Climate Change across the Playa Lakes Region

1. John H. Matthews, PhD Climate Adaptation Specialist, Freshwater 18 January 2008 Climate Change across the Playa Lakes Region • Understanding, Managing, Responding

2. Climate Trends Across the Playa Region • With little geographic relief, the region has relatively minor microclimatic variation • Two major climate gradients exist: temperature (north & south) and precipitation (east & west) • Regional climate has varied widely over the past 20k yrs; otters used to live in the Texas Panhandle precipitation temperature more-permanent surface water less-permanent surface water

3. This Period of Climate Change is Different The climate is changing quickly; the pace of change is increasing All aspects of climate are changing, not just air temperature It hasn’t been this warm for 650k years and probably >1.5 million • There is not a single new climate we are moving toward; we are entering a series of new climates over the next few centuries • During past climate shifts, the ranges of species moved around, but we because we have altered the natural landscape so much range shifts are far more difficult now • Many species face serious non-climate threats; climate change is another log on the fire Why Be Concerned Now?

4. changes relative to 1990 wetter drier Large-scale Trends: 1975–2015 • Annual precipitation is increasing over most of North America except for the southwestern USA • More extreme droughts and flooding are occurring • Spring precip is increasing (2 to 12%) and summer precip is declining (-15% to +4%) • Winter temps are increasing more than summer temps • Less snow and more rain in winter, earlier springs, longer summer & fall

5. rain-fed agriculture irrigated agriculture, ranching 100° longitude Agricultural Impacts • The 100th meridian is the traditional division between irrigated and reliably rain-fed agriculture • Widespread groundwater pumping extended this boundary west, but it is moving east again • Severe droughts like those of the 1930s and 1950s will become more common • Higher evapotranspiration rates may counteract increased spring precipitation trends • Aquifer use is likely to increase; Ag markets may need to move to “less-thirty” crops • Evapotranspiration rates are increasing in several regions already • Many crops maturing ~1–3 days per decade earlier over the past 50 years

6. Forest & Woodland Impacts • Fire is likely to return as a major form of disturbance • Junipers & cedars are sensitive to fires and are declining in some areas of the US & Canada • Invasive insect herbivores are moving north as a result of warmer winters • Increased drought stress reduces fertility

7. Grassland & Shrubland Impacts • Native grasses are resistant to “normal” droughts • Soil dynamics are changing from climate change in the prairies • Severe droughts & altered soil nutrient availability spread invasive grasses and shrubs • Invasive insect herbivores are also moving north

8. Freshwater Habitat Impacts • Unpredictable precip & temps reduces number of wetlands and size of lakes, rivers • Most stable: large, permanent, deep catchments • Most threatened: short-hydroperiod, small, shallow, playas in the SW • Special concern: shallow warm water sloughs, dry playas, wet meadows, temporary streams, sandhills • Invasive aquatic and emergent vegetation expanding with drought • Land-use has a major impact on hydroperiod

9. Impacts: 2015–2050 • Severe shortening of southern & southwestern playa hydroperiods • Number of wet playas in summer/fall will decline due to higher evaporation & lower precipitation rates • Migratory corridors will shift toward reliable water sources: rivers, large lakes/reservoirs. Many species will probably shift east of current routes, especially in fall • Overwintering waterfowl & waterbird species will be more concentrated, located around fewer & smaller water bodies • Avian disease tranmission frequency will increase as a result • Changes in soil moisture, nutrient availability will favor invasive grasses & insect herbivores • Fire frequency will increase, reducing deciduous forest cover and mature prairie, juniper, and cedar stands

10. Winners • Bird species that breed in the playa region in spring may do well with more precip, milder winter • Species with ranges now to the south and SW of the playa region will be moving north as “native exotics” • Species that are habitat generalists and found in other regions of the continent may prove more flexible • Species that consume primarily insects & plants rather than amphibians/reptiles • Species that are not threatened elsewhere in their range

11. Losers • Habitat specialists, as a group • Species that consume amphibians • Species that breed in summer or show drought mortality • Species that forage or breed in fire-sensitive habitats • Species that migrate south in late summer/early fall • Species already facing population declines • Species that prefer deeper playas & wetlands

12. New Planning Tools? • PLJV could model precipitation, hydroperiod, land use, and evapotranspiration interactions under different climate scenarios • 2007 Wetlands paper from Smith lab (Tsai et al. [27(3)] is an excellent start, but data from other regions is needed; must link weather with climate • How much regional variation will exist? Will precipitation increases outweigh ET increases in the sandhill wetlands? • Should the PLJV form a climate monitoring/analysis/study network or partnership?

13. Issues to Consider • The Conservation Reserve Program protects many playas; how can this program be improved/extended? • Will shifts in crops and ranching alter availability of surface water? • How to address increasing late-summer and early-fall impacts: fewer & smaller water bodies, containing less water with lower water quality? • How can farmers and ranchers actively help in improving grassland and playa quality & quantity in a changing climate?

14. Conclusions • The climate is already changing • Spring precipitation is increasing but will likely decline in other seasons, resulting in a regional net drying • The number of wet playas in summer/fall will likely decrease • Climate analyses should be incorporated into planning in the same way as GIS analyses • The ultimate impact may also depend on how farmers and ranchers respond to economic challenges of climate change

15. Author contact information:John H Matthews, PhDClimate Adaptation Specialist, FreshwaterWorld Wildlife Fundjohn.matthews@wwfus.org