HARI SREENIVASAN: Let's return to our top story.
President Trump weighed in on Twitter last night about the cold snap bracing much of
the country, and he seemed dismissive yet again about the effects of climate change.
At the same time, he seemed to conflate the latest weather with the broader issues around
climate.
John Yang is here to help break down the differences.
JOHN YANG: Hari, to help us understand that, and how climate change is viewed in the world
of science, I'm joined by Michael Oppenheimer.
He's a professor of geosciences and international affairs at Princeton University's Woodrow
Wilson School.
Michael Oppenheimer, thanks for joining us.
Let me just remind folks what the president said on Twitter last night after noting the
record forecast or the forecast for record cold on New Year's Eve on the East Coast.
He said: "Perhaps we could use a little bit of that good old global warming that our country,
but not other countries was going to pay trillions of dollars to protect against.
Bundle up."
Let's take that in two parts.
First of all, is he confusing climate and weather?
MICHAEL OPPENHEIMER, Professor of Geosciences and International Affairs, Princeton University:
It's impossible to say what was in the president's mind, but he probably was trying to confuse
other people about the reality of climate change.
This cold snap is weather.
Weather is what you experience day to day.
Climate is the long-term average of weather over periods of years, decades, centuries
or even longer.
Let me give you an analogy from the stock market.
It's perfectly possible for the stock market to be rising due to understood factors like
favorable economic forecasts, and yet to decrease significantly for one day, several days, a
month or even several months.
That happens all the time, even though the long-term trend might be continuing thereafter.
It's the same thing with climate change.
The Earth's temperature is going up.
It's been going up for about a century.
That increase is due to the buildup of the greenhouse gases caused by -- by and large,
by the burning of coal oil and natural gas.
And yet climate has certain unpredictable factors about it which can cause variations
like the current cold snap, which can cause temperatures to drop below normal, especially
for relatively small areas.
After all, what we're talking about here is the northern half of the United States.
So there's a long-term trend of warming.
This cold snap says nothing really about that long-term trend.
And that trend will continue until we make a radical reduction in the emissions of carbon
dioxide and other greenhouse gases.
JOHN YANG: So, given that distinction, do scientists see a connection between climate
change and episodes of extreme weather?
MICHAEL OPPENHEIMER: Yes, some episodes of extreme weather can be tied directly to the
buildup of the greenhouse gases caused by human activity.
For instance, the incidents of extreme heat has increased and episodes of heat waves are
increasing faster these days than they would without the buildup of greenhouse gases.
And that connection has been made clearly.
Similarly, incidents of very high water at the coasts, which is related to flooding,
for instance, when a storm comes along, has been tied in some cases to the buildup of
the greenhouse gases through its effect on sea level rise.
So, overall, there are some episodes of extreme weather that are directly related to the human
buildup of greenhouse gases.
JOHN YANG: Let's take the second part of what he said.
He said that the United States, but not other countries, was going to pay trillions of dollars
to protect against climate change.
I presume he's talking about the requirements of the Paris accord.
Is that true, what he said?
MICHAEL OPPENHEIMER: That's a complete fabrication.
For instance, the cost of the U.S. proposal to cut its emissions by 26 percent to 28 percent,
that reduction would have been obtained by and large by reductions in the power sector,
the so-called Clean Power Plan, electricity production.
And those would have cost a few billion dollars, not a few trillion dollars.
And, in fact, they would have produced more benefits in terms of reduced air pollution
starting right now and eventually reduced climate damages than they would have cost
in the first place.
So, this program was a net winner, but the Trump administration decided to rip it apart
anyway.
JOHN YANG: Michael Oppenheimer of the Woodrow Wilson School at Princeton University, thanks
for joining us.
MICHAEL OPPENHEIMER: Thanks for having me.