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