http://sciencepolicy.agu.org/files/2013/07/AGU-Climate-Change-Position-Statement_August-2013.pdf
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Human Activities are changing earth’s climate.
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At the global level, atmospheric concentrations
of carbon dioxide and other heat-trapping greenhouse gases have increased abruptly
since the industrial revolution.
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Fossil fuel burning dominates this increase.
·
Human-caused increases in greenhouse gases are responsible
for most of the observed global average surface warming.
·
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.
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‘Extensive, independent observations confirm the
reality of global warming’ – American Geophysical Union
·
Theese observations show large-scale inceases in
air and sea temperature, sea level, and atmospheric water vapour, they document
decreases in the extent of mountain glacier, snow cover, permafrost, and Artic
sea ice.
·
Theese changes are broadly consistent with long
understood physics and predications 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.
·
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.
