Recent Climate Trends in Georgia and their Impact on Trees Pam Knox Agricultural Climatologist, UGA
What we will cover in this talk • Review of last 15 years • Impacts of the past droughts • Looking at the longer time scale • What does the future hold?
Drought in Georgia Timeline from National Drought Monitor Timeline from the National Drought Monitor 2002 2004 2008 2010 2012 2000 2000 2002 2004 2008 2010 2012
Causes of drought in Georgia • Lack of tropical storms • La Niña • Longer term climate trends
Tropical Storms 2000-2002 2003-2005 2006-2008 Tropical storms can account for up to 30 percent of the summer season rain in Georgia.
Tropical Storms 2011 2012 Both 2011 and 2012 were active seasons for the tropics, but very few effects from these storms were felt in Georgia. This year (2013) is also supposed to be an active season.
El Niño and La Niña In an El Niño, the trade winds are weaker, allowing warm surface water to move towards the east. This causes a deepening in the pool of warm surface water near the coast and increased clouds and thunderstorms above the warmest water.
El Niño and La Niña El Niño is associated with unusually warm water in the eastern Pacific Ocean, usually observed near Christmas (so associated with the coming of “The Child”). La Niña is the opposite phase of El Niño, with unusually cool water in the eastern Pacific Ocean.
El Niño and La Niña El Niño and La Niña affect climate conditions around the world, especially in winter when they are strongest.
Impacts of El Niño and La Niña El Niño La Niña
Impacts of El Niño and La Niña on Forestry La Niña caused high death and disease rates in new plantings • due to dry conditions in 1999-2000 and stands planted during that time still show poor quality today. El Niño plantings from 1998 were well established except in • very low-lying areas where excessive rainfall drowned newly planted seedlings. In El Niño seasons, wet ground can make it hard to harvest • trees, especially in low-lying areas. In La Niña seasons, dry conditions can increase pest pressure • but also improve ability to get heavy machinery into low-lying areas for harvesting.
Impacts of last 15 years on trees and nursery owners Repeated episodes of stress on trees • related to three multi-year severe droughts Tree deaths increased due to stress and • insect pressure In wet periods, damage from trees falling • increased when wet soil failed to support root systems Watering restrictions reduced market for • young trees
End of the 2011-2013 Drought January February
Year to Date Rainfall Departure from Normal
Cause of Rainy Conditions Rainy pattern is due to a persistant trough of low pressure and a stalled stationary front south of Georgia.
Longer-term GA Temp Trend Georgia Annual Temperature (F) 67 66 65 64 63 62 61 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005 2015
Longer-term GA Temp Trend Georgia Annual Temperature (F) 67 66 65 64 63 62 61 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005 2015
Longer-term GA Temp Trend Georgia Annual Temperature (F) 67 66 65 64 63 62 61 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005 2015
Longer-term GA Temp Trend Georgia Annual Temperature (F) 67 66 65 64 63 62 61 1895 1905 1915 1925 1935 1945 1955 1965 1975 1985 1995 2005 2015
National Temperature Trends
GA Precipitation Trend http://www.ncdc.noaa.gov/cag/time-series/us
Southeast Precipitation Trends
National Precipitation Trends
Trends in Extremely Heavy Rain Heavy rains are increasing, and there are longer dry spells in between storms.
What can we expect in the future? • Short term forecasts • Longer term predictions and changing climate
Short-term forecast No major shift in the storm track, so rains are likely to continue.
Seasonal forecasts Fall P Winter T Fall is predicted to be equal chances of below, above and normal T and p. Wi nter P Winter is predicted to lean warm and have a higher likelihood of dry conditions especially in south GA. ENSO is predicted to be neutral through this winter.
Predictions for Future Temperatures Across the United States and the Southeast, temperatures are predicted to increase over the next 100 years, but the amount of warming predicted depends on the particular model used. Amounts range from 5 to 10 ˚F . http://www.usgcrp.gov/usgcrp/nacc/education/
Predictions for Future Precipitation Precipitation across the US is harder for the models to predict, and some models show increased precipitation while others show drying or no trend. Some datasets indicate that rainfall has become more intense with longer dry spells in between.
Predictions for Future Precipitation Seasonal predictions of rainfall change are more challenging, but in the Southeast winter, spring and summer and expected to continue to get drier and the fall slightly wetter than current conditions.
Impacts of Changing Climate on Trees • Warmer temperatures would increase growing degree days for trees but also weeds and insect pests and diseases as the growing season gets longer and hotter. • Increases in extremes of temperature may lead to more fires due to extended hot and dry spells. • Winter storms may change from snow to ice storms, increasing damage to trees.
Impacts of Changing Climate on Trees • Warmer temperatures will increase evaporation from soil, lakes and reservoirs as well as evapotranspiration from trees, which could affect water availability. • Hurricanes could increase in number and/or intensity, causing increased damage in Southeastern forests.
Impacts of Changing Climate on Trees • Uncertainty of rainfall predictions makes it hard to determine what to expect in the future, especially since there is already a lot of natural variability in rainfall patterns by location and season. • Higher intensity rainfall will increase erosion and runoff from fields and open areas and could increase localized flash flooding in storms.
Impacts of Changing Climate on Trees • Longer dry spells, coupled with warmer temperatures, will increase the likelihood of drought and will reduce average stream flows. • More info can be found at http://ncadac.globalchange.gov
Strategies for adaptation to changes in climate • Increase resistance to climate change to maintain current practices • Increase resilience to variations in climate by protecting against effects of disasters and increasing recovery from them • Transform operations by altering species or management practices
What does the Future Hold? Challenges Opportunities • • Warmer temperatures Population growth means increase diseases and pests potential for market growth • More stress on forestry • Parts of the US will see longer workers growing season and more rain • More potential for drought • Other parts of the world will • More extremes also undergo climate change • Market uncertainty • Smart management can • Economic costs of becoming improve budget while also resilient (for example, taking advantage of market irrigation or power sources) incentives • Changing tastes and • Forests capture carbon and demographics provide fuel
Thank You! Contact info: Pam Knox pknox@uga.edu 706-310-3467 office 706-621-1970 cell
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