Transcript global-climate-change-2

Causes of Global Climate Change
Most climate scientists agree the main cause of the current global warming
trend is human expansion of the "greenhouse effect" — warming that
results when the atmosphere traps heat radiating from Earth toward space.
Causes of Global Climate Change
The industrial activities that our modern civilization depends upon
have raised atmospheric carbon dioxide levels from 280 parts per
million to 400 parts per million in the last 150 years.
• Water vapor. The most abundant greenhouse gas, but
importantly, it acts as a feedback to the climate. Water vapor
increases as the Earth's atmosphere warms, but so does the
possibility of clouds and precipitation, making these some of the
most important feedback mechanisms to the greenhouse
effect.
• Carbon dioxide (CO2) is released through natural processes such
as respiration and volcano eruptions and through human
activities such as deforestation, land use changes, and burning
fossil fuels.
– Humans have increased atmospheric CO2 concentration by a third
since the Industrial Revolution began. This is the most important
long-lived "forcing" of climate change.
Causes of Global Climate Change
• Methane is produced both through natural sources and human activities,
including the decomposition of wastes in landfills, agriculture, and
especially rice cultivation, as well as ruminant digestion and manure
management associated with domestic livestock.
On a molecule-for-molecule basis, methane is a far more active
greenhouse gas than carbon dioxide, but also one which is much
less abundant in the atmosphere.
• Nitrous oxide. A powerful greenhouse gas produced by soil cultivation
practices, especially the use of commercial and organic fertilizers, fossil
fuel combustion, nitric acid production, and biomass burning.
• Chlorofluorocarbons (CFCs). Synthetic compounds entirely of industrial
origin used in a number of applications, but now largely regulated in
production and release to the atmosphere by international agreement for
their ability to contribute to destruction of the ozone layer.
They are also greenhouse gases.
Feedbacks can increase or decrease climate change
When we think about how anthropogenic greenhouse gases will
affect Earth, we must ask whether positive or negative feedbacks
will predominate.
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Positive feedbacks often lead to an unstable situation in
which small fluctuations in inputs lead to large effects.
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Negative feedbacks can have a dampening effect on
changes.
Your homework for this weekend is to research
feedback cycles and how they influence temperatures
on Earth.
 Global soils-permafrost etc.
 Plants response to increased CO2
 Ocean CO2 concentrations
The consequences of climate change
According to the IPCC, the extent of climate change effects on individual
regions will vary over time and with the ability of different societal and
environmental systems to mitigate or adapt to change.
U.S. regional effects (that are currently occurring)
• Northeast. Heat waves, heavy downpours and sea level rise pose
growing challenges to many aspects of life in the Northeast.
Infrastructure, agriculture, fisheries and ecosystems will be
increasingly compromised. Many states and cities are beginning to
incorporate climate change into their planning.
• Northwest. Changes in the timing of streamflow reduce water
supplies for competing demands. Sea level rise, erosion, inundation,
risks to infrastructure and increasing ocean acidity pose major
threats. Increasing wildfire, insect outbreaks and tree diseases are
causing widespread tree die-off.
The consequences of climate change
• Southeast. Sea level rise poses widespread and continuing threats
to the region’s economy and environment. Extreme heat will affect
health, energy, agriculture and more. Decreased water availability
will have economic and environmental impacts.
• Midwest. Extreme heat, heavy downpours and flooding will affect
infrastructure, health, agriculture, forestry, transportation, air and
water quality, and more. Climate change will also exacerbate a
range of risks to the Great Lakes.
• Southwest. Increased heat, drought and insect outbreaks, all linked
to climate change, have increased wildfires. Declining water
supplies, reduced agricultural yields, health impacts in cities due to
heat, and flooding and erosion in coastal areas are additional
concerns.
Future Climate Change Effects
• Temperatures will
continue to rise
• Frost-free season (and
growing season) will
lengthen
• Changes in precipitation
patterns
Figure 2.10: The frost-free season length, defined as the period between the last occurrence
of 32°F in the spring and the first occurrence of 32°F in the fall, has increased in each U.S.
region during 1991-2012 relative to 1901-1960. Increases in frost-free season length
correspond to similar increases in growing season length. (Figure source: NOAA NCDC / CICSNC).
Future Climate Change Effects
More droughts and heat waves
"Natural droughts like the 1930s
Dust Bowl and the current
drought in the Southwest have
historically lasted maybe a
decade or a little less," said Ben
Cook, climate scientist at NASA's
Goddard Institute for Space
Studies and the Lamont-Doherty
Earth Observatory at Columbia
University in New York City, and
lead author of the study. "What
these results are saying is we're
going to get a drought similar to
those events, but it is probably
going to last at least 30 to 35
years.“
Future Climate Change Effects
Hurricanes will become
stronger and more intense
Tropical Cyclone Winston just
after it made landfall on the north coast
of Viti Levu Island, which is the largest
and most populated island in the nation
of Fiji. At the time, Winston was one of
the most intense tropical cyclones
observed in the South Pacific Ocean, and
took an unusual track on the way to Fiji,
completing a large counter-clockwise
loop during the preceding week.
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http://www.cnn.com/videos/world/2016/02
/20/fiji-strong-storm-van-dam.cnn
http://www.theguardian.com/world/2016/fe
b/23/fijis-cyclone-winston-death-toll-risesas-news-comes-in-from-remote-areas
Future Climate Change Effects
• Sea level will rise 1-4 feet by 2100
Global sea level has risen by about 8 inches since reliable
record keeping began in 1880. It is projected to rise another 1
to 4 feet by 2100.
• Arctic likely to become ice-free
"most of North America has been experiencing more
unusually hot days and nights, fewer unusually cold days and
nights and fewer frost days. Heavy downpours have become
more frequent and intense. Droughts are becoming more
severe in some regions". U.S. Climate Change Science
Program (CCSP, 2008)
Is it hopeless?
So even if we stopped emitting all greenhouse gases today, global warming
and climate change will continue to affect future generations.
YES, THERE IS HOPE!!!
Mitigation and adaptation
Mitigation – reducing climate change – involves
reducing the flow of heat-trapping greenhouse gases
into the atmosphere
• by reducing sources of these gases (for example, the
burning of fossil fuels for electricity, heat or transport)
• or by enhancing the “sinks” that accumulate and store
these gases (such as the oceans, forests and soil).
• The goal of mitigation is to avoid dangerous human
interference with the climate system, and “stabilize
greenhouse gas levels in a timeframe sufficient to allow
ecosystems to adapt naturally to climate change, ensure
that food production is not threatened and to enable
economic development to proceed in a sustainable
manner”
(from the 2014 report on Mitigation of Climate Change from the United Nations
Intergovernmental Panel on Climate Change, page 4).
Adaptation – adapting to life in a changing climate –
involves adjusting to actual or expected future
climate.
The goal is to reduce our vulnerability to the harmful effects of
climate change (like sea-level encroachment, more intense
extreme weather events or food insecurity). It also encompasses
making the most of any potential beneficial opportunities
associated with climate change (for example, longer growing
seasons or increased yields in some regions).
https://www.ted.com/talks/vicki_arroyo_let_s_prepare_for_our_new_climate?language=en
The climate is quickly changing. Scientists increasingly talk of a new period in the Earth's history, the
"anthropocene", in which human impact on the planet has become dominant. Yet we remain
unprepared to deal with the consequences: specifically, the disruption and cost. Lawyer Vicki Arroyo, the
executive director of the Georgetown Climate Center, works on climate mitigation and adaptation
policies as viable solutions to climate change’s inevitable disruptions to current practices. Using the best
available science, Arroyo collaborates with US policymakers at both the state and federal level to develop
"planetary management" strategies.
https://www.ted.com/talks/alice_bows_larkin_we_re_too_late_to_prevent_climate_change_here_s_how_we_adapt?language=en
• http://bigpicture.unfccc.int/files/video-1.mp4