1998 No. 1
Экран солнца для земли
Sunscreen for Planet EarthGLOBAL WARMING IS TOO SERIOUS TO BE LEFT TO
THE POLITICIANS. HEREWITH A SCIENTIFIC SOLUTION TO THE PROBLEM. (IF THERE IS A PROBLEM, THAT IS.)
Society's emissions of carbon dioxide may or may not turn out to have something significant to do with global warming--the
jury is still out. As a scientist, I must stand silent on this issue until it's resolved scientifically. As a citizen, however,
I can tell you that I'm entertained by the high political theater that the nation's politicians have engaged in over the last
few months. It's wonderful to think that the world is so very wealthy that a single nation--America--can consider spending
$100 billion or so each year to address a problem that may not exist--and that, if it does exist, certainly has unknown dimensions.
This is especially dramatic given that contemporary technology offers considerably more-realistic options for addressing
It's wonderful to think that the world is so very wealthy that a single nation -- America
-- can consider spending $100 billion a year on a problem that may not exist.
any global warming effect than politicians and environmental activists are considering. Some of these may be far less
burdensome than even a system of market-allocated emissions permits. One particularly attractive approach involves diminishing
slightly--by about 1 percent--the amount of sunlight reaching the earth's surface in order to counteract any warming effect
of greenhouse gases.
This is not a new concept and certainly not a complex one. Nature does this routinely: In 1991, the large Philippine
volcano Mount Pinatubo threw
myriad fine particles into the upper atmosphere, where they scattered small fractions of the sun's light and heat back into
space. We already know that the eruption of Mexico's El Chichon a decade earlier induced cooling in the Northern Hemisphere
by about one-quarter as much as the average prediction of the global warming expected by 2100 (assuming no politically imposed
limits on emissions).
In 1979, physicist Freeman Dyson, in his characteristically prescient manner, proposed the deliberate, large-scale introduction
of such fine particles into the upper atmosphere to offset global warming, which he thought even then would eventually become
a human concern. Some of my colleagues and I have recently surveyed the current technological prospects for such an introduction.
We estimated the costs involved and presented our results last August at the Twenty-second International Seminar on Planetary
Emergencies. The most expensive such "geoengineering" option appears to be the one long ago proposed by Mr. Dyson, which may
cost as much as $1 billion a year. More technologically advanced options along the same lines might cost $100 million.
That's between 0.1 and 1.0 percent of the $100 billion a year it is estimated would be required to price-ration fossil
fuel usage back down to 1990 levels in the United States alone. As the National Academy of Sciences commented a few years
ago in a landmark report,
us play to our uniquely American strengths in innovation and technology, offsetting any global warming by the least costly
"Perhaps one of the surprises of this analysis is the relatively low costs at which some of the geoengineering options
might be implemented." Indeed, the director of the U.S. Global Change Research Program's Coordination Office has been promoting
such geoengineering for three decades. But for some reason, this option isn't as fashionable as all-out war on fossil fuels
and the people who use them.
Yet if the politics of global warming require that "something must be done" while we still don't know whether anything
really needs to be done--let alone what exactly--let us play to our uniquely American strengths in innovation and technology
to offset any global warming by the least costly means possible. While scientists continue research into any global climatic
effects of greenhouse gases, we ought to study ways to offset any possible ill effects.
Injecting sunlight-scattering particles into the stratosphere appears to be a promising approach. Why not do that?
Reprinted from the Wall Street Journal, October 17, 1997, from an article titled "The Planet Needs a Sunscreen."
Used with permission. © 1997 Dow Jones & Company, Inc. All rights reserved.
Ames Research Center, Moffett Field, Calif.
University of Colorado, Boulder
March 3, 2005
NASA Study Suggests Giant Space Clouds Iced Earth
Eons ago, giant clouds in space may have led to global extinctions,
according to two recent technical papers supported by NASA's Astrobiology Institute.
One paper outlines a rare scenario
in which Earth iced over during snowball glaciations, after the solar system passed through dense space clouds. In a more
likely scenario, less dense giant molecular clouds may have enabled charged particles to enter Earth's atmosphere, leading
to destruction of much of the planet's protective ozone layer.
This resulted in global extinctions, according to the second paper. Both recently appeared in the Geophysical Research
"Computer models show dramatic climate change can be caused by interstellar dust accumulating in Earth's atmosphere
during the solar system's immersion into a dense space cloud," said Alex Pavlov, principal author of the two papers. He is
a scientist at the University of Colorado, Boulder. The resulting
dust layer hovering over the Earth would absorb and scatter solar radiation, yet allow heat to escape from the planet into
space, causing runaway ice buildup and snowball glaciations.
"There are indications from 600 to 800 million years ago;
at least two of four glaciations were snowball glaciations. The big mystery revolves around how they are triggered," Pavlov
said. He concluded the snowball glaciations covered the entire Earth.
Pavlov said this hypothesis has to be tested
by geologists. They would look at Earth's rocks to find layers that relate to the snowball glaciations to assess whether uranium
235 is present in higher amounts. It cannot be produced naturally on Earth or in the solar system, but it is constantly produced
in space clouds by exploding stars called supernovae.
Sudden, small changes in the uranium 235/238-ratio in rock layers
would be proof interstellar material is present that originated from supernovae. Collisions of the solar system with dense
space clouds are rare, but according to Pavlov’s research, more frequent solar system collisions, with moderately dense
space clouds, can be devastating. He outlined a complex series of events that would result in loss of much of Earth's protective
ozone layer, if the solar system collided with a moderately dense space cloud.
The research outlined a scenario that
begins as Earth passes through a moderately dense space cloud that cannot compress the outer edge of the sun's heliosphere
into a region within the Earth's orbit. The heliosphere is the expanse that begins at the sun's surface and usually reaches
far past the orbits of the planets. Because it remains beyond Earth's orbit, the heliosphere continues to deflect dust particles
away from the planet.
However, because of the large flow of hydrogen from space clouds into the sun's heliosphere,
the sun greatly increases its production of electrically charged cosmic rays from the hydrogen particles. This also increases
the flow of cosmic rays towards Earth. Normally, Earth's magnetic field and ozone layer protect life from cosmic rays and
the sun's dangerous ultraviolet radiation.
Moderately dense space clouds are huge, and the solar system could take
as long as 500,000 years to cross one of them. Once in such a cloud, the Earth would be expected to undergo at least one magnetic
reversal. During a reversal, electrically charged cosmic rays can enter Earth's atmosphere instead of being deflected by the
planet's magnetic field.
Cosmic rays can fly into the atmosphere and break up nitrogen molecules to form nitrogen
oxides. Nitrogen oxide catalysts would set off the destruction of as much as 40 percent of the protective ozone in the planet's
upper atmosphere across the globe and destruction of about 80 percent of the ozone over the polar regions according to Pavlov.
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облака над атмосферой
neptune. Настолько высоко в
они находятся фактическ
в орбите над атмосферой!
These clouds are above
the atmosphere of Neptune. So high in fact that they are actually in orbit over the atmosphere! Remarkable, yes?
|PHOTO IS LINK TO NASA
[PDF] The iris hypothesis: A negative
or positive cloud feedback
B Lin, BA Wielicki, LH Chambers, Y Hu, KM
- View as HTML - Cited by 18 - Web Search
... model) to infer that these tropical UTA clouds could provide a strong
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Journal of Climate,
2002 - clouds.eos.ubc.ca - adsabs.harvard.edu
[PDF] Why is the global warming proceeding much slower than expected
L Bengtsson, E Roeckner, M Stendel - View as HTML - Cited by 29
... BENGTSSON ET AL.: WHY IS THE GLOBAL WARMING SLOWER THAN EXPECTED? ... Doiron, CC Schnetzler,
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Walter, Global tracking of the SO 2 clouds from the ...
J. Geophys. Res, 1999 - glwww.dmi.dk - agu.org - agu.org - adsabs.harvard.edu
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N Marsh, H Svensmark
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... tributed ∼1.4Wm −2 to the observed global warming. These observations provide
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Space Sci. Rev, 2000 - kluweronline.com - dsri.dk - dsri.dk - adsabs.harvard.edu
[PDF] Kyoto’s Unfinished Business
HD Jacoby, RG Prinn, R Schmalensee - View as HTML - Cited by 33 - Web Search
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Affairs, 1998 - dspace.mit.edu - hpds1.mit.edu
Global cooling after the eruption of Mount Pinatubo: A test
of climate feedback by water vapor
BJ Soden, RT Wetherald, GL Stenchikov, A Robock, … - Cached - Cited by 15 - Web Search
... just the longer (decadal to century) time scales associated with global warming. ...
atmospheric general circulation
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2002 - intl.sciencemag.org - gps.caltech.edu - dx.doi.org - adsabs.harvard.edu - all 5 versions »
The connection between tropical thunderstorms, upper tropospheric
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C Price, M Asfur - Web Search
... The amplitude of future global warming will depend strongly on how upper tropospheric
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EGS-AGU-EUG Joint Assembly, Abstracts from the meeting held …, 2003 - adsabs.harvard.edu
[PDF] Near-global survey of effective droplet radii in liquid water clouds using ISCCP
Han, WB Rossow, AA Lacis - View as HTML - Cited by 96 - Web Search
Page 1. VOLUME 7 Near-Global Survey of Effective Droplet Radii in Liquid
Water Clouds Using ISCCP Data 1 . Introduction
A global ...
J. Climate, 1994 - vortex.nsstc.uah.edu - nsstc.uah.edu - atmos.uah.edu - adsabs.harvard.edu - all 5 versions »
[PDF] Cirrus detrainment-temperature feedback
C Chou, JD Neelin
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... Many global warming exper- iments in general circulation models (GCMs) show an in-
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Geophys. Res. Lett, 1999 - ecrc.sinica.edu.tw - atmos.ucla.edu - agu.org - adsabs.harvard.edu - all 5 versions »
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H Masunaga, TY Nakajima, T Nakajima, M Kachi, K … - View as HTML - Cited by 4 - Web Search
... unknown factors. Clouds thus provide the largest uncertainty in predicting
the future climate change such as global
warming. Some of ...
JOURNAL OF GEOPHYSICAL RESEARCH,
2002 - ccsr.u-tokyo.ac.jp - rain.atmos.colostate.edu - rain.atmos.colostate.edu - adsabs.harvard.edu - all 6 versions »
[PDF] How dry is the tropical free troposphere? Implications for global warming theory
Spencer, WD Braswell - View as HTML - Cited by 37 - Web Search
... the magnitude of water vapor feedback and thus the magnitude of global warming. ... microwave
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Meteor. Soc, 1997 - earthscape.org
Potentially complex biosphere responses to transient global
RP Neilson, RJ Drapek -
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... However, increased AET could form more clouds, which could either act as a ... It may
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Global Change Biology, 1998 - blackwell-synergy.com - blackwell-synergy.com - ingenta.com - ingenta.com
[PDF] Water vapor feedback and global warming
IM Held, BJ Soden
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... WATER VAPOR/GLOBAL WARMING 447 T s ... in the atmosphere, including most of those emitted
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Annu. Rev. Energy Environ, 2000 - energy.annualreviews.org - spiderwort.gfdl.noaa.gov - soc.annualreviews.org - gfdl.gov - all 9 versions »
Uncertainties in projections of human-caused climate warming
JD Mahlman - Cited by 46 - Web Search
... warming in the range of 1.5 o to 4.5 o C. These generous uncertainty brackets reflect
remaining limitations in
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1997 - sciencemag.org - intl.sciencemag.org - dx.doi.org - sciencemag.org
[PDF] On the direct effect of clouds and atmospheric particles on the productivity and
structure of …
ML Roderick, GD Farquhar, SL Berry, IR Noble - Cited by 20 - Web Search
... On the direct effect of clouds and atmospheric particles. ... Thus when the solar
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or other atmospheric. 22. Fig. ...
- springerlink.com - as.wvu.edu
Science Now/ October 1995 - Clouds Impact Climate Change Scenarios
... Global cloud cover would provide less cooling than it does now. Clearly,
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www.sirs.com/corporate/newsletters/ snow/snow1095/snow1095.htm - 18k
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... and snow covers, and vegetation, providing high measurement accuracy, spatial
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|Sea Salt Inhibits Global Warming
|Scientists at The University of Manchester
Frequently Asked Questions
National Oceanic and Atmospheric Administration
All figures linked from this page with the exception of global
surface temperatures are from the IPCC 2001 report 'Climate Change 2001: The Scientific Basis'.
Is the hydrological cycle (evaporation and precipitation) changing?
Overall, land precipitation for the globe has increased by ~2%
since 1900, however, precipitation changes have been spatially variable over the last century. Instrumental records show that
there has been a general increase in precipitation of about 0.5-1.0%/decade over land in northern mid-high latitudes, except
in parts of eastern Russia.
However, a decrease of about -0.3%/decade in precipitation has occurred during the 20th century over land in sub-tropical
latitudes, though this trend has weakened in recent decades. Due to the difficulty in measuring precipitation, it has been
important to constrain these observations by analyzing other related variables. The measured changes in precipitation are
consistent with observed changes in streamflow, lake levels, and soil moisture (where data are available and have been analyzed).
Northern Hemisphere annual snow cover extent has consistently remained below average since 1987, and has decreased by about 10% since 1966. This is mostly
due to a decrease in spring and summer snowfall over both the Eurasian and North American continents since the mid-1980s.
However, winter and autumn snow cover extent has shown no significant trend for the northern hemisphere over the same period.
Improved satellite data shows that a general trend of increasing
cloud amount over both land and ocean since the early 1980s, seems to have reversed in the early 1990s, and total cloud amount
of land and ocean now appears to be decreasing. However, there are several studies that suggest regional cloudiness, perhaps
especially in the thick precipitating clouds has increased over the 20th century.
Can the observed changes be explained by natural variability,
including changes in solar output?
Since our entire climate system is fundamentally driven by energy
from the sun, it stands to reason that if the sun's energy output were to change, then so would the climate. Since the advent
of space-borne measurements in the late 1970s, solar output has indeed been shown to vary. There appears to be confirmation
of earlier suggestions of an 11 (and 22) year cycle of irradiance. With only 20 years of reliable measurements however, it
is difficult to deduce a trend. But, from the short record we have so far, the trend in solar irradiance is estimated at ~0.09
W/m2 compared to 0.4 W/m2 from well-mixed greenhouse gases. There are many indications that the sun also has a longer-term
variation which has potentially contributed to the century-scale forcing to a greater degree. There is though, a great deal
of uncertainty in estimates of solar irradiance beyond what can be measured by satellites, and still the contribution of direct
solar irradiance forcing is small compared to the greenhouse gas component. However, our understanding of the indirect effects
of changes in solar output and feedbacks in the climate system is minimal. There is much need to refine our understanding
of key natural forcing mechanisms of the climate, including solar irradiance changes, in order to reduce uncertainty in our
projections of future climate change.
In addition to changes in energy from the sun itself, the Earth's position and
orientation relative to the sun (our orbit) also varies slightly, thereby bringing us closer and further away from the sun
in predictable cycles (called Milankovitch cycles). Variations in these cycles are believed to be the cause of Earth's ice-ages
(glacials). Particularly important for the development of glacials is the radiation receipt at high northern latitudes. Diminishing
radiation at these latitudes during the summer months would have enabled winter snow and ice cover to persist throughout the
year, eventually leading to a permanent snow- or icepack. While Milankovitch cycles have tremendous value as a theory to explain
ice-ages and long-term changes in the climate, they are unlikely to have very much impact on the decade-century timescale.
Over several centuries, it may be possible to observe the effect of these orbital parameters, however for the prediction of
climate change in the 21st century, these changes will be far less important than radiative forcing from greenhouse gases.