Carbon offset companies, which claim to counter emissions from travel and other fossil fuel consumption, are popping up like spring daises, but they may be doing little to nothing to combat global warming.

A review of carbon offset programs in the U.K. by the Guardian shows that several programs there generated revenue but did nothing to reduce carbon dioxide in the atmosphere. Companies sold "empty" credits or promised to give money to energy saving projects that have yet to be started.

Delta Airlines is now offering to plant trees for customers who donate while booking travel on its website. The trees will be planted in the U.S. in areas that have been deforested, according to the company.

Does planting trees -- which promise to absorb carbon over decades -- do anything to help emissions that are being put into the air now? What good is removing 1 ton of carbon over 100 years compared to the damage done to the planet today?

I'm going to seek my reporting teeth into this issue now, and if you can contribute to the story, please email me.

Customers who purchase a ticket at delta.com can choose to contribute $5.50 for domestic roundtrip flights and $11 for international roundtrip flights to be used by The Conservation Fund to plant trees throughout the U.S. and abroad.

Delta also launched a comprehensive on-board recycling program that expands beyond traditional aluminum can recycling to include all aluminum, plastic and paper products on domestic flights into Atlanta.

These first trees will be planted within The United States in protected areas across the Gulf Coast region -- an area that has lost more than 20 million acres of forestland in the last century -- beginning this fall.