They include changes in solar irradiance, greenhouse gases, tropospheric aerosols, and volcanic aerosols.
Not exact matches
Important manifestations of such external forcing from space to the atmosphere are the variations
in different
solar parameters such as the
solar irradiance (
including solar UV) and
solar particle fluxes, which can induce
changes in the atmosphere both at local and global scales, and can influence over a large range of altitudes.
Jo's scientific interests
include radiative transfer
in the atmosphere, climate modelling, radiative forcing of climate
change and the influence of
solar irradiance variability on climate.
Critics of this result might argue that the
solar forcing
in these experiments is only based on the estimated
change in total
irradiance, which might be an underestimate, or that does not
include potential indirect amplifying effects (via an ozone response to UV
changes, or galactic cosmic rays affecting clouds).
[Response: the Milankovitch timescale is long and the forcing barely varies due to orbital
changes over 100 years so no, they aren't
included (they would be for people modelling the last glacial maximum);
solar forcing is modelled by
change in total
solar irradiance (probably as a total number; not sure if
changes at different wavelengths are
included)-- William]
See e.g. this review paper (Schmidt et al, 2004), where the response of a climate model to estimated past
changes in natural forcing due to
solar irradiance variations and explosive volcanic eruptions, is shown to match the spatial pattern of reconstructed temperature
changes during the «Little Ice Age» (which
includes enhanced cooling
in certain regions such as Europe).
Increasing CO2 does increase the greenhouse effect, but there are other factors which determine climate,
including solar irradiance, volcanism, albedo, orbital variations, continental drift, mountain building, variations
in sea currents,
changes in greenhouse gases, even cometary impacts.
When reconstructing Earth's climate history, it can't be explained without
including all the various influences,
including solar irradiance, volcanism, albedo, orbital variations, continental drift, mountain building, variations
in sea currents,
changes in greenhouse gases, even cometary impacts.
Why are «
Changes in solar irradiance»
included?
I have sought the best empirical evidence to show how
changes in incoming
solar radiation, accounted for by intrinsic
solar magnetic modulation of the
irradiance output as well as planetary modulation of the seasonal distribution of sunlight, affects the thermal properties of land and sea,
including temperatures.
As the Director of GISS and Principal Investigator for the GISS ModelE Earth System Model, I am interested
in understanding past, present and future climate and the impacts of multiple drivers of climate
change,
including solar irradiance, atmospheric chemistry, aerosols, and greenhouse gases.
These
include solar - related chemical - based UV
irradiance - related variations
in stratospheric temperatures and galactic cosmic ray - related
changes in cloud cover and surface temperatures, as well as ocean oscillations, such as the Pacific Decadal Oscillation and the North Atlantic Oscillation that significant affect the climate.
In order to reliably interpret surface temperature variations we need a good idea of all the causal factors, including El Niño, solar irradiance, volcanic eruptions, observational biases, changes in ocean circulation and possible long term oscillation
In order to reliably interpret surface temperature variations we need a good idea of all the causal factors,
including El Niño,
solar irradiance, volcanic eruptions, observational biases,
changes in ocean circulation and possible long term oscillation
in ocean circulation and possible long term oscillations.
Although we focus on a hypothesized CR - cloud connection, we note that it is difficult to separate
changes in the CR flux from accompanying variations
in solar irradiance and the
solar wind, for which numerous causal links to climate have also been proposed,
including: the influence of UV spectral
irradiance on stratospheric heating and dynamic stratosphere - troposphere links (Haigh 1996); UV
irradiance and radiative damage to phytoplankton influencing the release of volatile precursor compounds which form sulphate aerosols over ocean environments (Kniveton et al. 2003); an amplification of total
solar irradiance (TSI) variations by the addition of energy
in cloud - free regions enhancing tropospheric circulation features (Meehl et al. 2008; Roy & Haigh 2010); numerous
solar - related influences (
including solar wind inputs) to the properties of the global electric circuit (GEC) and associated microphysical cloud
changes (Tinsley 2008).
There have been numerous research papers and reviews published over the past 10 years,
including several
in prestigious journals such as Nature and Science, that conclude that the observed temperature
changes over the past 100 years are consistent with the combined
changes in atmospheric aerosols (volcanic and anthropogenic), land surface
changes, variations
in solar irradiance and increases
in greenhouse gases.