Yvo de Boer acknowledged that some mistakes were made in the 2007 report by the U.N.-affiliated Intergovernmental Panel on Climate Change but argued that the science behind global warming was robust and that the report itself was helping countries combat it.
The IPCC report warning that Himalayan glaciers could be gone by 2035 turned out to be off by hundreds of years. The error led to sharp criticism of the panel by scientists and skeptics who believe global warming theories are alarmist.
De Boer, who is on a visit to India, told journalists that the IPCC did not carry out any research itself, but reviewed the entire spectrum of international scientific analysis and provided conclusions that decision-makers could use.
The report warned that global temperatures were rising, and urged urgent steps by countries to cut carbon dioxide emissions.
The report said that global warming could result in 75 million to 250 million people in Africa suffering water shortages by 2020 and residents of Asia's large cities facing a greater risk of river and coastal flooding.
"Yes, some mistakes were made in relation to the pace of retreat of Himalayan glaciers, but the rest of the science remains robust and is underpinning political decision-making and policymaking in a very, very solid way," he said.
De Boer said the motivation behind some of the criticism, including calls for panel chairman Rajendra Pachauri to resign, may have emanated from companies that feel threatened as governments enforce cleaner but more expensive technologies to slow down or cut global warming.
"As governments become more serious about addressing climate change, the companies that feel threatened by ambitious action to address climate change are becoming more and more concerned," he said.
Although no binding agreement was reached on emissions cuts, De Boer hailed the recent Copenhagen change talks as proof of the political will being shown by major nations like the United States, China, India, Brazil, Germany and France to tackle global warming and the commitment by developed countries to provide billions of dollars to help poor countries adapt to climate change.
"The political significance of it (Copenhagen) was huge," he said.