STATE OF THE RAINFOREST 2014
17
Improved remote sensing and monitoring technology nevertheless
means that figures for forest cover, carbon content and the emissions
stemming from forest destruction gradually become more reliable.
In the 2007 IPCC report, emissions from deforestation were
estimated to be 17%. The fact that the current estimate has
been reduced to 11% does not primarily reflect reductions in
deforestation, however. Greenhouse gas emissions from other
sources have increased significantly, and methods for calculating
emissions have developed.
50
Even if deforestation currently contributes relatively less to overall
carbon emissions, it is still vital to reduce forest-related emissions
to reach the international goals of limiting climate change to below
two degrees centigrade. Halting the destruction of tropical forests
is more important than the 11% share would seem to indicate. In
addition to their role in regulating climate patterns and rainfall and
absorbing and storing carbon, emissions from tropical deforestation
may be reduced rapidly, as the Brazilian example demonstrates.
Given the urgency of rapidly reducing emissions, and the time it
will take to alter the global energy matrix from fossil to renewable
sources – reducing emissions from deforestation is vital.
Climate change threatens the rainforest
Rainforests are vulnerable to climate change. Higher temperatures
and less rainfall over a period of time can lead to drought in areas that
usually have moist rainforest, as we have seen happen in the Amazon
and Asia during recent years.
51
Rainforest inhabitants describe that the
climate is changing. Traditional signs indicating when to plant, for
instance, are no longer reliable, and although this is not systematic
and scientifically produced knowledge, it corresponds to the changes
being observed by researchers. The 2014 report from the IPCC states
that both in South America and in Central Africa one can conclude
with “medium certainty” that changes in rainfall, floods and droughts
are related to climate change.
52
The geographical distribution of species is changing because of
climate change.
53
There is an emerging debate about whether climate
change has already led to the extinction of species, and about what
level of climate change that may trigger large scale extinction.
54
The
IPCC has previously assessed that as much as 30% of the world’s
biodiversity could be threatened in a “medium scenario”, with
temperature rise by more than 3 degrees centigrade.
55
The huge, densely forested areas of the Amazon, the Congo Basin – and
to some extent Southeast Asia – have a direct impact on the planet’s
systems for exchanging oxygen and humidity, producing rainfall and
cloud formations. There is a lot of uncertainty regarding how climate
change will affect this, but the consequences may be far-reaching.
Both in the Amazon and in the Congo Basin the forests themselves
generate a large part of total rainfall. If the forests are reduced to such
an extent that their capacity to create their own rainfall is hampered, a
tipping point will be reached that may have irreversible consequences.
This mechanism is best understood in the Amazon, where the Andean
mountain range prevents humidity from escaping west into the Pacific,
driving rainfall north and south of the Equator. Reduced rainfall and
cloud formation are bound to affect agricultural production within
these regions, and the effect may reach other continents.
World biomes and carbon storage
Carbon stored by biome*
Billion of tonnes (Gigatonnes)
Tropical, Subtropical,
Savannas, Shrublands
Tropical, Subtropical
Forests
Deserts and Dry Shrubland
Temperate Grasslands,
Savannas Shrublands
Temperate Forest
Boreal Forest
Tundra
0
100
200
300
400
500
600
Source: Adapted from Olson, D., M., Terrestrial Ecoregions of the
World: a new map of life on Earth. Bioscience, 2001; WCMC 2009
* Carbon storage values include above- and below-ground storage
and soil storage. Values calculated by UNEP-WCMC, 2009
