Yadvinder Malhi Discusses Ecology & Functioning of Amazonian Forests

Fast Breaking Paper Commentary, December 2010

Yadvinder Malhi

Article: Exploring the likelihood and mechanism of a climate-change-induced dieback of the Amazon rainforest


Authors: Malhi, Y;Aragao, LEOC;Galbraith, D;Huntingford, C;Fisher, R;Zelazowski, P;Sitch, S;McSweeney, C;Meir, P
Journal: PROC NAT ACAD SCI USA
Volume: 106, Issue: 49, Page: 20610-20615, Year: DEC 8 2009
* Univ Oxford, Sch Geog & Environm, Environm Change Inst, S Parks Rd, Oxford OX1 3QY, England.
(Addresses have been truncated)

Yadvinder Malhi talks with ScienceWatch.com and answers a few questions about this month's Fast Breaking Paper paper in the field of Multidisciplinary.


SW: Why do you think your paper is highly cited?

The possible "dieback" of the Amazon forest is one of the iconic tipping points in discussion about the impacts of climate change, and yet there is much controversy, debate, and misunderstanding about what is known and what is not known. In this paper we explore many themes in this debate, and in particular try and relate the climate predictions with field-study based understanding of the ecology and functioning of Amazonian forests, and to satellite-based studies of the current distribution of the forest.

SW: Does it describe a new discovery, methodology, or synthesis of knowledge?

As part of the paper we present a new framework for examining the outputs of climate models and relating them to field and satellite data. This proved insightful, highlighting some of the limitations of climate models (most of them greatly underestimate current rainfall in Amazonia) as well as what is consistent amongst them (most models and a plausible theoretical understanding suggest dry seasons may intensify in Amazonia in a warming world).

SW: Would you summarize the significance of your paper in layman's terms?

Figure 1:
A photo of fire in Amazonian forest. Photo: Paulo Brando.
A photo of fire in Amazonian forest. View larger image in the tab below.

PhoTO by Paulo Brando.

Climate change is likely to cause increased seasonality of rainfall in Amazonia, with stronger dry seasons and stronger wet seasons. This suggests that parts of Amazonia (especially Eastern Amazonia) may tend towards a seasonal forest rather than a non-forest scrub. However, these seasonal dry forests are more likely to be flammable, and an interaction with increasing fire leakage from human settlements will have a strong influence on the future of the Amazon. The extreme climate change-induced dieback scenarios of the future of Amazonia are fairly unlikely, but still possible.

SW: How did you become involved in this research, and how would you describe the particular challenges, setbacks, and successes that you've encountered along the way?

For 15 years I have been involved in field research trying to understand the functioning of Amazonia and its sensitivity to climate change, having the privilege of working in some of the most pristine parts of this wonderful region. In recent years I see my challenge as trying to build an effective relationship between our field studies which describe in detail the functioning of Amazonian forests, and the global biosphere and climate studies that try and describe the functioning and future of the Earth system as a whole.

The challenges of doing this work are the usual ones of challenging tropical field studies: remote locations, difficult logistics, but wonderful adventures, comradeship, and humility arise from being immersed in and trying to unravel the mysteries of the natural world.

SW: Where do you see your research leading in the future?

I see increased experimental work, where we try and see how tropical ecosystems respond to variations in water supply, warming temperatures, and higher carbon dioxide. Also, I am currently on leave and living in Ghana, with the aim of developing similar research in African forests. African forests receive only a small fraction of the scientific attention that Amazonia does, and I would like to take some of the tools and insights we have developed in our Amazonian studies and apply them to African forests.

SW: Do you foresee any social or political implications for your research?

The fate of tropical forests in the context of climate change is a subject of major political importance. Intact tropical forests currently appear to be absorbing carbon dioxide, slowing down the rate of climate warming by 17%. If climate change starts causes dieback of tropical forests, even remote and protected tropical forests could become accelerators of climate warming.

Potential "tipping points" in the Earth system such as this would leave humanity with much less room to maneuver as it tries to decrease greenhouse gas emissions over this century. Hence identifying where these tipping points may lie is a topic with major consequences.End

Yadvinder Malhi
Professor of Ecosystem Science
University of Oxford
Environmental Change Institute
School of Geography and the Environment
Oxford, United Kingdom

KEYWORDS: CARBON DIOXIDE; DROUGHT; FIRE; TROPICAL FORESTS; ADAPTATION; SOUTH-AMERICA; DROUGHT; PRECIPITATION; IMPACTS; FUTURE; BASIN; DEFORESTATION; ECOSYSTEM; LIANAS; TREES.

 
Click the tab above for a larger view of Figure 1.

Figure 1:

A photo of fire in Amazonian forest. Photo: Paulo Brando.

Figure 1: A photo of fire in Amazonian forest. Photo: Paulo Brando.

 

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