Concerns over shipping's impact on the environment are nothing new, as a recently discovered cache of letters has illustrated.
Writing 175 years ago, British engineer Isambard Kingdom Brunel noted his fears that ships, trains and factories were harming the natural world.
The top-hat-wearing polymath worried that factory waste was polluting water supplies, but seemed to be more concerned over how Bristol docks were becoming clogged with mud, causing large vessels to run aground.
