A newly released statement by the world’s largest scientific society of Earth and space scientists – the American Geophysical Union (AGU) – warns that “the Earth’s climate is now clearly out of balance and is warming.”
The statement updates the organization’s position on climate change: the evidence for it, potential consequences from it, and how to respond to it. It replaces an earlier bulletin issued in 2003. The text of the revised statement is available online at: http://www.agu.org/sci_soc/policy/positions/climate_change2008.shtml).
The AGU indicated that “many components of the climate system” have undergone rapid changes. These include: “the temperatures of the atmosphere, land and ocean, the extent of sea ice and mountain glaciers, the sea level, the distribution of precipitation, and the length of seasons.”
All of these climate sectors are “changing at rates and in patterns that are not natural and are best explained by the increased atmospheric abundances of greenhouse gases and aerosols generated by human activity during the 20th century,” said the AGU. “Global average surface temperatures increased on average by about 0.6°C [1.08°F] over the period 1956-2006. As of 2006, eleven of the previous twelve years were warmer than any others since 1850.”
As previously released studies have shown (See IJ web site – https://www.insurancejournal.com/news/international/2007/08/14/82635.htm – the NSIDC report), “the observed rapid retreat of Arctic sea ice is expected to continue and lead to the disappearance of summertime ice within this century.”
Additional evidence “from most oceans and all continents except Antarctica shows warming attributable to human activities,” the report continued. “Recent changes in many physical and biological systems are linked with this regional climate change. A sustained research effort, involving many AGU members and summarized in the 2007 assessments of the Intergovernmental Panel on Climate Change, continues to improve our scientific understanding of the climate.”
The AGU points out that over the last millennia global climates have been “relatively stable.” Civilizations and populations grew rapidly, and have come too view these conditions as the normal state of things. However, the AGU points out, “even the lower limit of impending climate change – an additional global mean warming of 1°C above the last decade – is far beyond the range of climate variability experienced during the past thousand years and poses global problems in planning for and adapting to it.
“Warming greater than 2°C [3.6°F] above 19th century levels is projected to be disruptive, reducing global agricultural productivity, causing widespread loss of biodiversity, and—if sustained over centuries—melting much of the Greenland ice sheet with ensuing rise in sea level of several meters [6-7 feet].”
It has therefore become imperative to address the real possibility of temperatures rising by 2°C or more. This can only be avoided, said the AGU, by reducing “our net annual emissions of CO2…by more than 50 percent within this century.”
The AGU recognized that “there are many sources of scientific uncertainty,” but, the organization added, “none are known that could make the impact of climate change inconsequential. Given the uncertainty in climate projections, there can be surprises that may cause more dramatic disruptions than anticipated from the most probable model projections.”
The AGU likened climate change to the depletion of the ozone layer, noting that the “human footprint on Earth is apparent. The cause of disruptive climate change, unlike ozone depletion, is tied to energy use and runs through modern society. Solutions will necessarily involve all aspects of society. Mitigation strategies and adaptation responses will call for collaborations across science, technology, industry, and government.
“Members of the AGU, as part of the scientific community, collectively have special responsibilities: to pursue research needed to understand it; to educate the public on the causes, risks, and hazards; and to communicate clearly and objectively with those who can implement policies to shape future climate.”
Source: American Geophysical Union – http://www.agu.org.
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