Climate Change Feedback
Climate change feedback refers to the processes that either amplify or dampen the effects of climate change. These feedback mechanisms can either exacerbate or mitigate the impacts of global warming. For example, as temperatures rise, the melting of ice caps reduces the Earth's albedo, leading to further warming—a positive feedback loop. Understanding these feedbacks is crucial for predicting and addressing the consequences of climate change.
5 Key excerpts on "Climate Change Feedback"
eBook - ePub- Brian Dawson, Matt Spannagle(Authors)
- 2008(Publication Date)
- Routledge(Publisher)
...Climate Change FeedbackS Climate Change Feedbacks refers to global warming - induced changes to the earth’s natural climate regulation mechanisms that either amplify (positive feedback effects) or subdue (negative feedback effects) the rate of warming. Climate Change Feedbacks can manifest themselves through two principal means: changing the quantity of greenhouse gases residing in the atmosphere, through increasing (or reducing) emissions from natural sources (such as increased emissions of greenhouse gases from the thawing permafrost) or through altering the natural rate of removal of gases from the atmosphere (such as reducing the uptake of carbon dioxide by the land and oceans), or varying the amount of warming associated with a given atmospheric concentration of greenhouse gases through such mechanisms as changing the earth’s albedo (the amount of incoming solar energy reflected back into space), the amount of cloud cover, or several other mechanisms. While positive and negative feedback mechanisms are generally associated with natural processes, Climate Change Feedbacks can be expanded to include human-induced activities that may accelerate or reduce warming rates. For example, the increase in airborne particulate and sulphur emissions associated with fossil fuel consumption have had a net cooling effect on the planet and have kept global temperature increases below what would have occurred in their absence (see global dimming and aerosols). Projections of mean global temperature change over the course of this century and beyond are based largely on expected values of climate sensitivity (the amount of warming associated with a given concentration of greenhouse gases in the atmosphere) and estimates of future anthropogenic greenhouse gas emissions (see future emissions trends and stabilization targets)...
eBook - ePubApplied Climatology
Principles and Practice
- Allen Perry, Dr Russell Thompson, Russell Thompson(Authors)
- 2013(Publication Date)
- Routledge(Publisher)
...Such alterations in forcings are modified by feedback effects within the climate system.A feedback occurs when a portion of the output from the action of a system is added to the input and subsequently alters the output. The result can be either an amplification of the process (a positive feedback) or a dampening of the original disturbance (a negative feedback). These feedback effects can be simply illustrated. Someone slightly overweight who eats for consolation can become depressed by their increased food intake and so eat more and rapidly become enmeshed in a detrimental positive feedback effect. On the other hand, perception of a different kind can be used to illustrate negative feedback. As a city grows there is a tendency for immigration but the additional influx of industry, cars and people is often detrimental to the environment so that it may be offset by an outflux of wealthier inhabitants, with a potentially detrimental impact on the economy.The ice-albedo feedback is often used to illustrate how a perturbation can be modified in the climate system. If something acts to decrease the global surface temperature, then the formation of additional areas of snow and ice is likely. These cryospheric elements are bright and white, reflecting almost all the solar radiation incident upon them. Their albedo (ratio of reflected to incident radiation) is high and, therefore, the surface albedo, and probably the planetary albedo (the reflectivity of the whole atmosphere plus surface system as seen from ‘outside’ the planet), increases. Thus a greater amount of solar radiation is reflected away from the planet and temperatures decrease further. A further increase in snow and ice results from this decreased temperature and the process continues. This (positive) ice-albedo feedback mechanism is, of course, also positive if the initial perturbation causes an increase in global surface temperatures...
eBook - ePub- Roger G. Barry, Richard J Chorley(Authors)
- 2009(Publication Date)
- Routledge(Publisher)
...The most important are changes in water vapor and albedo (mentioned above). Both can operate over timescales of days and even less. Cloud cover can also change very quickly (hours). Examples of slow feedbacks are changes in the extent of continental ice sheets (influencing planetary albedo) and greenhouse gases during the Pleistocene in response to Milankovich periodicities. Records from ice cores show that these glacialinterglacial cycles were nearly coincident with fluctuations in both atmospheric carbon dioxide (±50ppm) and methane (±150ppb). The nature of these trace gas feedbacks remains incompletely resolved. Potential mechanisms include changes in ocean chemistry, increased plankton growth acting to sequester carbon dioxide, suppression of air–sea gas exchange by sea ice, changes in ocean temperature that affect the solubility of carbon dioxide, and altered ocean circulation. Most likely a suite of processes worked in concert. Negative (positive) excursions in greenhouse gas concentrations are associated with cold (warm) intervals, as illustrated in Figure 2.6. 3 Climate response How much does the global mean surface temperature change in response to a radiative forcing of a given magnitude? How long does it take for the change to occur? These are among the most important, pressing questions in climate change science. The first question deals with the issue of equilibrium climate sensitivity. In the IPCC framework, equilibrium climate sensitivity is the equilibrium change in annual mean global averaged surface air temperature following a doubling of the atmospheric equivalent carbon dioxide. Doubling the carbon dioxide concentration equates to a radiative forcing (top of atmosphere radiation imbalance) of about 4W m -2. In response to this doubling the surface and atmosphere would warm up. Eventually, radiative balance would be restored again with a new and higher surface temperature...
eBook - ePubEngaging with Climate Change
Psychoanalytic and Interdisciplinary Perspectives
- Sally Weintrobe, Sally Weintrobe(Authors)
- 2012(Publication Date)
- Routledge(Publisher)
...Earth system sensitivity is defined as the long-term equilibrium surface temperature change given an increase in CO 2, including all Earth system feedbacks, but neglecting processes associated with the carbon cycle (Lunt et al. 2010). Recent estimates using palaeoclimate data suggest that Earth system sensitivity is around 30% to over 100% higher than Climate sensitivity. However, one important caveat remains: it is not always possible to isolate the temperature response to changes in CO 2 as variations in other forcings often occur at the same time. Additionally, during past glaciations the climate was colder than it is now, and the feedbacks partly responsible for this were probably also different (Schneider von Deimling et al. 2006). Future climate change at the local or regional scale – problems with modelling The pattern and extent of future warming has enormously important policy implications for governments and business, and the methodology employed to understand and predict future climate change is to construct computer models that model the evolution and dynamics of the climate system. These are called general circulation models and were originally designed for short-term weather forecasting. For understanding climate change, global climate models were developed to include atmospheric and oceanic processes and the influence of land-use change, vegetation and ice sheets, and these models have been further extended to form Earth system models. These contain sub-models within them to describe the operation of carbon fluxes and other processes. The models are constructed on a grid structure so that the Earth’s surface is covered by a grid with spacing of around 1° of latitude and longitude and 20 to 40 atmosphere layers...
eBook - ePubBankrupting Nature
Denying Our Planetary Boundaries
- Anders Wijkman, Johan Rockström(Authors)
- 2013(Publication Date)
- Routledge(Publisher)
...10 The greenhouse effect Climate has undergone major changes in Earth’s history. Some of these changes have been sudden and overwhelming, as with the cooling that occurred more than 60 million years ago, leading to the extinction of the great reptiles. The probable cause was that Earth was hit by an asteroid that stirred up large amounts of dust and blocked the sunlight. Major volcanic eruptions have been among the other causes of sudden changes in climate. The Earth was warmest immediately after the birth of the planet. The atmosphere then contained large amounts of carbon, which meant that some of the energy radiated into the Earth was trapped as heat – what is called the greenhouse effect. As green vegetation evolved and began to use the carbon dioxide (CO 2) as a building material, the greenhouse effect was reduced. Changes in climate over long periods of time, especially when the Earth oscillates between glacial and temperate conditions, depend on several factors: the movement of continental plates, changes in the Earth’s orbit or the tilt of the Earth’s axis towards the sun, as well as variations in the strength of radiated energy from the sun. Various feedback mechanisms in nature, such as changes in the distribution of ice and snow on the planet, also have a great impact on changes in climate. Climate is a complex system where many factors are continuously interacting. The past two to three million years of Earth’s history have been characterized by fluctuations between ice ages and warmer periods. The difference between a glacial and temperate condition is like night and day. An ice sheet several kilometres thick covered parts of the northern hemisphere as recently as ten thousand years ago. The prospects for human societies in those latitudes were then nil...
