The Andes Meltdown
With the collaboration and support of AirClim, the Environment and Natural Resources Organization (FARN, Argentina) has recently published a comprehensive brief report summarizing the main findings on the impacts of climate change in the Andean cryosphere and the subsequent consequences for societies and ecosystems.
As 2019 marks the close of the hottest decade ever recorded and global emissions from fossil fuels hit yet another record high, climate change is affecting mountain regions at a faster rate than other terrestrial habitats. Worldwide, mountains are losing their ice and snow and the Andes are far from being the exception, representing one of the areas where this is happening at one of the most terrifying rates.
The cryosphere – the frozen-water portion of the Earth system – provides a plethora of services for humanity and our planet’s natural ecosystems. Ice and snow play a crucial role in feedback and regulation of the Earth’s weather and climate while storing and supplying freshwater essential for people’s survival, healthy ecosystems, agriculture, hydropower, and economic activities.
With an estimated number of 18,800 glaciers1, the Andes contain the largest glacierized area in the Southern hemisphere outside of Antarctica. Glacier runoff and seasonal snowmelt play a key role in freshwater supply for more than 85 million people living in the region, representing a critical contribution to Andean communities’ socioeconomic activities and their sustainability. Moreover, glacier melt acts as an important buffer during periods of drought, providing water to an extensive portion of the Tropical and Dry Andes.
Sadly, the future of the cryosphere in these mountains is at stake: Climate change has positioned Andean glaciers among the fastest-retreating and largest contributors to sea level rise on Earth.
Over recent decades, Andean glaciers have shrunk by up to 50 percent, a trend that is expected to accelerate. According to recent studies, between 2000 and 2018 the average ice mass loss rate in the Andes was 22.9 Gt per year2, which translates to an average loss of water equivalent to a four-storey building in 18 years.
Low-altitude glaciers in the Tropical Andes are particularly sensitive to warming because of their small size, and many will likely disappear in the coming decades, affecting the water supply of millions of people.
The Andean communities are already experiencing changes in hydrological regimes and water scarcity. Combined with a growing population, the climate emergency is putting unprecedented pressure on the existing water supply in metropolitan and rural areas of the Andes. Melting snow and glaciers are also increasingly exposing mountain communities to hazardous events such as glacial lake outburst floods (GLOFs) and landslides.
Biodiversity will also be affected as glacier retreat could seriously affect unique Andean ecosystems such as the northern tropical páramos and high-altitude wetlands, where meltwater depletion is likely to cause them to shrink.
The report stresses that the more heat-trapping gases we keep releasing into the atmosphere, the more severe the impacts from a melting cryosphere will become. Very few tropical glaciers will survive today’s 1.1°C of warming, and a great deal of the Southern Andes glaciers could resist 1.5°C. But most of them would disappear almost completely at 2°C.
As the IPCC points out, every fraction of a degree matters and all choices we make now are critical for the future of the cryosphere. Therefore, it becomes a human imperative to deeply cut greenhouse gas (GHG) emissions in the next few years if we want to preserve the vital services ice and snow provide in high-mountain areas and downstream.
Unfortunately – due to the GHGs that are already present in the atmosphere – the Andes are locked into increased warming. Andean countries thus face a serious need for more effective adaptation strategies, which should be planned and implemented incorporating both scientific and indigenous knowledge while engaging local communities.
1. Pfeffer, W. T. et al. The Randolph Glacier Inventory: a globally complete inventory of glaciers. J. Glaciol. 60, 537–552 (2014)
2. Dussaillant, I. et al. Two decades of glacier mass loss along the Andes. Nature Geoscience (2019). doi:10.1038/ s41561-019-0432-5
The full report is available both in Spanish and English at: https://farn.org.ar/archives/27148