Arctic Climate Change: Perspectives from Observations and Global Climate Models . David Lawrence NCAR With contributions from Andrew Slater, Marika Holland, Mark Serreze, Don Perovich. Observed global climate change. Spatial pattern of warming.
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Arctic Climate Change: Perspectives from Observationsand Global Climate Models
With contributions from Andrew Slater, Marika Holland, Mark Serreze, Don Perovich
Arctic warming at roughly twice the rate of the rest of the world
Arctic sea ice is disappearing …
Stroeve et al. 2008
Greenland Ice Sheet is melting …
Sea level rise
from thermal expansion of ocean water and melting glaciers
IPA Permafrost Distribution Map
Long term monitoring site in Quebec, Canada
Continuous (90 – 100%)
Discontinuous (50 – 90%)
Sporadic (10 – 50%)
Isolated (0 – 10%)
Payette et al, 2004
Brown et al. 1998
Shrub cover increasing at 1.2% per decade since 1950, 15% to 20% cover(Sturm et al. 2001, Tape et al. 2006)
Nation's Snowmen March Against Global Warming
January 25, 2006 | Issue 42-04
… Centigrade told the slowly melting snowcrowd that as recently as 15 years ago, the average life span of a snowperson built in late December was three weeks to a month. Today, that same snowperson has an average life span of two weeks.
See, e.g. Hinzman et al., Climatic Change, 2005
McGuire et al., Ann Rev Env Res, 2006
Serreze et al., Climatic Change, 2000
Arctic Climate Impact Assessment, 2004, updated in 2008
Global Climate Model
Peering into the future ….
Ocean-Atmosphere-Land-Sea Ice model
Climate models are a lot like weather forecast models, but include interactive ocean, land, and sea-ice components, and can also account for changes in atmospheric constituents like greenhouse gases. They are used to study the earth's past, present and future climate states.
How does a global climate model work?
solar radiation, temp,
soil moisture, [CO2] …
Vertical water flow
, T*, zo
High resolution climate model output
CAM T340- Jim Hack
National Center for Atmospheric ResearchBoulder, Colorado
Compare against observations; if comparison is poor, then something is wrong
GRACE satellite measures small changes in gravity which on seasonal timescales are due to variations in water storage
CCSM3 and CCSM4 data from
1870 and 1850 control
300 200 100 0 -100 -200 -300 (mm)
How do we use these models to study climate change?
Economists develop possible scenarios of population growth, economic growth, energy use, land use
Depending on the scenario, more or less greenhouse gas emissions
Simulated global mean temperatures during last millenium and into 20th and 21st centuries
Ammann et al.
Air Temperature: Typical “business as usual” scenario by 2100
Global mean warming of ~2.8oC (or ~5F);Much of land area warms by ~3.5oC (or ~6.3F)Arctic warms by ~7oC (or ~12.6F)
Abrupt reductions in the September sea ice cover
September sea ice extent
Ice Extent ( 106 km2 )
CCSM3 – smoothed
Holland et al., 2006
…and on broader Arctic climate … in the 1970’s
D. Perovich, CRREL
Not far from today…
D. Perovich, CRREL
3.5-fold increase in rate of warming over land during rapid sea ice loss
September Sea- ice Extent
Lawrence et al. 2008
Lawrence and Slater, 2005
Adapted from McGuire et al., 2006