Over the last 100 years, the average global
surface temperature has warmed ~0.75°C (~1.4°F) and
is projected to rise at an escalating rate over the next
century. This rate of warming is significantly larger than
the rate of sustained warming over the 6,000 years it
took for the globe to warm about 6°C from the last ice
age to our current warm interglacial period. Extrapolating
the more recent warming trend, we see that a 7°C/1000
years rise in temperature is some seven times faster
than in the last 18,000 years. As the planet warms, the
rate will continue to escalate.
Not only are wild species and their ecosystems
having to adapt to rapidly warming temperatures but
they also have to cope with other human-caused
problems, such as pollution, land-use change, and
invasive species. The synergistic effects of these stresses
are greatly affecting the resilience of many species and
ecosystems. Noticeable changes have been measured
in species over the last 30 to 40 years while the global
temperature increased around 0.5°C. As the Summary
for Policymakers of Working Group I of the Fourth
Assessment Report of the IPCC explained, the global
temperature could rise over the next 90 years as much
as 6.4°C if we stay on our current energy path—allowing
few species to adapt without severe disruptions.
Hundreds of studies have found that wild animals and
plants on all continents are already exhibiting discernible
changes in response to regional climatic changes.
CHANGES IN RANGES
As the globe warms, species in North America are
extending their ranges north and up in elevation, as
habitats in these areas have warmed sufficiently to allow
colonization. The movements of species forced by
rapidly rising temperatures, however, are frequently
slowed or blocked by other human-made stresses, such
as land-use changes. Consequently, moving populations
have to navigate around, over, or across freeways,
agricultural areas, industrial parks, and cities.
Species near the poleward side of continents (e. g.,
South Africa’s fynbos) and near mountaintops will
have no habitats into which they can disperse as their
habitat warms. Species living in these areas will be further stressed by species from farther inland or farther
down the mountain moving into their habitats. Indeed,
many species currently on islands, on the poleward
side of continents, and near the tops of mountains
could easily go extinct unless humans move them to
another location and make sure they survive there.
From pre-historic to more recent times, species have
been found to move independently from other species
in their ecosystem, depending on their unique metabolic,
physiological, and other requirements. Such independent
movement could tear apart communities and disrupt
biotic interactions such as predator-prey relationships.
Progressive acidification of oceans due to increasing
atmospheric carbon dioxide is also expected to have
negative impacts on marine shell-forming organisms
(e.g., corals) and their dependent species. Indeed, by
2100 ocean pH is very likely to be lower than during the
last 20 million years.
CHANGES IN TIMING
Species on every continent are shifting their timing,
such as frogs breeding earlier, cherry blossoms blooming
earlier, and leaves turning color later. Over the last
30 years, around 115 species that have exhibited
significant changes (plants and animals) in locations
around the globe were found to be changing the timing
of a spring event earlier by around five days per decade.Only six out of the 115 species (~5%) showed a later
timing change.
EXTIRPATION AND EXTINCTION
The escalating rise in average global temperatures over
the past century has put numerous species in danger
of extinction. “Functionally extinct” species, or species
highly likely to go extinct, include those that cannot
move to a different location as the temperature increases
due to either lack of available habitat or the inability to
access it. Without human assistance the probability of
these species going extinct is quite high.
Money, land, personnel, or political will are not
available for such adaptive endeavors to occur. Also
absent is the long-term commitment to translocate
even half of the functionally extinct species we know
of today. Consequently, many scientists predict that
we are standing at the brink of a mass extinction that
would be caused by one very careless species.
Roughly 20 to 30 percent of known species are likely
to be at increasingly high risk of extinction if global
mean temperatures exceed 2–3°C above pre-industrial
temperatures (1.3–2.3°C above current). Somewhere
between 340,000 and 570,000 of 1.7 million identified
species could be committed to extinction primarily
due to our negligence.
If we do not change our present trajectory of carbonemitting
energy, the global average temperature could
warm by 4°C, committing more than 40 percent of
the known species to eventual extinction. That is an
unethically high price to pay.
What can we do? LOTS! Just as each vote counts,
what each of us does adds up to help the Earth win.
Some suggestions: drive fuel-efficient cars; stop using
incandescent light bulbs in your home or office; when
replacing your roof install an insulating one; use highly
energy-efficient windows, heaters, air conditioners, and
appliances when remodeling. Use material that does
not need to be shipped long distances and make sure
those materials are harvested sustainably. Buy as much
locally produced food as possible, and, last but by no
means least, support government officials who are not
afraid to take the lead in solving this problem.
FINDINGS OF THE FOURTH ASSESSMENT REPORT OF THE INTERGOVERNMENTAL PANEL CLIMATE CHANGE
This time around, the Intergovernmental Panel on
Climate Change (IPCC) reports have bluntly stated
Findings of the Fourth Assessment
Report of the Intergovernmental Panel on
Climate Change
that humans are indeed causing the globe to warm
and the warming is more rapid than it has ever
been in the last 18,000 years. In unusually direct
language, Working Group I stated that recent
warming is “unequivocal” and that humans are
very likely to be a major cause in the past several
decades at least. Increased heat waves and more
intense hurricanes were also said to be associated
with this warming trend.
The warming trend is already greatly affecting wild plants and animals Working Group II noted. If we do not kick our carbonbased
energy source habits in the not-too-distant future, then the probability of having global average temperatures rise 4°C by 2080–2100 is higher than comfortable, given
that the increase could very well directly and indirectly cause more than 40 percent of the species on our planet to be committed to extinction unless humans intercede.
Peter Altman of the Natural Environmental Trust, with thoughtful oversight by various authors of the IPCC, constructed this telling graphic (above).