Why we should fear the Amazonian tipping point

In a series of blog posts curated by the World Economic Forum’s Climate Change Initiatives, a number of leading voices will present their perspectives on climate change. Contributions are linked to the Forum’s Green Growth Action Alliance project and the Forum’s Global Agenda Council on Climate Change. In the following post, Carlos Nobre, National Secretary of Research and Development Policies, Ministry of Science, Technology & Innovation of Brazil, and Juan Carlos Castilla-Rubio, Chief Executive Officer, Planetary Skin Institute (PSI), share their perspective on climate change. Both are active in the Global Agenda Council on Measuring Sustainability.

Humans have been part of the vast forest-river system of the Amazon Basin for thousands of years. But, unprecedented agriculture expansion, logging and urban dynamics during the past decades are upsetting the fragile environment.

The human population of the Brazilian Amazon region increased from 6 million in 1960 to 25 million in 2010; forest cover for the region has declined to about 80% of its original area. Efforts to reduce deforestation, however, have led to steep declines in deforestation rates from nearly 28,000 km²/y to 6,400 km²/year in 2011.

The river system produces about 20% of the world’s total freshwater discharge into the oceans. Forest biomass is estimated to hold about 120 billion tonnes of carbon – which is equivalent to 15 years’ worth of 100% fossil fuel emissions – and forest ecosystems harbour about 15% of terrestrial biodiversity.

Maintaining the ecosystem function integrity of the Amazon and the ecosystem services it provides to local, regional and global communities will require a step change in understanding the vulnerability and resilience of Amazonia in the face of rapid change.

The notion of climate-induced Amazon “dieback” has recently attracted more and more attention. The core motivation for developing an early warning system to detect risk of large-scale Amazon dieback is that predictions of Amazon forest dieback and “savannization” urgently need to be improved and the risk needs to be quantified. Modelling-based studies anticipate thresholds not to be transgressed for avoiding an Amazonia tipping point: warming not exceeding 4ºC in the Amazon and deforestation not exceeding 40%. So far, temperature increase is close to 1ºC and total deforestation close to 20%.

We lack understanding of human-driven changes of Amazonian land-use patterns in the climate system. In 2010, Amazonia experienced a record-breaking dry year as it did in 2005 (two 1 in 100 year events). In 2009 and 2012, Amazonia experienced the other extreme with heavy flooding (two 1 in 500 year events). Do we fully understand what happened?

No. It seems that Amazonia is oscillating within two extremes. Could be an early indicator of system phase change? In ecosystems, transitions between these states are often one way, or nearly irreversible and are many times preceded by oscillations between extremes. Studies have shown that this can happen for Amazonia, and that the less favourable stable state is one that resembles a savannah-type ecosystem.

Global climate change could negatively affect Amazon land cover over the next 30-50 years through a large scale dieback of Amazonian forests. Such a scenario would not only affect regional water resources and precipitation patterns, biodiversity and livelihoods, but also affect global climate as far as Europe and North America through alternations in energy exchange and circulation as well as through substantial emissions of greenhouse gases associated with forest loss.

Whether change comes gradually or suddenly, it is of great importance to enable early detection of any signals that point to substantive degradation. In addition to detection, there should be practical guidelines on appropriate response measures. Ambitious as it may be, an early warning system for detecting the risk of large-scale Amazon dieback is critically needed, decades in advance of any impending, sudden forest dieback. An early warning system should address in great detail the controlling aspects of these indicators.

In Amazonia, some systems are in place to monitor land-use change and rivers. However, there is little else operational to systematically monitor and integrate the state(s) of the climate, the biodiversity or even the regional economy.

We have the opportunity to develop an early view of more complex and dynamic land-change patterns by integrating advanced land-change geospatial mining approaches to better detect and characterize forest fragmentation and forest degradation dynamics historically and near real time Amazonia-wide (ALERTS).

Authors: Carlos Nobre, National Secretary of Research and Development Policies, Ministry of Science, Technology & Innovation of Brazil and Member of the Global Agenda Council on Measuring Sustainability; Juan Carlos Castilla-Rubio, Chief Executive Officer, Planetary Skin Institute (PSI), USA and Chair of the Global Agenda Council on Measuring Sustainability.

Image: Virgin Amazon jungle is observed over Mato Grosso State REUTERS/Rickey Rogers