Sample Global Climate Change Issues Global Climate Change Models Uncertainty Sea Level Rise Arctic Sea Ice Changes Global Climate Change and Hurricanes Competing Effects of GHG and Aerosols

Global Climate Change Models Uncertainty

1.5 to 4.5º C The climateprediction.net experiment (black lines) made use of a low-resolution, reduced-physics version of the Hadley Centre model, running on thousands of PCs using donated computer time. Clearly, not all runs have reached equilibrium in 15 years of integration, yet there is a much wider range of global warming projections due to doubled CO2 concentration than the standard IPCC 1.5-4.5C range. The full Hadley Centre model (red lines) was used to perform a subset of the climateprediction.net with selected parameter values. The range of equilibria is likewise wider than 1.5-4.5C. Change in globally averaged surface temperature with time after CO2 values in the atmosphere are doubled. The black lines show the 15 years of phase 3 from 2579 climateprediction.net runs, and the red lines show comparable results from 127 30-year simulations completed by the Hadley Centre on the Met Office's supercomputer.

Sea Level Rise

According the the IPCC TAR, global average sea level has risen about 12 cm in the past 100 years.

Local Sea Level Change - Selected Sites 3.5 cm Sea level change varies from location to location. Solomons Island in the Chesapeake Bay has shown a 3.5 cm rise over the past 62 years, and Galveston in the Gulf of Mexico has shown a 7.0 cm rise over the past 90 years. 7.0 cm

Why is Sea Level Changing? Sea Level Factors 2001 est. (cm/cy) Thermal expansion 3 to 7 Glaciers 2 to 4 Greenland 0 to 1 Antarctica -2 to 0 Other eustatic (mass changes) -11 to 10 Totals -8 to 22 Estimated from observations 10 to 20 Estimates of sea level change from various factors, as reported in IPCC TAR.

Pannir Kanagaratnam (U Kansas) and Eric Rignot (NASA) Recent Arctic Climate Impacts report indicates that mass balance of Greenland ice sheet is negative. Recent satellite measurements of glacier movement suggest that the rate of mass loss is accelerating. Pannir Kanagaratnam (U Kansas) and Eric Rignot (NASA) Feb. 17, 2006 issue of Science Mass loss of Greenland ice — through enhanced glacier flow and enhanced runoff — is increasing with time (2X between 1996 and 2005), particularly on the periphery of the glaciers.

Arctic Sea Ice Changes

Annual Minimum Sea Ice Extent (DMSP SSM/I) Shrinking Sea Ice Extent in Arctic: Result of Global Warming? - Yes High latitudes more vulnerable Ice-albedo feedback Perennial sea ice shrinking 9.6% per decade since 1979 2005 1979 Annual Minimum Sea Ice Extent (DMSP SSM/I)

Global Climate Change and Hurricanes

2005 Hurricane Season: Result of Global Warming? Wilma Katrina Epsilon Both 2004 and 2005 were record-breaking hurricane seasons in the north Atlantic with 26 named storms and several storms that made landfall in Central and North America. Epsilon (26 named storms!)

Atlantic Multidecadal Oscillation: North Atlantic SST anomaly is related to hurricane frequency One explanation for the change in frequency of hurricanes in the north Atlantic is the fact that there is a multi-decadal oscillation in the sea surface temperature of the subtropical Atlantic (averaged across the entire ocean between the equator and 30N. When the AMO is above average, the frequency of storms is significantly higher than when AMO is below average. The origin of the AMO is under study … it may be related to changes in the Atlantic thermohaline circulation. (Goldenberg, S.B., C.W. Landsea, A.M. Mestas-Nuñez and W.M. Gray, 2001: The recent increase in Atlantic hurricane activity : Causes and implications. Science, 293:474-479.)

Probability Shifting Toward Stronger Tropical Cyclones Another characteristic of hurricanes, not necessarily related to frequency, is intensity. Several papers (Emanuel, 2005, Webster et al., 2005, Curry et al., 2006) have documented the increase in hurricane intensity since the 1930s, and have convincingly related the increase to the increase in tropical sea surface temperature worldwide. Power Dissipitation Index (PDI) - A measure of the total power dissipated annually by tropical cyclones in the North Atlantic compared to September sea surface temperature. Note that total Atlantic hurricane power dissipation has more than doubled in the past 30 years. See http://wind.mit.edu/~emanuel/anthro2.htm for FAQ about hurricanes and global climate change Emanuel, Nature, 2005

Competing Effects of GHG and Aerosols

Global mean, volume mean ocean temperature GFDL Model Simulations Global average upper ocean heat content. The dots show two independent observational estimates of this quantity for the past several decades. The colored curves are from GFDL model simulations with various forcing factors included. The black curve, which includes all forcing factors, does a credible job of fitting the observations. The other curves show: response to well-mixed greenhouse gases and ozone (orange), all anthopogenic factors (red), natural factors (green), and aerosols only. The green triangles indicate major volcanic eruptions. The upshot is that volcanic and anthropogenic aerosols in the atmosphere have masked the ocean warming effect of the greenhouse gases, which would otherwise be substantially larger. Delworth et al., 2005 (Geophys. Res. Lett.) Courtesy of Tom Delworth (GFDL)