Fifty of the world’s 500 largest companies are responsible for nearly three quarters of the group’s 3.6 billion metric tons of greenhouse gas (GHG) emissions, according to the CDP Global 500 Climate Change Report 2013.

Most of the top 50 carbon-polluting companies operate in the energy, materials and utilities sectors, the report says. The carbon dioxide emitted by these companies has risen by 1.65 percent to 2.54 billion metric tons over the past four years — equivalent to adding more than 8.5 million pickup trucks to the streets.

The report, co-written by the Carbon Disclosure Project (CDP) and professional services firm PwC, is based on the climate and energy data of 389 companies listed on the FTSE Global 500 Equity Index collected by CDP at the request of 722 institutional investors representing $87 trillion in invested capital.

Atmospheric carbon dioxide recently surpassed a record high of 400 parts per million, which has compelled a number of investors to turn to CDP for insight on corporate environmental performance. However, CDP says that companies still are not doing enough to mitigate climate.

The report looks at what is driving climate change action in the world’s largest companies. Industry-specific analysis shows that the five highest-emitting companies from each sector have seen their emissions increase by an average of 2.3 percent since 2009.

"Clear scientific evidence and increasingly severe weather events are sending strong signals that we must pursue routes to economic prosperity whilst reducing emissions of greenhouse gases,” said Paul Simpson, chief executive at CDP. “It is imperative that big emitters improve their performance in this regard and governments provide more incentives to make this happen.”

While the biggest emitters present the greatest opportunity for large-scale change, the report identifies opportunities for all Global 500 companies to help build resilience to climate and policy shocks by significantly reducing the amount of carbon dioxide they produce each year.

For example, the emissions from nearly half (47%) of the most carbon intensive activities that companies identify across their value chains are yet to be measured. The lack of detailed reporting and information of GHGs from sources related to company activities (Scope 3 emissions), as opposed to those from sources owned or directly controlled by them, may lead companies to underestimate their full carbon impact.

Likewise, companies that demonstrate a strong commitment to managing their impact on the environment are generating improved financial and environmental results, according to the report. Some of the corporations leading on climate progress include BMW, Nestlé and Cisco Systems. Additionally, businesses that offer employees monetary incentives related to energy consumption and carbon emissions are 18 percent more successful at accomplishing reductions.

Members of the G20 recently agreed to use the resources of the Montreal Protocol to initiate a global phase-down of hydrofluorocarbons (HFCs), a significant group of super greenhouse gases (GHGs). According to the Environmental Investigation Agency (EIA), HFCs are primarily used in refrigeration and air conditioning and are thousands of times more potent than carbon dioxide. However, climate-friendly alternatives are already widely available.