Parallel Session 1. Session 3: Theme A: Impacts-Vulnerability-Adaptation in Central and South America: Results from IPCC WG2

1. Climate Change 2014:
Jose A. Marengo
CCST INPE
Sao Paulo, Brazil
jose.marengo@inpe.br
CLIMATIC STRESSORS: MAJOR RECENT CHANGES AND PROJECTIONS IN THE CENTRAL AND
SOUTH AMERICA: MAIN RESULTS OF CHAPTER 27 CENTRAL AND SOUTH AMERICA OF THE IPCC
AR5 WG2

2. IPCC SPM WG1 (2013)

3. Executive Summary: Observed trends
Significant trends in precipitation and temperature have been observed in
CA and SESA (high confidence ). Besides, changes in climate variability and in
extreme events have severely affected the region (medium confidence ).
Increasing trends in annual rainfall in Southeastern South America (SESA;
0.6 mm/day/50years during 1950-2008) contrast with decreasing trends in
CA and Central-Southern Chile (-1mm/day /50 years during 1950-2008).
Warming has been detected throughout CA and SA (near to 0.7-1°C/40
years since the mid-1970’s), except for a cooling off the Chilean coast of
about -1 °/40 years. Increases in temperature extremes have been identified
in CA and most of tropical and subtropical SA (medium confidence), while
more frequent extreme rainfall in SESA has favoured the occurrence of
landslides and flash floods (medium confidence).

4. IPCC WG2, Chapter 21 (2014)

7. Risk of climate-related impacts results from the interaction of climate-related hazards (including
hazardous events and trends) with the vulnerability and exposure of human and natural
systems. Changes in both the climate system (left) and socioeconomic processes including
adaptation and mitigation (right) are drivers of hazards, exposure, and vulnerability.

11. Projected changes in annual average temperature and precipitation. CMIP5 multi-model mean
projections of annual average temperature changes (left panel ) and average percent change in
annual mean precipitation (right panel) for 2046-2065 and 2081-2100 under RCP2.6 and 8.5.
Solid colors indicate areas with very strong agreement, where the multi-model mean change is
greater than twice the baseline variability, and>90% of models agree on sign of change.

13. Warm nights 1951-2010Consecutive dry days 1951-2010 Heavy precip days 1951-2010
Consecutive dry days 1951-2003 Warm nights 1951-2003Heavy precip days 1951-2003
Alexander et al (2006)
Donat et al (2013)
Stations
coverage
Decay
Improve

14. Executive Summary: Projeted trends
Climate projections suggest increases in temperature, and increases or
decreases in precipitation for CA and SA by 2100 (medium confidence ).
Post-AR4 climate projections, derived from dynamic downscaling forced by
CMIP3 models for various SRES scenarios, and to different global climate
models from the CMIP5 for various RCPs (4.5 and 8.5), warming varies from
+1.6°C to +4.0°C in CA, and +1.7°C to +6.7°C in SA (medium confidence).
Rainfall changes for CA range between -22% to +7% by 2100, while in SA
rainfall varies geographically, most notably showing a reduction of -22% in
Northeast Brazil, and an increase of +25% in SESA (low confidence). By 2100
projections show an increase in dry spells in tropical SA east of the Andes,
and in warm days and nights in most of SA (medium confidence)

15. Key messages
• Observation systems are improving and hence our assessment
is better than AR4
• There are very major gaps (Africa, S. America..)
• Linking climatic, biophysical and human data is a promising way to
improve impacts assessment
• This allows us to distinguish climate change impacts from
consequences of other aspects of policy and development
• Many impacts may not have been observed, but that does not
mean that no impacts have occurred.