The Most Important Thing You Will Read Today – The Clearest Statement on Climate Science From the Most Definitive Source

Seth Kaplan


You just can’t find a more solid, conservative, reliable and grounded group than the American Geophysical Union.  Since 1919 the AGU has been the hub of the physical sciences in the United States providing a gathering place and information exchange for earth, air and space scientists and then communicating carefully reviewed scientific information to the public and decision-makers in government, business and throughout society.

When a group like the AGU speaks through an official statement you know that every word of the statement has been scrutinized and carefully chosen to communicate important ideas and complex climate science as accurately as possible. The process of creating these statements involves hours, days, weeks and years of meetings, reviews, re-reviews and painstaking scrutiny.

This means when that when the AGU issues (as it did in 2003) and then updates (as it did again last week) its official position statement on a subject like global warming, attention should be paid. The latest version of that statement can be downloaded in PDF form from the AGU website and is “pasted” below in its entirety.

The calm and carefully chosen words of the AGU should reinforce a critical realization that immediate and dramatic action is needed to reduce our greenhouse gas emissions immediately. By becoming much more efficient in our use of energy and dramatically reducing the amount of fossil fuels that we burn, we can reduce greenhouse gas emissions.  Meeting these goals will require developing dense and sustainable cities where most trips can be made on foot and convenient and affordable public transit plays a strong and supporting role as well as technological shifts to highly efficient buildings powered by renewable energy like wind and solar power.  The AGU also reminds us that even if we slash our greenhouse gas emissions very sharply and immediately we must deal with the implications of the emissions of the past and the warming that is already baked into the system, warming that is bringing us rising sea levels and extreme and disrupted weather.

The call to action that the scientists of the AGU is sounding is being heard here in New England – laws like the renewable energy and energy efficiency standards are on the books in part because of this fundamental challenge.  This legislative response to climate science is even more obvious in the case of laws specifically requiring emissions reductions – like the Massachusetts Global Warming Solutions Act.  But passing laws is only one in a series of needed steps forward.

Translating the law into regulations (as the Massachusetts Department of Environmental Protection just refused to do when pressed by a remarkable group of kids) and then action, actually delivering on the promise of reduced pollution emissions, will not be easy.  But we really don’t have a choice . . .


Human-induced climate change requires urgent action.

Humanity is the major influence on the global climate change observed over the past 50 years.

Rapid societal responses can significantly lessen negative outcomes.

“Human activities are changing Earth’s climate. At the global level, atmospheric concentrations of carbon dioxide and other heat-trapping greenhouse gases have increased sharply since the Industrial Revolution. Fossil fuel burning dominates this increase. Human-caused increases in greenhouse gases are responsible for most of the observed global average surface warming of roughly 0.8°C (1.5°F) over the past 140 years. Because natural processes cannot quickly remove some of these gases (notably carbon dioxide) from the atmosphere, our past, present, and future emissions will influence the climate system for millennia.

Extensive, independent observations confirm the reality of global warming. These observations show large-scale increases in air and sea temperatures, sea level, and atmospheric water vapor; they document decreases in the extent of mountain glaciers, snow cover, permafrost, and Arctic sea ice. These changes are broadly consistent with long-understood physics and predictions of how the climate system is expected to respond to human-caused increases in greenhouse gases. The changes are inconsistent with explanations of climate change that rely on known natural influences.

Climate models predict that global temperatures will continue to rise, with the amount of warming primarily determined by the level of emissions. Higher emissions of greenhouse gases will lead to larger warming, and greater risks to society and ecosystems. Some additional warming is unavoidable due to past emissions.

Climate change is not expected to be uniform over space or time. Deforestation, urbanization, and particulate pollution can have complex geographical, seasonal, and longer-term effects on temperature, precipitation, and cloud properties. In addition, human-induced climate change may alter atmospheric circulation, dislocating historical patterns of natural variability and storminess.

In the current climate, weather experienced at a given location or region varies from year to year; in a changing climate, both the nature of that variability and the basic patterns of weather experienced can change, sometimes in counterintuitive ways — some areas may experience cooling, for instance. This raises no challenge to the reality of human-induced climate change.

Impacts harmful to society, including increased extremes of heat, precipitation, and coastal high water are currently being experienced, and are projected to increase. Other projected outcomes involve threats to public health, water availability, agricultural productivity (particularly in low-latitude developing countries), and coastal infrastructure, though some benefits may be seen at some times and places. Biodiversity loss is expected to accelerate due to both climate change and acidification of the oceans, which is a direct result of increasing carbon dioxide levels.

While important scientific uncertainties remain as to which particular impacts will be experienced where, no uncertainties are known that could make the impacts of climate change inconsequential. Furthermore, surprise outcomes, such as the unexpectedly rapid loss of Arctic summer sea ice, may entail even more dramatic changes than anticipated.

Actions that could diminish the threats posed by climate change to society and ecosystems include substantial emissions cuts to reduce the magnitude of climate change, as well as preparing for changes that are now unavoidable. The community of scientists has responsibilities to improve overall understanding of climate change and its impacts. Improvements will come from pursuing the research needed to understand climate change, working with stakeholders to identify relevant information, and conveying understanding clearly and accurately, both to decision makers and to the general public.”

Adopted by the American Geophysical Union December 2003; Revised and Reaffirmed December 2007, February 2012, August 2013.

Focus Areas

Climate Change



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