Climate change challenges to mountain ecosystems in the Tropical Andes

Luis Germán Naranjo Ecoregional Conservation Director

WWF Colombia Program Office

Asunción, 25 July 2008

Third Western Hemisphere Migratory Species Initiative

Adapting habitats of importance to migratory species in the face of climate change

Climate change has arrived in Latin America….

• Eight of the 15 Colombian glaciers have been lost and the rest have retreated approximately 20 meters during the last half century.

• In the tropical Andes of Peru 10 glaciers, monitored since 1932, retreated between 590 m and 1910 m through 1994 (Ames, 1998).

• On the Antisana glacier in Ecuador mass balance measurements indicate an average negative trend of 600–700 mm yr−1 during the last decade.

• In Bolivia the Chacaltaya glacier lost 60% (93%) of its ice volume between 1940 and 1983 (Francou et al., 2000, 2003).

Photo: Jorge Lotero

Rising temperature may be the most likely candidate to explain glacier retreat over the last few decades, but glaciers may also suffer from a negative mass balance due to negative trends in precipitation and/or enhanced absorption of solar radiation due to a decrease in cloudiness.

• Within the last decade, annual rainfall in the Colombian páramos has decreased up to 2 mm/ year.

• It is estimated that 75% of the páramos will be lost during the next century.

• Observational evidence indicates a general tendency toward slightly drier conditions for southern Peru and western Bolivia.

• Precipitation amounts have changed little over the last 45 years, to the north, although there are several reports which indicate a precipitation increase on a regional scale to the east of the Andes, (Vuille et al., 2000a), and NW-Argentina (Villalba et al., 1998).

• Relative humidity in near-surface levels has increased by 0–2.5% decade−1 between 1950 and 1994.

• The observed increase in relative humidity is also apparent in model simulations, but on a regional scale the results between model and observations vary significantly.

• This increase in relative humidity shows that the absolute humidity increase is larger than what could be expected from a temperature increase alone.

• Temperature shows an average warming of 0.09–0.15 ºC decade−1 between 1950 and 1994 with most of the warming taking place after the mid 1970s.

• Near-surface temperature has increased significantly throughout most of the tropical Andes, and varies markedly between the eastern and western Andean slopes.

• Lower elevations west of the Andes have experienced the greatest warming, while the warming to the east is only moderate below 1000 m. Higher elevations show higher warming on the eastern than on the western slopes.

Miroc3_2_hires ModelSRES A1B

Climate models, downscaling and uncertainty in complex landscapes

Precipitation

2010 - 2029 2050 - 2069 2080 - 2099

Δ mm

ECHAM A2

Humidity

2010 - 2029 2050 - 2069 2080 - 2099

Δ %

ECHAM A2

Temperature

2010 - 2029 2050 - 2069 2080 - 2099

Δ ºC ECHAM A2

Δ %

• Extreme droughts reduction of food production, increased fire intensity and frequency.

• Extreme rainfall floods and landslides, increased erosion, damage to infrastructure, losses of human lives,.

• Glacier retreat decrease of available water for human consumption, hydropower, and irrigation. Increased risk of “natural” disasters.

• Changes of distribution patterns of plants and animals disturbance of food chains, expansion of ranges of disease vectors

Source: Robledo 2007

Climate-related risks and impacts in high Andean ecosystems

• In Ecuador, a 1oC increase and a 15% reduction in rainfall would increase the current deficit of water availability during the dry season.

• In Colombia, 84% of the municipalities and 91.3% of irrigation districts would suffer water shortages and 1/3 of Andean agricultural lands will be affected.

• Water level of the dams generating hydropower would be compromised affecting 78% of Colombia and Peru and 70% of Ecuador and Venezuela.

• 34% of current supply of potatoes in Ecuador will have to be replaced by imports or a 38% increase of cultivated land

Source: Soto 2007

• Warming and drying trends may increase the frequency and intensity of fires in the paramos and the downward contraction of cloud forests.

• The downward expansion of paramos, as we know them, may be prevented by the slow growth of dominant plant species and reduced humidity.

• Range contractions of invertebrate populations may affect the distributions of their predators even if they are more resilient to climate change.

• Changes in the floristic composition and phenological patterns along elevational gradients are likely to disrupt altitudinal migrations.

• Cascading effects of the disruption of species assemblages are likely.

Cristal balling: ecological responses to CC

Drier paramos

Loss of very humid Andean forests

Loss of Andean forests and humid paramos

2008 2030 2060

Expected changes in life zones in the Eastern Cordillera Real

Drier sub Andean forests

Climate trends and migratory birds: Baird’s Sandpiper (Calidris bairdii)

Climate trends and migratory birds: Cerulean Warbler (Dendroica cerulea)

To ensure the maintenance of biodiversity, and the provision of ecosystem services for human populations in high Andean ecosystems, it is essential to develop climate change mitigation measures, adaptation strategies to its potential impacts, and increased public awareness to face the challenge of living in a fast changing environment.

www.wwf.org.co