On Wednesday, Feb. 16, the Kyoto Protocol takes effect, requiring the 141 voluntarily participating industrialized countries to cut emissions related to global warming. The pact was agreed to at a United Nations conference in Kyoto, Japan, in 1997. President Bush, while acknowledging that there are risks from global climate change, pulled out of the pact in 2001, saying that it was too costly and that its targets and timetable-cutting developed nations' emissions of carbon dioxide by 5.2 percent below 1990 levels by 2008-2012-were arbitrary. Yet he's presented no clear alternatives, even though global warming is now upon us.

I wanted to cook smelt for dinner the other night, but I ran into a friend of mine who said he took his fishing shack off the ice two weeks ago. The smelt stopped running early in the rivers this year, so it will be hard to find some, he told me. I share this story with someone else, who mentions he knows some people who have been tapping their maple trees for sap, about a month early. He pauses, then mentions how he heard some early spring birdsongs a few weeks ago, about a month early.

We laugh.

Ha ha.

For decades, talking about global warming has been the equivalent of saying the sky is falling. That is, until recently, when-suddenly, it seemed- everyone agreed that yes, the Earth is warming, it's too late to stop it, it's our fault, and it will keep warming if we don't do anything about it.

So now that global warming is real, what's going to happen to us?

Fifteen years ago, Bill McKibben published "The End of Nature," which took a frank look at how we've altered the rate of change to the planet's biosystems. Rain is no longer rain, he proffered. We've warmed the climate, and a warmer climate means more rain, but artificially produced.

We started it, but we can end it, if we act quickly enough.

"We can talk about that, but we don't know exactly what the impacts are going to be," says Cameron Wake, research assistant professor at the University of New Hampshire Climate Change Research Center. "The impacts are not just a result of how climate changes, but also a result of how we respond to those changes and how we adapt. It's not a static system."

Since the beginning of the Industrial Revolution, we've been pumping unnatural quantities of greenhouse gases-by burning fossil fuels like coal, oil and gas-into the atmosphere. Aided by deforestation and urbanization, the increased concentration of the gases, the most common of which is carbon dioxide, is overburdening the natural greenhouse-type effect of the atmosphere.

NASA scientists recently released a statement saying a combination of human-made greenhouse gases and a weak El Nino will likely make 2005 the warmest year since recordkeeping began in the 1860s. The warmest year by far was 1998, followed by 2002 and 2003. Short-term factors like El Nino and volcanic eruptions can affect the climate, too, but there's no denying an overall warming trend over the last 30 years, which NASA attributes primarily to increasing greenhouse gases in the atmosphere. In addition, Earth's surface now absorbs more of the sun's energy than gets reflected back to space, according to NASA.

Earth's average surface temperature has risen by 0.6 degrees Celsius, or 1.1 degrees Fahrenheit, since the late 1800s.

"It's unknown how the Seacoast region is going to be affected. It's unknown about everything. The models are saying some places will get drier, some places will get wetter," says Mark Twickler, assistant director at the Climate Change Research Center.

The Environmental Protection Agency reports that New Hampshire is getting warmer. The temperature in Hanover has increased 2 degrees Fahrenheit over the last century. Consistent with global predictions, by 2100 temperatures in New Hampshire could increase by about 4 degrees Fahrenheit, or about 2 degrees Celsius. The European Union and the United Nations' Intergovernmental Panel on Climate Change each have set a threshold of "dangerous warming" at 2.5 degrees Celsius above current conditions, projecting a rise of 1.4-5.8 degrees Celsius by 2100. That would drastically alter climates. But that's just a best guess, because no one has ever seen the results before. How much, and exactly how, things will change is impossible to measure or describe because each variable brings with it an array of unforeseen consequences.

Here's what we see now around the world: Sea levels are rising, and glaciers and sea ice are melting. Tundra is thawing, and animals are on the move. In North America alone, we see polar warming in Alaska, coral reef bleaching in Florida, animal range shifts in California, glaciers melting in Glacier National Park, and loss of marshes in Chesapeake Bay. "The current rate of a sea-level rise is three times the historical rate and appears to be accelerating," according to the Web site Global Warming: Early Warning Signs (www.climatehotmap.org). "Since 1938, about one-third of the marsh at Blackwater National Wildlife Refuge has been submerged." These things are happening right now.

In New Hampshire, that means warmer weather and longer growing seasons. Bloom times for apples, lilacs and grapes are coming earlier.

"The long and short of it is it's getting warmer, especially in winter, over the past 100 years. Over the past 30 years, our temperature has changed in winter by 4.4 degrees warmer. That's a significant change. If you're in the winter tourism business ... there's a lot of lost ski areas," Wake says.

Ice-out dates are earlier in spring.

"I was looking at a report of ice-out dates," Wake says. "and 90 percent of them are earlier, by one to two weeks. Perhaps the most shocking is that on Lake Champlain, there are years when the ice does not freeze over completely, and the majority of those years have occurred since 1970. This is a really important point. There are significant thresholds in the climate systems. This lake ice in Lake Champlain is a perfect example. There's a general slow warming that we see, but in terms of a response, either there's ice or there isn't ice. The response in the system is much greater. A small change that results in a really large change."

Our whole ecosystem will see a shift. We can expect increases in precipitation and increases in the number of extreme precipitation events. We can expect more disrupted seasons-heavier than usual downpours and snowstorms, longer but drier and hotter growing seasons.

"A two-degree shift, that's a big shift," agrees Doug Grout, a marine biologist with New Hampshire Fish and Game, Region 3 in Durham. "Certainly it's something we are concerned about over the long term. If it does occur and start affecting species ranges and abundance around here, it would have substantial effects on the resources up here."

In regard to the missing smelt, NHFG monitors the fishery on a regular basis.

"We've seen some very good, unusually good catches out on Great Bay (this year), and it seems up on the rivers where we've seen some of best catches in recent years it's not as good this year. Smelt go through natural fluctuations. Every five or six years you see big increases in catch per unit effort. But there has been a long-term gradual decline in peaks of that abundance. But some of that may have to do with predations. We now have a very high striped bass population. They feed on smelt. Marine mammal protection has increased populations of marine mammals, like harbor seals around the bay in winter time, and they could be affecting it," Grout says.

Most scientists agree even slightly warmer weather here would have a significant impact on much that we take for granted. Rising sea levels would affect development along shorelines and marshes, of course. But a warming New England would have a significant impact on plants and animals. An earlier spring would likely disrupt animal migrations, alter competitive balances among species and cause unforeseen problems.

N.H. Fish and Game in Concord is conducting a study mandated by Congress to assess the current condition of wildlife in the state, identify species at risk and develop actions to protect the species at greatest risk.

"We're coming at it from a wildlife angle, (looking at) what are the threats to these species that are rare. Global climate change is one potential threat, it's something that comes up time and again," says John Kanter, nongame and endangered wildlife program coordinator at N.H. Fish and Game in Concord. Two species of butterflies, the White Mountain Butterfly and the White Mountain Fritillary, endemic to the alpine regions of the White Mountains, fit into that category.

"They're really a subspecies of Arctic species. Our alpine zones are like little mini tundra places isolated here. Anything that would magnify a change in the vegetation there... insects have a very close relationship with the plants... If things are warmer and we lose that alpine community, we lose that endemic species.

"A little lower down the mountains, New Hampshire has 80-90 percent of the U.S. population of Bicknell's thrush. The bird occurs in that area just when you get into the tree line when you get really dense conifer growth. If we saw a change in structure where that became more heavily forested with taller trees, then you would see the loss of habitat for that species," Kanter says.

We can expect to lose snow cover in winter, and maple forests will give way to oaks, which means less syrup in spring and less foliage in fall. We'll also see the spread of mosquito-borne disease. Maybe not malaria or dengue fever just yet, but more ticks, and more of them further north, carrying more Lyme disease. A longer breeding season for mosquitoes means greater opportunity for them to spread West Nile Virus and other diseases.

There will also be significant changes in the oceans, an enigmatic piece of the global climate change puzzle. The Seacoast Science Center has been assisting researchers monitoring global climate change and educating the public on the topic for several years now.

"We think there will probably be changes to the phytoplankton community. Now we're talking about the first link in the food chain. Has this ever happened?" president Wendy Lull asks. "Temperature, salinity, hours of daylight and water chemistry. As you start shifting those things around a little bit, you're going to have impact on bloom and growth. One thing we know is it's never happened this fast before."

One of the most dramatic shifts in the ocean has not been the rise of water levels or sudden change in temperature, but the rapid movement of species.

"Tunicates. This is an animal that certainly looks like it's benefiting from warming," says Larry Harris, UNH professor of zoology who's been studying marine communities for 30 years. The small creature caught researchers' attention in 2000, growing on floats and pylons around Cape Cod. "We found it at the Coast Guard station in Portsmouth that winter. It had never been there before. You can't miss it. It looks like somebody's poured very thick pancake batter, and it's kind of poured down. It's very grotestque."

In 2003, researchers from Wood's Hole were surveying Georges Bank with cameras, looking at the composition of the bottom in a no-take zone. They found six and a half square miles 90 percent covered with tunicates. "When it grows over gravel and cobble bottoms, it basically smothers everything underneath it. Fish, especially juveniles that depend on little animals in that habitat, have nothing to eat. (Recently), they went out and looked again. It's now covering 40 square miles of area."

The tunicates are believed to have arrived in the 1980s during an oyster aquaculture effort on the coast of Maine. Another traveler is codium, an intertidal algae that previously "never" traveled north of Cape Cod. "It's in Nova Scotia now. They're about 10 years behind us in replacement of kelp beds with codium beds. Now it's happening in Chile. This plant, an invader from Asia, is happening all over the world.

"If you want to get an idea of how things have changed, go to Rye Harbor State Park," Harris says. Walk out on the cobble behind the south breakwater and turn over some of the rocks. "You will see nothing but Japanese shore crabs. They have totally taken over and replaced the green crab. Last week we found 20 under one rock," Harris says. "It used to be that I would take classes to the coast and we would say 'we want to see if we can find a Japanese shore crab because they're coming this way.' Now in some areas, like that cobble area, you tell the students 'see if you can find a green crab.' That's been over about three or four years. There are still areas where green crabs are common, wetter areas, like outside the breakwater, but they are being overwhelmed by increase in Japanese shore crabs."

Of all the different challenges facing the planet, climate change is the one that has the most universal impact, says Wendy Lull of the Seacoast Science Center. "The two big ones are biodiversity of plants and animals. The more diverse the population of organisms around the planet, the more healthier and robust it is, and we're seeing rapid extinction of species that causes concerns among scientists. Temperature, weather patterns, air quality, water quality, hours of daylight. All of these things come together and have an impact on a species ability to survive in a certain area," Lull says.

Researchers have been hard at work for two decades now on so-called "safety net" solutions to global climate change. They are experimenting with giant mirrors to deflect the Sun's rays, burying compressed carbon dioxide underground, and seeding the oceans with iron to generate algal blooms that would absorb greenhouse gases, then sink them below the sea.

Others see more traditional opportunities, like cap-and-trade programs, in which companies voluntarily cap emissions. Low-emitters sell "credits" for cash to large emitters.

Energy efficiency is also opening doors to new technology. At the University of New Hampshire, a new co-generation power and heating plant will go online this fall. It will cut campus greenhouse gas emissions 20 percent below 1990 levels, almost three times below what Kyoto calls for. "Most impressive," says Cameron Wake, "is that over next 20 years, we expect to save $30-$40 million in 2004 dollars. So what we've been able to do is really explode this myth that it's either the environment or the economy. In fact, it was done here because it made smart fiscal sense."

Can individuals make a difference? If you choose a car with better gas mileage, if you carpool once a week, if you buy more energy-efficient appliances... you are not going to make a bit of difference. Yet the kind of change that is necessary is so fundamental that it's going to require these kinds of choices from all of us, because we can only get there by first taking small, individual steps of understanding and responsibility. In time, that may give us the capacity to undertake true change.

We don't know what will happen. Global temperatures might surge. They might not. This may have happened before, but maybe not. We may be able to arrest the process. The response in the system may be much greater than the initial change, or the system may prove more resilient and elastic than we knew.

Regardless, we need to have a greater understanding of our responsibility as Earth's dominant species.

"This is an issue we need to step up to, we need to address," Wake says. "The environment and climate change has become a very partisan issue, but it should not be one."