On Thursday, President Donald Trump announced that he would begin pulling the US out of the Paris Agreement on climate change. The accord, signed by all but two countries, aims to keep the world from warming by more than 2 degrees Celsius above pre-industrial levels, a threshold that scientists say could save the planet from the worst-case scenarios of climate change.
During a White House news conference, Trump outlined his reasons for leaving the agreement. Many of them, however, were based on questionable data. Here are some of Trump's main arguments for exiting the pact — and what the numbers say about them.
Trump suggested that US compliance with the Paris accord could "cost America as much as 2.7 million lost jobs by 2025, according to the National Economic Research Associates."
The report on which that claim is based has been widely criticized by environmental groups. As the World Resources Institute pointed out, the NERA study uses a scenario in which the US industrial sector is forced to reduce the country's overall emissions by nearly 40% in 20 years. That calculation doesn't take into account the role of other sectors in reducing emissions.
The WRI also faults the NERA report for assuming a low rate of clean-energy innovation. That rate was calculated by the Department of Energy as a minimal case that "may underestimate advances." What's more likely, the National Resources Defense Council suggests, is that the development of clean energy technologies will accelerate. Even since 2016, solar costs have decreased by about 8%.
Today, solar jobs vastly outnumber those in coal, and those numbers continue to grow — a recent report from the International Renewably Energy Agency estimated that employment in the solar industry expanded 17 times as fast as the US economy overall in 2016.
Just a tiny temperature decrease
Trump also suggested that the Paris Agreement would lead to only a minuscule reduction in global temperature.
"Even if the Paris Agreement were implemented in full, with total compliance from all nations, 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," he said. "Tiny, tiny amount."
A detailed analysis of the impact of the Paris goals by Climate Interactive suggests those numbers are off.
The global temperature will rise — there is no scenario in which there will be an overall reduction. But let's assume that Trump meant a reduction from the projections of temperature increases that would happen without the Paris Agreement.
Under a "business as usual" scenario in which past trends continue, the expected temperature increase in 2100 is 4.2 degrees Celsius (7.6 degrees Fahrenheit). If all nations fully achieve their Paris pledges, however, the average global surface temperature in 2100 is expected to be 3.3 degrees. That means the accord would lead to a reduction of nine-tenths of one degree, not two.
Nine-tenths of a degree on a global scale is huge. Since the industrial revolution, global temperatures on average have risen 0.99 degrees Celsius, according to NASA. That's not so far from .90, and we're already seeing plenty of dramatic changes around the planet. Even a reduction of two-tenths of a degree would not be "tiny" — it would be 20% of the increase we've already seen.