Donald Trump has just promised to ““, for United Nations climate change programmes, and roll back the “” Obama administration regulations to cut power plant emissions.

The Republican presidential candidate has often defied party orthodoxy on major issues, shocking conservatives with his off-the-cuff remarks. But his directly echoed the party’s line on climate change and energy.

, and his speech was a clear sign that he seeks to capitalise on financial support from the powerful fossil fuel industry. His call to roll back industry regulations also deepens his appeal to voters in oil, gas and coal-producing states.

“Obama has done everything he can to get in the way of American energy, for whatever reason,” Trump said, in an attack sure to be a centrepiece of his campaign. “If ‘crooked’ Hillary Clinton is in charge, things will get much worse, believe me.”

Climate incoherence

Yet a Trump presidency poses an existential threat qualitatively different from past Republican candidates who have doubted climate change. It could set in motion a wave of political and economic crises, creating global turmoil that would fatally disrupt efforts to tackle this issue in the US and abroad.

Alarmed by the possibility of a Trump victory in November, international negotiators are urgently the UN Paris agreement, in the hope that it can become legally binding before President Obama leaves office. Yet even if the gambit is successful, a Trump victory could cripple international progress in other ways.

To meet the aggressive targets set at Paris, countries will have to substantially ratchet up efforts to end reliance on fossil fuels over the next few years. At the very moment when the world needs American leadership on this, Trump’s incoherence on climate and energy policy and his outright disgust for global collaboration would have a severe chilling effect on progress.

In past comments, he has said he is ““, declaring that climate change is a “” and ““, “” to hurt US manufacturing. On energy policy, he has when asked about specifics, even fumbling the name of the Environmental Protection Agency, .

Civil unrest

The broader disruption of a Trump presidency would do even greater damage, weakening efforts to create a sense of urgency over climate change. Trump’s candidacy has brought public discourse in the US to its ugliest level, as he trades in trash talk and outrageous insults, spreading falsehood and innuendo, fomenting bigotry and prejudice.

He has threatened the censure of critics in the media, even condoning violence against protesters, calling them . His success emboldens far right and ultra-nationalist movements in the US and across Europe, risking further destabilisation.

At home, Trump’s promise to ban Muslims from entering the US, to erect a wall at the Mexican border, and to will provoke widespread protest and civil unrest.

Abroad, Trump’s bravado and reckless unpredictability, his vow to renegotiate trade deals and to walk away from security alliances will generate deep tensions with China, Russia and Europe, risking financial collapse and military conflict.

In the midst of such dysfunction and upheaval, the glimmer of hope offered by the historic climate change pact agreed to in Paris last year may forever fade. The stakes riding on a US presidential election have never been higher.

(Image: Mario Tama/Getty)

Pope Francis is to make history this week with a call for international cooperation to avert dangerous global warming – the Vatican’s most powerful statement yet on the environment and climate change.

A of the encyclical – a special type of edict used to define key priorities for the Catholic church and its 1.3 billion adherents – emphasises moral responsibilities to reduce reliance on fossil fuels and calls for changes in lifestyle and energy use to avoid the “unprecedented destruction of the ecosystem”. It highlights human release of greenhouse gases and warns that failure to act would have “grave consequences”. It also calls for a new global political authority to reduce pollution and help poor countries and regions develop.

The message could have particular impact in the US, home to 78 million Catholics and vital to international climate talks, but where moves to reduce carbon emissions remain highly divisive. Coming months will see coordinated sermons, homilies, and media outreach by US bishops as part of a Vatican-led campaign setting the stage for the pope’s September visit.

He’s due to address the United Nations General Assembly and a joint session of Congress. All this is just ahead of the crucial UN climate conference starting in Paris in late November.

suggest that US Catholics – about a quarter of all voters – will be receptive to his climate message. This group, who divide their loyalties between Republicans and Democrats, are more likely than non-Catholics to believe that climate change is happening, that humans are the cause, and to support action. But these are mostly weakly held sentiments. Rather than identify the issue as a moral one, most, like other Americans, still think about it abstractly and in technical terms. The Vatican campaign could reframe it as a religious and moral imperative, boosted by blanket coverage of the pope’s visit and exhortations in church.

Moral imperative

Political resistance to climate action could weaken too. Over the past year, a number of prominent Republican voices have argued their party must rethink its long-standing opposition to measures designed to address climate change. The pope’s visit will only strengthen these appeals. Andrew Hoffman and Jenna White at the University of Michigan, Ann Arbor, recently , saying it would create “political cover for emerging Republicans to upend the notion that you can’t be a conservative and believe in climate change”.

The papal visit will also coincide with the start of the Republican party’s nomination race for presidential candidates, posing a serious challenge to conservatives who continue to deny the warnings of climate science or oppose efforts to limit greenhouse gas emissions. Among the field of declared or likely candidates, Jeb Bush, Chris Christie, Marco Rubio, Rick Santorum, George Pataki, and Bobby Jindal all identify themselves as faithful Catholics. The pope’s stance may well mean uncomfortable questions dog them on the campaign trail and in debates.

His address to Congress will trigger similar tensions for the more than 80 , including Speaker of the House, John Boehner and former vice-presidential candidate Paul Ryan.

The potential impact on US climate politics is huge. As Jay Faison, a conservative Republican and entrepreneur behind a $165 million endowment for a foundation devoted to climate change and clean energy, told : “There’s a good argument to be made that losing Catholics will lose you the election.”

Matthew Nisbet is a professor of communication, public policy, and urban affairs at Northeastern University, Boston, Massachusetts

In a carefully crafted , UK environment minister Owen Paterson announced that the government would be leading “a more informed discussion” on genetically modified (GM) crops and that he was “conscious of the views of those who have concerns and who need reassurance on this matter”.

His remarks signal that the UK wants to build support for GM crops despite there being an effective moratorium on their use in Europe. But no matter how well framed the messages might be from political leaders, other engagement strategies and voices are needed if it is to succeed.

A recent suggests that when prompted to consider the benefits to human health and the environment, a strong majority of the British public are supportive of GM crops. But when asked more generally, roughly 40 per cent remain uncertain about risks and benefits. There also remains strong scepticism from about 1 in 10 people. Across Europe opposition is even stronger.

Ambivalence and entrenched scepticism do not stem from scientific ignorance; but from differences in values and world views. Opponents of GM crops often espouse idealised visions of nature and farming, voice concerns over changes to cultural practices and traditions, and are deeply suspicious of the food biotech industry.

Trusted sources

As I wrote last year in ��è����Ƶ, when protests over a trial of genetically modified wheat in the UK were making headlines, no amount of smart messaging by government officials and scientists is likely to overcome this opposition or to assuage the uncertainty of those who remain ambivalent. Efforts to defend and translate the science of GM crops too often avoid the real roots of contention.

Instead, across Europe, proponents of GM crops need to initiate conversations within their local communities and regions not just about the science of GM crops, but also about issues related to governance, transparency, ownership, and cultural and economic impacts.

Responsible voices from the environmental community also need to step forward. In general, we tend to pay closest attention to the opinions of people perceived to share our values and identity. In this regard, former anti-GM-organism activist , who publicly ended his opposition to the technology, is an important example.

Given the vocal opposition of their peers, until recently, there have been few incentives for environmentalists to voice support for GM crops, even if they quietly recognise the benefits of the technology in coping with challenges like climate change.

Shift in perceptions

By speaking out about his change of mind and support for GM crops, Lynas has helped to create the conditions for other prominent environmentalists to step forward. What’s needed now is for others to find the courage to follow his lead. At stake is the credibility of the environmental community.

Public engagement efforts can further catalyse a shift in perceptions by identifying and recruiting everyday opinion-leaders within communities. Environmentalists, farmers, health professionals and others are the trusted confidants and information brokers who can start conservations with their peers about the benefits, risks, trade-offs and cultural implications of GM crops.

People are much more likely to be receptive to reconsidering their views on the issue if engaged in a conversation by those they view as a friend, neighbour or work colleague, rather than by a government representative or scientist.

Given the polarised nature of the debate, GM crop proponents will have to compromise and negotiate on aspects of regulation and policy; with a mix of incremental victories and short-term defeats to be expected. But this process can be made easier with careful thought and investment in communication and public engagement efforts, and if new voices have the courage to step forward.