Mediterranean Ecosystems Worldwide: Climate Adaptation - Recent Advances and Issues in Environmental Science - page 36

In addition to showing where the MCE is projected to contract, we also wanted
to determine if there was AOGCM agreement on why it will contract (e.g., a warmer
winter temperature, or less annual precipitation). These changes will have important
implications for the persistence of native plants and animals in the mediterranean bi-
ome. To do this, we determined the level of agreement among the AOGCM simulations
on which Aschmann's conditions were no longer met for the areas with a projected
contraction. We report the results for areas where at least 90% of the AOGCM simula-
tions agree that the MCE will contract and agree on the changing climatic condition
causing the contraction under the high emissions scenario. Across all fi ve regions, we
can project with the most confi dence that 7.2% of the current MCE will contract. Over
half of this projected contraction, or 4.0% of the current MCE, results from warming
in the winter. Almost a quarter of the projected contraction, or 1.7% of the current
MCE, results from a drop in total annual precipitation below the 275 mm threshold.
For one fi fth of the projected contraction, or 1.5% of the current MCE, the AOGCM
simulations agree that an area will contract, but they do not agree on which condition
will change. By country, most of the loss in Australia, the US, Iran, Israel, and Libya
is attributable to a warming winter, while the majority of the loss in Argentina, South
Africa, Morocco, and Syria is due to a drop in annual precipitation.
Current land conversion and protection status and confi guration relative to these
climatic changes will play an important role in determining the extrinsic adaptation
potential for the species of the mediterranean biome. Approximately one third of the
area in the current MCE has already been converted to agricultural and urban land
uses. If most of the converted land is in areas where the MCE is projected to contract,
extrinsic adaptation potential will not be signifi cantly reduced because these areas
are poor habitat for native species. However, if the areas projected to have a stable
or expanded MCE are disproportionately converted, this will exacerbate the negative
impacts of climate change on biodiversity in the mediterranean biome. When look-
ing across all fi ve regions, we found the land conversion patterns are similar in areas
where the MCE is projected to contract with confi dence (23%) and in areas projected
to remain stable with confi dence (29%), but the regional patterns were more variable
(Figure 3). In California and Mexico, extrinsic adaptation potential is conserved in the
future because most of the conversion lies in areas that are projected to contract, and
there is little conversion in the areas of stability. Similarly, Chile/Argentina and South
Africa also have low levels of conversion in the confi dent stable areas. The opposite is
true in Australia, where 64% of the likely stable area and 49% of the confi dent stable
area is already converted, greatly diminishing the extrinsic adaptation potential of na-
tive biota.
At 4%, the level of protection for biodiversity in the current MCE is below that
of the more expansive mediterranean biome (5%) and well below the global average
(12%) for all terrestrial biome types [5]. We wanted to determine if the level of pro-
tection is higher or lower in areas with high likelihood of retaining a mediterranean
climate. For the entire biome, just over half of the existing protected areas are pro-
jected to retain the mediterranean climate with high confi dence, even under the high
emissions scenario (Figure 4). The projected status of protected lands in some regions
is much better, as over 70% of the protected areas in California/Mexico, South Africa,