Evaluating climate simulations against observational data is a fundamental step in the evaluation and eventual improvement of models. Models can also help test our understanding of the causes of past variations of climate seen in the historical record. This analysis shows how current climate models, including those developed by NOAA, compare with observations in terms of their regional surface temperature trends since 1901.
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GFDL Research Highlights
The impacts of climate change on the North America-North Atlantic-Europe sector are studied using a coupled general circulation model (CM3) and a high-resolution atmosphere-only model (HiRAM), both developed at the Geophysical Fluid Dynamics Laboratory. Long-term changes in surface temperature, precipitation and storminess patterns over Europe and the North Atlantic are projected.
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This study investigates the impact of the late 20th century increase of anthropogenic aerosols on the onset of the Indian summer monsoon. Aerosols are likely responsible for the observed earlier onset, resulting in enhanced June precipitation over most of India. This shift is preceded by strong aerosol forcing over the Bay of Bengal and Indochina, mostly attributable to the direct effect, resulting in increased atmospheric stability that inhibits the monsoon migration in May.
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The authors explored the influence of anthropogenic climate change on Atlantic hurricane activity in the 21stcentury, using dynamical climate models. The results of experiments using multi-model climate change scenarios were compared, with one scenario taken from CMIP3 (A1B), and one from CMIP5 (RCP4.5). A significant reduction in the frequency of tropical storms and hurricanes is projected for both CMIP3 and CMIP5 ensembles. However, the authors found significantly increased frequency of category 4 and 5 hurricanes in experiments with the CMIP3 ensemble. Experiments with the CMIP5 ensemble showed a smaller increase in the strongest storms. In addition, tropical cyclone-related rainfall rates, increased significantly–by about 30% in the hurricane inner core (within 50 km of the storm center) with a smaller increase of about 10% for rainfall rate averaged within 200 km to 400 km of the storm center.
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The authors simulated the response of sea surface temperature (SST) in the Atlantic Hurricane Main Development Region (MDR) to a doubling of CO2, using a cutting-edge global high-resolution coupled model developed at GFDL (CM2.5). This model has been shown to produce a very faithful simulation of the observed seasonal cycle and year-to-year (or interannual) variability in the tropical Atlantic. The skillful representation of Atlantic interannual variability enables the exploration of the response of interannual variability to increasing CO2 – in addition to exploring changes in the average conditions in the Atlantic.
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Biomass burning is one of the largest sources of trace gases and aerosols in the atmosphere, and has profound influence on tropospheric oxidants and radiative forcing. Using a fully coupled chemistry-climate model (GFDL AM3), the authors found that co-emission of trace gases and aerosol from present-day biomass burning increases the global tropospheric ozone burden by 5.1%, and decreases global mean OH, a major sink for methane, by 6.3%.
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Future changes in wind-wave patterns have broad implications for ecosystems, as well as the design and operation of coastal, near-and-off-shore industries. Changes in response to global warming may further exacerbate the anticipated vulnerabilities of coastal regions to projected sea-level rise.
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March 4th, 2013 - Cloud tuning in a coupled climate model: impact on 20th century warming
Clouds remain one of the largest sources of uncertainty in predictions from climate models. Globally, clouds cool the Earth through the net effect of two opposing contributions: cooling from reflection of incoming solar radiation and warming from trapping of infrared radiation emitted by the Earth. By comparison, the cooling effect of clouds is estimated to be about six times larger than the warming effect resulting from the increase in anthropogenic greenhouse gases since 1750. This is why uncertainties in the representation of clouds can have considerable impact on the simulated climate.
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February 24th, 2013 - Heat stress reduces labor capacity under climate warming
The authors use existing occupational health and safety thresholds to establish a new metric to quantify a healthy, acclimated individual’s capacity to safely perform sustained labor under environmental heat stress (labor capacity). Using climate model projections, we apply this metric to quantify the direct impact of global warming on the global human population in the future.
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February 15th, 2013 - Controls of Global Snow Under a Changed Climate
Understanding snowfall variability is key to understanding future water supply in snowmelt-dominated regions, like the western U.S. This research validated GFDL’s coupled climate models, CM2.5 and CM2.1, for snowfall and explored changes in snowfall in a future climate experiment, to determine if resolution differences in the models influence snowfall signals.
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