Actions without thought or concern for the consequences are the pattern of the day as political agendas trump facts or logic. Consider the dangerous and baseless proposal to offset global warming by adding particulates to the atmosphere. It was in the news as a strategy, albeit a last resort, from a member of the Obama administration.
Unfortunately, last resorts often attain higher priority once considered, especially if blindness about the problem exists and persists. The idea is purely political because it is completely without scientific justification. If done it will trigger severe cooling, including global harvest failures and much more severe weather. It is a much greater threat than warming.
The proposal is in the category of geo-engineering, which I examined in a wider context here.
Even as a last resort the proposal underscores complete lack of knowledge of the science and the consequences of such actions. Simple theory says particulates reduce sunlight reaching the ground, creating a cooler surface and cooler air, because the ground heats the air. Here is a plot of reduction of sunlight caused by four volcanoes.
However, even with limited knowledge we know the actual effects are much more complex. To act without understanding them is a serious abrogation of responsibility. It is even more egregious to do it for political reasons, as is the case with Obama’s administration.
The biggest problem in the world is cooling so to induce more cooling on the basis of a debunked hypothesis will create bigger problems than if warming occurs. Emphasis on only negative aspects of warming have masked the fact cooling is a much greater problem for flora, fauna and humans. There is an historic and natural example of what happens when a singular event exacerbates cooling.
In 1992, we organized a conference in Ottawa Canada to analyze the climate impacts of the Indonesian volcano Tambora. It was the largest eruption in historic times and considered the cause of the history changing record cold year of 1816, known as the ”The Year Without a Summer.”
John Eddy, who put the sunspot issue in the public arena with a 1977 Scientific American article titled “The Case of the Missing Sunspots,” presented the keynote paper.
He identified the cooling associated with the lack of sunspots from 1790 to 1830 known as the Dalton Minimum. This meant global temperatures were falling before volcanic cooling was added in 1815. Clearly the cooling due to the volcanic dust injected into the atmosphere amplified a cooling trend.
Current cooling is expected to approximate cool conditions similar to those between 1790 and 1830.
Adding particulates would exacerbate the cooling and trigger a year like 1816. The impact of that year are well documented in the Ottawa publication, but also in J D Posts’ “The Last Great Subsistence Crisis in the Western World” and Stommel and Stommel’s “Volcano Weather.” Harvest failures alone would be devastating for a world with such limited stockpiles. Consider the impact of biofuels on world food supplies.
There are many other problems with adding more particulates. We know they will cause cooling at the surface, but they also cause warming in the atmosphere. Contrary to popular understanding virtually all numbers used in climate studies are estimates. These determine the amount of sunlight absorbed in the atmosphere at approximately 19%, but this number varies depending on the source. For example, in this diagram of global energy flows it is 22% (78 Wm-2). Absorbing materials are collectively called aerosols and they vary over time. How much they vary is poorly determined yet their effect is very significant especially when compared with the effects of human produced CO2.
The most recent report of the Intergovernmental Panel on Climate Change (IPCC) acknowledges the problem (IPCC AR4 Chapter 2 section 2.4).
There are very few estimates of the actual amount of material in the atmosphere. Mitchell (1973) estimated the total amount of dust, smoke and other particles as approximately 4 x 107 tons (40 million tons). In 1970 Hubert Lamb published an article on volcanic dust in the atmosphere.
From this he evolved a Dust Veil Index (DVI), a quantification of changes in atmospheric composition and its impact on the Earth’s energy balance. It covers eruptions from 1500 to 1983 A.D.
In the early days the word particulates was used to apply specifically to solids in the atmosphere. Then the word aerosol came in to use encompassing the solid particles but also water droplets. This is massively confusing and goes part way to explaining why so little is known and the issue is not fully considered. NASA confirms the problems; Scientists have much to learn about the way aerosols affect regional and global climate. We have yet to accurately quantify the relative impacts on climate of natural aerosols and those of human origin. Moreover, we do not know in what regions of the planet the amount of atmospheric aerosol is increasing, is diminishing, and is remaining roughly constant. Overall, we are even unsure whether aerosols are warming or cooling our planet.
This statement alone should tell the Obama administration not to consider adding particulates even as a last resort. However there is further evidence of the lack of information.
Aerosol effects are generally measured by comparing observations of reflected and transmitted sunlight between satellite sensors and ground sensors. The few observations available produce columnar data, which are then used in models to simulate what they think is happening. The Global Earth Observation and Monitoring GEOMON proposed in 2006 underscores how inadequate the methods and data are. The project is designed as “a first step to build a future integrated pan-European Atmospheric Observing System dealing with systematic observations of long-lived greenhouse gases, reactive gases, aerosols, and stratospheric ozone.”
The strategic objectives of the project summarize the limitations of the information available on atmospheric composition and how it changes through time. One wider question they want to answer is, ”What are the global trends of atmospheric composition from ground-based and satellite observations assimilated in modelling studies, and what key measurements should be added for reducing uncertainties on surface emissions and atmospheric processes?”
Many factors cause climate change, but only a few are considered in the current scientific debate and most are based on estimated or inadequate data. Even fewer factors or data are part of the political debate including how the amount and nature of aerosols in the atmosphere affect the amount of solar energy at the surface and in the atmosphere. The proposal to add particulates to offset warming is the environmental equivalent of adding to the debt to get out of debt, only worse. Despite this politicians demonstrate their lack of knowledge of the science by proposing to play God. Maybe they should wait until there is enough space debris to block the sun and cause cooling.