So Dear Leader Knows Someone Could Guess What's Coming

Just like a picture of a hurricane in the Gulf of Mexico provided by an NOAA satellite (which the Bush administration wants to cut funding for, and Republicans want to make it so a private corporation charges you for, even though you've already paid for it), so scientists across the world have been trying to alert us to the radical changes the uncontrolled burning of fossil fuels produces worldwide.

For your consideration, an example, greatly condensed and hopefully easy enough to understand:

Modern Global Climate Change
Thomas R. Karl and Kevin E. Trenberth
Science 5 December 2003; 302: 1719-1723 [DOI: 10.1126/science.1090228]

Modern climate change is dominated by human in•uences, which are now large enough to exceed the bounds of natural variability. The main source of global climate change is human-induced changes in atmospheric composition. These perturbations primarily result from emissions associated with energy use, but on local and regional scales, urbanization and land use changes are also important. Although there has been progress in monitoring and understanding climate change, there remain many scienti•c, technical, and institutional impediments to precisely planning for, adapting to, and mitigating the effects of climate change. There is still considerable uncertainty about the rates of change that can be expected, but it is clear that these changes will be increasingly manifested in important and tangible ways, such as changes in extremes of temperature and precipitation, decreases in seasonal and perennial snow and ice extent, and sea level rise. Anthropogenic climate change is now likely to continue for many centuries. We are venturing into the unknown with climate, and its associated impacts could be quite disruptive.

...Planet Earth is habitable because of its location relative to the sun and because of the natural greenhouse effect of its atmosphere. Various atmospheric gases contribute to the greenhouse effect, whose impact in clear skies is ~60% from water vapor, ~25% from carbon dioxide, ~8% from ozone, and the rest from trace gases including methane and nitrous oxide (1). Clouds also have a greenhouse effect. On average, the energy from the sun received at the top of the Earth’s atmosphere amounts to 175 petawatts (PW) (or 175 quadrillion watts), of which ~31% is reflected by clouds and from the surface. The rest (120 PW) is absorbed by the atmosphere, land, or ocean and ultimately emitted back space as infrared radiation (1). Over the century, infrequent volcanic eruptions gases and debris into the atmosphere have significantly perturbed these energy flows; however, the resulting cooling has lasted for a few years (2). Inferred changes in total irradiance appear to have increased mean temperatures by perhaps as much as 0.2°C in the first half of the 20th century, but measured changes in the past 25 years have been small (2). Over the past 50 years, human influences have been the dominant detectable influence on climate change (2). The following briefly describes the human influences climate, the resulting temperature and precipitation changes, the time scale of responses, some important processes involved, the development of climate models for assessing the past or making projections into the future, and the need for better observational and information systems.

The main way in which humans alter global climate is by interference with the natural flows of energy through changes in atmospheric composition, not by the actual generation of heat in energy usage. On a global scale, even a 1% change in the energy flows, which is the order of the estimated change to date (2), dominates all other direct influences humans have on climate. For example, an energy output of just one PW is equivalent to that of a million power stations of 1000-MW capacity, among the largest in the world. Total human energy use is about a factor of 9000 less than the natural flow (3).

Global changes in atmospheric composition occur from anthropogenic emissions of greenhouse gases, such as carbon dioxide that results from the burning of fossil fuels and methane and nitrous oxide from multiple human activities. Because these gases have long (decades to centuries) atmospheric lifetimes, the result is an accumulation in the atmosphere and a buildup in concentrations that are clearly shown both by instrumental observations of air samples since 1958 and in bubbles of air trapped in ice cores before then. Moreover, these gases are well distributed in the atmosphere across the globe, simplifying a global monitoring strategy. Carbon dioxide has increased 31% since preindustrial times, from 280 parts per million by volume (ppmv) to more than 370 ppmv today, and half of the increase has been since 1965 (4) (Fig. 1). The greenhouse gases trap outgoing radiation from the Earth to space, creating a warming of the planet.

Fig. 1. Time series of departures from the 1961 to 1990 base period for an annual mean global temperature of 14.0°C (bars) and for a carbon dioxide mean of 334 ppmv (solid curve) during the base period, using data fromice cores and (after 1958) from Mauna Loa (4). The global average surface heating approximates that of carbon dioxide increases, because of the cancellation of aerosols and other greenhouse gas effects, but this does not apply regionally (2). Many other factors (such as the effects of volcanic eruptions and solar irradiance changes) are also important.


...There is no doubt that the composition of the atmosphere is changing because of human activities, and today greenhouse gases are the largest human influence on global climate (2). Recent greenhouse gas emission trends in the United States are upward (11), as are global emissions trends, with increases between 0.5 and 1% per year over the past few decades (12). Concentrations of both reflective and nonreflective aerosols are also estimated to be increasing (2). Because radiative forcing from greenhouse gases dominates over the net cooling forcings from aerosols (2), the popular term for the human influence on global climate is “global warming,” although it really means global heating, of which the observed global temperature increase is only one consequence (13) (Fig. 1). Already it is estimated that the Earth’s climate has exceeded the bounds of natural variability (2), and this has been the case since about 1980...

...There is considerable uncertainty as to exactly how anthropogenic global heating will affect the climate system, how long it will last, and how large the effects will be. Climate has varied naturally in the past, but today’s circumstances are unique because of human influences on atmospheric composition. As we progress into the future, the magnitude of the present anthropogenic change will become overwhelmingly large compared to that of natural changes. In the absence of climate mitigation policies, the 90% probability interval for warming from 1990 to 2100 is 1.7° to 4.9°C (19). About half of this range is due to uncertainty in future emissions and about half is due to uncertainties in climate models (2, 19), especially in their sensitivity to forcings that are complicated by feedbacks, discussed below, and in their rate of heat uptake by the oceans (20). Even with these uncertainties, the likely outcome is more frequent heat waves, droughts, extreme precipitation events, and related impacts (such as wild fires, heat stress, vegetation changes, and sea level rise) that will be regionally dependent. ....

...Our understanding of the climate system is complicated by feedbacks that either amplify or damp perturbations, the most important of which involve water in various phases. As temperatures increase, the water-holding capacity of the atmosphere increases along with water vapor amounts, producing water vapor feedback. As water vapor is a strong greenhouse gas, this diminishes the loss of energy through infrared radiation to space. Currently, water vapor feedback is estimated to contribute a radiative effect from one to two times the size of the direct effect of increases in anthropogenic greenhouse gases (24, 25). Precipitation-runoff feedbacks occur because more intense rains run off at the expense of soil moisture, and warming promotes rain rather than snow. These changes in turn alter the partitioning of solar radiation into sensible versus latent heating (14). Heat storage feedbacks include the rate at which the oceans take up heat and the currents redistribute and release it back into the atmosphere at variable later times and different locations...

Here I skip some fairly technical material and a figure regarding how as temperatures and the associated water holding capacity of the atmosphere (15) increase, more precipitation falls in heavy (more than 40 mm/day) to extreme (more than 100 mm/day) daily amounts.

In other words, as a climate gets hotter, it rains heavier.

Fig. 3. Components of the climate system and the interactions among them, including the human component. All these components have to be modeled as a coupled system that includes the oceans, atmosphere, land, cryosphere, and biosphere. GCM, General Circulation Model.



...Ensembles of model predictions have to be run to generate probabilities and address the chaotic aspects of weather and climate. This can be addressed in principle with adequate computing power, a challenge in itself. However, improving models to a point where they are more reliable and have sufficient resolution to be properly able to represent known important processes also requires the right observations, understanding, and insights (brain power). Global climate models will need to better integrate the biological, chemical, and physical components of the Earth system (Fig. 3). Even more challenging is the seamless flow of data and information among observing systems, Earth system models, socioeconomic models, and models that address managed and unmanaged ecosystems. Progress here is dependent on overcoming not only scientific and technical issues but also major institutional and international obstacles related to the free flow of climate-related data and information. In large part, reduction in uncertainty about future climate change will be driven by studies of climate change assessment and attribution. Along with climate model simulations of past climates, this requires comprehensive and long-term climate-related data sets and observing systems that deliver data free of time-dependent biases. These observations would ensure that model simulations are evaluated on the basis of actual changes in the climate system and not on artifacts of changes in observing system technology or analysis methods (34). The recent controversy regarding the effects that changes in observing systems have had on the rate of surface versus tropospheric warming (35, 36) highlights this issue. Global monitoring through space-based and surface-based systems is an international matter, much like global climate change. There are encouraging signs, such as the adoption in 1999 of a set of climate monitoring principles (37), but these principles are impotent without implementation. International implementation of these principles is spotty at best (38). We are entering the unknown with our climate. We need a global climate observing system, but only parts of it exist. We must not only take the vital signs of the planet but also assess why they are fluctuating and changing. Consequently, the system must embrace comprehensive analysis and assessment as integral components on an ongoing basis, as well as innovative research to better interpret results and improve our diagnostic capabilities. Projections into the future are part of such activity, and all aspects of an Earth information system feed into planning for the future, whether by planned adaptation or mitigation. Climate change is truly a global issue, one that may prove to be humanity’s greatest challenge. It is very unlikely to be adequately addressed without greatly improved international cooperation and action.

References and Notes
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4. Atmospheric CO2 concentrations fromair samples and from ice cores are available at http://cdiac.esd.ornl.gov/trends/co2/sio-mlo.htm and http://cdiac.esd.ornl.gov/trends/co2/siple.htm, respectively.
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37. The climate principles were adopted by the Subsidiary Body on Science, Technology and Assessment of the United Nations Framework Convention on Climate Change (UNFCCC).
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39. We thank A. Leetmaa, J. Hurrell, J. Mahlman, and R. Cicerone for helpful comments, and J. Enloe for providing the calculations for Fig. 2. This article reflects the views of the authors and does not reflect government policy. The National Climatic Data Center is part of NOAA’s Satellite and Information Services. The National Center for Atmospheric Research is sponsored by the NSF.
Web Resources
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