Dangerous Climate Change Addendum to McGuire, B (2007). Dangerous Climate Change: Rising Sea-levels and Ocean Circulation Changes. Issues in Risk Science, vol. 5. Benfield Hazard Research Centre.

Dangerous Climate Change Specific indicators of dangerous climate change include: circumstances that could lead to global and unprecedented consequences, extinction of iconic species (e.g., the Polar Bear), loss of entire ecosystems or human cultures, a threat to water resources, and a significant rise in mortality rates.

Dangerous Climate Change Examples include: the collapse and melting of the Greenland or West Antarctic ice sheets, leading to wholesale, catastrophic sea-level rise. a shutdown or significant slow-down in the Atlantic Thermohaline Circulation (including the Gulf Stream), spawning bitterly cold winters in the UK and Europe. Can we think of other possible examples?

Health Weather-related mortality Infectious diseases Air-quality respiratory illnesses Agriculture Crop yields Irrigation demands Pest outbrreaks Water Resources Changes in water supply Water quality Increased competition for water Coastal Areas Erosion of beaches Inundation of coastal lands Costs to protect coastal communities Forests Change in forest composition Shift geographic range of forests Forest health and productivity Pest outbreaks Species and Natural Areas Shift in ecological zones Loss of habitat and species Potential Climate Change Impacts Climate Changes Sea Level Rise Temperature Precipitation Source: EPA

Recent Global Temperature Trends Are We Experiencing Global Warming Now? 2005 is now #1

Hansen et al., Science vol. 308 What Controls Global Warming?

Hansen et al., Science vol. 308 What Controls Global Warming?

Where Do You Go To Find Records of Climate Change? Antarctica Vostok ice core

The Change in Temperature Depends on Where You Are Last 50 Years Surface Temperature Change Based on Linear Trends

Observed and modeled ocean temp. changes Hansen et al., Science vol. 308

Observed and modeled ocean temp. changes Red circles: observed warming signal strength Green hatched area: range of signal strengths in PCM model with anthropogenic forcing included (Barnett et al, 2005)

Models of Future Warming Will temperature increase be uniform across the globe? +10°F

Differential Temp Change The results are based on climate change simulations made with the Coupled Global Climate Model developed by Environment Canada. From Atlas of Canada Annual Temperature Change from to (°C)

Why Different Temps at Same Latitude?

The Thermohaline Circulation a.k.a. the “Global Conveyor Belt”

Thermohaline Circulation in Cross-Section CO 2

Thermohaline Circulation in Cross-Section

Models of Future Global Warming

General Predictions of Impacts over 21st Century Source - IPCC WGII TAR 2001Thanks to Martha Groom

Hurricane Power Dissipation Index (PDI) PDI has increased dramatically in recent decades in both the Atlantic and Pacific Ocean basins. From Emanuel (2005)

Alpine Glacier Retreat Retreat of 7 miles and 800 meter thinning. Source: National Snow and Ice Data Center

Sea Ice Loss Over Time Source: National Snow and Ice Data Center

Northern Hemisphere Sea Ice Extent (1979 versus 2003) Image courtesy of NASA-Goddard Space Flight Center

Northern Hemisphere Sea Ice Thickness

Greenland Ice Sheet Meltdown

Helheim Glacier on Greenland 2001

Helheim Glacier on Greenland 2005 Glacier flow has doubled since Benfield Hazard Research Centre (2006)

Northeast Atlantic Salinity

Modeled Impact of Thermohaline Current Shutdown Temperatures across Europe and eastern North America would fall by ~ 4° C within 20 years, bringing chillier summers and appalling winters. Weakening of the Indian Monsoon and halving of rainfall in parts of Central and South America. This could slash agricultural productivity and place what remains of the Amazon Rainforest in peril.

Modeled Impact of Thermohaline Current Shutdown Winter temps in Europe would frequently plunge below -10°C

Change in annual temperature 30 years after a collapse of the thermohaline circulation From Michael Vellinga, Hadley Centre and the Climatic Research Unit

Potential Impacts of Thermohaline Shutdown From Schwartz, P and Randall, D, 2003.

From Stocker, T. F., Future CO 2 vs NADW Formation

What Has Sea Level Been Doing?

Sea Level Rise – “Non-Catastrophic”

People at Risk from Sea-level Rise In 1990, it was estimated that around 1.2 billion people (~ 23 percent of the global population) lived within the coastal zone This includes more than 250 million inhabitants of 14 of the world’s megacities (population = 10 million). By 2015, more than 340 million people will live in 21 megacities, 18 of which will occupy coastal locations. The highest population densities are encountered below the 20 m elevation. The near-coastal population could rise as high as 5.2 billion by the 2080s.

Source: R. Nicholls, Middlesex University in the U.K. Meteorological Office Climate Change and Its Impacts: A Global Perspective. People at Risk from a 17-inch Sea-level Rise by the 2080s* *Assuming 1990s level of flood protection

Source: EPA Louisiana Shoreline Change with a 20-inch Rise in Sea Level Lake Charles Lafayette Baton Rouge Morgan City Houma New Orleans Gulf of Mexico Land Lost

South Florida Shoreline Change with a 1m Rise in Sea Level

Source: EPA U.S. East Coast Flooding with a 1m Rise in Sea Level

Source: EPA Bangladesh Flooding with a 1.5m Rise in Sea Level

Flooding in the Sacramento- San Joaquin Delta

Increased Frequency of Floods

The rate of melting of the Greenland Ice Sheet has doubled in the last 10 years, from 96 km 3 in 1996 to 220 km 3 in 2005, with three of the biggest glaciers draining the ice sheet doubling their rates of sliding seawards in the last 7 years. A local temperature rise of just 2.7° C (corresponding to a global rise of less than 2° C) is predicted to result in irreversible melting of the Greenland Ice Sheet and an eventual ~ 7 m sea-level rise. This threshold could be reached as early as Sea Level Rise – “Catastrophic”

Increased ice loss is also occurring in Antarctica, where the West Antarctic Ice Sheet is now losing about 150 km 3 a year. Over the last 50 years, an area of ice shelves the size of Jamaica have broken up and melted, while on the Antarctic Peninsula, the Pine Island and Thwaites glaciers are now moving three times faster than 10 years ago. Melting of these glaciers alone would raise sea- levels by more than a metre, with complete melting of the West Antarctic Ice Sheet raising global sea-levels by ~ 5 m. Sea Level Rise – “Catastrophic”

The question is not… “Will it happen?” It’s “How soon?” Initial estimates had the Greenland Ice Sheet melting completely in 1,000 years. Now looking more like a few centuries. Sea Level Rise – Up 6m

Greenland Ice Sheet Meltdown

Antarctica – The Wild Card

West Antarctic Ice Sheet

Ross Ice Shelf

Models of Future Global Warming 2050 Sea Level Rise Associated with collapse of West Antarctic Ice Sheet

Models of Future Global Warming 2050 Sea Level Rise Associated with collapse of West Antarctic Ice Sheet

Models of Future Global Warming 2050 Sea Level Rise Associated with collapse of West Antarctic Ice Sheet