Search

The article reports on the climate impacts of anthropogenic carbon dioxide emissions. In its Fourth Assessment Report, the Intergovernmental Panel on Climate Change (IPCC) suggests that about 50 percent of a carbon dioxide increase will be removed from the atmosphere within 30 years. It is reported that the logarithmic relationship between carbon dioxide and its radiative forcing implies that the time scale at which atmospheric temperature declines will be longer.

This article discusses climate change and hurricanes. Papers that appeared in the scholarly journals "Nature" and "Science" during the summer of 2005 raised the question of global warming being the cause of the record-breaking hurricane season of 2005. The article examines that argument, noting that many scientists believe that human-induced climate warming is indeed real. Also discussed is the increasing intensity of hurricanes since 1975, as well as the rise in seas surface temperatures and greenhouse gases in the atmosphere.

A novel satellite image processing technique developed at the Canada Centre for Remote Sensing has been utilized to produce annual time series of the minimum snow/ice (MSI) extent over the northern circumpolar landmass area (9,000 km × 9,000 km) for 2000-19. The information has been derived from the Moderate Resolution Imaging Spectroradiometer 10-day clear-sky composites generated at 250-m spatial resolution over the April-September period. Derived interannual variations agree very well with the warm-season average surface air temperatures from the European reanalysis (ERA5). The region-average correlation coefficient is -0.78. The total MSI extent demonstrated a statistically significant declining trend equal to -1,477 km2 yr-1. Results have been compared with data from the Randolph Glacier Inventory (RGI 6.0). The comparison points to a significant contribution of minimum seasonal snow cover relative to RGI glacierized areas. Quantitative estimates obtained for the first time showed that the region-average snow extent that survives the summer melt and resides outside of RGI area can be as high as 15% (or 53 × 103 km2) while in the northern Canadian Arctic it can reach 41% (or 43 × 103 km2). The derived MSI time series data can be recommended to the glacier and land-cover scientific community as a source of validation data and annual updates of snow and ice maps over the northern circumpolar landmass. [ABSTRACT FROM AUTHOR]

The article explores urban temperature studies in 2011. Population growth and climate change are two factors significantly affecting the study of urban heat islands, which is a term defined as the atmospheric warmth of a city compared to its countryside. The Local Climate Zone (LCZ) Classification System was used by the authors in observing the heat island effect in all urban areas. They conclude that the system could be used in classification of urban and rural sites for temperature studies.

El Niño is widely recognized as a source of global climate variability. However, because of limited ocean observations during the early part of the twentieth century, little is known about El Niño events prior to the 1950s. An ocean model, driven with surface boundary conditions from a recently completed atmospheric reanalysis of the first half of the twentieth century, is used to provide the first comprehensive description of the structure and evolution of the 1918/19 El Niño. In contrast with previous descriptions, the modeled El Niño is one of the strongest of the twentieth century, comparable in intensity to the prominent events of 1982/83 and 1997/98. [ABSTRACT FROM AUTHOR]

Questions have been raised about whether poor siting practices that have existed in recent years at some in situ weather-observing stations are causing a bias in U.S. temperature change analysis. This potential bias was examined using homogeneity-adjusted maximum, minimum, and mean temperature data from five stations in eastern Colorado—two with good current siting and three with poor current siting. No siting-induced bias was found in the homogeneity-adjusted data. Furthermore, the results indicate that homogeneity-adjusted time series from the stations with poor current siting represent the temperature variability and change in the region as a whole quite well because they are very similar to the time series from stations with excellent siting. [ABSTRACT FROM AUTHOR]

Historically, meteorological observations have been made for operational forecasting rather than long-term monitoring purposes, so that there have been numerous changes in instrumentation and procedures. Hence to create climate quality datasets requires the identification, estimation, and removal of many nonclimatic biases from the historical data. Construction of a number of new tropospheric temperature climate datasets has highlighted previously unrecognized uncertainty in multidecadal temperature trends aloft. The choice of dataset can even change the sign of upper-air trends relative to those reported at the surface. So structural uncertainty introduced unintentionally through dataset construction choices is important and needs to be understood and mitigated. A number of ways that this could be addressed for historical records are discussed, as is the question of How it needs to be reduced through future coordinated observing systems with long-term monitoring as a driver, enabling explicit calculation, and removal of nonclimatic biases. Although upper-air temperature records are used to illustrate the arguments, it is strongly believed that the findings are applicable to all long-term climate datasets and variables. A full characterization of observational uncertainty is as vitally important as recent intensive efforts to understand climate model uncertainties if the goal to rigorously reduce the uncertainty regarding both past and future climate changes is to be achieved. [ABSTRACT FROM AUTHOR]

This article highlights the workshop on vertical profiles of temperature trends held in Great Britain on September 13-17, 2004. Technical talks by participants covered a broad range of topics from the latest advances in observational climate records and climate models through efforts to achieve a process-based understanding of the underlying physical mechanisms driving climate change. The workshop focused on the Tropics and tropical processes, as this is generally recognized to be the region of the greatest observational and model uncertainty. An invited talk on the Global Energy and Water Experiment emphasized the importance of considering temperature changes in the context of changes in the energy of the system. Four working groups focused on specific problems that make it a challenge to obtain accurate vertical profiles of temperature trends and to understand their physical causes.

Measuring the small changes associated with long-term global climate change from space is a daunting task. The satellite instruments must be capable of observing atmospheric and surface temperature trends as small as 0.1°C decade-1, ozone changes as little as 1% decade-1, and variations in the sun's output as tiny as 0.1% decade-1. To address these problems and recommend directions for improvements in satellite instrument calibration, the National Institute of Standards and Technology (NIST), National Polar-orbiting Operational Environmental Satellite System–Integrated Program Office (NPOESS-IPO), National Oceanic and Atmospheric Administration (NOAA), and National Aeronautics and Space Administration (NASA) organized a workshop at the University of Maryland Inn and Conference Center, College Park, Maryland, 12–14 November 2002. Some 75 scientists participated including researchers who develop and analyze long-term datasets from satellites, experts in the field of satellite instrument calibration, and physicists working on state-of-the-art calibration sources and standards. The workshop defined the absolute accuracies and long-term stabilities of global climate datasets that are needed to detect expected trends, translated these dataset accuracies and stabilities to required satellite instrument accuracies and stabilities, and evaluated the ability of current observing systems to meet these requirements. The workshop's recommendations include a set of basic axioms or overarching principles that must guide high quality climate observations in general, and a road map for improving satellite instrument characterization, calibration, intercalibration, and associated activities to meet the challenge of measuring global climate change. The workshop also recommended that a follow-up workshop be conducted to discuss implementation of the road map developed at this workshop. [ABSTRACT FROM AUTHOR]

Accurate and reliable predictions and an understanding of future changes in the stratosphere are major aspects of the subject of climate change. Simulating the interaction between chemistry and climate is of particular importance, because continued increases in greenhouse gases and a slow decrease in halogen loading are expected. These both influence the abundance of stratospheric ozone. In recent years a number of coupled chemistry–climate models (CCMs) with different levels of complexity have been developed. They produce a wide range of results concerning the timing and extent of ozone-layer recovery. Interest in reducing this range has created a need to address how the main dynamical, chemical, and physical processes that determine the long-term behavior of ozone are represented in the models and to validate these model processes through comparisons with observations and other models. A set of core validation processes structured around four major topics (transport, dynamics, radiation, and stratospheric chemistry and microphysics) has been developed. Each process is associated with one or more model diagnostics and with relevant datasets that can be used for validation. This approach provides a coherent framework for validating CCMs and can be used as a basis for future assessments. Similar efforts may benefit other modeling communities with a focus on earth science research as their models increase in complexity. [ABSTRACT FROM AUTHOR]