James Alexander, who lives near Canterbury in Kent, said his winning picture depicts the impact of drought that has killed 100,000 cattle in Kenya through lack of water.
He has been awarded first prize of a photography masterclass with Getty Images and a boat trip to photograph a wind farm off the Teesside coast.
James said: ‘I wanted to illustrate how humankind’s actions have resulted in a world that is fast becoming ever more inhospitable to wildlife.
‘As a wildlife and environmental photographer, I am committed to raising awareness of the environmental issues our planet is currently facing, as well as showing the beauty that remains in increasingly smaller pockets of the natural world.’
The Department of Energy and Climate Change, which launched the contest last month, claims that the winning image sends a ‘stark message of the consequences of climate change’.
The #BackClimateAction 2015 competition pulled in hundreds of entries, covering areas such as the impact of climate change on health and local environments.
Entries were submitted via Instagram and Twitter.
Organisers were after an image that ‘challenges us to re-imagine climate change in the most original and engaging way’.
Secretary of State for Energy and Climate Change Ed Davey, one of the judges, said: ‘These images bring home the very personal impact that climate change will have on all parts of our lives, threatening our way of life as well as livelihoods, communities and economies.
‘The pictures also hint at some of the things we can do.
‘The UK has led the way and championed an ambitious contribution to the crunch climate talks in Paris at the end of the year.
‘It is up to the rest of the world to now meet that ambition, to secure the future for our children.’