NEW YORK, US: Google Inc. aims to voluntarily cut or offset all of its greenhouse emissions by the end of the year, the Web search leader said on Tuesday.

Google is one of a number of companies, including News Corp., and Yahoo Inc. that are attempting to cut emissions of gases scientists link to global warming.

To make the cuts, Google is investing in energy efficiency, renewable energy like solar, and will purchase carbon offsets for emissions it cannot reduce directly, the company said.

"On their own, carbon offsets are not capable of creating the kinds of fundamental changes to our energy infrastructure that will be necessary to stabilize global greenhouse gas emissions to safe levels," Google said on its Web site.

"But we believe that offsets can offer real, measurable, and additional emissions reductions that allow us to take full responsibility for our footprint today."

European companies can invest in carbon offsets through a Kyoto Protocol U.N. program that allows rich countries to invest in clean projects in developing nations. The United States did not ratify the Kyoto pact, but some U.S. companies have begun to offset emissions on a voluntary, unregulated basis.

Google said it would invest in projects like capturing and burning methane, a greenhouse gas with about 20 times the warming potential of carbon dioxide, from animal waste at Mexican and Brazilian farms.

"Our funding makes it possible for anaerobic digesters to be installed, which capture and flare the biogas produced while simultaneously improving local air quality and reducing land and water contamination," Google said.

Separately, Google is planning to spend $600 million to build a data center in western Iowa that will receive power from a MidAmerican Energy Co. plant fired by coal, the fuel that emits the most carbon dioxide. A Google spokesman told Reuters all emissions from its Iowa project were accounted for in its carbon neutral plan.