The e-mails leaked from the University of East Anglia in November 2009 produced what is popularly called "Climategate." They exposed the thoroughly unethical behavior of a group of climate scientists, mainly in the UK and US, involved in producing the global surface temperature record used and relied on by governments.
Not only did these climate scientists hide their raw data and their methodology of selection and adjustment of temperature data, but they fought hard against all attempts by independent outside scientists to replicate their results. They also undermined the peer-review system and tried to make it impossible for skeptical scientists to publish their work in scientific journals. There is voluminous evidence in the e-mails to this effect. In the process, they damaged not only the science enterprise -- full publication of data and methods, replication of results, open debate, etc -- but they also undermined the public credibility of all scientists.
However, the most serious revelation from the e-mails is that they tried to "hide the decline" in temperatures, using various "tricks" in order to keep alive a myth of rising temperatures in support of the dogma of anthropogenic global warming. There have now been a number of investigations of the activities of this group, mainly in the UK. These have all turned out to be complete whitewashes, aimed to exonerate the scientists involved. None of these investigations has even attempted to learn how and in what way the data might have been manipulated.