Research Theme: Climate System Variability
Climate changes that occur both in the short term—seasons to decades—
and those that occur across millennia.
Why this Research Theme?
Short-term climate changes occur with weather events: floods, droughts, storms, temperature extremes and vacillations, and volcanic eruptions. Because they affect air quality and water availability and quality, such events impact agricultural practices, recreation, and the health of ecosystems and populations. In the short term, climate change often creates a need for natural resource management strategies, or natural hazards mitigation.
By comparison, long-term climate change has more to do with environmental sustainability, conservation, and species survival than with weather events. Therefore, scientists, planners and legislators are most concerned with understanding the underlying causes and eventual repercussions of climate change in order to craft effective responses.
How We're Doing this Research
CIRES research in climate system variability aims at gaining a breadth of understanding in science fields that specialize in detection of climate trends, understanding the mechanisms and forcings of climate variability, understanding climate and cryosphere interactions, prediction of climate variability, study of extreme events and rapid climate change, and atmospheric ozone.
Objective
Climate variability affects virtually all natural systems and human activities, including agriculture, water quantity and quality, ecosystems, and human health. Understanding, and potentially predicting, climate changes is a significant effort within CIRES' research community.
Research
Climate variations may have natural or human-induced causes. Understanding, and potentially predicting, climate changes is critical to the public, as well as to a broad array of decision-makers within federal and state government, industry, resources management and hazard mitigation. Indeed, basic issues include determining whether observed changes are attributable to natural or anthropogenic forcing, and the extent to which natural and human-induced changes may be linked. Clarifying the relative importance of these two causes is an outstanding research and societal issue. Also, "large-scale" and "long-term" climate variations may be linked to variations in local weather conditions such as temperature, precipitation, cloud cover and storminess, as well as in atmospheric carbon dioxide, ozone, and water vapor. Understanding links across scales is vitally important. Predictions of the likelihood of extreme events and abrupt climate changes are especially important because of potentially major societal and ecosystem impacts. To address these fundamental problems, six sub-topics, which are in established areas of CIRES expertise, comprise the institute's scope in climate variability.
- Detection of Climate Modes, Trends, and Variability
- Mechanisms and Forcings of Climate Variability
- Climate and Cryosphere Interactions
- Prediction of Climate Variability
- Development of Extreme Events and Rapid Climate Change
- Atmospheric Ozone
Goals
- Detect and describe climate variations
- Diagnose and attribute the cause of climate variations to natural or man-made forcing
- Understand the roles of clouds in radiative and climate forcing
- Understand the upper troposphere, a crucial region for climate and global change
- Provide improved predictability of chaotic systems
- Forecast and predict climate events
- Understand current and potential future depletion of the stratospheric ozone layer
- Measure stratospheric aerosol following major volcanic eruptions to determination the effects on ozone and climate
- Improve our understanding of the Arctic climate and improve predictive climate models
Overview
Climate variability affects virtually all natural systems and human activities. Direct impacts of climate include such vital areas as agriculture, water quantity and quality, ecosystems, and human health. Understanding, and potentially predicting, climate changes is therefore critical to the public, as well as a broad array of decision-makers within federal and state government, industry, resources management and hazard mitigation. Indeed, basic issues include determining whether observed changes may be attributable to either natural or anthropogenic forcing, and the extent to which natural and human-induced changes may be linked. Fundamental problems include: 1) detection and description of climate changes; 2) identification of causes (attribution); and 3) prediction, which is intrinsically probabilistic in nature. Prediction problems of vital importance include estimating changes in the likelihood of extreme events, and identifying risks for abrupt climate change, because the potential for major societal and ecosystem impacts is likely to be particularly large in such cases. The following are examples of the questions being addressed in areas of established CIRES expertise.
1. Detection of climate modes, trends, and variability
The goal is a better understanding of the structure and range of natural climate variability, to help, among other things, in distinguishing it from anthropogenic climate change. This is particularly important since the power spectra of the major modes of climate variability such as ENSO, the NAO, and the Arctic and Antarctic "oscillations" are difficult to distinguish from noise at the lowest frequencies.
2. Mechanisms and forcings of climate variability
To what degree is tropical Pacific Ocean variability, or ENSO, the basic cause of all natural climate variability from seasonal to decadal scales? Are the pronounced changes in the Arctic environment observed over the past several decades a reflection of natural variability or human influences? To what extent is the cryosphere a driver of climate variability?
3. Stratospheric Ozone Depletion
To what extent are changes in the stratospheric ozone layer affecting the stratospheric thermal and wind structure, and hence wave propagation characteristics which may in turn influence tropospheric structure and climate?
4. Prediction of climate variability
To what extent does the longer memory of the deep ocean, and/or changes of sea ice, contribute to atmospheric predictability on decadal and longer scales? Are fully coupled ocean-atmosphere-cryosphere-land surface models likely to lead to significant further improvements in climate prediction? What is best way to utilize probabilistic predictions?
5. Development of extreme events and rapid climate change
To what extent are extreme anomalies and events predictable? What is the likelihood of abrupt climate change, for example, the collapse of the thermohaline circulation, and what would be the global and regional manifestations of such a change? How can we improve our use of the paleoclimate record to detect extreme events and measure their frequency?
More Information
For more detailed information about climate system variability research at CIRES, contact Theme Leader Mark Serreze or see this full text description for research linkages and plans.
