Climate Models

An important aspect of climate scientists is the creation of models that give approximations of our climate. These models allow scientists to understand current climate conditions and to predict future climate conditions. This page gives links to scientific research about climate models.

They found a fairly high degree of consensus on the general character of the pace of climate change. In response to an instantaneous increase in greenhouse gas emissions, climate change is fast out of the starting gate but then slows down, and takes a long time to approach the finish line.
There is substantial quantitative disagreement among climate models, however. For example, one model reaches 38 percent of the maximum warming in the first decade after a step increase in CO2 concentration, while another model reaches 61 percent of the maximum warming in this time period. Similarly, one model reaches only 60 percent of maximum warming in the first century after the step increase, while another achieves 86 percent of maximum warming during this interval.

Scientists from UC Irvine and the National Center for Atmospheric Research have developed a new computer model to measure global warming's effect on soil worldwide that accounts for how bacteria and fungi in soil control carbon.

New research findings from the Centre for Permafrost (CENPERM) at the Department of Geosciences and Natural Resource Management, University of Copenhagen, document that permafrost during thawing may result in a substantial release of carbon dioxide into the atmosphere and that the future water content in the soil is crucial to predict the effect of permafrost thawing. The findings may lead to more accurate climate models in the future.

"The fact that we are experiencing more fires and that climate change may increase fire frequency underscores the need to include these specialized particles in the computer models, and our results show how this can be done," Dubey said.

Only a few climate models were able to reproduce the observed changes in extreme precipitation in China over the last 50 years. This is the finding of a doctoral thesis from the University of Gothenburg, Sweden.

It seems counterintuitive that clouds over the Southern Ocean, which circles Antarctica, would cause rain in Zambia or the tropical island of Java. But new research finds that one of the most persistent biases in global climate models -- a phantom band of rainfall just south of the equator that does not occur in reality -- is caused by poor simulation of the cloud cover thousands of miles farther to the south.

Researchers rely on models that use estimated ice thickness data and simulated atmospheric conditions to forecast how sea ice will change during the summer. For the first time, near real-time ice thickness data obtained by NASA's Operation IceBridge has been used to correct a forecast model's initial measurements, which could lead to improved seasonal predictions.

"We have shown that adding polar storms into computer-generated models of the ocean results in significant changes in ocean circulation -- including an increase in heat traveling north in the Atlantic Ocean and more overturning in the Sub-polar seas.

The researchers tested their approach on data originally taken in 1996 and 1997 in the Labrador Sea, an arm of the North Atlantic Ocean that lies between Greenland and Canada. They included satellite observations of ice cover, as well as local readings of wind speed, water and air temperature, and water salinity. The approach produced a tight fit between simulated and observed sea-ice and ocean conditions in the Labrador Sea -- a large improvement over existing models.

"New climate models will have to take these findings into account," says Professor Dr. Thorsten Hoffmann of the Institute of Inorganic Chemistry and Analytical Chemistry at Johannes Gutenberg University Mainz (JGU) in Germany. The Mainz researchers contributed primarily to the development of analytical techniques for studying the chemical composition of the aerosol particles in the Muchachas project. Thanks to their development of so-called 'soft ionization' techniques and the corresponding mass spectrometers, Hoffmann's work group was able to track the concentration of individual molecule species in the atmospheric simulation chamber and thus observe the chemical aging of the atmospheric aerosols at the molecular level. It was clearly demonstrated that oxidation occurred in the gaseous phase and not in the particle phase. "Now the goal is to integrate these underlying reactions in models of regional and global atmospheric chemistry and so reduce the discrepancy between the expected and the actually observed concentrations of organic aerosol particles," explains Hoffmann.

Climate-prediction models show skills in forecasting climate trends over time spans of greater than 30 years and at the geographical scale of continents, but they deteriorate when applied to shorter time frames and smaller geographical regions, a new study has found.

The findings do not change broader concerns about global warming. Temperatures are still projected to increase about four to 11 degrees by the end of this century, and the study actually confirms that some of the world’s most sophisticated climate models are accurate.

In the 1990s, observations did not show the troposphere, particularly in the tropics, to be warming, even though surface temperatures were rapidly warming. This lack of tropospheric warming was used by some to question both the reality of the surface warming trend and the reliability of climate models as tools. This new paper extensively reviews the relevant scientific analyses — 195 cited papers, model results and atmospheric data sets — and finds that there is no longer evidence for a fundamental discrepancy and that the troposphere is warming.

One popular climate record that shows a slower atmospheric warming trend than other studies contains a data calibration problem, and when the problem is corrected the results fall in line with other records and climate models, according to a new University of Washington study.

"One of the criticisms from climate-change skeptics is that different climate models give different results, so they argue that they don't know what to believe," he said. "We wanted to develop a way to determine the likelihood of different outcomes, and combine them into a consensus climate projection. We show that there are shared conclusions upon which scientists can agree with some certainty, and we are able to statistically quantify that certainty."