With luck, the people who don’t believe in global warming won’t be affected by it. However, the odds are not good.

Already, scientists say rising ocean and land temperatures are exposing people to diseases and pathogens they have never known before and threatening the food supply.

A shellfish farmer in Cordova, Alaska, grew oysters in the icy waters of Prince William Sound for 25 years without ever encountering the bacterium Vibrio parahaemolyticus, a microbe which commonly infects seafood far farther south, in the warm waters of the Gulf of Mexico. When water temperatures in the Sound rose above 59 degrees in 2004, cruise ship passengers who ate local oysters came down with Alaska’s first known cases of Vibrio food poisoning, replete with vomiting, diarrhea and cramping. Some of the oyster farms were closed down for a year. An Alaskan researcher who studied and published a report on the event, called the Vibrio outbreak “the best example to date of how global climate change is changing the importation of infectious diseases.”

The World Health Organization estimates that in 2000, climate change caused disease outbreaks that accounted for about 154,000 deaths worldwide. Although the temperature change seems tiny – only 1.4 degrees over 150 years, that’s enough to change disease patterns.

In Sweden, fewer winter days below 10 degrees and more summer days above 50 degrees have allowed the northward movement of ticks, which coincided with an increase in cases of tick-borne encephalitis since the 1980s. Mosquitoes are moving higher up Africa’s Mount Kenya, bringing malaria to high villages once safe from the disease.

Scientists say increased levels of carbon dioxide are encouraging the lush growth of plants such as poison ivy and ragweed. Current temperature levels produce 131 percent more pollen in ragweed than pre-industrial conditions did. Researchers say if temperatures continue to rise, in the future ragweed will produce 320 percent more pollen.

Besides an increase in food-borne illnesses, researchers say the food supply itself will be affected – both grains grown on land and fish harvested from the oceans – and soon. Agricultural experts say global warming could produce food shortages even before sea level rise causes flooding in coastal cities. The food supply for 200 million people will be affected when heat and subsequent drought destroy a lot of the wheat crop that supplies one-fifth the world’s food, said the Consultative Group on International Agricultural Research (CGIAR).

These conditions will slash production of other important cereals and grains grown in the world’s breadbasket, such as rice in India and Southeast Asia. Many crops such as wheat, corn and rice are already growing in temperatures close to the limit of heat they can withstand. The pressure’s on to solve the problem, say scientists, because already in six out of the last seven years world grain production fell short of consumption.

Last year, a United Nations panel of 2,500 scientists from 130 countries all agreed on one thing — humans have caused global warming through the production of greenhouse gases produced by burning fossil fuels.

The sad irony of our human error is that the people who will be most hurt by the effects on the food supply will not be the people who caused global warming. The victims will be residents of the developing world, some already plagued by crop failures and famine, who will increasingly lose the ability to produce their own food.

While southern pathogens will move north, so will the wheat belt — perhaps extending from midway up the coast of Labrador across North America to the Alaskan panhandle in the West.

The UN panel’s report predicts temperatures will rise by between 3.2 and 7.8 Fahrenheit in the 21st century, causing more droughts, heat waves and a slow gain in sea levels that could last for more than 1,000 years even if greenhouse gas emissions are capped. Temperatures rose 0.7 degrees in the 20th century and the 10 hottest years since records began in the 1850s have occurred since 1994.

If that’s not enough, it appears that “upwellings” caused by temperature changes may be creating dead zones in the ocean where fewer juvenile fish survive to adulthood. Coastal upwelling regions such as those off Peru, northern California, Oregon and the west coast of Africa collectively cover less than 1 percent of the ocean, but they account for 20 percent of the world’s already beleaguered fish catch.

Recently, Australia’s respected government-backed Commonwealth Scientific and Industrial Research Organization issued a report stating global warming is already driving Australian fish and seabirds further south and threatening coral reefs. Much more severe impacts may occur in coming decades, altering sea life, fishing communities and tourism. Warmer oceans, changes in currents will lead to disruption of reproductive cycles and mass migration of species.

Already, nesting sea turtles, yellowfin tuna, dugongs and stinging jellyfish are moving south as seas warm, said the report. “It’s not a disaster for the ones that can move south. It is for the ones that can’t move south,” said the lead author of the report, Dr Alistair Hobday. “If you’re at the tip of Tasmania, you’ve got nowhere else to go.”

Naturally, low-lying islands are at the most immediate risk from sea level rise. President Anote Tong of Kiribati, a group of 33 Pacific coral atolls threatened by rising seas, recently said time was running out. “The question is, what can we do now? There’s very little we can do about arresting the process.”

Rajendra Pachauri, the head of the IPCC, told Reuters recently that the impact of climate change is already dangerous for some. “Small island states will say we’ve already gone past the state of danger. Where you have the poorest people in the world (dependent on) rain-fed agriculture, for them also it’s dangerous.”