The Climate System

Transcription

1 The Climate System Nili Harnik DEES, Lamont-Doherty Earth Observatory

2 What is Climate? Climate is the long term average of weather. - Local climate and global climate Described using various weather variables: wind, temperature, precipitation, humidity, cloudiness, pressure, visibility, and air quality. The definition of climate can also include a statement on the typical range of variability in values of environmental variables (for example - the standard deviation of temperature).

3 Weather and Climate The actual minimum and maximum temperatures (in degrees Fahrenheit) measured in New York City (La Guardia Airport) for Jan 1-20, Superimposed in grey is their climatological range for that time of year.

4 Climate Variability and Climate Change Climate is continually changing due to internal and external influences. We distinguish between predictable (deterministic) and unpredictable (stochastic) variations. San Francisco, CA rainfall Monthly climatology: the long term average for each month. Seasonal variations are largely deterministic. The monthly averaged rainfall in 1976 Year-to to-year variations are in large part stochastic.

5 Climate Variability and Climate Change Variations of the Earth s Surface Temperature* *relative to average Source: IPCC TAR 2001

6 Elements of the Climate system

7 A wider definition of climate The study of climate is a quantitative science, involving the understanding of the transfer of energy from the sun to the earth, from earth to space, and between atmosphere, ocean, and land, all under fundamental physical laws such as conservation of mass, heat, and momentum. A complete description of the climate system and the understanding of its characteristics and change also require the study of the physical properties of the high atmosphere, deep ocean, and the land surface, and sometimes the measurement of their chemical properties. The traditional disciplines of Meteorology, Oceanography, Biology, Geology, focus on specific climate sub-systems. systems. This tends to obscure the properties of the whole system. The modern science of climate is interested in climate as a dynamical system, changing in space and time.

8 This course Describe the properties of the climate system and explain the forces and processes that shape and determine these properties. Look at the different sub-components of climate system: atmosphere, ocean and land, and their interactions. Help understand the issues that face science and society regarding climate change. Provide descriptive & quantitative introduction to the physics of o the Earth s climate system. Introduce the tools used in modern climate research. We will draw from the traditional disciplines of physics, chemistry, and biology for concepts to help us understand the planet's processes and history

9 Subjects covered Energy to drive the climate system: the Earth radiation budget. The fluid systems - atmosphere and ocean: moving heat and moisture in the climate system. Climate and life: interaction between the climate system and the biosphere. Climate variability and change - past and present: phenomena, mechanisms and characteristic patterns.

10 Why is studying climate important? Climate affects life on earth: Humans and other forms of life have continually evolved and adopted to climate changes. Climate affects our nutrition, and health. It constrains our activities, and determines ermines our comfort. The diversity of life on Earth and social and cultural spectrum of human traditions are strongly influenced by the way climate varies from one region to another. Life affects climate. this is true for plants, humans, and other animals. The increasing size of human population and our industrial activity ity threaten to change the climate in a significant way over a relatively short time interval. Advances in instrumental observations, theory, and numerical techniques allow us to simulate and understand the Earth s climate system and make scientific projections of its future evolution. Knowledge of the climate system can help us make decisions on how to avoid, reduce or mitigate the impact of climate change.