SEARCH BLOG: GLOBAL WARMING
When we talk about "down under" with regard to geography, we normally refer to Australia. Today, I am writing about the other "down under": South America.
Most of the focus of global warming studies have been elsewhere in the world. South America tends to be overlooked as that quaint continent where there is a lot of beef (Argentina), sugar cane (Brazil), oil (Venezuela), cocaine and coffee (Columbia) and the great Amazon rain forest. Political revolutions come and go while economies struggle and the rest of the world ignores this isolated piece of real estate.
I was curious about how global warming might be perceived in South America. Sure, we read about the Amazon rain forest and droughts, but we've also learned that the very act of clearing those forests reduces the rainfall associated with them. But what about those high temperature extremes that are supposed to occur with greater frequency. You know, the heat waves predicted by the IPCC. Are they roasting the coffee in South America?
This study says:
This study presents an examination of the trends in
indices of daily temperature extremes for South
America during 1960–2000. Data quality and homogeneity
assessments are crucial before trends in climate
indices are computed. Erroneous outlier values and artificial
steps due to changes in instrument exposure will
affect the trends in temperature extremes. [see this] In addition,
it is essential to use a consistent methodology to define
and calculate the climate extremes for a better comparison
The results show that temperature extremes are
changing in South America. The findings reveal no consistent
changes in the indices based on daily maximum
temperature. However, significant trends were observed
in the indices based on daily minimum temperatures.
The coldest night of the year is getting warmer
and there are more tropical nights. The percentage of
cold nights is decreasing while the percentage of warm
nights is increasing, and these changes are more pronounced
during the summer (DJF) and fall (MAM).
The nighttime warming corresponds to a significant decrease
in the diurnal temperature range over the continent.
Since the stations with significant trends appear to be
located closer to the west and east coasts of South
America, future work could involve an analysis of the
correlation between the sea surface temperature and
the land temperature extremes. [see this] In addition, since
ENSO events seem to have considerable impact on the
surface temperature in the southern part of the continent
(Barros et al. 2002), further work could examine
the relation between the circulation pattern and the
land surface temperature and extremes over the entire
South American landmass.
These results generally agree with what has been observed
in many other parts of the world. The nearglobal
analysis by Frich et al. (2002) has indicated an
increase in the frequency of warm nights, a decrease in
the extreme temperature range, and also a decrease in
the number of frost days. Frost days is not a representative
index for South America since the temperature
remains above 0°C almost everywhere with the exception
of the stations located in the high mountains of
Ecuador, Peru, and Bolivia, and for those stations located
in the southern part of Argentina and Chile. The
results from the Caribbean region have indicated that
the frequency of warm nights and warm days has significantly
increased since the late 1950s while it seems
that in South America only the warm nights have increased.
I'll refer you to one of my previous posts. Note the graph at the end.
Global Warming Without New High Temperature Extremes?