Reading a newspaper digitally rather than in traditional paper form is probably less damaging to the environment. The cradle-to-cradle process of milling wood to pulp, paper production, printing, distribution and recycling requires resources and energy expenditures in excess of online websites, and higher CO2 emissions.
But other factors must be considered:
How long a reader spends reading. The longer you spend online, the more energy you consume.
Where you do your reading. In Sweden, whose energy grid relies on low-carbon renewables and nuclear power, reading online has a lower carbon impact. But if you look at Europe as a whole, with its mix of traditional fossil fuels and renewables, carbon emissions increase.
Whether you recycle paper. You might think recycling would even things out, but recycling paper also produces carbon emissions, even as it cuts down on the first stage of paper production—chopping down and milling trees for pulp.
Our own actions may impact the environment negatively. All we can do is be thoughtful about the choices we make—and push the providers we use to be more responsible about their choices.