Climate , Climate Change, and climate modeling Anthony R. Lupo Atmospheric Science, University of Missouri Columbia, MO 65211 America First Energy Conference | The Heartland Institute Houston, Texas | November 9, 2017

What is Climate? What is Climate? How does it differ from weather (synoptic, or even the General Circulation)? How is this different from Climatology? Weather  the day to day state of the atmosphere. Includes state variables (T, P) and descriptive material such as cloud cover and precipitation amount and type, etc. Climate  Is the long-term or time mean state of the Earth-Atmosphere system and the state variables along with higher order statistics. Also, we must describe extremes and recurrence frequencies.

What is Climate? Schematic of the earth- atmosphere system Dr. Richard Rood. (http://aoss.engin.umich.edu/class/aoss605/lectures/)

Climate Change We can define climate change as any change in the statistical character of our variables which define climate on time–scales longer than the climatic averaging period (30 years). Key Issues Regarding Climate Change: 1) Does climate change occur on all time-scales, or are there time-scales that are preferred (e.g., have large climatic variability)?

Climate Change Climate change through the ages!

Climate Change Climate Change Through the Ages (cont.)

Climate Change Is climatic change global or regional? This question is difficult to answer. Maybe. It’s popular to think it’s global and even some scientists think so. It might be given the interconnectedness of the general circulation. But if one look in more detail, many differences are primarily regional. Example, the Pleistocene Ice ages affected mostly mid and high latitude Northern Hemisphere and the equatorial region and southern hemispheres were less affected.

Climate Change Regional Changes – The World Over!

Extreme phenomena Climate Change

CLIMATE Change The Future?

Climate Change Is climate change primarily forced by external factors (forced modes – changes in the boundary conditions), or internal dynamics of the climate system (free modes – non-linear interactions / feedbacks)? Both are very important. There are obvious external forcings: orbital parameter changes, continental drift, changes in solar radiation, volcanism, etc. However, it also appears that interactions between variables within the earth-atmosphere system may also lead to climatic change. This could represent changes in atmospheric composition or changes in surface or deep ocean temperatures.

Climate Models Definition of a Weather / General Circulation Model: A hypothesis, in the form of mathematical statements, that describes a process or processes that are physically important in describing the climate and/or climate change. The physical consistency of the model formulation and the agreement with observations serve as a test of the hypothesis.

Climate Modelling The General Circulation model – What are they? Solves for thermodynamic and dynamic state of the atmosphere on Instantaneous Time scales. Essentially same as a weather forecast model, yields arbitrary 'weather' data that are post processed to yield model climate statistics. (just like observations!) relatively fine resolution in the vertical (50+ layers), but relatively coarse in the horizontal 2.5 – 2.5 degrees in both latitude and longitude, but 1 x 1 simulations are common, sometimes less.

Climate Modeling A schematic of a General Circulation Model

Climate Modeling Four physical principles that must be contained (laws observed): Conservation of Energy (First Law of Thermodynamics) Conservation of Mass (Continuity – Carrier, Trace substances) Conservation of Momentum (Navier Stokes / Newton’s Second Law of Motion) Elemental Kinetic Theory of Gasses (Equation of state) These form the dynamic core of the model

Climate Modeling We know how the ‘core’ behaves – it’s complicated!

CLIMATE Modeling It’s all the other processes that must represented using our best knowledge (To name a few): Precipitation Clouds (stratiform and Convective) Atmosphere / Surface Interactions Inputs and outputs of Energy

Climate Modeling Advantages / What the models do well 1. most comprehensive model currently available 2. Represents the current general circulation (even seeing improvement in interannual variability – El Niño) 3. full vertical latitudinal and longitudinal resolution 4. most comprehensive in representing interaction between climate components and feedbacks.

Climate Modeling Disadvantages / What they are not 1. Very costly and slow to run or very complex (provide a wide range of scenarios or projections. 2. Massive amount of output, makes analysis/interpretation difficult. 3. large number of parameterizations, needs considerable 'tuning' making predictive capabilities uncertain. They are OK for the present weather, but for studying past or future climates, use is uncertain. 4. Not a genuine climate model. Solves for weather, which is post-processed to get a climate.

The End Thank you for your Attention! Comments? lupoa@Missouri.edu