Climate Change: Globally and In Iowa Eugene S. Takle Director, Climate Science Initiative Professor of Atmospheric Science Department of Geological and Atmospheric Sciences Professor of Agricultural Meteorology Department of Agronomy Iowa State University Ames, Iowa 50011 gstakle@iastate.edu PEO Ames, Iowa  22 June 2010

Observations: global mean temperature and carbon dioxide are rising together since 1860 This slide shows trends from observations of average global surface temperature (color bars) and carbon dioxide, CO2 (thick black line based on annual averages). Carbon dioxide measurements and trends are extremely reliable, especially since 1957 when direct measurements at Mauna Loa, Hawaii, began. Earlier estimates are from ice core records. The scale for CO2 concentrations is parts per million by volume (ppmv), relative to a mean of 333.7 ppmv. The temperatures are departures from a mean of 14º C. Global average surface temperature estimates are based on several different types of observations, mostly direct thermometer measurements over land and oceans in the early part of the record and a mixture of thermometer and satellite observations since about 1980. The temperature data and trends have been computed by three independent groups, NASA (Goddard Institute for Space Studies) and NOAA (National Climate Data Center) in the US and the Meteorological Office in the UK. The data and trends from the three groups agree very well. Reference: Updated from Tom Karl and Kevin Trenberth (2003): Modern global climate change. Science, 302, p. 1719-1723. This slide demonstrates an overall positive correlation of increasing CO2 and the global average surface temperature. The positive correlation is easily explained by basic physics---radiation theory. No complex climate models are required.  The temperature increase shows a lot of variability from year to year and over several years on top of the upward trend. This variability indicates that other important natural processes and phenomena are occurring on time scales of years to decades, including atmosphere-ocean interactions such as El Niño, solar variability, and occasional volcanoes.  It also shows that we should not be surprised when one or two years are colder than a few years earlier, even in a world that is warming overall. Base period 1961-90

Global average sea level is rising from expansion of water due to warming and melting glaciers Since 1992 sea level has risen 55mm (2.2 inches) This slide shows a steady rise in average global sea level since 1992 when satellite data became available. The sea level is measured from satellites (named TOPEX, Jason 1 and Jason 2) using a technique called radar altimetry. Radar altimetry uses a radar on a satellite to precisely measure the distance between the sea surface and the satellite. The observed increasing global sea level is a compelling confirmation of global warming, because sea level is a great integrator--it is not affected appreciably by a cold winter or two in Washington or London, a hot summer in Kansas, or a hurricane like Katrina.  It occurs because of melting glaciers (ice over land), and the thermal expansion of warming sea water. This figure is from www.aviso.oceanobs.com/en/news/ocean-indicators/mean-sea-level/ , where one may also obtain the raw data that produced the figure. Other independent groups have also computed sea level rise (e.g. NOAA, http://ibis.grdl.noaa.gov/SAT/SeaLevelRise/ , and the results are very similar to this one.) www.aviso.oceanobs.com/en/news/ocean-indicators/mean-sea-level/

Models: Natural processes do not account for observed 20th century warming after 1965 This slide shows the observed average global surface temperature anomalies (departures from the 1890-1919 average, black line) and complex three-dimensional global climate models with both natural (blue line) and anthropogenic (human, red line) effects. The natural effects include volcanoes and solar variability. The human effects include emissions of greenhouse gases (mostly carbon dioxide), ozone, and aerosols. The light red and blue envelopes around the red and blue lines show the range of temperatures produced by four different simulations with the same model, providing some indication of the model uncertainty. This slide shows that climate models that account for human as well as natural effects can pretty well explain the observed temperature warming trend and variability, over the entire time period (1890-2000). However, models that include only natural effects show a significant and widening departure from the observations starting in the mid 1960s. This result provides strong evidence confirming the hypothesis that human activities are the main cause of global warming (the models cannot match the observations without including human effects; they produce climates that are too cold compared to observations). This slide, like the first one, also shows that other important natural processes and phenomena (such as El Niños) are going on from one year or even decades to the next. These natural effects cause the irregularities in the upward trend of temperature, as shown in the observations and the model results. Reference: G. Meehl, W. Washington and co-authors, 2004: Combinations of natural and anthropogenic forcings in twentieth century climate. Journal of Climate, p. 3721-3727

Observed Trends in Iowa Precipitation

State-Wide Average Data

State-Wide Average Data 37.5” 31.5” 19% increase

State-Wide Average Data Totals above 40” 8 years 2 years

State-Wide Average Data

Cedar Rapids Data 28.0” 32% increase 37.0”

Cedar Rapids Data 51% increase 11.8” 7.8”

Cedar Rapids Data 34% increase 20.2” 26.8”

“One of the clearest trends in the United States observational record is an increasing frequency and intensity of heavy precipitation events… Over the last century there was a 50% increase in the frequency of days with precipitation over 101.6 mm (four inches) in the upper midwestern U.S.; this trend is statistically significant “ Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009, 196pp.

Cedar Rapids Data 57% increase 6.6 days 4.2 days

Years having more than 8 days Cedar Rapids Data Years having more than 8 days 11 2 57% increase 6.6 days 4.2 days

Great Flood of 1993 in the US Midwest: A New “Great Lake” Historical Data indicate this should happen about once every 500 years Lakshmi, V., and K. Schaaf, 2001: Analysis of the 1993 Midwestern flood using satellite and ground data. IEEE Trans. Geosci & Remote Sens., 39, 1736-1743.

Projected Future Trends in Iowa Precipitation

“The future isn’t what it used to be” Yogi Berra

Global Carbon Emissions (Gt) Actual emissions are exceeding worst case scenarios projected in 1990

Source: Jerry Meehl, National Center for Atmospheric Research From Jerry Meehl This slide shows the time evolution of globally averaged surface air temperature from multiple ensemble simulations of 20th century climate from the NCAR Parallel Climate Model (PCM) compared to observations. The simulations start in the late 19th century, and continue to the year 2000. The temperature scale at left is in degrees Centigrade, and temperature anomalies are calculated relative to a reference period averaged from 1890 to 1919. The black line shows the observed data, or the actual, recorded globally averaged surface air temperatures from the past century. The blue and red lines are the average of four simulations each from the computer model. The pink and light blue shaded areas depict the range of the four simulations for each experiment, giving an idea of the uncertainty of a given realization of 20th century climate from the climate model. The blue line shows the average from the four member ensemble of the simulated time evolution of globally average surface air temperature when only "natural" influences (solar variability and volcanic eruptions) are included in the model. Therefore, the blue line represents what the model says global average temperatures would have been if there had been no human influences. The red line shows the average of the four member ensemble experiment when natural forcings AND anthropogenic influences (greenhouse gases including carbon dioxide, sulfate aerosols from air pollution, and ozone changes) are included in the model. Note that this model can reproduce the actual, observed data very well only if the combined effects of natural and anthropogenic factors are included. The conclusion that can be drawn is that naturally occuring influences on climate contributed to most of the warming that occurred before WWII, but that the large observed temperature increases since the 1970s can only be simulated in the model if anthropogenic factors are included. This confirms the conclusion of the IPCC Third Assessment Report that most of the warming we have observed in the latter part of the 20th century has been due to human influences. Source: Jerry Meehl, National Center for Atmospheric Research

2oC limit Energy intensive Balanced fuel sources More environmentally friendly Limit to avoid “dangerous anthropogenic Interference” with the climate system 2oC limit IPCC Fourth Assessment Report Summary for Policy Makers

Karl, T. R. , J. M. Melillo, and T. C. Peterson, (eds Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009, 196pp.

Karl, T. R. , J. M. Melillo, and T. C. Peterson, (eds Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009, 196pp.

Low confidence Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009, 196pp.

Trend of increase in occurrence of heavy precipitation over the 20th C is consistent with increasing GHG concentrations. Frequency of intense precipitation events is likely to increase in the future. Karl, T. R., J. M. Melillo, and T. C. Peterson, (eds.), 2009: Global Climate Change Impacts in the United States. Cambridge University Press, 2009, 196pp.

Relationship of Streamflow to Precipitation in Current and Future Climates

SWAT (RegCM2): 21 % increase in precip -> 50% increase in streamflow Relationship of Streamflow to Precipitation in Current and Future Climates DrainMod (RegCM2): 24 % increase in precip -> 35% increase in tile drainage DrainMod (HIRHAM): 32 % increase in precip -> 80% increase in tile drainage

Iowa Agricultural Producers’ Adaptations to Climate Change Longer growing season: plant earlier, plant longer season hybrids, harvest later Wetter springs: larger machinery enables planting in smaller weather windows More summer precipitation: higher planting densities for higher yields Wetter springs and summers: more subsurface drainage tile is being installed, closer spacing, sloped surfaces Fewer extreme heat events: higher planting densities, fewer pollination failures Higher humidity: more spraying for pathogens favored by moist conditions. more problems with fall crop dry-down, wider bean heads for faster harvest due to shorter harvest period during the daytime. Drier autumns: delay harvest to take advantage of natural dry-down conditions Is it genetics or climate? Likely some of each. HIGHER YIELDS!!

For More Information North American Regional Climate Change Assessment Program: http://www.narccap.ucar.edu/ For current activities on the ISU campus, regionally and nationally relating to climate change see the Climate Science Initiative website: http://climate.agron.iastate.edu/ Contact me directly: gstakle@iastate.edu