Gazing out the window at the dogwood you planted last spring, you might be tempted to pat yourself on the back for helping to save the planet.
But extend that logic from neighborhoods to nations, and you have all the makings of a diplomatic donnybrook.
Which is precisely what has been playing out here at a UN-sponsored global climate conference this week, where more than 160 nations are trying to turn the 1997 Kyoto Protocols into a fully formed rule book for reducing industrial emissions of gases held to be warming Earth's climate.
The issue is pitting EU countries and some environmental groups, including the World Wildlife Fund and Greenpeace, against the US, Canada, Japan, Australia, and other environmental groups, such as Environmental Defense and The Nature Conservancy.
Under the protocols, industrial countries agreed to cut their emissions an average of 5.2 percent below 1990 levels over a five-year period beginning in 2008. But within the average is a wide range of targets for individual countries. The US target was set at 7 percent below 1990 levels.
A key issue is how much carbon dioxide should countries be allowed to deduct from their Kyoto emissions targets by claiming that CO2 is being soaked up by their forests, farmlands, and by changes in the way they manage land - which could include planting forests where none now stand.
The debate over carbon "sinks" was sparked by Washington's initial position that it be allowed to draw on all the country's carbon-hungry greenery in order to meet its Kyoto targets. By some estimates, this would propel the country toward meeting as much as half its Kyoto emissions target without having to cut emissions. And while the US appeared to soften its stand as the week progressed, officials involved in talks on the issue suggest that plenty of tough bargaining still lies ahead.
The quantities of CO2 locked up in forests in countries such as the US and Canada are so vast that "if we count forests already available toward Kyoto, we would not be respecting the commitments we made," insists Jos Delbeke, chief negotiator for the European Union's executive council. "Kyoto is about additional efforts."
Yet the protocols clearly permit the use of sinks, a senior US official here says, and they permit countries to claim credit for forest, crop, and range land that already exists. The official adds that the US made it clear when the ribbon was being tied on the protocols at Kyoto that if the US wasn't allowed to take credit for sinks that already existed, the US couldn't sign the agreement. In the end, he says, when it comes to reducing carbon, the atmosphere doesn't care where or what actions are taken.
Researchers acknowledge the point.
"There is no difference in the climatological effect between CO2 taken up by the land and CO2 reductions due to other causes," note Ian Noble and Robert Scholes, who helped write the International Panel on Climate Change report on land use and forestry before The Hague meeting.
Writing in Climate Policy, a new journal devoted to climate-change issues, they add that the challenges come in trying to set up a system to govern the use of sinks to meet targets.
"The issues related to sinks are very complicated technically," Mr. Delbeke agrees. "The uncertainty is huge."
One of those uncertainties involves trying to distinguish between natural variations in the carbon uptake of plants in a plot and those that occur because of human intervention.
In an attempt to help define natural changes, French climatologist Philippe Bousquet led a team that used atmospheric measurements and computer simulations to track changes in carbon exchanges among the forests, oceans, and the atmosphere during the 1980s and 1990s.
In a study published in today's issue of the journal Science, they found that, globally, CO2 exchanges over land can change dramatically several times over a decade. Moreover, tropical ecosystems seemed to dominate the land-air CO2 exchanges during the 1980s, while mid- and high-latitude ecosystems appeared to take command in the 1990s, perhaps suggesting a periodic latitudinal swing.
"This makes it a tough game to say whether forests are a long-term sink or source for carbon," says Inez Fung, director of the Center for Atmospheric Sciences at the University of California at Berkeley. It also implies that five years - the length of time Kyoto's initial targets hold - may not be long enough to figure out a forest's value as a sink under the protocols.
Ironically, under some circumstances, planting trees could have unintended climatic consequences.
In a study published earlier this month, Richard Betts of Britain's Hadley Center for Climate Prediction and Research found that in northern climes, the warming effects of carbon dioxide reduced by planting new forests could be more than offset by warming that results from changes in the amount of sunlight the surface absorbs. The darker the surface, the warmer it gets. Dr. Betts holds that this effect would be most pronounced in winter, where evergreens and stands of leafless trees would present a darker surface to the sun than would open, snow-covered fields or meadows they replace.
Such uncertainties have helped drive EU and some environmental opposition to the US position, which has drawn support from Canada, Japan, and Australia.
"Every ton that you allow to come out from underground and be stored in a tree is a less certain way of solving global warming, because a tree's carbon is not permanent," says Jennifer Morgan, director of the World Wildlife Fund's Climate Change Campaign. "It will either hit its saturation point, it'll burn down, or be affected by climate change, and the carbon will be re-released into the atmosphere.
"Trees are just not as certain in their security, and they're not as certain in their measurability," she says.
The issue grows more complex when sinks figure in projects to help developing countries slow greenhouse-gas emissions.
Industrialized countries can earn credit against their own emissions targets from "clean development mechanisms" in other nations.
Environmentalists and indigenous peoples worry that companies or countries will come in, plant trees for credit, then do nothing to maintain the stands or keep them from being cut for fuel or shelter.
Worse, the critics say, would be projects that fell ancient stands of timber and replace them with fast-growing but shorter-lived species. This could upset ecosystems and threaten indigenous populations who depend on the continued viability of older forests.
Ms. Morgan cites a WWF report that describes a deal between an Australian timber company and two Japanese companies - Tokyo Electric Power Company and Mitsubishi.
The Japanese firms have established a tree plantation on land that once held older forest stock that the environmental group says had considerable conservation value or served as habitats for endangered species. The Japanese companies signed on to the project to get credits against Kyoto Protocol emissions targets.
IPCC chairman Robert Watson, who indicates that he has no problem with countries using domestic sinks to reach their emissions targets, says he, too, is concerned about such issues "in developing countries with no national commitments to carry out."
Thus the debate over sinks has spread across several aspects of the Kyoto Protocols.
For its part, the IPCC has acknowledged that sinks can play a role in fighting climate change.
And in a report published earlier this year, the advisory body laid out options negotiators could ponder as they try to set up rules on sinks.
The US remains confident that those options can help provide a basis for closing the gap between its position and that of the EU.
In the meantime, US negotiators at the conference this week offered to compromise by phasing in US sink credits - in effect claiming as much credit as possible for sinks that soak up the least atmospheric carbon while claiming something less than full credit for more-effective absorbers during the 2008-2012 period.
Just what that "something" is remains to be negotiated next week, when national ministers arrive to complete work on the Protocol rules.
(c) Copyright 2000. The Christian Science Publishing Society