Potential Impacts of Climate Change on Oklahoma During the 21st Century Ken Crawford State Climatologist for Oklahoma Regents’ Professor of Meteorology Director, Oklahoma Climatological Survey (Prepared with the Assistance of Derek Arndt, Gary McManus and Mark Shafer)

Climate Change & Global Warming: Extreme Viewpoints Senator James Inhofe (R, Oklahoma), Chair, Senate Environmental and Public Works Comm., in a speech to the US Senate on January 4, 2005 — “I called the threat of catastrophic global warming the ‘greatest hoax ever perpetrated on the American people’.” British Prime Minister Tony Blair in a speech on September 14, 2004 — “I want to concentrate on what I believe to be the world's greatest environmental challenge: climate change.”

Why These Extreme Views? (The Reporter’s Dilemma) Recognizing that not every scientist agrees, do you: Present the consensus view as fact? Present both sides to be fair? Understanding science Scientific methods and terms create barriers (caveats, uncertainty) Observations and predictions used interchangeably Other dynamics within the media: Event-driven – bias is toward current weather events; difficult to tell stories of things not happening or things happening slowly Need for visual aids – how do you show climate change? Need a compelling story to attract readers / viewers Human Impact – people ‘being impacted’ gets more coverage Limited space or time – difficult to convey complexity, uncertainty

‘Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.’

“Paleoclimate information supports the interpretation that the warmth of the last half century is unusual in at least the previous 1300 years.” Last 100 Years

The IPCC Consensus Higher confidence now exists in projected patterns of warming than exists for other elements such as rainfall. It is very likely that hot extremes, heat waves, and heavy precipitation events (due to higher moisture content in the atmosphere) will continue to become more frequent. Snow cover is projected to contract and sea ice is projected to shrink in both the Arctic and Antarctic. Thus, sea levels will rise. Storm tracks are projected to move poleward, with resultant changes in wind, precipitation, and temperature patterns. Increasing atmospheric CO2 concentrations will lead to increasing acidification of the ocean. Anthropogenic CO2 emissions during the 21st century will contribute to warming & sea level rise for more than a millennium, due to the long timescales required for removal of this gas.

Beginning Point of All Discussions Consistency of Wet Period: Most of the 1980s & 1990s confined to a very narrow range of variance Duration of Wet Period: 15-20 years … versus the dominant 8-12 year cycle Magnitude of Wet Period: Larger than any other wet period; on par with deficits of the great droughts during the 20th century

Climate Change and the Continental Interior Strong observational evidence and results from modeling studies indicate that, at least over the last 50 years, human activities are a major contributor to climate change and global warming. Annual precipitation is projected to decrease across the southwestern United States, especially during the summer. Warmer temperatures will cause more evaporation in summer and less soil moisture. As a result, drier conditions will contribute to severe episodes of extreme heat, particularly across the southwest USA. ‘Ordinary’ droughts may be transformed into a ‘30s- and ‘50s-style. Warmer temperatures and drier conditions in summer will increase the risk and intensity of wildfires. But…climate model projections are uncertain because the impact depends on socio-economic responses to climate change.

The New Climate (climate’s changing ‘base state’)

August 12, 1936 – Is This Our Future August 12, 1936 – Is This Our Future? (an example of extreme heat during a drought) 120 degrees!

Climate Change and Oklahoma Fairly Safe Assumptions (But Not Completely Safe): ET will not decrease Vast new sources of fresh, potable water will not materialize Oklahoma’s population will increase The projected changes will miss reality by some amount The results of projected warming and drying: Earlier springs, longer frost-free periods, and longer growing seasons (positive impacts). Significant implications for water resources management due to increased evapotranspiration year-round and less precipitation (negative impacts + many more).

Climate Change and Oklahoma Other impacts from climate change: A projected >50% decrease in cold air outbreaks — Imagine an Oklahoma without a winter! Natural systems will have to adapt, but the larger and faster the changes in climate, the more difficult it will be to adapt. The push for biofuels could ignite another Dust Bowl style of consumptive use (i.e., from aquifers). If the choice is corn, the state’s aquifers face enormous chalenges. Shrinking water supplies mean an increase in pollution. More Oklahomans will be exposed to water stress!

Consider Headlines Already Being Written (From The Norman Transcript)

Other Headlines Being Written (From Other Newspapers)

Unresolved Water Resource Issues What is the cumulative effect of riparian vegetation (e.g., cottonwoods and willows potentially transpire hundreds of gallons per week)? What about the population growth of the eastern red cedar (e.g., some cedars use 3-4 acre-feet of water per acre of densely- vegetated land)? The seasonality of climate change will be extremely important. People and economies are affected by the calendar as much as anything and the timing of weather/climate changes will have as great an impact, perhaps more so, than the magnitude of the change. What is the possibility of recharging aquifers by harvesting runoff? Can the OWRB help OCS identify what would qualify as an opportunity? If recharging opportunities are rare, a more precise and informed strategy is needed.

Unresolved Water Resource Issues Even if the projected precipitation declines, extreme events are expected to increase. Results: less recharge, more runoff, more flash flooding, and uncertain opportunities for aquifer recharge. How will small water districts across Oklahoma handle the stress? If Perth, Australia is perhaps near abandonment due to a long lasting drought, how will an Elk City cope? Will a migratory population towards urban areas place too great a stress on urban water supplies? Mean daily temperature is the average of a daily high and low temperature. How will the warming be realized across Oklahoma? Does warming mean higher maximums and/or higher minimums or both?

…We Pause for a Commercial Break… Planning for climate change requires the data already collected and the relevant expertise be made available, in the most user- friendly way possible, to state decision-makers and others who are able to make informed decisions. Oklahoma’s climate always has been highly variable. Mitigation efforts should be ongoing regardless of threat of climate change. OCS is well equipped to assist the OWRB with these issues and to serve as the best such portal for the State of Oklahoma. For example…..

Modeled Pan Evaporation (Inches) (based on the Mesonet ET model and Mesonet Data — 1994-2006)

Final Thoughts Whatever your view is of climate change — be it man-made or part of a normal cycle — the globe is currently warming. That fact means the citizens of Oklahoma will depend upon and require adequate supplies of fresh water. Our future lies in access to fresh water. Thus…. We must exercise due diligence to protect our water resources. A “no regrets” mitigation strategy has the best of both worlds: Should a major climate shift not occur, the benefits of mitigation would be profound. Who would complain about less pollution and a more robust water supply? “Prudence dictates extreme care in managing our relationship with the only planet known to be capable of sustaining human life*” *American Meteorological Society - February 2007

Questions?