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How Climate Change Is
Affecting Living Things
• Organisms can only survive, grow, and
reproduce in a limited range of
environmental conditions
• No two species will react the same to
climate change
• Scientists use
observational studies,
experiments, and
modeling to measure
the effects of climate
change on living things
and to predict future
effects.
Free-Air C02
Enrichment experiments
HOW HAVE BIOLOGICAL
SYSTEMS CHANGED?
Physiology and Morphology
• Climate change can affect the physiology
and morphology (life processes and body
form) of some organisms.
• When exposed to stress, some organisms
may acclimatize within days or weeks,
undergo genetic change over many
generations, or go extinct.
• The effects can be positive or negative.
– Ex. Some species may grow more quickly and
get bigger, such as lizards (ectothermic =
“cold-blooded”)
– whereas other species may sicken and die
because of heat or drought.
• Temperature sensitivity
will increase the effects
– Ex. Most sea turtles
undergo temperature
dependent sex
determination (above 29
degrees = mostly
female, below = mostly
males)
Phenology • Climate change can change the timing, or
phenology, of some life processes,
including flowering, ripening, migration,
reproduction, and hibernation.
– Ex. In some tree species, buds can open
earlier in the spring and leaves can drop later
in the fall.
• Trophic mismatches
may arise (the
phenology of one
species no longer
matches that of its
food source)
Ex. Songbirds and their
caterpillar prey
Abundance and Distribution
• Climate change can affect where
populations live (range) and how many
individuals there are in each population
(abundance).
• As the Earth warms, scientists expect
organisms to move to higher altitudes and
pole ward to higher latitudes
• A population’s range (the area in which it
lives) can expand, contract, or shift to a
new area.
– Ex. Some tree species, such as hemlock,
white pine, maple, and beech are migrating
hundreds of meters per year
• The size of a population may increase or
decrease.
– Ex. Aldabra banded snail went extinct around
2000. It was found on only a few island in the
Indian Ocean
• Populations with small ranges, low
populations, narrow climate tolerances,
and lack of alternative habitats will be
more at risk for extinction
Ecosystem Structure and Function
• Climate change can
affect whole
ecosystems.
• Systems that grow
and adapt slowly are
especially vulnerable
– Ex. Coral reefs are
under stress from
rapid ocean warming
Coral bleaching
(expulsion of
symbiotic algae) is a
serious concern
• It can cause native species to be lost from
one area and be replaced by non-native
species that don’t belong in that area.
• It can create novel ecosystems where
combinations of species that haven’t
previously co-existed form
• Climate change also can alter the
productivity of plants and how organisms
in a food web interact with one another.
• Scientists unsure the effects on ecosystem
services important to humans ( ex. Clean
drinking water, pollination of crop plants,
medicines and foods, etc.)
Evolution
• Some populations may be able to evolve
in response to climate change,
• More likely when the populations are large
and the individuals in the population have
a short life spans.
• Ex. Northern Canada red squirrel – evolved
earlier reproduction times in response to warmer
springs in just 10 years.
• Ex: modern three-toed skinks in Australia -
in warm low lying areas they lay eggs, but
some in colder higher altitudes have
started giving birth to live young. May
eventually form two separate species
• However, widespread rapid evolution is
not common and is unlikely to provide a
biological solution to climate change.
• Evolution normally requires long periods
of time