The flow of energy through the climate system is described along with its perturbations arising from human-induced climate change. The role of the atmosphere, oceans, land, and ice components of the climate system are detailed along with the hydrological cycle and interactions that give rise to large variability, such as the El Niño phenomenon. The mass and specific heat of the main components play a major role in storing and moving heat and energy around. The main cause of climate change is the changes in composition of the atmosphere and the enhanced greenhouse effect from increasing carbon dioxide and other greenhouse gases, offset somewhat by pollution. A simple mathematical model is introduced to demonstrate how global temperatures arise and the greenhouse effect works. The Earth Energy Imbalance and thus the extra heat has profound influences, including increasing the global mean surface temperature.
A detailed analysis has been made of a quasi-biennial oscillation (QBO) in the tropospheric ultralong waves of the Southern Hemisphere and interrelationships with the QBO in zonal mean westerly winds of the equatorial stratosphere. In spite of the fact that highly significant spectral peaks at a period close to 26 months occur in both phenomena, results of cross-spectral analysis reveal that the two QBO's are unrelated. The manner in which these QBO's relate to a recently discovered QBO in the 500 mb zonal mean westerly winds throughout the Southern Hemisphere is also considered.
No abstract is provided for this article.
Internal climate variability masks climate-warming trends
Earth’s energy imbalance is associated with the forcings of the climate system and how it responds, including all of the feedbacks. EEI is actually the net outcome, but climate models facilitate the understanding of the actual flows of energy through the climate system and in turn are a key step toward estimating the consequences. Hence, climate models are extensively used to encapsulate the knowledge and understanding of the climate system and how it works, and for making projections of the future. However, as noted in Chapter 1, the models are not perfect and involve approximations and assumptions. The IPCC approach has been very democratic in that all models have been treated equally even though some models have been shown to contain substantial errors. It makes sense to use only the models that perform well. Of course, all models contain errors, but some models actually violate physical principles, such as conservation of mass or energy, and these should not be used. Certainly, some models are a lot better than others.
No abstract is provided for this article.
The problem of global warming arises from the buildup of greenhouse gases such as carbon dioxide from burning of fossil fuels and other human activities that change the composition of the atmosphere and alter outgoing longwave radiation (OLR). One geoengineering solution being proposed is to reduce the incoming sunshine by emulating a volcanic eruption. In between the incoming solar radiation and the OLR is the entire weather and climate system and the hydrological cycle. The precipitation and streamflow records from 1950 to 2004 are examined for the effects of volcanic eruptions from El Chichón in March 1982 and Pinatubo in June 1991, taking into account changes from El Niño‐Southern Oscillation. Following the eruption of Mount Pinatubo in June 1991 there was a substantial decrease in precipitation over land and a record decrease in runoff and river discharge into the ocean from October 1991–September 1992. The results suggest that major adverse effects, including drought, could arise from geoengineering solutions.
There is compelling evidence that the climate is changing, for whatever reason. We discuss the degree, nature, and cause of the climate variations and whether there is in fact a change, but the only way to resolve the issue is with solid information. This requires improved global observations of the state variables and the variables causing change (the forcings), the means to process these and understand them, and the ability to set them in a coherent physical (as well as chemical and biological) framework with models for diagnostic and prognostic purposes. Meanwhile, the information that helps settle these arguments and reduces uncertainties is also extremely valuable for many other purposes, including a myriad of practical applications for business, industry, government, and the general public. The following is a list of strategic requirements necessary for a comprehensive climate observing system: Climate observations from both space-based and in situ platforms are taken in ways that address climate needs and adhere to the 10 principles outlined by the NRC. The international framework for sharing data is vital. A global telecommunications and satellite ground systems network and satellite data telemetry capacity to enable data and products from all observing platforms to be disseminated. A climate observations analysis and tracking capability that produces global and regional analyses of various products for the atmosphere, oceans, land surface and hydrology, and the cryosphere. Four-dimensional data assimilation and reanalysis capabilities that process the multivariate data in a physically consistent framework to enable production of the analyses, not just for the atmosphere, but also for the oceans, land surface, and cryosphere. Global climate models that encompass all parts of the climate system and that are utilized in data assimilation and in making ensemble predictions originating from the initial observed state. A climate observation oversight and observing system monitoring capability that tracks the performance of the observations, the gathering of the data, and the processing systems. This must also include the resources and influence to fix problems and the capability to communicate climate requirements when observational systems are being discussed and established, such as for weather purposes or in establishing requirements for instruments on satellites. Although much has been learned about climate from past and present observing systems, we do not have an adequate climate observing system at present. Instead, we make do with an eclectic mix of observations mostly taken for other purposes. Nor are they adequately synthesized. Hence, in addition to making new observations, there is a strong rationale for building the system, and incorporating the management principles described here.
The marked increase in land-falling hurricanes in Florida and Japan in 2004 has raised questions about whether global warming is playing a role. In his Perspective, Trenberth explains that the observational hurricane record reveals large natural variability from El NiA±o and on multidecadal time scales, and that trends are therefore relatively small. However, sea surface temperatures are rising and atmospheric water vapor is increasing. These factors are potentially enhancing tropical convection, including thunderstorms, and the development of tropical storms. These changes are expected to increase hurricane intensity and rainfall, but the effect on hurricane numbers and tracks remains unclear.
The primary driver of the climate system is the uneven distribution of incoming and outgoing radiation on earth. The incoming radiant energy is transformed into various forms (internal heat, potential energy, latent energy, and kinetic energy), moved around in various ways primarily by the atmosphere and oceans, stored and sequestered in the ocean, land, and ice components of the climate system, and ultimately radiated back to space as infrared radiation. The requirement for an equilibrium climate mandates a balance between the incoming and outgoing radiation, and further mandates that the flows of energy are systematic. These drive the weather systems in the atmosphere, currents in the ocean, and fundamentally determine the climate. Values are provided for the seasonal uptake and release of heat by the oceans that substantially moderate the climate in maritime regions. In the atmosphere, the poleward transports are brought about mainly by large‐scale overturning, including the Hadley circulation in low latitudes, and baroclinic storms in the extratropics, but the seamless nature of the transports on about monthly time‐scales indicates a fundamental link between the two rather different mechanisms. The flows of energy can be perturbed, causing climate change. This article provides an overview of the flows of energy, its transformations, transports, uptake, storage and release, and the processes involved. The focus is on the region 60°N to 60°S, and results are presented for the solstitial seasons and their differences to highlight the annual cycle. Challenges in better determining the surface heat balance and its changes with time are discussed. Copyright © 2004 Royal Meteorological Society
Where has the energy from global warming gone?
No abstract is provided for this article.
The purpose of this paper is to put forward a new estimate, in the context of previous assessments, of the annual global mean energy budget. A description is provided of the source of each component to this budget. The top-of-atmosphere shortwave and longwave flux of energy is constrained by satellite observations. Partitioning of the radiative energy throughout the atmosphere is achieved through the use of detailed radiation models for both the longwave and shortwave spectral regions. Spectral features of shortwave and longwave fluxes at both the top and surface of the earth's system are presented. The longwave radiative forcing of the climate system for both clear (125 W m−2) and cloudy (155 W m−2) conditions are discussed. The authors find that for the clear sky case the contribution due to water vapor to the total longwave radiative forcing is 75 W m−2, while for carbon dioxide it is 32 W m−2. Clouds alter these values, and the effects of clouds on both the longwave and shortwave budget are addressed. In particular, the shielding effect by clouds on absorption and emission by water vapor is as large as the direct cloud forcing. Because the net surface heat budget must balance, the radiative fluxes constrain the sum of the sensible and latent heat fluxes, which can also be estimated independently.
The 1988 summer drought in the United States was the most extensive in many years. Because the drought developed in different places at different times, not all regional effects can be traced to the same cause. Along the West Coast and in the northwestern United States drought conditions developed during 1987 in association with the 1986 to 1987 El Niño in the tropical Pacific Ocean. Record low rainfalls from April to June 1988 led to rapid development of drought in the North Central United States. Strong anticyclonic conditions and a northward displaced jet stream in the upper atmosphere over North America throughout this period were only part of pronounced and distinctive wavetrain of anomalies in the atmospheric circulation that appeared to emanate from the tropical Pacific. Below average sea surface temperatures along the equator in the Pacific in the northern spring of 1988, combined with warmer than normal water from 10 degrees to 20 degrees N, led to a northward displaced but still active intertropical convergence zone (ITCZ) southeast of Hawaii. Results from a steady-state planetarywave atmospheric model indicate that the atmospheric heating anomalies associated with the displaced ITCZ can force an anomalous wavetrain across North America similar to that observed. Land surface processes probably contributed to the severity and persistence of the drought; however, the large-scale atmospheric circulation perturbations associated with natural variations in the coupled atmosphere-ocean system in the tropical Pacific were most likely the primary cause.
The oceans are wet, and play a major role in the hydrological cycle. They also have a high heat capacity. Section 6.2 provided the basic character of sea water and ocean structure. Figures 5.2 and 5.3 presented maps and the annual cycle of the mean surface air temperatures, and Fig. 5.4 gave the sea surface temperatures (SSTs). The latter are closely related to water vapor and precipitation in the atmosphere over the oceans. The SSTs are supported by the upper ocean temperatures and especially the mixed layer, which is the part of the ocean in direct contact with the surface through wind effects and heating from both radiation and temperatures in the atmosphere (see Fig. 8.8).
The extent to which mass is conserved in European Centre for Medium Range Weather Forecasts (ECMWF) analyses archived on pressure surfaces is examined from two perspectives and with two different datasets. The data used come from the WMO archive of 7-level, twice daily initialized analyses and from the WCRP archive of 14-level, four-times daily uninitialized analyses. The first perspective, which considers the equation of continuity in pressure coordinates locally in three dimensions, reveals spurious residuals in the equation of up to 100% of the size of the divergence term, with largest errors of 60% to 100% in the tropics. In this case the horizontal velocity and vertical p-velodty (ω) fields are checked for consistency. Modest improvements occur when 14 versus 7 levels are used. The second perspective considers the vertical integral in which the surface pressure tendency should balance the total mass convergence into a column, and thus does not involve the omega fields. The latter reveals that the dominant residual is due to the failure to resolve the semidiurnal tide with only twice-daily data, so that a large-scale wavenumber 2 pattern with maxima in the tropics results as a residual. However, there are also many smaller scale and smaller amplitude features in the residual that cannot be explained simply. The residuals from the uninitialized analyses are much larger so that while four-times daily data removes much of the wavenumber 2 semidiurnal tide structure, the total residuals are just as large as with the twice-daily initialized data. Improvements in using 14 levels versus 7 are marginal for the vertical integral. The moisture budget, which is an important part of the overall mass budget, produces plausible estimates of vertically integrated evaporation minus precipitation, but needs to be validated. The primary source of the mass imbalance arises from the methods of postprocessing the variables onto pressure surfaces. Because sophisticated four-dimensional data assimilation now performs analyses of fields on model (sigma) surfaces, the postprocessing performs interpolations (using splines under tension) from model coordinates to pressure coordinates, with the result that the archived variables are really representative of individual levels rather than finite-sized layers. The implications are that residuals computed in other budgets, such as diabatic heating from the thermodynamic equation, will also include large errors, most of which will, however, be systematic. The effects of several common approximations in the treatment of the lower boundary on mass conservation are examined, and proper accounting for the full variations in both space and time of surface pressure on vertical mass integrals lead to the computation of kinematic orographic forcing from the analyses as a residual. The diagnosed lower boundary-induced vertical motions are weak and do not reveal the strong dipole patterns normally expected, which may indicate that the planetary waves are not adequately forced in the forecast model used in the four-dimensional data assimilation.
