Transcript Lecture #10 Global Climate Change

Schematic framework of anthropogenic climate change drivers, impacts and
responses to climate change, and their linkages (IPCC, 2007).
Warming of the climate system is
unequivocal, as is evident from
observations of increases in
global average air and ocean
temperatures, widespread
melting of snow and ice and
rising global average sea level
(IPCC, 2007).
Of the 29,000 observational
data series from 75 studies,
that show significant change in
many physical and biological
systems, more than 89% are
consistent with the direction of
change expected as a
response to warming (IPCC,
2007).
Changes in physical and biological systems and surface temperature 1970-2004
(IPCC, 2007).
(a) Global annual emissions of anthropogenic GHGs from 1970 to 2004. (b)
Share of different anthropogenic GHGs in total emissions in 2004 in terms of
CO2-eq. (c) Share of different sectors in total anthropogenic GHG emissions in
2004 in terms of CO2-eq. (forestry includes deforestation) (IPCC, 2007).
(a) Distribution of regional per capita GHG emissions
according to the population of different country groupings in
2004. (b) Distribution of regional GHG emissions per US$
over the GDP of different country groupings in 2004. The
percentages in the bars in both panels indicate a region’s
share in global GHG emissions. (IPCC, 2007).
Relative importance of
atmospheric gases and
particulate matter on global
warming versus cooling.
Note that methane gas has a
greater greenhouse effect
than CO2 gas, but its
anthropogenic productioin
and overall atmospheric level
is lower.
Anthropogenic concentrations of CO2,
CH4 and N2O) over the last 10,000
years (large panels) and since 1750
(inset panels). Measurements are
shown from ice cores (symbols with
different colors for different studies) and
atmospheric samples (red lines). The
corresponding radiative forcings relative
to 1750 are shown on the right hand
axes of the large panel (IPCC, 2007).
The atmospheric concentrations of CO2
and CH4 in 2005 exceed by far the
natural range over the past 650,000
years.
Global average radiative forcing (RF) in 2005 with respect to 1750 for CO2, CH4 and
N2O and other important agents and mechanisms (IPCC, 2007).
Comparison of observed continental- and global-scale changes in surface temperature
with results simulated by climate models using either natural or both natural and
anthropogenic forcings.
Scenarios for GHG emissions from 2000 to 2100 in absence of additional climate
policies (IPCC, 2007) . SRES - (Special Report on Emission Scenarios, 2000).
Boundary conditions used to produce general circulation
models of past and future climate change.
CLIMAP reconstruction of SST (°C) during the Last Glacial
Maximum, ~18000 years ago.
Atmosphere-Ocean General Circulation Model projections
of surface warming (2020-2029 and 2090-2099). IPCC,
2007.
Relative changes in precipitation (in percent) for the period
2090-2099, relative to 1980-1999. Values are multi-model
averages based on the SRES A1B scenario for December
to February (left) and June to August (right). White areas
are where less than 66% of the models agree in the sign of
the change and stippled areas are where more than 90% of
the models agree in the sign of the change (IPCC, 2007).
CO2 emissions and equilibrium temperature increases
(above pre-industrial for a range of stabilization levels.