US leaves Paris climate agreement: Here's how Trump misunderstood the science

The MIT scientist who published a study quoted by Donald Trump in his announcement on withdrawing from the Paris climate pact says that the president has completely misunderstood the science.

"It is estimated it would only produce a two-tenths of one degree – think of that; this much – Celsius reduction in global temperature by the year 2100. Tiny, tiny amount," Trump said at a press conference on Thursday.

White House officials have reiterated their view that this is the scientific consensus, and the Paris agreement won't make much difference.

But the scientists who wrote the study that Trump has relied on say that this is a wild misinterpretation of their work.

The study was published in a European Geosciences Union journal in April 2016. The research was quoted in White House documents seen by Reuters, but the scientists in question were not invited to explain what their findings meant.

They have denied that their work supports withdrawal from the climate pact – if anything, it supports even stronger action.

"This idea that the Paris Agreement has a negligible impact on future climate change is certainly not what we conveyed and was not the conclusion of our analysis," Monier told the MIT Technology Review in the wake of Trump's announcement.

"We make clear that if we want to limit warming to 2C, we need to do more and we need continued effort past 2030."

President Barack Obama, who pledged that the US would join the agreement in 2015, committed to a national reduction in greenhouse gas emissions by at least 26% below 2005 levels by 2025.

How did Trump get the numbers wrong?

The evidence used to support Trump's decision has been shoddily interpreted, according to researchers specialising in modelling and predicting climate change.

"Basically, they have the science completely wrong," Piers Forster, climate scientist and director of the Priestley International Centre for Climate at the University of Leeds, told IBTimes UK.

"We were on course for around 4.4C increases without mitigation. Current policy gets us to around 3.6C warming. Paris pledges carried out to 2030 get us to around 2.6C warming."

The notion that Paris was intended to be just the start of much more ambitious targets has also been "completely ignored" by the administration, Forster said.

"The effect of the Paris agreement is definitely not a 0.2C decrease like Trump is saying," agreed Corinne Le Quéré, director of the Tyndall Centre for Climate Change Research at the University of East Anglia.

"What Trump has said is not what is in the study. What is in the study is that the Paris agreement would lead to between 0.6 and 1.1C less warming. This is actually quite large when you think that we've had already a full 1C of warming."

Exploiting uncertainty

There is a range of predictions for how much the climate will warm in coming years. This is because we don't know how quickly the atmosphere, oceans and ice will respond to increasing carbon emissions, said Simon Tett of the University of Edinburgh.

"We have some idea how strong the feedback from climate systems are and how fast the oceans take up heat," Tett said. "There are no real analogues in the past we can use. We're going into a very uncertain world."

These subtleties have been lost in the White House's interpretation of the science. "It doesn't look like they've understood the science correctly," he said. "I think it's a disaster."

Finding hope elsewhere

World leaders from France to China have reaffirmed their commitment after the announcement that the US would withdraw from the pact. French president Emmanuel Macron said in a video statement that the task ahead would be to "make our planet great again".

"Recommitment to the pact is very important," said Le Quéré. "But also in the US at the levels of states, cities and businesses – all these people have the intention and interest in moving towards a low-carbon economy.

"They have the good health of the planet at heart. They need now to take their position forward, regardless of what the president of the US says."