The scientific community is virtually unanimous in calling for a crash program to reduce emissions of carbon dioxide and methane, the principal greenhouse gases. Here are a few words for the remaining doubters: The Arctic is our "canary in the mine" in this matter.

Recently, each year has seen a reduction from the previous year in the summer ice cover of the Arctic Ocean. What is particularly worrying is that this reduction, by itself, increases polar heating from sunlight, as ice is a far better reflector than exposed water. A further destabilizing effect is that warming of permafrost releases some of the huge quantity of methane captured there. The more ice cover lost, the more heat received and the more greenhouse gas freed -- a destabilizing downward spiral.

Most of the concern we read about is over the consequences of the resulting warming of Earth's atmosphere. However, there may be an even greater threat to our biosphere in the amount of carbon dioxide dissolved in the oceans. A rise in that gas in the atmosphere increases that dissolved in ocean water, making carbonic acid. We are familiar with that acid in carbonated water. It is a weak acid, yet it will dissolve calcium carbonate, the principal mineral in shellfish, coral and much of the plankton at the foundation of the marine food chain.

WORSE, AS THE concentration of carbon dioxide increases in the water, the formation of calcium carbonate in living organisms is hindered. At some point the weaker of those organisms will no longer be able to grow sufficiently protective body parts, and won't survive. We do not know the level of CO2 in the atmosphere that passes the point of adversely affecting the very lives of our marine species, but already we are seeing negative effects in our coral reefs.

The G-8 recently set a world goal of a 50 percent reduction in greenhouse gas emissions by 2050. This will be an extremely difficult goal to meet. For the United States, this will require major changes in our generation and use of energy, most of which is now based on coal, natural gas and oil -- all based on carbon. Congress has now failed to take action on cap-and-trade as a carbon limiter. Those rejecting the measure feared that our action would spur movement of energy-intensive industries offshore. That may be, but Americans are in no position to urge any action by China or India, for example, when we are the highest emitters of greenhouse gases in the world, per person. We must take the lead if we are to lecture others.

To reduce carbon emissions, we can set a trade value for CO2 or a tax on carbon to be burnt to achieve our part of the G-8 goal. Either will substantially increase our cost of carbon-based energy. However, we have little basis for where that carbon penalty must be set to achieve the objective.

THERE IS A recent lesson from oil in how much its price had to increase before there was significant reduction in demand. We have found that there was little effect even with tripling the price of oil (or of gasoline). It was only 15 years ago that we nearly failed to raise the gasoline tax by less than five cents a gallon, fearing its economic impact. We clearly have little to guide us in estimating what increase in carbon costs will be needed to reduce our demand for electricity. We will need to try some value and see if it needs to be increased to have the needed effect. This can take more time than we have, particularly with cap-and-trade.

In the meantime, what advice can be offered? Will our utility bills have to double or even quadruple before we reduce our demand sufficiently to begin to phase out coal based electricity? We just do not know. One thing we certainly should be doing immediately is to stop building such large houses on large lots that will require much energy to maintain. The construction industry needs a wake-up call.

With a life of about 20 years, autos can be scrapped at acceptable cost at half that age. But we think of homes as more or less permanent investments. We will try to live in them until they become an intolerable hardship. In the goal year 2050, houses and offices being built now will be barely 40 years old, hardly ready to be torn down.

We must face up to a major change coming in our lives. We can no longer ignore or to minimize what could be a catastrophe like no other.

(The writer holds a Ph.D in chemistry, and spent 40 years in the industrial chemistry field. He is retired and lives in Aiken County.)