Section 20. Global Warming
Contents
Contents.................................................................................................................................................. 20-1
Why Global Warming Is a Threat ....................................................................................................... 20-1
Hazard Profile ....................................................................................................................................... 20-3
Location of Hazardous Areas .............................................................................................................. 20-4
History of Chlimate Change ................................................................................................................ 20-4
People and Property at Risk ................................................................................................................ 20-5
Why Global Warming Is a Threat
The Rio Grande Border Region, especially the Lower Rio Grande Valley, is at risk from global
warming, but its effects will not be seen for some time and thus is not identified in this Plan for
mitigation action between 2007 and 2012, the period covered by this Plan.
The last few decades have been marked by a gradual increase in average global temperatures.
A majority of climatologists believe that human activity, in particular the emission of
greenhouse gases, has played a large part in this warming. Other scientists believe the earth
may just be on the upward swing of a recurrent cycle of cooling and warming. Regardless of
causation, continued rises in atmospheric temperatures would pose several threats throughout
the globe area including the following:
 Hotter summers
 More frequent and prolonged droughts
 In the longer run, higher ocean levels leading to inundation of low lying areas
 And, possibly, more unstable weather patterns and more severe hurricanes
The following graphic (Figure 20-1) from the Austin American Statesman on February 3, 2007
summarizes the possible effects of global warming on Texas through the end of this century
under three scenarios. The scenarios differ in how much emissions are projected to climb as the
result of economic growth across the globe. The mid-range projections, which assume that
growth would leave economies still primarily dependent on fossil fuels but with significant
gains in efficiency, have average temperatures climbing 5.5 to 8 degrees Fahrenheit ( or 3.1 to
4.4 degrees Centigrade) and sea levels rising by about one to two feet.
Section 20
Indeed, the Earth’s atmosphere is so thin that we have the
capacity to dramatically alter the concentration of some of its
basic molecular components. In particular, we have vastly
increased the amount of carbon dioxide—the most important of
the so-called greenhouse
1 gases. An Inconvenient Truth, p.25.
Figure 20-1
Section 20
2
Almost all of the mountain
glaciers in the world are now
melting, many of them quite
rapidly.
An Inconvenient Truth, p. 48.
The Center for Earth and Environmental Sciences at Texas A&M University International has
examined possible effects of global warming on the Rio Grande Basin in particular. While there
is consensus about global trends, the potential impact on relatively small areas is somewhat less
agreed upon. For the Rio Grande Basin, general agreement upon the likelihood of higher
temperatures is not matched by confidence upon whether rainfall is likely to increase or fall. In
fact, the outlook is for precipitation to be as much as 50 percent higher or lower than historical
averages.
Hazard Profile
Figure 20-2. Global Warming Hazard Profile Summary for the Rio Grande Basin
The future probability of continued warming in the Rio Grande Basin is “Highly Likely”,
although the effects would be felt more in some years than in others and much more over the
long term. The spatial extent of global warming is “Large,” expected to affect all parts of the
Basin. The potential impact of global warming is “Critical” resulting in measurable increases in
deaths from high temperatures and significant agricultural losses. Higher winter time
temperatures across the country may lessen the attractiveness of the Basin as a destination of
“snow birds.” The most severe losses in the long run will be along coastal areas where
valuable developed areas are inundated.
Section 20
3
Since the 1970s, the extent and thickness of the
Artic ice cap has diminished precipitously. There
are now studies showing that if we continue with
business as usual, the Artic ice cap will
completely disappear each year during the
summertime.
An Inconvenient Truth, p. 143
Location of Hazardous Areas
As the term implies, global warming would not be a localized phenomenon. Higher
temperatures and more severe droughts would affect all area in the basin more or less evenly.
Higher sea levels would be of most immediate concern in Cameron County because of its
coastal location. The elevations of South Padre Island, Laguna Heights, Laguna Vista, and Port
Isabel are all near sea level so even a one foot increase in ocean levels could have dramatic
effects.
History of Climate Change
The following evidence of global warming comes from “Climate Change 2007: The Physical
Science Basis,” February 5, 2007, issued by the Intergovernmental Panel on Climate Change.
 Eleven of the twelve warmest years recorded since 1850 have occurred from 1995 to the
present.
 Over the past 50 years, average global temperatures have gone up by 0.13 degrees
Centigrade per decade, a rate of increase much greater than in the preceding 50 years.
 Observations over the last 45 years show that ocean temperatures up to 3000 meters
have climbed and that the ocean is absorbing more than 80% of the heat added to the
climate system.
 Mountain glaciers and snow cover have declined in both hemispheres.
 The 20th century rise in ocean levels is estimated to be 0.17 meters.
 Temperatures in the Artic have increased at almost twice the global average.
 Although there is not a clear trend in the number of North Atlantic hurricanes since
1970, observations suggest that the power of the storms has increased, perhaps related to
higher ocean surface temperatures.
Section 20
4
People and Property at Risk
There is no defined geographic boundary for climate changes. All population, buildings, critical
facilities, infrastructure and lifelines, and hazardous materials facilities are considered exposed
and could potentially be impacted. Coastal areas would be at risk from changes in ocean levels.
Based on a qualitative analysis of the impacts that this hazard would have on the social,
economic, and environmental components of the region, the risk of global warming is not
sufficient to merit mitigation consideration.
Section 20
5