Climate change is the most pressing challenge of our time, yet meaningful action to address this global threat seems increasingly elusive. What’s standing in the way? There are numerous individuals, organizations, and corporations that actively work to obstruct attempts to cut our carbon emissions, advance clean energy, and prepare communities for the devastating impacts of climate change. Here is a list of just a few of these thwarters who stood out in 2013.

Tony Abbott

Shortly after being elected Australia’s prime minister in September, Tony Abbott started making good on campaign pledges to dismantle the country’s ambitious climate change framework. This includes abandoning the country’s emissions target, taking steps toward repealing Australia’s hard-won carbon emissions trading scheme, and axing the country’s climate commission, an independent panel of experts that provided information on how climate change is affecting the country.

When a heavy spate of bushfires erupted around Sydney early in the bushfire season, Abbott denied any links to climate change, going as far as to get in a public debate with U.N. Climate Chief Christiana Figueres and Nobel laureate Al Gore. Causing a further international row, he shunned the November U.N. climate talks in Warsaw by opting not to send a senior elected member of his government — a purely political move with little regard for the dire need for international cooperation in confronting climate change.

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Stephen Harper

Canada has a reputation for being an environmentally friendly country, not a petro-state, but Prime Minster Stephen Harper is changing the face of his country. With the Alberta tar-sands project he is literally turning a landscape of boreal forest into oily muck inhospitable for life. But he is also changing Canada’s global reputation for the worse by steering energy and environmental policies in favor of fossil fuel companies. The Harper administration has even gone so far as censoring artists whose work doesn’t align with their pro-fossil fuel agenda.

The rise in emissions that accompanies developing the tar sands means that Canada won’t be able to meet its 2020 targets for overall greenhouse gas emissions reductions.

Rupert Murdoch

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Bjorn Lomborg is not your typical climate grinch. Lomborg, a Danish political scientist, directs the Copenhagen Consensus Center, which compares global problems in an effort to determine how to best allocate available resources. However, some of Lomberg’s arguments relating to climate change are way off base, like criticizing green energy subsidies or promoting continued reliance on fossil fuels as the best way to lift people out of poverty.

Recently Lomborg wrote an editorial in the U.K. Times that asserts that, “global warming has mostly been a net benefit so far” and will be for decades. So while Lomborg does not deny that climate change is happening, he might be considered a confusionist, as Climate Progress’ Joe Romm recently labeled him. With Lomborg holding such a high perch from which to espouse his confusing — and even confounding — views, the potential negative impact he could have on combating climate change stands to be tall.