Understanding Global Change

IHEAL – Master Pro

2011/09/23

Three questions about Global Change

• How physical processes related with the atmosphere will affect the environment as a whole ?

• How global processes will affect local/regional situations ? Reversely, how local/regional situations and evolutions can influence global processes ? (think global, act local)

• How are physical processes perceived and qualified by social actors and institutions ?

What are we talking about ?

• Changes in the characteristics of the atmosphere and climate variation, measured in specific places. Challenges for models

• Changes of the global climate, understood by scientists as a complex system of interactions = climate change

• Changes in the world environment connected to changes of the climate = global change

• Changes captured from the physical view point, or from the political / institutional one

Definitions

• According to the IPCC, “Climate change refers to a statistically significant variation in either the mean state of the climate or in its variability, persisting for an extended period (typically decades or longer). Climate change may be due to natural internal processes or external forcings, or to persistent anthropogenic changes in the composition of the atmosphere or in land use.”

• The UNFCC defines Climate change as ”a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods”

Radiative energy budget

Modelling climate change •Better horizontal resolution •Better vertical resolution •Coupling atmosphere-ocean • Inclusion of a wide array of variables (eg: snow cover, albedo)

Climate change in the quaternary

Changes over the last 20 000 years

IPCC Fourth Assessment Report, Climate

Change 2007 (AR4)

IPCC Fourth

Assessment Report,

Climate Change 2007

(AR4)

Mechanisms of global change

Les gaz à effets de serre d’origine humaine

(GES /GHG) • Gaz carbonique (CO2) : combustion

d’hydrocarbures et de bois, industries (notamment ciment)

• Méthane (CH4) : Digestion des ruminants, décomposition des résidus organiques, rizières

• Oxyde nitreux (NO2) : provenant des engrais

• Halocarbures : aérosols

Green house gases

• Carbon dioxyde (CO2) due to the use of fuels and industries such as cement, steel mills.

• Methane (CH4): coming from land use change, fermentation, cattle, rice fields

• Nitrous oxide : due to fertilizers

Carbon

dioxide

Methane

Concentration of GHG from 10 000 BP

Presence in the atmosphere

GHG

CO2 100 years

CH4 12 years

NO2 120 years

CFC 50 000 years

Durée de présence dans l’atmosphère

Carbon dioxide equivalent

• GHGs differ in their warming influence (radiative forcing) on the global climate system due to their different radiative properties and lifetimes in the atmosphere. These warming influences may be expressed through a common metric based on the radiative forcing of CO2.

• CO2-equivalent emission is the amount of CO2 emission that would cause the same time-integrated radiative forcing, over a given time horizon, as an emitted amount of a long-lived GHG or a mixture of GHGs. The equivalent CO2 emission is obtained by multiplying the emission of a GHG by its Global Warming Potential (GWP) for the given time horizon.[6] For a mix of GHGs it is obtained by summing the equivalent CO2 emissions of each gas. Equivalent CO2 emission is a standard and useful metric for comparing emissions of different GHGs but does not imply the same climate change responses (see WGI 2.10).

• CO2-equivalent concentration is the concentration of CO2 that would cause the same amount of radiative forcing as a given mixture of CO2 and other forcing components.[7]

http://www.ipcc.ch/publications_and_data/ar4/syr/en/mains2-1.htmlhttp://www.ipcc.ch/publications_and_data/ar4/syr/en/mains2-1.html

CO2 equivalent

Gaz PRG Carbon equivalent

CO2 1 0,273

CH4 25 6,82

N2O 298 81,3

Emissions scenarios and global warming

LATIN AMERICA

Emissions of GHG

Historical emissions

Emissions by country

Observed changes 1960-2000

Precipitation (change shown in % unless otherwise indicated)

Period Change

Amazonia – northern/southern (Marengo, 2004)

1949-1999 -11 to -17/-23 to +18

Bolivian Amazonia (Ronchail et al., 2005) since 1970 +15

Argentina – central and north-east (Penalba and Vargas, 2004)

1900-2000 +1 STD to +2 STD

Uruguay (Bidegain et al., 2005) 1961-2002 + 20

Chile – central (Camilloni, 2005a) last 50 years -50

Colombia (Pabón, 2003a) 1961-1990 -4 to +6

Mean temperature (°C/10 years)

Amazonia (Marengo, 2003) 1901-2001 +0.08

Uruguay, Montevideo (Bidegain et al., 2005)

1900-2000 +0.08

Ecuador (NC-Ecuador, 2000) 1930-1990 +0.08 to +0.27

Colombia (Pabón, 2003a) 1961-1990 +0.1 to +0.2

Maximum temperature (°C/10 years)

Brazil – south (Marengo and Camargo, 2007)

1960-2000 +0.39 to +0.62

Argentina – central (Rusticucci and Barrucand, 2004)

1959-1998 -0.2 to -0.8 (DJF)

Argentina – Patagonia (Rusticucci and Barrucand, 2004)

1959-1998 +0.2 to +0.4 (DJF)

Minimum temperature (ºC/10 years)

Brazil – south (Marengo and Camargo, 2007)

1960-2000 +0.51 to +0.82

Brazil – Campinas and Sete Lagoas (Pinto et al., 2002)

1890-2000 +0.2

Brazil – Pelotas (Pinto et al., 2002) 1890-2000 +0.08

Argentina (Rusticucci and Barrucand, 2004)

1959-1998 +0.2 to +0.8 (DJF/JJA)

Sea-level rise (mm/yr)

Glaciers/Period Changes/Impacts

Perua, b Last 35 years

22% reduction in glacier total area; reduction of 12% in freshwater in the coastal zone (where 60% of the country’s population live). Estimated water loss almost 7,000 Mm3

Peruc Last 30 years Reduction up to 80% of glacier surface from small ranges; loss of 188 Mm3 in water reserves during the last 50 years.

Colombiad 1990-2000

82% reduction in glaciers, showing a linear withdrawal of the ice of 10-15 m/yr; under the current climate trends, Colombia’s glaciers will disappear completely within the next 100 years.

Ecuadore 1956-1998

There has been a gradual decline glacier length; reduction of water supply for irrigation, clean water supply for the city of Quito, and hydropower generation for the cities of La Paz and Lima.

Boliviaf Since mid-1990s Chacaltaya glacier has lost half of its surface and two-thirds of its volume and could disappear by 2010. Total loss of tourism and skiing.

Boliviaf Since 1991

Zongo glacier has lost 9.4% of its surface area and could disappear by 2045-2050; serious problems in agriculture, sustainability of ‘bofedales’[1] and impacts in terms of socio-economics for the rural populations.

Boliviaf Since 1940 Charquini glacier has lost 47.4% of its surface area.

http://www.ipcc.ch/publications_and_data/ar4/wg2/en/ch13s13-2-4.html

Chacaltaya – Bolivia (from Francou)

2020 2050 2080

Changes in temperature (°C)

Central America Dry season +0.4 to +1.1 +1.0 to +3.0 +1.0 to +5.0

Wet season +0.5 to +1.7 +1.0 to +4.0 +1.3 to +6.6

Amazonia Dry season +0.7 to +1.8 +1.0 to +4.0 +1.8 to +7.5

Wet season +0.5 to +1.5 +1.0 to +4.0 +1.6 to +6.0

Southern South America

Winter (JJA) +0.6 to +1.1 +1.0 to +2.9 +1.8 to +4.5

Summer (DJF) +0.8 to +1.2 +1.0 to +3.0 +1.8 to +4.5

Change in precipitation (%)

Central America Dry season Wet season

-7 to +7 -10 to +4

-12 to +5 -15 to +3

-20 to +8 -30 to +5

Amazonia Dry season Wet season

-10 to +4 -3 to +6

-20 to +10 -5 to +10

-40 to +10 -10 to +10

Southern South America

Winter (JJA) Summer (DJF)

-5 to +3 -3 to +5 -12 to +10 -5 to +10

-12 to +12 -10 to +10