There are many methodologies used around the world. So we need to start bysurveying them. In the main it seems to be based upon calculating carbonfootprint and, sometimes, in converting other greenhouse gases to CO2equivalent. There are a number of problems with this that need to beconsidered. Other components of climate change are largely ignored. Thereis a need to consider all methodologies used and then develop a best practicemethod. This method must be readily useable by companies and must beverifiable as part of the audit process. And it must be flexible to cater for thefuture.The research has the following stages:Identify current practice worldwideDevelop a best practice methodologyThe sample of BUMNs companies has been selected including mining,manufacturing, and construction industry. They include Aneka Tambang,Bukit Asam,Pertamina, Timah, Pusri, Bio Farma, Adhi karya, Wijaya karyaand Jasa Marga. They have being analyzed for their content of annual reportand sustainably report. Disclosure model index, developed by GRI, has beenused to identify the current practice. The model index has 7 (seven)dimensions. It is found that only three dimensions: environmental profile,GHG environmental performance, and environmental initiative to be verykey factor determining the current index of climate change issue bycompanies. To improve those companies’ responses to the climate changeissue, it is suggested that authorized parties to adopt the market mechanismto encourage companies to do the changes.