to agricultural and urban expansion influential (Pielke) –Effects on energy budget in summer and winter More recent development around Sanford station Change in duration, timing of Florida’s hot season (Winsberg, Simmons) Global climate change effects

Long Term Land Cover Change (Pielke)

Large majority of land cover change = Wetlands, Forest, Grasslands Urban, barren 500 m

Large majority of land cover change = Wetlands, Forest, Grasslands Urban, barren 500 m

Max Temperature Extremes for Orlando Intl Apt, Fl and Sanford, Fl The years: 1981 (42), 1987 (50), and 1998 (48) were the only times Orlando had more than (or equal to) 40 days with max temperatures greater than or equal to 95 °F. The years: 1981 (40), 1998 (62), and 1999 (42) were the only times Orlando had more than (or equal to) 40 days with max temperatures greater than or equal to 95 °F. Both sites show growth in the number of days with extreme max temperatures. The growth in the number of days is significantly greater for Orlando than Sanford.

Seasonal Variation in Max Temperatures for Orlando Intl Apt, Fl and Sanford, Fl The average winter and spring max temperatures for Orlando, Fl are increasing at a similar rate. Highest winter avg °F in 1974 and 1981 and lowest 66.4 °F in 1957 Highest spring avg °F in 1978 and lowest 82 °F in 1958 The average max temperatures for Sanford, Fl are decreasing for both winter and spring, with a greater decrease in winter. Highest winter avg °F in 1973 and lowest 65.4 °F in 1977 Highest spring avg °F in 1998 and lowest 81.3 °F in 1983

Seasonal Variation in Max Temperatures for Orlando Intl Apt, Fl and Sanford, Fl The average winter and spring max temperatures for Orlando, Fl are increasing at a relatively similar rate. Highest summer avg °F in 1987 and lowest 87.9 °F in 1965 Highest fall avg °F in 1986 and lowest 75.7 °F in 1963 The average max temperatures for Sanford, Fl are decreasing in the summer and increasing in the fall. Highest summer avg °F in 1951 and 1987 and lowest 89.2 °F in 1988 Highest fall avg °F in 1971 and lowest 76.3 °F in 1987

Orlando Intl Apt, Fl and Sanford, Fl Seasonal and annual trends indicate that the urban Orlando site has an increasing max temperature. Seasonal and annual trends indicate that the rural Sanford site has a decreasing max temperature (except in the fall). The 15 year timescale above supports both trends

Increase in temperature but very small correlation (R²=0.0065) Increase in less than ½ ⁰F over the 56 years AVERAGE ANNUAL LOW TEMPERATURES FOR ORLANDO

Winter = December 21 – March 19 Again, increase in temperature but very small correlation (R²=0.0081) Increase in almost 1 ⁰F over the 56 years WINTER LOW TEMPS

Spring = March 20 – June 20 Decrease in temperature but very small correlation again (R²=0.0026) Decrease in less than ½ ⁰F over the 55 years SPRING LOW TEMPS

Summer = June 21 – September 21 Increase in temperature and correlation is larger (R²=0.058) Increase in about ½ ⁰F over the 56 years SUMMER LOW TEMPS

Fall = September 22 – December 20 Increase in temperature and relatively larger correlation (R²=0.0625) Increase in about than 1 ½ ⁰F over the 56 years FALL LOW TEMPS

Conclusions and Implications In general, temperatures seem to be increasing in Orlando Increases due to change in albedo Heat island affect Greater increase in max temperatures than min temperatures Less swampland due to development = less precipitation