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Climate Change

Science Supporting Policy in California and Beyond

Photo: Hurricane

Models use computers to calculate the outcomes of multiple variables that determine climate.

Forecasting and Modeling

What do global climate models tell us about exteme events in climate?

Richard Grotjahn, professor, land, air and water resources; builds global climate models based on known, underlying principles that explain how the elements of the climate system operate. The climate elements include the atmosphere, the ocean, the land surfaces, and ice. Grotjahn's research investigates ways to improve further state-of-the-art climate models. His current focus is on simulating the Arctic climate since that region is highly sensitive to global warming scenarios. Grotjahn investigates whether the properties of extreme weather events are likely to change in the future. Examples of extreme events include: heat waves, hard freezes and heavy precipitation. The properties he studies include the severity, the frequency and the duration of extreme events.

What are particles in the atmosphere made up of?

Anthony Wexler, director, Air Quality Research Center, collaborates with international scientists on the Aerosol Inorganics Model Project (AIM); funded by the North Atlantic Treaty Organization (NATO), the UK Meteorology Office and the US National Oceanic and Atmospheric Administration.  AIM calculates the distribution of water and electrolytes in the atmosphere depending on temperature and humidity.  AIM is used to understand measurements, to validate aerosol thermodynamic modules used in global climate change models, and to educate students.

Will climate change impact how frequently the air is polluted in California?

Shu-Hua Chen; land, air, water resources; studies mesoscale meteorology and the impact of climate change on regional air quality in California. Climate change will modify the strength and frequency of weather phenomena, such as high pressure systems, which are associated with air pollution. Chen seeks to understand the variation of weather patterns influenced by changing climate and uses that to model the stagnant atmospheric conditions over California's Central Valley and the Los Angeles basin. She uses data from severe weather and regional climate to predict pollutant transport.

How do land use changes influence the climate of California?

Bryan Weare; land, air, water resources; is studying the effects of irrigation changes and other factors on California climate. Projects in his field of atmospheric sciences improve understanding of how climate is influenced by local to global changes over time periods from months to decades. Weare’s techniques range from the analysis of long term weather observations to the use of sophisticated global and regional weather forecast models. These provide information about how exchanges of moisture and heat between the atmosphere and the earth's surface affect climate. Recent evidence of the influence of human activity on the climate system has led to increased research attention on the hydrologic cycle as an important focus for the study of climate change.

How are models used at Lake Tahoe to predict the clarity of the lake and climate change impacts on local ecology?

Geoff Schladow, director, Tahoe Environmental Research Center, uses models to predict the magnitude of changes in clarity due to climate change. Rises in lake temperature have profound impacts on the lake ecology. Current research is looking at the impacts of climate change on algal species composition, invasive fish and aquatic weed populations, and the food web. The hundred year data record from Tahoe City, California shows that minimum air temperatures have risen over four degrees Celsius and are now above the freezing point of water, the result of which is less snow, more rain, increased runoff and more erosion. Lake Tahoe's clarity is largely affected by very fine particles that come from the air or enter the lake with the runoff from streams and urban areas. As precipitation patterns continue to change in response to climate change -- for example more rain and less snow -- and as the runoff changes with earlier snowmelt, the quantity and size of fine particles will change. There has also been a measured increase in the temperature of the lake over the last 40 years. The warming of the lake is double the rate of warming of the surface of the world's oceans.

How will natural and human-caused forcing of the stratosphere affect global climate?

Terry Nathan, land, air and water resources, is studying the effects of natural and human-caused variations in the upper atmosphere on the lower atmosphere. Particular attention is focused on the effects of solar variability and increasing greenhouse gas concentrations on stratospheric ozone and temperature. Nathan is currently leading a multi-institutional research effort to examine how stratospheric variations affect tropospheric climate.

What should be the optimal level and time profile of carbon taxes and carbon permits to control climate change, taking into account the dynamics of global carbon cycle?

Y. Hossein Farzin, agricultural and resource economics, forecasts and models demand and supply, pricing of fossil fuels, technological change and measures of natural resource scarcity. He has addressed the economic aspects of climate change and the use of economic disincentives such as carbon taxes and carbon permits. He has examined the optimal timing of investment in climate change policies and the economic costs of delaying action. He investigates the optimal economic incentives for the timely adoption of clean technologies and the introduction of alternative energy sources to control the climate change. His publications have described the economic obstacles and prospects of the Kyoto treaty. Farzin has expertise in environmental regulations and market structure, environmental regulation and uncertainty, and linkages between environmental and economic development.