HOOVER INSTITUTION

HOOVER DIGEST
1998 No. 1



EDWARD TELLER

Экран солнца для земли планеты

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

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,

"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.

Эти облака над атмосферой neptune. Настолько высоко в действительности что они находятся фактическ в орбите над атмосферой! Замечательно, да?

These clouds are above the atmosphere of Neptune.  So high in fact that they are actually in orbit over the atmosphere!  Remarkable, yes?

Frequently Asked Questions

National Oceanic and Atmospheric Administration

Global Warming

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.