Changes in precipitation and water
in the Americas
with climate change
Kevin E Trenberth
NCAR
Thanks to Ray Bradley
Global temperature and carbon dioxide:
anomalies through 2010
Base period 1900-99; data from NOAA
How should precipitation change
as climate changes?
Usually only total amount is considered
• But most of the time it does not rain
• The frequency and duration (how often)
• The intensity (the rate when it does rain)
• The sequence
• The phase:
phase snow or rain
The intensity and phase affect
how much runs off versus how
much soaks into the soils.
Most precipitation comes from moisture
convergence by weather systems
Rain comes
from moisture
convergence by
low level winds:
More moisture means heavier rains
Land precipitation is changing significantly over broad areas
Increases
Decreases
Smoothed annual anomalies for precipitation (%) over land from
1900 to 2005; other regions are dominated by variability.
IPCC
Precipitation
Observed trends
(%) per decade
for 1951–2003
contribution to
total annual from
very wet days
> 95th %ile.
Alexander
Alexander et
et al
al 2006
2006
IPCC
IPCC AR4
AR4
Heavy precipitation days are increasing even in
places where precipitation is decreasing.
Drought is increasing most places
The most
Mainly decrease
in rain
over landimportant
in tropicsspatial
and
pattern
(top) of
subtropics,
but enhanced
theatmospheric
monthly
by increased
Drought
demand Palmer
with warming
Severity Index
(PDSI) for 1900
to 2002.
The time series
(below) accounts
for most of the
trend in PDSI.
Dai et al 2004
IPCC 2007
Glaciers are retreating around the world
Change in length and area of 10 tropical Andean glaciers
Ecuador
Peru
Bolivia
Source: Francou & Vincent, 2007
Glaciers will continue to melt!
Projected change in temperature* (1990-99) to (2090-99)
along the American Cordillera, from Alaska to Chile
Mountain peaks
Limited data
Limited data
South
North
*Mean of 8 GCM simulations from IPCC 4th Assessment
using scenario A2
Source: Bradley et al., 2006
The cost of glacier recession
• Energy
Andean countries depend on hydropower generation
Bolivia
50%
Colombia
73%
Ecuador
72%
Peru
81%
• Water for urban areas
– Quito, La Paz, Lima & other cities
– (Bogota, Quito depend equally on paramo-derived water)
• Agriculture
– Changes in seasonality of runoff affect irrigation, crop types etc
GARP 0102 “Introduction to Physical Geography” Lecture 1 (Wednesday, 01/21/09)
Jan 2009
Pico Humboldt, Venezuelan Andes
Photo: Carsten Braun
Spring 1934 (Kern, 1937)
Photo: Carsten Braun
GARP 0102 “Introduction to Physical Geography” Lecture 1 (Wednesday, 01/21/09)
Jan 2009
Pico Humboldt, Venezuelan Andes
4942m
4680m
1952: 4500m
1934: 4300?m
Spring 1934 (Kern, 1937)
Ice margin was ~200m lower in 1952,
even lower in 1934 (inset)
Photo: Carsten Braun
Nevado de Santa Isabel, Colombia
44% mass loss
Ruiz: 5320m
Santa Isabel: 4965m
Tolima: 5215m
Sources: J. Ramírez Cadena & GRID‐ARENAL, UNEP
Cotopaxi, Ecuador (5897m)
Mean loss in glacier area, 1976‐1997: 30%
Photo: Dave Semler and Marsha Steffen
Source: Jordan et al., 2005
Qori Kalis glacier, Quelccaya Ice Cap, Peru: June, 2007
2009
Model predictions
“Rich get richer, poor get poorer”
Projections: Wet get wetter; dry get drier.
Combined effects of increased precipitation intensity, more dry
days, and stronger evaporation contribute to lower soil moisture
2090-2100
IPCC
Conclusions:
The need for environmental justice
1. Global warming increases temperatures and water vapor
2. It directly changes precipitation: more intense; longer
dry spells; shorter snow season, less snow pack
3. Rich get richer, poor get poorer; but patterns complex
4. Greater risk of flooding and droughts
5. Temperatures are rising—globally & across S. America
6. High elevations are being affected—glaciers are melting
7. Future warming will be greater at high elevations
8. Seasonal changes in river flow can be expected
9. All regions are affected, some more than others, and
regardless of whether they contributed to the problem
10.Water management will be major challenge in the future
Climate and Earth System observations and models will
contribute to environmental justice by assessing the
impacts of climate change on food production, flooding,
drought, sea level rise, and health.
Who is going to be most affected by climate change?
From Istockphoto.com
Comunidad Khapi y el Illimani
Alivio Aruquipa Lazo
1920
2008
¿Nuestro Futuro?
Human Rights Implications of
Climate-Induced Threats
to Access to Freshwater
Martin Wagner
Managing Attorney, International Program
[email protected]
Other Climate Impacts on
Access to Water
Saltwater Intrusion
Drought
Flooding
The Right to Water
1920
2008
Climate change will, and already does, impact on people’s rights to water
and sanitation by causing floods and droughts, changes in precipitation
and temperature extremes that result in water scarcity, contamination of
drinking water and exacerbation of the spread of disease.
- UN Independent Expert
The Right to Water
• Inter-American Court of Human Rights. Access to a sufficient quantity of
adequate quality freshwater is essential to realization of the right to a life of
dignity. (Caso Communidad Indígena Xákmok Kásek v. Paraguay (2010), ¶¶ 196, 217)
• UN General Assembly. “The right to safe and clean drinking water and
sanitation [is] a human right that is essential for the full enjoyment of life and all
human rights.” (The Human Right to Water and Sanitation, Resolution 64/292, July 2010)
• UN Human Rights Conventions
– Committee on Econ., Soc., Cultural Rights. “The human right to water
entitles everyone to sufficient, safe, acceptable, physically accessible and
affordable water for personal and domestic uses.” (General Comment No. 15,
“The Right to Water” (2002))
– CEDAW, Art. 14. Women have the right to “enjoy adequate living conditions,
particularly in relation to … water supply”
– Convention on the Rights of the Child, Art. 24. Right to attain highest
standard of health requires “the provision of adequate … and clean drinkingwater.”
Some Other Rights Affected by
Climate-Induced Changes
to Freshwater Resources
• Right to life
• Right to health and sanitation
• Right to food and means of subsistence
• Rights of indigenous and other resource-dependent peoples
to enjoy the benefits of their culture, and to use and enjoy the
lands they have traditionally used and occupied.
Climate Change and Human Rights
UN Human Rights Council resolution 10/4 (2009)
– “[C]limate change-related impacts have a range of
implications, both direct and indirect, for the effective
enjoyment of human rights including … obligations related
to access to safe drinking water and sanitation.”
OHCHR, Report on the Relationship between
Climate Change and Human Rights
– “[G]lobal warming will potentially have implications for the
full range of human rights.”
– “Climate change will ... exacerbate existing stresses on water
resources and compound the problem of access to safe
drinking water.”
What This Commission Can Do
• Formally recognize that climate change is a human rights
•
•
issue, particularly in the context of water;
Call upon all governments to make special efforts to
promote equitable access to freshwater and to take steps
now to prepare for increased constraints on freshwater
access; and
Call upon the governments most responsible for climate
change:
- to make the greatest possible efforts to mitigate climate
change to minimize its impacts, through national and
international action; and
- to provide substantial assistance to the most-vulnerable,
least-responsible governments as they address climateinduced threats to human rights.