+

Evidence of Climate ChangeGlaciers, geographic ranges, flower bursts, migratory patterns, and mating seasons

2+Global temperature change has affected ecosystems in the past and present“Bleaching” of reef building coralsShift of species geographic rangesMigratory birds arrive earlier at their

summer breeding groundsInsects and amphibians breed earlierNot a new occurrence

3+If climate change is real…So are the problems

Rate of warming increasing greater than other warming events in geologic time?

Evolutionary adaptations for species survival may not have time to occur

Natural areas no longer cover the whole landscape

Species that shift to higher altitudes may have reached the peak of the mountain

Species’ habitat disappears entirely Species disappear entirely

+Climate plays a major role in defining the niche of all speciesTemperatures too hot or too cold, too

much moisture or too little, all determine where plants can grow and where animals can survive.

The niche space in which species can survive is determined in large part by suitable climatic conditions.

+Species’ ranges shift over time to track suitable climate. When climate changes in a location, some

species may find themselves in suddenly hostile conditions.

Others will find that previously unsuitable climates have changed in their favor.

Individuals in unsuitable conditions will die or fail to reproduce, gradually disappearing from the location, whereas individuals near newly suitable habitat will gradually occupy areas in which they have not occurred previously.

+First Sign of Change: Coral BleachingCorals harbor microscopic algae called

zooxanthellae within their tissues. Zooxanthellae provide products of

photosynthesis to the coral, while the coral in turn provides a physical reef structure that keeps the zooxanthellae near the surface, where light for photosynthesis is abundant.

When this symbiotic relationship breaks down due to high water temperature, corals expel their zooxanthellae, causing them to appear white or “bleached.”

+Coral head in St. Croix bleached in 1995

+Bleaching is directly related to temperature Bleaching occurs when SST rises more than 1 or

2°C above normal summer maximal temperatures for periods longer than 3–5 weeks.

Thus, both temperature and duration of exposure are important determinants of whether bleaching occurs and its severity once it happens.

Coral bleaching was undescribed in the scientific literature 50 years ago, yet it is so common and widespread today that almost all coral reefs in the world have been affected at one time or another.

+Evidence of coral bleaching In the central lagoon of Belize, staghorn coral

(Acropora cervicornis) was the dominant species until the 1980s, when it was wiped out by a combination of disease and rising water temperatures. The scroll-like coral Agaricia tenuifolia took over as the dominant coral, only to be wiped out in the high water temperatures of the 1998 El Niño event.

These massive mortalities were the worst in at least 3000 years, resulting in range changes over large areas of the Caribbean for staghorn and other corals.

+Evidence of coral bleachingThere were seven major coral bleaching

events, affecting reefs in all areas of the world, between 1979 and 2002.

There have been several pan-global mass bleaching events since.

All of these events are associated with El Niño conditions. The 1997–1998 El Niño was the worst of the last century for coral bleaching. In that event, reefs throughout the world were affected.

More than 10% of all the world's corals died in that event, with mortality in some regions, such as the Indian Ocean, as high as 46%.

+A terrestrial sign of change: Butterfly distributionCheckerspot butterflies (genus Euphydras) had

been known to be vulnerable to population crashes or booms due to weather conditions for some time.

A 1996 study showed that Edith's checkerspot butterfly (Euphydras editha) was undergoing a major range shift. Populations of Edith's checkerspot are found from Mexico to Canada, and populations in the south and in the lowlands were found to be disappearing faster than populations in the north and in the uplands.

+Butterflies & birds have moved north in Europe In Europe, a study of 35

butterfly species found that 63% had undergone northward range shifts Only 3% had shifted southward.

Range shifts were large—between 35 and 240 km.

Of 59 species of birds in Great Britain, a mean northward range shift of nearly 20 km was observed over 20 years. Speckled wood butterfly

1970-1997: blue1915-1939: black

+More shifts recorded in last 100 years in Europe Dragonflies in Great Britain have expanded

northward; 23 of 24 well-documented species haves hown a northward shift, with a mean shift of 88 km.

A total of 77 lichen species have expanded their ranges northward into The Netherlands.

Alpine plants have been moving upslope in Swiss mountains.

These results are all for relatively well-known species for which good historical records exist.

+The number of documented cases of invasions of non-native species is rising steadily

+Shift seen in arctic animal ranges

+Reduction in algae in Antarctic and phytoplankton in N Atlantic The freshwater input to the North Atlantic

increased stratification in shelf waters off Canada and Europe in the 1990s. When dense waters of the Gulf Stream hit the lighter freshwater, they were less likely to sink, meaning that phytoplankton stayed closer to the surface and photosynthesized more.

The rise in phytoplankton caused autumn spikes in the zooplankton that fed on them and, ultimately, increases in commercially valuable species such as herring.

+Reduction in algae in Antarctic and phytoplankton in N Atlantic Decline in the

abundance of algae that grows on the underside of the ice

Resultant declines and range retractions in krill that feed on the algae

Populations of krill-supported fish, birds, and mammals higher in the food chain decrease

+Tree lines have shifted poleward and upslope in wide variety of settings and regionsUpslope migration of tree line is

mediated by a number of factors, which in many instances has made it difficult to demonstrate a tree line effect of climate change alone.

+Evidence of range shifts from several areas of the tropics In the Monteverde cloud

forest of Costa Rica, toucans and other birds are moving upslope in synch with warming.

Mountaintop amphibians at Monteverde have declined or disappeared.

Butterflies from North Africa are expanding their ranges into southern Europe.

+Phenologic changes are occurringChanges in timing of biological eventsBud burst, flowering, arrival of

migratory birds, nesting patterns, length of growing season are all timed events

+A six-century-long record of cherry blossom in Japan indicates earlier bloom during past 200 yrs.Timing begins to advance at approximately the

same time that human fossil fuel use intensifies, becoming statistically significant after 1900.

The rate of acceleration in advancement increases after 1950, tracking the acceleration in the use of fossil fuels in the latter half of the previous century.

By the end of the record, timing of the Japanese cherry bloom was several days earlier than at the start of the record in 1400.

+Similar patterns recorded in other species, not just plants Lilac & honeysuckle Ecologist Aldo Leopold recorded spring events for

55 species during the 1930s and 1940s. When these species were resampled in the 1990s,

33% showed earlier spring timing. A study of spring vocalization in six frog species

from the early 1900s was compared with similar measurements taken almost 100 years later, revealing an advancement of almost 2 weeks during the course of the century.

Directly related to earlier mating season

+Different species respond to warming at different rates, leading to possible mismatches in timing between speciesPredator–prey, herbivore–food plant,

pollinator–plant, and other species–species interactions may be affected

In the Netherlands, leaf emergence in trees is advancing, resulting in earlier peak insect abundances. Blue tit bird populations are responding to

this change in food supply & laying eggs earlier.

25+Glacial evidence is mountingIce free seasons are 2.5 wks longerGlaciers decreasing in sizeDirectly affects snow-dependent

ecosystems within the cryosphere

+Worldwide, glaciers are receding and disappearingOn Mount Kenya in eastern Africa, of 18

glaciers present in 1900, only 11 remained by 1986.

During the same period, 75% of the glacier cover of the mountain was lost (from 1.6 to 0.4 km2).

+Worldwide, glaciers are receding and disappearingThe Qori Kalis glacier in Peru, the main

outlet glacier of the biggest tropical ice cap in the world, is retreating at a rate of more than 1 km per decade.

1970s / 2004

28+Disappearing glaciers on Mt. Kilimanjaro

1970

2000

+Past terrestrial response is that things moveOur record of climate change and

biological responses is best for the past 500,000 years.

The movement of the continents & plates is always occurring and changes in climate conditions follows

+The result was a constant shifting of species associationsSpecies found together at the height of

the glaciation might not be found together at the advancing edge of vegetation occupying the habitats newly vacated by the ice.

Several species might be found together in one region, only to have one or more of the group be absent in another region.

+Bottom line, climate change isn’t new, but human influences are The affinity of northern floras in North America and

Eurasia and in southern floras and faunas from South America to Australia results from geographic and climatic connections dating back 50 million to 100 million years.

Response to more recent, rapid climate changes indicates that vegetation has been able to respond even to very rapid climate flickers of 100–1000 years.

Whether this response capacity will be fast enough to keep pace with human activity remains to be seen.