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Ecosystems are subject to many pressures. You can probably name
several. Land-use changes, pollutants, grazing by livestock, introduction
of exotic species, and natural climate variability, all affect
ecosystems.
In many parts of the world, scientists have observed changes in
ecosystems that are consistent across a wide variety of localities.
These changes are just what you would expect as a result of regional
temperature change. 'The probability that the observed changes
in the expected direction could occur by chance alone, is negligible.' Climate
Change 2001 Synthesis Report, p 54
Figure 1 below, shows the locations at which studies have documented
regional temperature change impacts. The consistency in these observed
changes across regions, heightens the confidence that changes in
the biological systems is a result of the changes in regional climate.
There is high confidence that 20th century climate changes have
had a discernible impact on many biological systems. What's more,
these systems are sensitive to climatic changes that are small,
relative to changes that have been projected for the 21st century.
Changes have been seen in species distributions, population sizes,
and the timing of reproduction or migration events. For example,
some animal ranges are moving toward the poles, i.e. north in the
northern hemisphere and south in the southern hemisphere. Some
animals are moving to higher elevations. There are changes in body
size. Animal breeding, plant flowering and insect emergence are
all happening earlier in the spring. Regional climate change appears
to be a major contributing factor. (IPCC WGII section 5.4.3)
Disturbances such as fires, droughts, and blowdowns have changed
in intensity, and frequency. These events are affected by regional
climatic change and land-use practices. These events then affect
the productivity of species, and the species composition within
an ecosystem, particularly at high latitudes and high altitudes.
Frequency of pest and disease outbreaks have also changed, especially
in forested systems, and can be linked to changes in climate.
Figure 1. Locations of long-term studies which show regional climate
change impacts on biological systems.
Locations at which systematic long-term studies meet stringent
criteria documenting recent temperature-related regional climate
change impacts on physical and biological systems. Hydrology,
glacial retreat, and sea-ice data represent decadal to century
trends. Terrestrial and marine ecosystem data represent trends
of at least 2 decades. Remote-sensing studies cover large areas.
Data are for single or multiple impacts that are consistent with
known mechanisms of physical/biological system responses to observed
regional temperature-related changes. For reported impacts spanning
large areas, a representative location on the map was selected.
Source: Climate Change 2001 Synthesis Report p. 285
Many threatened systems are at risk from climate change because
they face pressures from human activities such as land-use and
pollution. Critically endangered species are generally species
with small ranges, low population densities, restricted habitat
requirements, and species with suitable habitat distributed
| Table 1: State of some of the
world's vertebrate wildlife. For each region, the table lists
the number of critically endangered, endangered, and vulnerable
species respectively, separated by slashes (UNEP, 2000). |
| Region |
Totals |
Amphibians |
Reptiles |
Birds |
Mammals |
| Africa |
102 / 109 / 350 |
0 / 4 / 13 |
2 / 12 / 34 |
37 / 30 / 140 |
63 / 63 / 163 |
| Asia and the Pacific |
148 / 300 / 739 |
6 / 18 / 23 |
13 / 24 / 67 |
60 / 95 / 366 |
69 / 163 / 283 |
| Europe and Central Asia |
23 / 43 / 117 |
2 / 2 / 8 |
8 / 11 / 10 |
6 / 7 / 40 |
7 / 23 / 59 |
| Western Asia |
7 / 11 / 35 |
0 / 0 / 0 |
2 / 4 / 2 |
2 / 0 / 20 |
3 / 7 / 13 |
| Latin Americaa and the Caribbean |
120 / 205 / 394 |
7 / 3/ 17 |
21 / 20/ 35 |
59 / 102 / 192 |
33 / 80 / 150 |
| North America |
8 / 85 / 117 |
2 / 8 /17 |
3 / 12 / 20 |
19 / 26 / 39 |
14 / 39 / 41 |
| a UNEP data place Mexico in
North America because of similarity of biomes. |
Source: Climate Change 2001 WG II, section 5.4.3
Table 2: Species found in studies to be associated
with regional temperature change.a
| Region |
Vegetation |
Invertebrates |
Amphibians and Reptiles |
Birds |
Mammals |
| Africa |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
| Antarctica |
2 |
0 |
-- |
-- |
-- |
-- |
2 |
0 |
-- |
-- |
| Asia |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
| Australia |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
| Europe |
13 |
1 |
46 |
1 |
7 |
0 |
258 |
92 |
7 |
0 |
| North America |
32 |
11 |
-- |
-- |
-- |
-- |
17 |
4 |
3 |
0 |
| Latin America |
-- |
-- |
-- |
-- |
22 |
0 |
15 |
0 |
-- |
-- |
| Total |
47 |
12 |
46 |
1 |
29 |
0 |
292 |
96 |
10 |
0 |
a The columns represent the number of species
in each region that were found in each particular study to be associated
with regional temperature change. For inclusion in the table, each
study needed to show that the species was changing over time and
that the regional temperature was changing over time; most studies
also found a significant association between how the temperature
and species were changing. The first number indicates the number
of species changing in the manner predicted with global warming.
The second number is the number of species changing in a manner
opposite to that predicted with a warming planet. Empty cells indicate
that no studies were found for this region and category.
Source: Climate Change 2001 Synthesis Report p. 286
Content Updated Sept 2005
Activity:
- What do you think is the difference between
critically endangered, endangered and vulnerable species?
- Are critically endangered, endangered or
vulnerable species more susceptible to climate change? Why?
- Create a bar graph using the Table 1 data,
for critically endangered species of each type for each region.
- Is there a class of vertebrate species which
is has the most species represented across all regions?
- Is there a region that has more critically
endangered species than others?
- Look at Table 2. What kinds of species have
been added compared to Table 1?
- What is the difference between the 2 numbers
for each type of species?
- Look at the numbers of species changing
in the manner opposite to what you would expect with a warming
planet. What are some possible explanations for this?
- What areas have had the most studies? See
table 2 and Figure 1. Why do you think this is the case?
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