After lunch, Session 3 began at 1:30 PM. This session was on the Effect of Changing Climate on Northeast Pastures. Dr. Howard Skinner, plant physiologist with the USDA-ARS Pasture Systems and Watershed Management Research Unit at University Park, PA and Executive Committee member, was moderator and first speaker.
Dr. Howard Skinner, What will the Climate be like for our Children and Grandchildren?
Seven different scenarios showed what would happen with the release of varying levels of CO2 emissions over this century. These scenarios predict substantial changes in the climate of the northeastern United States
Dr. Jack Morgan, plant physiologist, USDA-ARS Crops Research Laboratory, Fort Collins, CO gave the next presentation, Implications of Rising Atmospheric CO2 and Climate Change for Grazinglands.
Atmospheric CO2 levels remained essentially constant from 0 AD to about 1900 at around 280 ppm. It then shot up to 380 ppm over the last century. In the same time span, methane gas has climbed from 800 parts per billion (ppb) to over 1900 ppb. While, nitrous oxide has increased from 270 ppb to 340 ppb after being fairly constant over the first 1900 years.
The third speaker of Session 3 was Dr. Lewis Ziska, research plant physiologist, USDA-ARS, Crop Systems and Global Change Lab, Beltsville, MD. His presentation was Invasive Plants, Climate and CO2: Implications for Agriculture.
So what happens if CO2 goes up? An indirect effect of rising carbon dioxide is warmer temperatures. For example: No H2O and CO2? Surface temperature of Earth would be -18o C on average. With H2O and CO2? Surface temperature averages 15o C. A direct effect of rising CO2: Stimulation of plant growth. Any change in light, water, nutrients, or carbon dioxide will alter plant growth.
Dr. Larry Chase, Professor of Animal Science-Nutrition from Cornell University, was the last speaker of session 3. The title of his presentation was What Will Climate Change Mean to Grazing Animals?
All animals have a zone of thermoneutral temperatures conducive to normal function. The upper critical temperature is where the effects of heat stress start to appear. Heat stress is when the heat load of cow is greater than the cow’s ability to dissipate heat. More generally, it is the inability to maintain /stabilize body temperature within very narrow limits. Without proper maintenance of body temperature, there is a drop in biochemical reactions and physiological processes, and metabolism is abnormal. The thermoneutral zone or comfort zone is the combination of temperature and humidity where dairy cattle are comfortable and not under heat or cold stress.