John Fasullo wrote: «Discussions
of global radiative budgets and their trends without consideration of water vapor (particularly given the title of Palle et al's piece) is wholly simplistic.»
Discussion
of global radiative budgets and their trends without consideration of water vapor (particularly given the title of Palle et al's piece) is wholly simplistic.
The diagnosis
of global radiative feedbacks allows better understanding of the spread of equilibrium climate sensitivity estimates among current GCMs.
As the following graphic shows, the researchers find that roughly 75 percent
of global radiative GHG forcing is attributable to carbon dioxide, while 16.7 percent is attributable to methane, including 8.8 percent attributable to human - caused methane emissions.
Not exact matches
A past study that Kravitz helped run at GeoMIP found that the abrupt termination
of radiative forcing would cause
global warming to effectively speed up to make up for all the time it lost, cramming five decades
of warming into five or 10 years (ClimateWire, Nov. 27).
The researchers [3] quantified China's current contribution to
global «
radiative forcing» (the imbalance,
of human origin,
of our planet's radiation budget), by differentiating between the contributions
of long - life greenhouse gases, the ozone and its precursors, as well as aerosols.
China's stated aim
of improving air quality over the coming years would change this
radiative forcing, leading to a rather counter-intuitive consequence; the increase in China's contribution to
global warming.
They thereby estimated that China contributes an average
of 10 % to current,
global radiative forcing.
Near -
global satellite aerosol data imply a negative
radiative forcing due to stratospheric aerosol changes over this period
of about — 0.1 W / m2, reducing the recent
global warming that would otherwise have occurred.
Using
global climate models and NASA satellite observations
of Earth's energy budget from the last 15 years, the study finds that a warming Earth is able to restore its temperature equilibrium through complex and seemingly paradoxical changes in the atmosphere and the way
radiative heat is transported.
After the field campaign, Fast will perform computer simulations to help evaluate all
of the field campaign data and quantify the uncertainties associated with using coarse grid
global climate models to study megacity emissions and to determine the
radiative impact
of the Mexico City particulates on the local and regional climate.
Sally, who was nominated by Dr. Beat Schmid, Associate Director, Atmospheric Sciences and
Global Change Division, was honored for her exceptional contribution in the field
of atmospheric science, particularly in her efforts to improve understanding
of the
radiative effect
of clouds and aerosols on the Earth's atmosphere and their representation in climate models.
James A. Edmonds • Member, IPCC Steering Committee on «New Integrated Scenarios» (2006 - present) • Lead Author, Working Group III, «Framing Issues,» IPCC Fourth Assessment Report (2007) • Lead Author, Working Group III, «
Global, Regional, and National Costs and Ancillary Benefits
of Mitigation,» IPCC Third Assessment Report (2001) • Lead Author, Working Group III, «Decision - Making Frameworks,» IPCC Third Assessment Report (2001) • Lead Author, Working Group III, Summary for Policy Makers, IPCC Third Assessment Report (2001) • Lead Author, Working Group II, «Energy Supply Mitigation Options,» IPCC Second Assessment Report (1996) • Lead Author, Working Group II, «Mitigation: Cross-Sectoral and Other Issues,» IPCC Second Assessment Report (1996) • Lead Author, Working Group III, «Estimating the Costs
of Mitigating Greenhouse Gases,» IPCC Second Assessment Report (1996) • Lead Author, Working Group III, «A Review
of Mitigation Cost Studies,» IPCC Second Assessment Report (1996) • Lead Author, Working Group III, «Integrated Assessment
of Climate Change: An Overview and Comparison
of Approaches and Results,» IPCC Second Assessment Report (1996) • Lead Author, IPCC Special Report, Climate Change 1994:
Radiative Forcing
of Climate Change and An Evaluation
of the IPCC IS92 Emission Scenarios (1994) • Lead Author, IPCC Special Report, Climate Change 1992: The Supplementary Report to the IPCC Scientific Assessment (1992) • Major contributor, IPCC First Assessment Report, Working Group III, Response Strategies Working Group (1991).
(Top left)
Global annual mean
radiative influences (W m — 2)
of LGM climate change agents, generally feedbacks in glacial - interglacial cycles, but also specified in most Atmosphere - Ocean General Circulation Model (AOGCM) simulations for the LGM.
The mechanism for reducing anthropogenic
global warming, initiated through
radiative forcing
of greenhouse gases, is to stop emissions and reduce their concentration in the atmosphere to levels which do not stimulate carbon feedbacks.
Tsushima, Y., A. Abe - Ouchi, and S. Manabe, 2005:
Radiative damping
of annual variation in
global mean surface temperature: Comparison between observed and simulated feedback.
Greenwald, T.J., G.L. Stephens, S.A. Christopher, and T.H.V. Haar, 1995: Observations
of the
global characteristics and regional
radiative effects
of marine cloud liquid water.
Takemura, T., et al., 2002: Single scattering albedo and
radiative forcing
of various aerosol species with a
global three - dimensional model.
To contribute to an understanding
of the underlying causes
of these changes we compile various environmental records (and model - based interpretations
of some
of them) in order to calculate the direct effect
of various processes on Earth's
radiative budget and, thus, on
global annual mean surface temperature over the last 800,000 years.
The regional climate feedbacks formulation reveals fundamental biases in a widely - used method for diagnosing climate sensitivity, feedbacks and
radiative forcing — the regression
of the
global top -
of - atmosphere radiation flux on
global surface temperature.
Specifically, it refers to the ratio
of the
global temperature change to the
radiative perturbation that causes it (and thus has units
of degrees C per Watts per square meter, for example).
Nevertheless, the results described here provide key evidence
of the reliability
of water vapor feedback predicted by current climate models in response to a
global perturbation in the
radiative energy balance.»
We note, however, that Mount Pinatubo does not provide a perfect proxy for
global warming, because the nature
of the external
radiative forcing obviously differs between the two.
Abstract:» The sensitivity
of global climate with respect to forcing is generally described in terms
of the
global climate feedback — the
global radiative response per degree
of global annual mean surface temperature change.
Ice sheet albedo forcing is estimated to have caused a
global mean forcing
of about — 3.2 W m — 2 (based on a range
of several LGM simulations) and
radiative forcing from increased atmospheric aerosols (primarily dust and vegetation) is estimated to have been about — 1 W m — 2 each.
M2009 use a simplified carbon cycle and climate model to make a large ensemble
of simulations in which principal uncertainties in the carbon cycle,
radiative forcings, and climate response are allowed to vary, thus yielding a probability distribution for
global warming as a function
of time throughout the 21st century.
However,
global mean precipitation is controlled not by the availability
of water vapour, but by a balance between the latent heat
of condensation and
radiative cooling in the troposphere.
As long as the temporal pattern
of variation in aerosol forcing is approximately correct, the need to achieve a reasonable fit to the temporal variation in
global mean temperature and the difference between Northern and Southern Hemisphere temperatures can provide a useful constraint on the net aerosol
radiative forcing (as demonstrated, e.g., by Harvey and Kaufmann, 2002; Stott et al., 2006c).
A clear explanation
of radiative forcing, CO2 infrared opacity and how additional atmospheric CO2 will contribute to significant warming would be important to many
of trying to explain the physics
of global warming.
Some other forcings have a very small
global radiative forcing and yet lead to large impacts (orbital changes for instance) through components
of the climate that aren't included in the default set - up.
Despite your insistence otherwise, you evince at best a shallow understanding
of basic principles
of climate science (hint: while
radiative forcing is known to be at least partially controlled by atmospheric CO2, no «natural», i.e. internal source
of variability has been demonstrated that could drive a
global temperature trend for half a century), as well as an inability to recognize genuine expertise.
Despite the difficulties
of calibration that makes an absolute
radiative imbalance measurement impossible — the anomalies data contains essential information on climate variability that can be used to understand and close out the
global energy budget — changes in which are largely OHC.
While the local, seasonal climate forcing by the Milankovitch cycles is large (
of the order 30 W / m2), the net forcing provided by Milankovitch is close to zero in the
global mean, requiring other
radiative terms (like albedo or greenhouse gas anomalies) to force
global - mean temperature change.
Brown, P. T., W. Li, L. Li, and Y. Ming (2014), Top -
of - atmosphere
radiative contribution to unforced decadal
global temperature variability in climate models, Geophys.
On the possibility
of a changing cloud cover «forcing»
global warming in recent times (assuming we can just ignore the CO2 physics and current literature on feedbacks, since I don't see a contradiction between an internal
radiative forcing and positive feedbacks), one would have to explain a few things, like why the diurnal temperature gradient would decrease with a planet being warmed by decreased albedo... why the stratosphere should cool... why winters should warm faster than summers... essentially the same questions that come with the cosmic ray hypothesis.
But you can still find
radiative explanations
of greenhouse warming (W in, 2W radiated from the interior, W back from the glass, W out, Page 18
of Global Warming by John Houghton, for example).
Gavin disputes that the main driver
of the sea ice retreat is the albedo flip, but we are seeing not only polar amplification
of global warming but positive feedback, which would not be explained simply by
radiative forces and ocean currents.
Because we understand the energy balance
of our Earth, we also know that
global warming is caused by greenhouse gases — which have caused the largest imbalance in the
radiative energy budget over the last century.
Mike's work, like that
of previous award winners, is diverse, and includes pioneering and highly cited work in time series analysis (an elegant use
of Thomson's multitaper spectral analysis approach to detect spatiotemporal oscillations in the climate record and methods for smoothing temporal data), decadal climate variability (the term «Atlantic Multidecadal Oscillation» or «AMO» was coined by Mike in an interview with Science's Richard Kerr about a paper he had published with Tom Delworth
of GFDL showing evidence in both climate model simulations and observational data for a 50 - 70 year oscillation in the climate system; significantly Mike also published work with Kerry Emanuel in 2006 showing that the AMO concept has been overstated as regards its role in 20th century tropical Atlantic SST changes, a finding recently reaffirmed by a study published in Nature), in showing how changes in
radiative forcing from volcanoes can affect ENSO, in examining the role
of solar variations in explaining the pattern
of the Medieval Climate Anomaly and Little Ice Age, the relationship between the climate changes
of past centuries and phenomena such as Atlantic tropical cyclones and
global sea level, and even a bit
of work in atmospheric chemistry (an analysis
of beryllium - 7 measurements).
It actually has something like 100x the
global warming impact (
radiative forcing)
of CO2.
Abstract:» The sensitivity
of global climate with respect to forcing is generally described in terms
of the
global climate feedback — the
global radiative response per degree
of global annual mean surface temperature change.
It's painfully easy to paint oneself logically into a corner by arguing that either (i) vigorous natural variability caused 20th century climate change, but the climate is insensitive to
radiative forcing by greenhouse gases; or (ii) the climate is very sensitive to greenhouse gases, but we still are able to attribute details
of inter-decadal wiggles in the
global mean temperature to a specific forcing cause.
Jain, A.K., et al.,
Radiative forcings and
global warming potentials
of 39 greenhouse gases.
Nature (with hopefully some constructive input from humans) will decide the
global warming question based upon climate sensitivity, net
radiative forcing, and oceanic storage
of heat, not on the type
of multi-decadal time scale variability we are discussing here.
So for example deglaciation warmed
global mean temps by about 5 C over 10k years with a
radiative forcing
of about 6.5 W / m2 (total
of both GHG increases and albedo decreases).
The main changes in
radiative forcing from the precessional cycle are in the latitudinal and seasonal distribution, not in the
global mean, which is why the nature
of the response can be expected to be different from doubling CO2.
Reminds me
of the UK met Office annual predictions, which forecast annual
global temperatures based on atlantic multidecadal oscillation, ENSO, solar, recent volcanic activity and, crucially,
radiative forcing due to GHG.
So, even conservative estimates
of committed warming indicate that we have to urgently reduce
radiative forcing, in other words peak
global GHG emissions as soon as possible and then reduce them as quickly as possible by reducing our use
of fossil fuels drastically, if we want to have a chance at keeping warming under 2C.
Summary for Policymakers Chapter 1: Introduction Chapter 2: Observations: Atmosphere and Surface Chapter 3: Observations: Ocean Chapter 4: Observations: Cryosphere Chapter 5: Information from Paleoclimate Archives Chapter 6: Carbon and Other Biogeochemical Cycles Chapter 7: Clouds and Aerosols Chapter 8: Anthropogenic and Natural
Radiative Forcing Chapter 8 Supplement Chapter 9: Evaluation
of Climate Models Chapter 10: Detection and Attribution
of Climate Change: from
Global to Regional Chapter 11: Near - term Climate Change: Projections and Predictability Chapter 12: Long - term Climate Change: Projections, Commitments and Irreversibility Chapter 13: Sea Level Change Chapter 14: Climate Phenomena and their Relevance for Future Regional Climate Change Chapter 14 Supplement Technical Summary
Because latent heat release in the course
of precipitation must be balanced in the
global mean by infrared
radiative cooling
of the troposphere (over time scales at which the atmosphere is approximately in equilibrium), it is sometimes argued that
radiative constraints limit the rate at which precipitation can increase in response to increasing CO2.