The Ecology Book

276

M

ost scientists now agree

that climate change,

driven by an increase

in greenhouse gases, is raising

the global mean temperature. The

Intergovernmental Panel on Climate

Change (IPCC) cites an increase

of 1.8°F (1°C) since 1880, although

in some regions the warming has

been even more marked. This

warming has affected both plant

and animal behavior, and the IPCC

forecasts a further increase

of 2.5–9.9 °F (1.4–5.5°C) during the

next 100 years.

The life cycles of plants and

animals change in line with the

seasons. Phenology is the study

of these seasonal changes. They

may be triggered by temperature,

rainfall, or the length of daylight,

but temperature is probably the

single most important factor in

Earth’s temperate and polar regions,

whereas rainfall is the key factor in

the tropics. In 2003, climate change

scientists Camille Parmesan and

Gary Yohe proved that spring

change is now happening earlier—

a phenomenon called spring creep.

Season creep

For several decades, people have

observed leaves and flowers

appearing earlier in spring. In

the past, these claims were often

dismissed as lacking “hard science,”

such as facts, figures, or datasets.

SPRING CREEP

Seasonal changes

in the weather

Plants grow leaves,

produce flowers and fruit,

and shed their leaves.

After hatching, amphibians, insects, and

some other animals metamorphose from

one body form into another.

Birds nest and breed. Many birds

(and some other animals) make

long-distance migrations.

The impact of seasonal

changes on plants and animals

All life forms respond to changes in weather brought

about by the seasonal cycle. Migration, breeding,

flowering, hibernation, and metamorphosis are

some of the events affected by this cycle.

Mammals breed and raise

young. Some mammals go into

hibernation over the winter.

IN CONTEXT

KEY FIGURE

Camille Parmesan (1961–)

BEFORE

1997 A group of American

scientists publishes evidence

of a longer plant growing

season at northern high

latitudes in 1981–91.

2002 Naturalist Richard Fitter

reveals that the first flowering

date of 385 plant species in the

UK has advanced by 4.5 days

in the previous decade.

AFTER

2006 Jonathan Banks, from

the American Clean Air Task

Force, is the first person to use

the term “season creep” to

describe the increasingly early

onset of the seasons as a result

of climate change.

2014 In the US, the National

Climate Assessment confirms

long-term trends toward

shorter, milder winters and

earlier spring thaws.

We are seeing

change happen

much faster than

I thought it would

10 years ago.

Camille Parmesan

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