They said that both the letter and the Society's public statements "inaccurately and unfairly" describe the company as a sceptic to climate change. They go on to say, "We know that carbon emissions are one of the factors that contribute to climate change - we don't debate or dispute this."
ExxonMobil says they are taking steps to reduce greenhouse gas emissions from its operations, yet defend an apprehensive course of action by saying, "We support approaches to reduce emissions more broadly in ways that are cost effective for society and that consider the uncertainties that remain."
Apparently, the Guardian isn't flawless in their reporting. The article says that ExxonMobil allegedly distributed $2.9 billion to organizations that misrepresented the science of global warming. The Royal Society's letter instead states $2.9 million.