Battisti food&climate1

292 views

Published on

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
292
On SlideShare
0
From Embeds
0
Number of Embeds
2
Actions
Shares
0
Downloads
2
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide
  • Notes: MOST of uncertainty on physical side is in what will happen to clouds.
  • The color fig: observed precip, 1970-1990 minus 1940-60 (in mm/month)
  • NB: 79% of normal winter is only a deficit of 21% of winter, or about 5% below annual average total. The recent drought (50% winter; 10% of annual average) The Dust Bowl was a relatively small drought (5% for 7 years). The mega droughts dwarf theses two droughts in their duration and intensity
  • Various groups of researchers have attempted to simulate the 20 th century climate using “climate models”, sophisticated computer programs that represent the laws of physics as they apply to the Earth’s atmosphere, ocean, land, and ice. This figure shows one such study in which a climate model was run several times with natural climate influences (solar variations, volcanic eruptions), human climate influences (greenhouse gases and sulfate aerosols), and both kinds of influences. The best simulation of the 20 th century climate uses all climate influences. In particular, the warming of the last 30 years (when human climate influence is expected to have grown strongest)
  • Global average temperature: expect about 3C (2-4.5) with mid-range model sensitivity and emissions scenario with mid-range scenarios for population, economic growth and moderately aggressive movements toward alternative energy sources and implementation of carbon sequestration technologies;
  • The IPCC came up with a range of future scenarios of CO2 emissions, leading to a wide range of projected temperature changes. At the top end (5.8C) you have to assume extreme growth in CO2 emissions combined with very high sensitivity of climate to greenhouse gases, more than what is consistent with the observed 20 th century warming. Likewise, the low end is probably also unrealistic without significant policy efforts. The warming continues beyond 2100.
  • Mean changes in temperature from a set of 9 climate models. Note that most continental areas outside the Arctic warm 3-5C, the Arctic warms the most, and the oceans warm only 1-3C. This is Figure 9-10d of IPCC (page 547). Shading shows temperature change, blue contours show the range, green contours show multi-model mean change divided by multi-model standard deviation. SRES A2 is the highest of the 4 main marker scenarios (CO2 856 ppmv by 2100, or 3x). Nine models were used.
  • igure. 2.2: Trends in annual diurnal temperature range (DTR, °C/decade), from 1950 to 1993, for non-urban stations only, updated from Easterling et al. (1997). Decreases are in blue and increases in red. This data set of maximum and minimum temperature differs from and has more restricted coverage than those of mean temperature used elsewhere in Section 2.2 .
  • Mean changes in precipitation from a set of 9 climate models. Colors are % change. Red lines are model range. Green lines are contours of model ensemble change to model ensemble sd. This is Figure 9-11d of IPCC (page 550). Shading shows precip change, red contours show the range, green contours show multi-model mean change divided by multi-model standard deviation. SRES A2 is the highest of the 4 main marker scenarios (CO2 856 ppmv by 2100, or 3x). Nine models were used.
  • Battisti food&climate1

    1. 1. Climate and Food Security Thank youto the Yaqui Valley and Indonesian Food Security Teams at Stanford 1. Seasonal Climate Forecasts 2. Natural cycles of drought 3. Global Warming 4. Impact of Agriculture on Climate
    2. 2. El Nino/Southern Oscillation (ENSO): A natural mode of tropical atmosphere/ocean variabilityWarm events return every 2-7 years, and tend to peak in NH winter
    3. 3. El Nino - Southern Oscillation (ENSO)ENSO is a natural pattern of climate variability that is dueto tight coupling between the atmosphere and ocean.• Small changes in the distribution of sea surface temperature are coordinatedwith changes in atmospheric circulation and rainfall patterns;• The changed rainfall patterns in the tropics force atmospheric circulationchanges that affect climate world-wide. Temperature Anomalies Precipitation Anomalies
    4. 4. DJF ENSO Impacts http://www.cpc.ncep.noaa.gov/
    5. 5. ENSO is Predictable• ENSO is a true mode of the coupled atmosphere/ocean system (eg, patterns of oscillation in a guitar string)• The long period (3-4 years) of the ENSO mode allows for skillful seasonal climate forecasts (2-4 seasons in advance)• Presently, empirically based forecast models are at least as skillful as the numerical climate models.
    6. 6. Examples of applications of seasonal forecast (based on ENSO forecasts)• Yaqui Valley, Mexico – Winter precipitation and reservoir inflow; in-field precipitation; health of grazing lands• Indonesia – Rice yields• Hurricane forecasts – frequency and intensity (Atlantic and Pacific)• Florida – Frost and citrus crops• Pacific Northwest – Snowpack and hydropower, flood events, recreation, stream flow, etc.
    7. 7. Products: Forecasts of wintertime precipitation in the Yaqui Valley Catchment (winter reservoir inflow is correlated with wintertime precipitation at r =0.87)Winter Precipitation (mm) ENSO and NDJFMA precipitation Nino 3.4 •For use with a forecast of ENSO •The prediction skill of the wintertime state of ENSO starting in October is > 0.9
    8. 8. ENSO Impacts: Java Monsoon onset is delayed during ENSO warm events. The delayed monsoon onset results in reduced cumulative rainfall through wet season.ENSO accounts for 61% of the variance in annual riceproduction (1C Nino3.4 <---> 1 Gt rice production)
    9. 9. Climate and Food Security Thank youto the Yaqui Valley and Indonesian Food Security Teams at Stanford • Seasonal Climate Forecasts • Natural cycles of drought • Global Warming • Impact of Agriculture on Climate
    10. 10. Decadal Variability in Sahel Precipitation Change in Summer Precip 1970-90 Minus 1940-60• Precipitation in the Sahel is linked to Sea Surface Temperature changes (wet is associated with Correlation of Sahel Summer lower SST in the S. Atlantic and Precipitation with SST Indian Oceans)• Mainly due to natural climate variability; some part due to 20th Century changes in CO2 and NH aerosols.• Future role of Global Warming unclear
    11. 11. Historical Yaqui Reservoir Runoff, 1965-2004 Main Reservoir Yaqui System8000700060005000400030002000 19921000 0 1965 Fig. From Jose-Luis Minjares 2003
    12. 12. The recent drought in the Yaqui Valley: how extreme? • The reconstructed precipitation record extends from 1650 to 1985 AD. • The average return time for a drought similar to the most recent (winter) drought – six years at 63% of normal precipitation is about a century; – Five years (1998-9 to 2002-3) at 50% of normal is unprecedent in 350 yrs. – For reference, the winter average precipitation for 1950-1960 was 79% of normal.Note: paleo records suggest numerous “megadroughts”in past 1000 years in the US that are presumably naturalvariability.
    13. 13. Climate and Food Security Thank youto the Yaqui Valley and Indonesian Food Security Teams at Stanford • Seasonal Climate Forecasts • Natural cycles of drought • Global Warming • Impact of Agriculture on Climate
    14. 14. Natural Climate Influence Human Climate Influence All Climate Influences
    15. 15. We Are We Headed? st21 Century ClimateChange Projections
    16. 16. 21st century temperature change IPCC (www.ipcc.ch)
    17. 17. Projections of Future ClimateTemperature change, 2071-2100 minus 1961-1990
    18. 18. How will climate change due to increasing greenhouse gases?Many changes projected by the models are robust andreliable. Examples of changes that are very likely* over thenext 100 years include: • the planet will warm, more so in middle and high latitudes than in the tropics; • the hydrologic cycle will speed up; • the area covered by snow and sea ice in winter will decrease; • the sea level will rise; • Increased flooding in some areas.These changes will be much, much greater than the changesseen over the past 150 years that have been attributed toincreased greenhouse gases and aerosols.
    19. 19. Trend in Daily Temperature Range 1950-1993 • Night is warming faster than day.
    20. 20. Impacts of Climate Change on Agriculture• Increased growing season at high latitudes• Increased minimum temperature (crop growth and pest/pathogen effects)• Continental drying in midlatitudes (?)• Changes in timing of stream flow in mid and high latitudes (water availability, etc)• Changes in heat wave frequency and intensity; change in frost days.• Changing patterns of drought.• CO2 effects on soil BGC, plant pathology; ocean acidification, etc.
    21. 21. Projections of Future ClimatePrecipitation change, 2071-2100 minus 1961-1990
    22. 22. How will climate change affect agriculture in the tropics and subtropics? It is highly likely that increasing CO2 will cause large changes in the patterns and intensity of precipitation throughout the tropics within the next 50yrs, including: • Changes in the annual cycle in precipitation throughout the tropics: – The spatial and temporal structure of the monsoons will change in a significant way (eg, making places dry that are presently wet; changing the duration of the monsoon) • Changes in ENSO • Changes in the teleconnection patterns associated with ENSO – Changing patterns, duration and intensity of drought (world-wide).Unfortunately, the present generation of climate models cannot address these issues. But we are making progress ….
    23. 23. Thank you

    ×