From the micro to the macro, from plankton in the oceans to polar bears in the far north and seals in the far south, global warming has begun changing life on Earth, international scientists will report next Friday.

"Changes in climate are now affecting physical and biological systems on every continent," says a draft obtained by The Associated Press of a report on warming's impacts, to be issued by the Intergovernmental Panel on Climate Change (IPCC), the authoritative U.N. network of 2,000 scientists and more than 100 governments.

In February the panel declared it "very likely" most global warming has been caused by man-made emissions of carbon dioxide and other greenhouse gases .

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Animal and plant life in the Arctic and Antarctic is undergoing substantial change, scientists say. Rising sea levels elsewhere are damaging coastal wetlands. Warmer waters are bleaching and killing coral reefs, pushing marine species toward the poles, reducing fish populations in African lakes, research finds.

"Hundreds of species have already changed their ranges, and ecosystems are being disrupted," said University of Michigan ecologist Rosina Bierbaum, former head of the U.S. IPCC delegation. "It is clear that a number of species are going to be lost."

The IPCC draft estimates that if temperatures rise approximately 2 to 4 degrees Fahrenheit more, one-third of species will be lost from their current range, either moved elsewhere or vanished.

From Associated Press bureaus around the world, here are snapshots of animals and plants the IPCC will identify as already affected by climate change:

SAN JUAN, Puerto Rico — Back in the Puerto Rican rain forest for the first time in five years, biologist Rafael Joglar sensed something was wrong. He wasn't hearing the frogs whose nocturnal calls he had long recorded in the misty highlands.

It was as if a small orchestra had lost key players, he recalled.

After that discovery in 1981, Joglar and wife Patricia Burrowes, a fellow University of Puerto Rico amphibian specialist, found that other populations of frogs in the genus Eleutherodactylus — known locally as coquis for the distinctive co-kee sound made by two species — were also mysteriously absent. Similar reports trickled in from frog specialists worldwide, particularly in Central and South America.

Working their way through such suspected culprits as pollution and habitat loss, researchers here eventually zeroed in on climate change. The average minimum temperature had risen from 1970 to 2000 by 2 degrees Fahrenheit, a significant rise for climate-sensitive amphibians.

Scientists believe higher temperatures lead to more dry periods and a chain reaction, at higher elevations, that leaves the frogs vulnerable to a devastating fungus, Burrowes said.

In Puerto Rico and nearby islands, experts believe three of 17 known Eleutherodactylus species are extinct and seven or eight are declining. Loss of the frogs, scientists warn, could have disastrous consequences, depriving birds and other predators of a food source, eliminating a consumer of insects and disrupting the ecosystem in ways impossible to guess.

SYDNEY, Australia — The rainbow world of the Great Barrier Reef may fade away.

Scientists say rising sea temperatures worldwide are causing more coral bleaching — the draining of color when the fragile animals that form reefs become stressed and spew out the algae that give coral its color and energy to build massive reef structures.

Oceans are also absorbing more carbon dioxide, increasing their acidity and eroding coral's ability to build reef skeletons.

Because just a 2-degree-Fahrenheit shift can trigger a major bleaching event, the behavior of corals is an early sign that global warming is already changing our world, experts say.

"We've got about 20 years to turn (greenhouse gas emissions) around or it's going to cost the world a lot environmentally but also economically," said Terry Hughes, a leading Australian coral specialist.

The 1,250-mile-long Great Barrier Reef, off Australia's northeast coast, produces $4 billion a year in tourism revenues. Forecasts vary, but many experts say ocean temperature rises projected for the next 50 years could strip this natural wonder of most of its color. The changes will affect countless millions of fish and other marine organisms that depend on the reef.

Many reefs worldwide will fare worse, since they don't have the protection against pollution and overfishing provided by the Great Barrier Reef World Heritage Area.

STOCKHOLM, Sweden — A bloodthirsty parasite is popping up in parts of Sweden where deep winter chills used to make survival difficult, if not impossible.

Ticks are spreading north along the Scandinavian country's shorelines, pestering pets and spreading infectious diseases to humans.

"It probably has to do with the greenhouse effect," said Thomas Jaenson, professor in medical entomology at Uppsala University. "The fact that we've seen ticks in January indicates that there has been a major change."

Swedish studies have shown that ticks have multiplied countrywide in recent decades, spreading north from traditional breeding grounds in the Stockholm archipelago. The pinhead-sized arachnids have even turned up near the Arctic Circle.

"There are more of them now. And they show up earlier in the year," said Marja Lodin, 69, who has a summer house near the northern city of Umea.

Two years ago she was infected with Lyme disease, which causes fever, headache, fatigue and skin rash, from a tick lodged in her navel.

Sweden's disease control agency doesn't keep records on Lyme disease, but said the potentially deadly tick-borne encephalitis virus, known as TBE, is on the rise. Reported annual cases more than doubled from 60 in the late 1990s to 131 in the 2001-2005 period. In 2006, there were 155 cases, two of which turned fatal.

"It is possible that these people would be alive if we had had a more stable climate," Jaenson said.

TORONTO — Inuit hunters in Canada's Arctic say they have seen polar bears moving farther north as the polar ice cap recedes, or farther south in search of new sources of food.

The northern people who have hunted these majestic marine mammals for thousands of years say they haven't seen a dramatic decline yet in their numbers. But scientists worry that the polar bear will be pushed steadily toward extinction by 2050, to be found only in zoos, as Arctic waters grow warmer.

The bears depend on sea ice for survival. They have their pups and they hunt seal and walrus on ice floes. But the summer ice cap is about 20 percent smaller today than in 1978, the U.N. climate panel reported in February. And as sea ice shrinks, bears are forced to hunt and to fast for longer periods.

Biologists believe 20,000 to 25,000 polar bears roam the frozen Arctic, about 60 percent in Canada. The research group Polar Bears International says one polar bear population, in Canada's western Hudson Bay, has dropped 22 percent since the 1980s, about the time Inuit hunters started noticing dramatic changes in wind and weather patterns.

The trends are so troubling that the U.S. government has proposed listing polar bears as threatened under the Endangered Species Act.

LONDON — Overfishing has cut deeply into the North Sea's cod population in recent decades, and scientists now say this important food fish faces a second challenge — climate change.

North Sea water temperatures have climbed 1 degree Fahrenheit over the past 100 years, and that has shifted currents, carrying a major food source, plankton, away from the cod, said scientist Chris Reid of the Partnership for Observation of the Global Oceans in Plymouth, England.

"The only way that these increases can be explained is by greenhouse gas emissions," Reid said.

In their larval stage, the cod feed on the minute plants and animals known as plankton. Chances of survival without them are slim. North Sea cod that do survive today are smaller and less successful at mating and reproducing, Reid explained.

In addition, warmer temperatures increase cod metabolism and the larvae's need for nutrition, he and other marine scientists noted in a 2003 research paper.

Because the European Union's 2003 cod recovery plan isn't working, scientists and fishing industry representatives met March 9-10 to discuss new ways to counter the threats and help the cod.

DAKAR, Senegal — It's getting harder for villagers in the north of this dry West African country to find a favored ingredient for a traditional couscous dish — the fruit of the dimb tree.

The once-prevalent tree with its meaty fruit has disappeared from all but one village in an area the size of Connecticut, as shifting rainfall patterns have made northern Senegal drier and hotter, research has found.

Many tree species like the dimb are retreating from the Sahel, the arid region south of the Sahara Desert, losing ground to more arid species. In the zone that climate change scientist Patrick Gonzalez studied, the dimb's range decreased 96 percent between 1945 and 1994 — from 27 villages to one.

Gonzalez said he looked at many factors, including population shifts and tree cutting, but "precipitation and temperature explained most of the variance in the data."

The greenhouse effect has warmed the southern Atlantic Ocean, source of the African monsoon, causing more rain to fall over the sea and less over the Sahel, said the Nature Conservancy's Gonzalez, who did the research while with the U.S. Geological Survey.

Fig and firewood species also are dying, forcing women gatherers to range farther and spend more time hunting firewood.

"Once you don't have that, people start burning cow dung. And that's when environmentally the area is in great trouble," Gonzalez said.