The coastal area includes the southern coast of the United States of America and the eastern shoreline of Mexico. Covering about 140,753 km2, current and projected population in 2100 are both in the large population size category (high risk) with a density of 81 persons per km2 in 2010 and increasing to 129 per km2 in 2100. About 24% of coastal population lives in rural areas, and is projected to decrease slightly to 23% in 2100.
The indigent population makes up 31% of the LME’s coastal dwellers. The Gulf of Mexico places in the highest-risk category based on percentage and absolute number of coastal poor (present day estimate).
Revenues and Spatial Wealth Distribution:
Fishing and tourism depend on ecosystem services provided by LMEs
. The Gulf of Mexico LME ranks in the high revenue category in fishing revenues based on yearly average total ex-vessel price of US 2013 $1.7 billion (thousand million) for the period 2001-2010. Fish protein accounts for 8% of the total animal protein consumption of the coastal population. Its yearly average tourism revenue for 2004-2013 of US 2013 $252 billion places it in the highest revenue category. On average, LME-based tourism income contributes 9% to the national GDPs of the LME coastal states. Spatial distribution of economic activity (e.g. spatial wealth distribution) measured by night-light and population distribution as coarse proxies can range from 0.0000 (totally equal distribution and lowest risk) to 1.0000 (concentrated in 1 place and most inequitable and highest risk). The Night Light Development Index (NLDI) thus indicates the level of spatial economic development, and that for the Gulf of Mexico LME falls in the category with lowest risk.
Human Development Index:
Using the Human Development Index (HDI) that integrates measures of health, education and income, the present-day Gulf of Mexico LME HDI belongs to the highest HDI and lowest risk category. Based on an HDI of 0.856, this LME has an HDI Gap of 0.144, the difference between present and highest possible HDI (1.000). The HDI Gap measures an overall vulnerability to external events such as disease or extreme climate related events, due to less than perfect health, education, and income levels, and is independent of the harshness of and exposure to specific external shocks.
HDI values are projected to the year 2100 in the contexts of shared socioeconomic development pathways (SSPs). The Gulf of Mexico LME is projected to maintain its position in the lowest risk category (highest HDI) in 2100 under a sustainable development pathway or scenario. Under a fragmented world scenario, this LME is projected to slip to the high risk category (low HDI) because of reduced income level and bigger population size compared to estimated income and population values in a sustainable development pathway.
Climate-Related Threat Indices:
The Climate-Related Threat Indices utilize the HDI Gaps for present-day and projected 2100 scenarios. The contemporary climate index accounts for deaths and property losses due to storms, flooding and extreme temperatures incurred by coastal states during a 20-year period from 1994 to 2013 as hazard measures, the 2010 coastal population as proxy for exposure, and the present day HDI Gap as vulnerability measure.
The Contemporary Threat Index incorporates a Dependence Factor based on the fish protein contribution to dietary animal protein, and on the mean contribution of LME tourism to the national GDPs of LME coastal states. The HDI Gap and the degree of dependence on LME ecosystem services define the vulnerability of a coastal population. It also includes the average of risk related to extreme climate events, and the risk based on the degrading system states of an LME (e.g. overexploited fisheries, pollution levels, decrease in coastal ecosystem areas).
The 2100 sea level rise threat indices, each computed for the sustainable world and fragmented world development pathways, use the maximum projected sea level rise at the highest level of warming of 8.5 W/m2 in 2100 as hazard measure, development pathway-specific 2100 populations in the 10 m × 10 km coast as exposure metrics, and development pathway-specific 2100 HDI Gaps as vulnerability estimates.
Present day climate threat index to the Gulf of Mexico LME is within the high-risk (high threat) category. The combined contemporaneous risk due to extreme climate events, degrading LME states and the level of vulnerability of the coastal population, is medium. In a sustainable development scenario, the risk index for sea level rise in 2100 is in the lowest risk category, and which increases to high-risk category under a fragmented world development pathway.