Amazon As Carbon Sink: Over the past 40 years, eastern Amazonia has been subjected to more deforestation, warming, and moisture stress than the western part, especially during the dry season, with the southeast experiencing the strongest trends” said the study.
Explained: How Role of Amazon As Carbon Sink is Declining ?
New Delhi (ABC Live India): Amazon As Carbon Sink: Amazonia hosts the Earth’s largest tropical forests and has been shown to be an important carbon sink. This carbon sink seems to be in decline, however, as a result of factors such as deforestation and climate change, according to a new paper published in Nature.
A carbon sink is any reservoir, natural or otherwise, that accumulates and stores
some carbon-containing chemical compound for an indefinite period and thereby
lowers the concentration of CO2 from the atmosphere.
Globally, the two most important carbon sinks are vegetation and the ocean. Public awareness of the significance of CO2 sinks has grown since the passage of the Kyoto Protocol, which promotes their use as a form of carbon offset.
The study was led by Lucia Gatti, Group Leader, Brazil’s
National Institute of Space Research /Center of Earth System Science and a
member of the steering committee for the Integrated Global Greenhouse Gas
Information System spearheaded by WMO.
The authors investigated Amazonia’s carbon budget and the main
drivers responsible for its change into a carbon source. The group used
observational-based approach to evaluate the ecosystem carbon fluxes
evaluation and performed 590 aircraft vertical profiling measurements of
lower-tropospheric concentrations of carbon dioxide and carbon monoxide at four
sites in Amazonia from 2010 to 2018.
They found that total carbon emissions are greater in eastern
Amazonia than in the western part because this part experiences stronger
increase in dry-season temperature and reduced precipitation. Southeastern
Amazonia, in particular, acts as a net carbon source (total carbon flux minus
fire emissions) to the atmosphere.
“Over the past 40 years, eastern Amazonia has been subjected to
more deforestation, warming, and moisture stress than the western part,
especially during the dry season, with the southeast experiencing the strongest
trends” said the study.
explore the effect of climate change and deforestation trends on carbon
emissions at our study sites, and find that the intensification of the dry
season and an increase in deforestation seem to promote ecosystem stress,
increase in fire occurrence, and higher carbon emissions in the eastern Amazon.
This is in line with recent studies that indicate an increase in tree mortality
and a reduction in photosynthesis as a result of climatic changes across
Amazonia,” it said.
Carbon sinks such as the carbon uptake by the terrestrial biosphere is a vital regulator of climate change by removing one quarter of
the carbon dioxide emitted into the atmosphere by humans.
If sinks such as the Amazon become net emitters, because of
deforestation and fires, as well as a result of climate change, there is the
potential for this to become a “tipping point” in the climate system. This
would consequently have far-reaching implications for slowing the pace of
climate change and temperature increase.
Achievement of the Paris Agreement targets requires a certain
balance between sources and sinks of greenhouse gases. In the race for net-zero
more countries are looking at reforestation projects to increase the uptake of
carbon dioxide from the atmosphere. Tropical forests were considered as a sink
for CO2 until now, but changes in temperature and precipitation patterns create severe environments for vegetation that can turn them to carbon sources.
About one-quarter of the 2030 mitigation pledged by countries in their initial
nationally determined contributions (NDCs) under the Paris Agreement is
expected to come from land-based mitigation options.
The Intergovernmental Panel on Climate Change Special Report
on Land said: “Concurrent with these climate envelope shifts
will be the emergence of new, hot climates in the tropics and increases in the
frequency, intensity, and duration of extreme events (e.g., heatwaves, very
heavy rainfall, drought). These emergent hot climates will negatively affect
land use (through changes in crop productivity, irrigation needs, and management
practices) and land cover through loss of vegetation productivity in many parts
of the world, and would overwhelm any benefits to land use and land cover
derived from increased atmospheric CO2 concentrations”
Atmospheric concentrations of CO2 continue to increase to record levels, and
deforestation is one of the reasons for this, according to WMO's Greenhouse Gas
WMO’s Global Atmosphere Watch network, spanning more than 50
countries provide accurate measurements which form the basis of our
understanding of greenhouse gas concentrations, including their many sources, sinks
and chemical transformations in the atmosphere.
Details of the Nature study are here.