US climate change skeptics and deniers said Thursday that Pope Francis was wrong to urge action against global warming because continuing to burn cheap fossil fuels could actually help the poor.

The reactions to Pope Francis' encyclical on climate change ranged from anger to polite disagreement, with US Republican presidential candidate Jeb Bush saying he respects the Catholic leader but prefers to make decisions about the environment in the political realm.

"Look, the climate is changing," Bush said at a campaign event in Iowa, according to CNN.

"I believe there are technological solutions for just about everything. And I'm sure there's one for this as well. So I respect the Pope, I think he's an incredible leader, but I think it's better to solve this problem in the political realm."

Bush, who announced his candidacy for US president on Monday, is Catholic but said religion would not guide his leadership on climate change.

"I don't go to mass for economic policy or for things in politics," he said.

Some opponents of the Pope took to Twitter to express their disapproval.

"Red Pope calls for CULTURAL REVOLUTION.' Been there, done that," former energy executive and activist Steve Milloy posted from the Twitter handle @JunkScience, along with a picture of Chinese communist revolutionary Mao Tse-tung.

After a draft of the Pope's speech leaked on Wednesday, the conservative Heartland Institute took issue with the Pope's declaration that human activity, including the reliance on polluting fossil fuels, is harming the Earth.

"The Church should speak for the poor, who need cheap, reliable, base-load coal-fired power. Yet Pope Francis has sided with the rich profiteers of doom," wrote Christopher Monckton, chief policy advisor at the Heartland Institute.

Tom Sheahen, a physicist and policy advisor at the Heartland Institute, also said that inexpensive fuels could be leveraged to assist the poor.

"If the developing countries use fossil fuels for a century or two, thereby lifting themselves out of poverty, that will not subtract from the prosperity of the entire world," Sheahen said.

"There will be a better energy source in the future."

According to Marc Morano, the publisher of the denialist website Climate Depot, "the Vatican's partnering with the United Nations climate agenda is nothing short of an unholy alliance."

He said UN global warming solutions "are at odds with most Catholic teachings on issues such as abortion, contraception, overpopulation, and helping the poor nations develop."

"Ultimately, the pope's views on climate science will do little to alter the opinions of Catholics about global warming."

The green vision of Pope Francis
Vatican City (AFP) June 18, 2015 - Main points of Pope Francis's Encyclical on the environment, released on Thursday:

- Main Challenge -

Climate change represents one of the principal challenges facing humanity in our time. Its worst impact will probably be felt by developing countries in coming decades.

"The urgent challenge to protect our common home includes a concern to bring the whole human family together to seek sustainable and integral development."

- A man-made problem -

Scientific studies indicate that most global warming in recent decades is mainly as a result of human activity.

Humanity must recognise the need for changes of lifestyle, production and consumption.

- Conflict and war -

"It is foreseeable that, once certain resources have been depleted, the scene will be set for new wars."

- Throwaway culture -

"The earth, our home, is beginning to look more and more like an immense pile of filth...

"These problems are closely linked to a throwaway culture."

- Carbon emissions -

"We know that technology based on the use of highly polluting fossil fuels - especially coal, but also oil and, to a lesser degree, gas - needs to be progressively replaced without delay."

- Consequences -

"If present trends continue, this century may well witness extraordinary climate change and an unprecedented destruction of ecosystems, with serious consequences for all of us."

A quarter of the world's population lives on, or near, the coast so sea level rises would be extremely dangerous.

- Drastic reductions -

Polluting gases must be "drastically reduced" with the reduction of fossil fuels and development of renewable energy.

- Rich to blame -

Developed countries ought to significantly limit their consumption of non-renewable energy and assist poorer countries to support policies and programmes of sustainable development.

"Many of those who possess more resources and economic or political power seem mostly to be concerned with masking the problems or concealing their symptoms."

- Drinking water -

"Access to safe drinkable water is a basic and universal human right.... Some studies warn that an acute water shortage may occur within a few decades unless urgent action is taken."

- Biodiversity -

"The earth's resources are also being plundered because of short-sighted approaches to the economy, commerce and production. The loss of forests and woodlands entails the loss of species which may constitute extremely important resources in the future, not only for food but also for curing disease and other uses."

- Binding agreements -

Enforceable international agreements are urgently needed, since local authorities are not always capable of effective intervention.

- Carbon credits -

The strategy of buying and selling carbon credits "can lead to a new form of speculation which would not help reduce the emission of polluting gases worldwide".

It may simply become a ploy which permits maintaining the excessive consumption of some countries and sectors.

- Religion -

"Most people profess to be believers. This should spur religions to dialogue among themselves for the sake of protecting nature, defending the poor, and building networks of respect and fraternity."

- Economy and growth -

"We need also to think of containing growth by setting some reasonable limits and even retracing our steps before it is too late...

"That is why the time has come to accept decreased growth in some parts of the world."

- Consumerism -

"Obsession with a consumerist lifestyle, above all when few people are capable of maintaining it, can only lead to violence and mutual destruction."

- Technology and profit -

"The economy accepts every advance in technology with a view to profit, without concern for its potentially negative impact on human beings."