Successful and Sustainable Gardening in a Changing Climate Global Warming, 1884 2011 - variation through time - variation across space Dr. Sara Via Professor & Climate Extension Specialist UMD, College Park svia@umd.edu This is EVIDENCE, not opinion Source: NASA Goddard Space Flight Center Scientific VisualizationStudio Difference from 1951 1980 Average - 2 C 0 + 2 C 1.0 Last three years the hottest since 1884 2017 Why is it getting so hot?? 1. Current CO 2 levels way out of pre-industrial range Carbon dioxide over 400,000 yrs 0.5 2000 CO2 concentration 0.0 400K 300K 200K 100K now Years Ago 15 15 of 16 of 16 hottest hottest years years all all since since 2000 2000-0.2 1964 1974 1984 1994 2004 2014 Source: Nucitelli, dian, 1/3/2018 Dana The Guar Why is it getting so hot?? 1. Current CO 2 levels way out of pre-industrial range 2. Temperature tracks CO 2 Carbon dioxide over 400,000 yrs 400K 300K 200K 100K now Years Ago CO2 concentration from ice cores CO2 now obser ved dir ectly both 0 500 1000 1500 2000 Year (AD) So are methane and N 2O but not solar radiation or volcanoes = solar r adiation, volcanoes How does CO 2 cause warming?
The Greenhouse Effect: More CO 2 in the atmosphere slows heat loss Some energy is radiated back into space as infrared (heat) waves Greenhouse gas molecules absorb infrared waves and reflect some heat back to Earth, slowing heat loss *more gas molecules, **slower heat loss ***more warming Most solar radiation is absorbed by the Earth and warms it Severe Weather Global warming is contributing to an increased incidence of extreme weather because the environment in which all storms form has changed -warmer air -warmer ocean -more water vapor in air -higher sea level Dr. Kevin Trenberth, June 2011 National Center for Atmospheric Research This is the New Normal mitigation Climate Change Gardening adaptation The NEW NORMAL for Gardens 1. More CO 2: Is this a benefit? 2. Rising temperatures - warmer winters, earlier springs - more extremely hot days, fewer cool nights - increased temperature variability 3. Heavier downpours, more severe weather 4. More possibility of drought 5. Possibility of salination (Eastern Shore) Yes: Plants use CO 2 in photosynthesis, so more should be good, but No: Isn t more CO 2 good for plants? As CO 2 rises in the atmosphere, - temperature rises, soil moisture decreases - summer droughts more likely - photosynthesis drops b/c stomates close to prevent water loss Net effect of increased CO 2 is negative for most plants 12
-Minimum temperature rising faster than maximum -Fewer cold nights for required plant chilling - perennials, bulbs, some fruit trees (apples) Effects on winter: New Hardiness Zones Warmer temperature, earlier blooming 1990 USDA 6 2006 Arbor Day Foundation Average lowest temperature reached in the 15 previous years. Cherries bloom 7 days earlier than 30 yrs ago Lilacs bloom 4 days earlier than in the 1950s -planting, harvest dates -length of season -overwinter survival 7 Grapes bloom 6 days earlier Modified fr om D. Wolfe [Sourc es: http://persoon.si.edu/dcflora/springflowers/release.htm Wolfe DW et al. 2005. InternatJ Biometeor 49:303-309.] Flowering trees may lose the year s blooms False Spring in your garden Warm February, freeze in March or April cover up if possible Effects of warmer winters Weeds benefit the most -better overwinter survival -earlier flowering time Weeds can outcompete crops or native plants
Adapting to Increasing weed pressure - Weed early - Weed often - Mulch for weeds (sustainably) - Stop tilling -Deer: more browse during winter - healthier populations - higher overwinter survival - increase in # offspring - White-footed mouse also benefits, so more Lyme disease. Effects of warmer winters on animals. Effects of warmer winters on animals Pest insects & disease - better overwinter survival Pests appear earlier, reproduce more quickly and may differ year to year. - Be vigilant (learn signs of damage!) - earlier appearance - more generations/yr - range expansion - Consider row covers - Decide on control strategy before pests arrive Call in the experts at Home & Garden Info Center Mismatched timing in species interactions Biocontrol: Host adds a generation, parasitoid doesn t Effects of Climate Change: Temperature stress in plants 23 Modified fr om D. Wolfe Expected # days > 86 degrees F
Heat stress reduces pollination, fruit set Heat stress: reduced pollination, leaf scald Tomato Pollination and Excessive Heat July 12, 2012 Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu Leaf Scald in Sweet Corn Again in 2012 July 12, 2012 Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.ed u Peppers drop flowers and fruit when Day temp > 90 Nite temp > 75 Source: TAMU potatoes Adapting to increased temperature - Plant earlier in spring, later in fall - Mulch (plant material, white or reflective) - Try heat tolerant varieties - Build shade - Use existing shade Some heat-tolerant vegetables are already available Bita et al. 2011. BMC Genomics 12:384. Reflective mulch, shade cloth saves GA peppers (Carlos Diaz-Perez UGA) Or, try varieties usually planted further south Is it really hot?? Shade helps! Tomato plants 30% shade, July 2012 Shaded NOT shaded Source: J. Brust UME May delay planting, wash out or contaminate fields, stunt or kill plants, increase disease, cause soil compaction
What s a gardener to do? Too much water -Improve drainage -monitor food safety What s a gardener to do? Too little water - drought tolerant plants - mulch around plants - drip irrigation Climate Friendly Gardening Gardeners are part of the solution! Climate Change Climate-Friendly (Sustainable) Gardening Reduce emissions - Use hand tools (or electric) - Weed smart, weed early, mulch mitigation - Cover crops, NO bare soil Gardening Unfriendly Climate Friendly Gardening Climate-Friendly Gardening Build up the soil! Reduce emissions: No-till planting plus mulch - Leaves soil structure, worms,\ - Keeps decomposible carbon underground - Bonus: keeps weed seed underground Friendly -Organic material holds water, yet drains -Add compost (compost your leaves this year!) -Plant cover crops - add organic material - can add nitrogen - feed soil microbes -Control erosion
Cultural controls Insectary Plants attract beneficials & pollinators Provide nectar, pollen, protection from predators Climate-Friendly Gardening Reduce inputs - Reduce chemicals, synthetic fertilizer - Increase compost Control erosion -Garden design, raingardens - Native plants (bayscaping) Bachelor buttons in celery, beneficials reduce aphids Reduce Lawn!! - 42 million acres of lawn in US -Lawns often over-fertilized N washes out into water, NO 2 released If you really want lawn. -Plant grasses that need little N (fescue vs. bluegrass, white clover?) - Mow less - Mow high for root growth, mulch clippings Reduce Lawn! -Consider eco-landscaping, bayscaping, permaculture Is lawn really the most beautiful landscape??? Help for gardens at new houses: the Tillage Radish! credit: SoilHealthNY Climate Friendly Landscaping To Reduce Energy Use - Plant evergreens north or windy side (20%) - Deciduous trees on south side - Shade air conditioning unit (20%) - Shrubs around foundation reduce heat loss credit: livingthecountrylife.com credit: countrysideag.com
You may not run the world, but you can control your part of it Thank you! Email me anytime with questions: Dr. Sara Via Dept. of Biology & Dept. of Entomology UMD, College Park svia@umd.edu