Amazon Rainforest and Climate Change
Submitting InstitutionUniversity of Exeter
Unit of AssessmentEarth Systems and Environmental Sciences
Summary Impact TypeEnvironmental
Research Subject Area(s)
Earth Sciences: Oceanography
Biological Sciences: Ecology, Other Biological Sciences
Summary of the impact
Research at the University of Exeter on the links between the Amazon
rainforest and climate change has influenced international climate policy,
has directly assisted Brazilian environmental policymakers, and has
received international media coverage. The underpinning research spans the
vulnerability of the rainforest to anthropogenic climate change and the
mechanisms behind the Amazonian droughts of 2005 and 2010. Impact has been
achieved by stimulating public debate through the media, by contribution
to science-into-policy documents produced by the World Bank and for the
United Nations Framework Convention on Climate Change (UNFCCC), and by
direct face-to-face interaction with UK and Brazilian policymakers.
The Amazon basin is a key component of the Earth System providing about a
fifth of all of the freshwater inputs to the global oceans. It is a
hotspot for biodiversity that houses about 10% of all species on Earth,
and it is home to 25 million people. The Amazon rainforest also stores 120
billion tonnes of carbon, and exchanges about 10 billion tonnes of carbon
per year with the atmosphere. The future of the Amazon rainforest is
therefore of critical importance for the climate system, for the global
carbon cycle and biodiversity, and therefore for the well-being of
The Amazon rainforest is however currently suffering from multiple
pressures associated with direct deforestation and from changes in mean
climate and climatic extremes. Research carried-out by University of
Exeter researchers has led to concerns that the Amazon rainforest could
"dieback" in the 21st century, releasing carbon to the
atmosphere and accelerating climate change, as well as damaging the
ecosystem services that the forest currently provides. This notion of
"Amazon forest dieback" emerged from climate-carbon cycle projections
carried out by University of Exeter researchers Peter Cox and Richard
Betts when they were both full-time at the Met Office-Hadley Centre.
Underpinning the impact here is subsequent research, all carried out since
Cox moved to the University of Exeter in 2006, which has developed a
deeper understanding of the mechanisms and risk of Amazon dieback.
A key paper in 2008 identified an unexpected link between changes in air
quality and the risk of 2005-like droughts in Amazonia . It showed that
reducing anthropogenic aerosol pollution in the Northern Hemisphere,
associated primarily with reduced sulphur dioxide emissions from burning
sulphurous coal, has allowed the tropical north Atlantic to warm relative
to the south, prompting the Inter-tropical Convergence Zone (ITCZ) to move
northwards and delaying the onset of the rainy season in the south and
west of Amazonia.
This research helped motivate a special issue of New Phytologist
in 2010, in which Cox, Jupp and their collaborators on a World Bank funded
project (see section 4) estimated the risk of future drying in key regions
of Amazonia based on projections from 23 climate models . In 2010, Luiz
Aragao of the University of Exeter also published an influential paper
which suggested that some of the additional carbon storage arising from
avoided deforestation would be offset by increases in the frequency of
forest fires .
Recent research by Cox, Friedlingstein and collaborators, published in
2013 , has identified an "emergent constraint" on the loss of tropical
land carbon as a result of climate change, which arises from the observed
inter-annual variability in the atmospheric CO2 concentration.
As such it significantly reduced the uncertainties concerning the risk of
Amazon forest dieback , and identified the extent of the CO2
fertilization of tropical forest growth as the remaining key uncertainty.
References to the research
Key references to research that underpins the impact described in this
case study (University of Exeter researchers in italics):
1) Cox, P.M., Harris, P., Huntingford C., Betts, R.A., Collins,
M., Jones, C.D., Jupp, T.E., Marengo J., Nobre, C., 2008.
Increasing risk of Amazonian drought due to decreasing aerosol pollution.
Nature, 453, 212-216. #
2) Jupp, T.E., Cox P.M., Rammig, A., Thonicke, K., Lucht,
W., Cramer, W., 2010. Development of probability density functions for
future Amazonian rainfall. New Phytologist, 18, 682-693.
3) Aragao, L.E.O.C., Shimabukuro, Y.E., 2010. The incidence of
fire in Amazonian forests with implications for REDD. Science,
328, 1275-1278. #
4) Cox, P.M., Pearson, D., Booth, B.B.B., Friedlingstein, P.,
Huntingford, C., Jones, C.D., Luke, C.M., 2013. Sensitivity of
tropical carbon to climate change constrained by carbon dioxide
variability. Nature, doi:10.1038/nature11882. #
5) Huntingford, C. et al (includes Cox, P.M.), 2013. Simulated
resilience of tropical rainforest to CO2-induced climate
change. Nature Geoscience, doi: 10.1038/ngeo1741.
# References that best indicate the quality of the underpinning
Grant support related to this research:
• World Bank Project on Amazon Dieback, Exeter PI: Peter Cox, Sponsor:
World Bank, Period: 2008-2009, Value: £125,000.
• NERC Emergency Grant on Amazon 2010 drought, Exeter PI: Luiz Aragao,
Sponsor: NERC, Period: 2010-2012, Value: £52,566.
• NERC International Opportunities Fund: PULSE-Brasil project, Exeter PI:
Peter Cox, Sponsor: NERC, Period: 2012-2015, Value: £240,803.
Details of the impact
Our close engagement with key stakeholders has led to impacts on
international policy and Brazilian environmental policy. Extensive media
coverage has stimulated widespread public debate.
Informing International Policy
The intact Amazon rainforest is currently absorbing about 1 billion
tonnes of carbon per year (i.e. more than 10% of annual anthropogenic CO2
emissions), but this has been almost completely offset by the carbon
dioxide emissions due to deforestation over the last few decades. Largely
in response to widespread tropical deforestation, the UNFCCC introduced
the mechanism Reducing Emissions from Deforestation and Forest
Degradation (REDD) in 1995. REDD is a set of steps designed to use
market and financial incentives to reduce the emissions of greenhouse
gases from deforestation and forest degradation. Exeter's research
concerning changing fire frequency in Amazonia and the implications for
REDD policy  is referenced in UNEP and FAO documents [a,b].
More general concerns over the risk and impact of Amazonian forest
dieback led the World Bank to fund a project in 2008 with the goal "to
assist in understanding the risk of a potential reduction in biomass
density in the Amazon basin induced by climate change impacts (Amazon
dieback) and its implications". Cox and Jupp of the University of
Exeter were contracted members of the World Bank's project team along with
collaborators from Brazil, Japan and Germany. Interim reports from the
project were presented to the UNFCCC "Subsidiary Body for Scientific
and Technical Advice (SBSTA)", and the project outcomes continue to
feed into public debate [c] and UNFCCC policy discussions
concerning the "permanence" or otherwise of tropical carbon stores [d].
The project published its full report in 2010 [e], concluding that
fertilization effects of elevated atmospheric carbon dioxide
levels on forest ecosystems like the Amazon have proven to be a key
unknown", and that "Amazon dieback should be considered a
threshold for dangerous climate change". Both of these conclusions
derive in large part from work carried-out by researchers at the
University of Exeter (see Section 2).
Our most recent research findings, which constrains the loss of tropical
land carbon under climate change, were reported by the International
Geosphere-Biosphere Programme (IGBP) to the United Nations
Framework Convention on Climate Change (UNFCCC) "Subsidiary Body for
Scientific and Technical Advice (SBSTA)", at its meeting in Bonn in
June 2013 [f]. The results of this research have also been made
available to UK policymakers through Cox's position on the Scientific
Advisory Group of the Department of Energy and Climate Change (DECC),
where they have contributed to the UK's more positive attitude towards
avoided deforestation within the UNFCCC negotiations.
Brazilian Environmental Policy
Our research in this field has also had a very direct impact on
environmental policymakers in Brazil. After the publication of his paper
in 2010 , Luiz Aragao met with policymakers from the Acre regional
government of Brazil to discuss the policy implications. Out of that
meeting grew a long-term collaboration between the University of Exeter, the
Brazilian National Institute for Space Research (INPE), and the Brazilian
State Government of Acre, which culminated in the funding of a joint
project called "PULSE-Brazil", which Cox leads. This project is developing
a Geographical Information System (GIS) to display and analyse data on the
changing environmental conditions in Brazilian Amazonia, so as to inform
policy concerning responses to environmental change in the State of Acre
and other vulnerable States of Brazil [g]. PULSE-Brazil has
enabled very direct interaction with the Environmental Secretary of Acre
(Vera Reis) who has attended all of the project meetings, and has been
aided by the hiring of a Portuguese speaking project manager (Duarte
Costa) who is spending extended periods working alongside the Acre
officials in Brazil to facilitate effective knowledge exchange.
Informing Public Debate through the Media
The iconic nature of the Amazonian rainforest and its importance for the
Earth System, make our research of great interest to the public and the
media. Research from the University of Exeter has contributed
significantly to public debate, appearing in newspapers and television
programmes. For example, the Amazonian drought of 2010 and its mechanisms
were discussed extensively by the BBC [h], and the "Amazon Dieback
Scenario" was covered by the New York Times in 2011 [i]. Amazon
dieback was also described in the BBC1 Horizon "Hot Planet" episode that
aired in 2009 and 2010, and on which Cox appeared and was the scientific
consultant [j]. In 2012, Cox spent 2 weeks in Amazonia making a TV
programme, which aired in the US in October 2013 (http://www.thetippingpoints.com/).
Sources to corroborate the impact
a) A safer bet for REDD+: review of the evidence on the relationship
between biodiversity and the resilience of forest carbon stocks (2010).
b) UN Food and Agriculture Organization publication on: REDD-plus and
biodiversity: opportunities and challenges http://www.fao.org/docrep/013/i1758e/i1758e14.pdf
c) World Bank Report on Amazon Dieback (2010)
d) Amazon Dieback and the 21st Century (2011).
e) Submission to the UNFCCC AWG-LCA (2012).
f) UNFCCC Subsidiary Body for Scientific and Technical Advice, Bonn, June
g) PULSE-Brazil website and GIS tool. http://www.pulse-brasil.org/?page_id=76
h) BBC1 New article on 2010 Amazon Drought (2010). http://www.bbc.co.uk/news/science-environment-12362111.
i) New York Times (2011), "The Amazon Dieback Scenario".
j) BBC1 Horizon Documentary, "Hot Planet" (2009).