Carbon Dioxide levels will continue to rise...
IPCC
Atmospheric CO2 concentration from year
1000 to year 2000 from ice core data and from direct atmospheric measurements
over the past few decades. Projections of CO2 concentrations for the
period 2000 to 2100 are based on model predictions (see IPCC
2001 Synthesis report for more details).
...and so temperatures will increase...
IPCC
Variations of the Earth's surface temperature: years
1000 to 2100. From year 1000 to year 1860 variations in average surface
temperature of the Northern Hemisphere are shown (corresponding data
from the Southern Hemisphere not available) reconstructed from proxy
data (tree rings, corals, ice cores, and historical records). The
line shows the 50-year average, the gray region the 95% confidence
limit in the annual data. From years 1860 to 2000 are shown variations
in observations of globally and annually averaged surface temperature
from the instrumental record; the line shows the decadal average.
From years 2000 to 2100 projections of globally averaged surface temperature
are shown for several model scenarios using a model with average climate
sensitivity. The gray region shows the range of results from the full
range of 35 model scenarios in addition to those from a range of models
with different climate sensitivities (see IPCC
2001 Synthesis report for more details).
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...and so sea ice continues to decrease...
Observed and modeled variation of annual averages
of Arctic sea-ice extent, based on Vinnikov et al. (1999). Observed
data are from Chapman and Walsh (1993) and Parkinson et al. (1999).
Sea-ice curves are produced by GFDL low-resolution R15 climate model
and by HADCM2 climate model, both forced by CO2 and aerosols.
Virtually all predictive models lead to a seasonally ice-free Arctic
Ocean by about 2050. One – the Hadley Centre model - leads to
a completely ice-free ocean but starts with an assumed lower initial
ice extent than the other models.
There are obvious benefits in terms of navigation, and perhaps even
real estate prices above the Arctic Circle, to this loss of sea ice.
However, there would also be species loss or redistribution, and significant
but uncertain consequences for the Arctic's role in global climate.
Like most aspects of climate change, one issue is how quickly the
change occurs relative to an ecosystem's and Man's ability to respond.
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...and sea levels rise
Sea levels will rise from 2 factors: thermal expansion from the warming
ocean, and the melting of water locked away as ice in Antarctica, Greenland,
and other temperate glaciers. Various climate models that attempt to take
this melting into account predict sea level rises of between 10 cm and
1 m within one century.
This is the projected sea level rise in the next
100 years ( (see IPCC
2001 Synthesis report for more details). The most likely scenario
is for sea level rise of about 0.4 meter by 2100, sufficient to
cause severe problems with coastal erosion, flooding of low-lying
areas particularly during storms, and groundwater contamination.
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