Meteorologists’ new statement reaffirms scientific ‘consensus,’ runs counter to widespread views of meteorologists as disproportionately ‘skeptical.’

The nation’s leading association of meteorologists August 27 announced its new seven-page statement on climate change, reaffirming its commitment to “peer reviewed-scientific literature” and what it called “the vast weight of current scientific understanding.”

The statement comes at a time of continued anxieties among some that broadcast meteorologists in particular are disproportionately skeptical of what many have come to characterize as the “consensus” scientific- and evidence-based view on a warmer climate and principal causes for the warming over the past half-century.

Observed Warming ‘Unequivocal,’ CO2 ‘Most Important’

The new American Meteorological Society statement points to “observed” and “unequivocal” warming of the climate system going “beyond what can be explained by natural variability of the climate.”

“It is clear from extensive scientific evidence that the dominant cause of the rapid change in climate of the past half century is human-induced increases in the amount of atmospheric greenhouse gases, including carbon dioxide (CO2),” the AMS statement says. It stipulates that CO2 is “the most important” of the greenhouse gases, pointing, for instance, to its long life time in the atmosphere.

Noting that warming effects are “especially evident in the planet’s polar regions,” the AMS statement says that human and natural factors “will continue to alter climate in the future” and calls further warming “inevitable for many years” because of the accumulation of greenhouse gases in the atmosphere and oceans. While largely avoiding policy issues, the AMS statement says “amelioration might be possible through devising and implementing environmentally responsible geoengineering approaches, such as capture and storage measures” for reducing atmospheric CO2 loadings, but it also cautions that “potential risks of geoengineering may be quite large.”

“Were future technologies and policies able to achieve a rapid reduction of greenhouse gas emissions — an approach termed ‘mitigation’ — this would greatly lessen future global warming and its impacts,” the group’s new statement says.

Forecast for Strong Hurricanes, Heat Waves

Addressing potential weather impacts in a warmer world, the AMS statement points to modeling simulations projecting “an increased proportion of global hurricanes that are in the strongest categories … although the total counts of hurricanes may not change or may even decrease. It points to continuing heat waves and cold snaps but says “proportionately more extreme warm periods and fewer cold periods are expected. Indeed, what many people traditionally consider a cold wave is already changing toward less severe conditions. Frost days (those with minimum temperature below freezing) will be fewer and growing seasons longer.” Look for “more severe episodes of extreme heat,” the statement cautions.

It points to “already thawing” regions of Alaskan and other northern polar area permafrost, “with the potential to release massive amounts of carbon into the atmosphere beyond those being directly added by human activity.” It also points to increased acidification of the planet’s oceans, with risks in particular for shell fish and other organisms and for ocean ecosystems more broadly.

The AMS climate change statement concludes that “there is unequivocal evidence that Earth’s lower atmosphere, ocean, and land surface are warming; sea level is rising; and snow cover, mountain glaciers, and Arctic sea ice are shrinking” and that the “dominant cause” since the 1950s is “human activities.”

“Avoiding this future warming will require a large and rapid reduction in global greenhouse gas emissions,” it says, and “technological, economic, and policy choices in the near future” will determine the extent of future impacts.

Uncertainty … and Weather/Climate Distinction

“Science–based decisions are seldom made in a context of absolute certainty,” it says, but mitigation and adaptation efforts can help reduce risks and impacts “that are potentially large and dangerous.”

In discussing climate and related weather issues, the AMS statement says “climate is potentially predictable for much longer time scales than weather …. climate can be meaningfully characterized by seasonal-to-decadal averages and other statistical measures, and the average weather is more predictable than individual weather events.”

The statement introduces a useful metaphor or analogy in this regard: “Population averages of human mortality are predictable while life spans of individuals are not.”

The statement also points to long time scales in climate physical systems and processes in contrast to short time scales in weather and related atmospheric phenomena, such as thunderstorms and intense snow storms.

The statement was approved unanimously by the AMS’s 21-person Council, according to AMS Executive Director Keith Seiter, a member of that council. He said the “guiding issue” in writing the statement was that it be supported by peer-reviewed literature.

“Quite a number of people contributed in various ways along the line, helping to shape the language in specific parts of the document.  Many AMS members submitted comments on the draft posted for member comment — with some questioning statements that needed to be refined to be more precise and others suggesting additions,” Seiter said.

“All of those comments were reviewed and helped shape the final form.   The number of people involved and the range of checking and rechecking that was done by Council members and outside experts who provided input to the Council is why this statement took so long to complete.”

Seiter said he personally accepts that some dismissive of the underlying climate science “may still not like what they read, and they may still feel that the peer-reviewed literature is not presenting the correct answers on some aspects of all this, but I think everything in this can be traced directly back to the literature in clear ways.”

AMS is among a relatively small group of key scientific organizations and “fraternities” whose climate change policy statements are closely watched in climate policy circles eager to detect and softening or hardening of their positions based, for instance, on ongoing scientific reports or on political and scientific arguments advanced by climate “skeptic” interests. The new statement is unlikely to provoke howls of protest from those generally in sync with the Intergovernmental Panel on Climate Change (IPCC), the National Academy of Sciences, or the U.S. Global Change Research Program. Those determined to deny the climate science positions of such interests, on the other hand, are likely to find little, if anything, in the AMS statement to their liking.

The new AMS statement is expected to be in force until August 2017 unless superseded by a new one issued by AMS prior to then.

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