Local warming? They see it in China

Floods in Fargo and droughts in China. Observers in two such far-distant locales trace at least some of their troubles to the same cause: climate change.

In China's case, though, scientists are claiming an unusual distinction. They say they are able to detect local warming from local pollution. If they're right, it's the first time that such a cause and effect have been observed within a single country.

China, which is building more and more coal-fired power plants to fuel its economic development, spews more carbon dioxide into the atmosphere than any other country. A clear link between its energy practices and climate change could help create the conditions for political action.

The flood forecast in Fargo-Moorhead, meanwhile, has eased a bit in recent days. And the heavy snow and rain this month should bring some relief from the drought that has gripped the region for so long. For farmers, though, conditions remain far from ideal.

"The downside is that the farmers that had poor yields due to drought last year," said Steve Buan, hydrologist with the National Weather Service in Chanhassen, are "flooded out and they can't get their seeds in a timely fashion, [and] may suffer from a lower yield due to the limited nature of what they can plant on areas that are flooded this spring."

MPR News Chief Meteorologist Paul Huttner joins The Daily Circuit to discuss the climate issues of the day. Here is an edited transcript of the conversation:

Weber: You sent along a really interesting study that links global warming in China to stuff being done in China. I think that's interesting.

Huttner: We've always said all weather is local but this may be the first study to confirm that some climate change is local, directly linked to greenhouse gases from a region. This really is the first study to directly link warmer temperatures in climate change in one single nation rather than on a global scale. This is from Geophysical Research Letters, funded by the Chinese government, confirming the direct link to emissions and warming from the Institute of Atmospheric Physics in Beijing.

Weber: We hear that it's a global problem and I think some people would say maybe some politicians take it as an out. If we build a plant in Minnesota, that might have an effect on China — and China can't do anything to stop us from building that plant and so nothing is going to get done. This study maybe turns that on its side a little.

Huttner: It may. It's groundbreaking in that it's the first one to make this local link. China is now the No. 1 emitter of carbon dioxide. It's far ahead of the United States and they're planning to build 363 new coal-fired power plants to meet their energy demand. This study found that the daily minimum and maximum temperatures — they looked at 2,416 weather stations in China between 1961 and 2007 — they ran it against the climate models and they calculated that the carbon dioxide and the locally produced greenhouse gases raised the warmest annual temperatures for the hottest days by 1.6 degrees, the warmest nights over three degrees. Like Minnesota, the greatest warming is in winter, raising the daytime highs by five degrees and the overnight lows by eight degrees. That's the Climate Cast number for this week: Eight degrees warmer in China since 1961 at night in winter.

Weber: How localized is it? If we have a cluster of plants that emit carbon, can we say that the temperature goes up even more in that square mile? Is it that narrow and focused?

Huttner: I don't think we know that yet. Obviously these greenhouse gases mix out, they're transported around the globe. But one of the things that this might be showing is that it's not even and that it takes time. The effects may be greater in local areas where more greenhouse gases are produced.

Weber: Let's come back home to Minnesota where we're keeping an eye on all the rivers everywhere basically. We've been in a drought, and it might just take a whole flood to end a drought, wouldn't it?

Huttner: That's what Mark Twain said, "It takes a flood to end a drought." You are so right. This is remarkable, Tom. We've seen a major improvement in the U.S. drought since fall. This is the first time since last June that less than 50 percent of the continental United States is in drought. It's 47 percent now, compared with 65 percent last September. That's a big drop. The biggest improvement is in Mississippi and Ohio River Valley states: Minnesota, Wisconsin, Illinois, Indiana, down through Missouri and Arkansas. Ninety-one percent of the Midwest was in drought on Sept. 25. It's now 32 percent. Minnesota has fallen even more, from 98 percent down into the 60s now. For the first time, as this map that came out this morning shows, southeast Minnesota is drought-free and even the south metro (parts of Dakota and Scott county) are drought-free and the northern tier of the state. Big improvement in Minnesota.

Weber: Over the winter you were talking about how the snow on the ground may not have much of an effect because the ground was frozen. You said the snow has to melt first before the ground can melt and soak in some water. What happened?

Huttner: We had a situation where we melted a lot of that snow a month or so ago when it warmed up briefly and the ground did thaw out to the top 8-10 inches of the soil. Then we got more snow. As that additional snow fell, it actually melted down into the soil, which was now thawed. Because we had a slow warm-up this year that was actually ideal to try to soak some of that moisture in from the snow and it could be one of the things that's helping to ease the Red River flood crest a bit.

Weber: Are you saying this snowstorm we had last week was a good thing?

Huttner: What's the old saying? There really is no bad weather, just different kinds of good weather. This weather we've had was very good for the drought. In fact, I just ran into a gentleman from Red Wing Boots here at the studio today. He says they had a great April. They had a huge run on work boots in April because of all the slush. One man's trash is another man's treasure, as they say, and that's how weather is sometimes.

Weber: We had that one storm, 20-something inches in Two Harbors, 50 inches of snow in Duluth in just the past month or two and yet we had the story that came out this week that said the Great Lakes are still well below where they should be.

Huttner: They are at near record-low levels. All this snow — there's still two feet of snow up on the North Shore and the Upper Peninsula of Michigan — that is going to melt and run into the lakes. I think we're going to get a good shot of runoff here into Lake Superior in the next month or so. That may help lake levels temporarily, but if we continue to see these very hot summers with little precipitation and a lot of humidity, that increases evaporation. Longer term we are concerned with these low lake levels.

Weber: It's not so much the runoff with a big snow like this. If the lakes don't freeze as much in the winter, which they're not, it evaporates more. That's what was interesting to me.

Huttner: There's a trend toward as much as 70 percent less winter ice cover since the 1970s on the Great Lakes. That lake is not ice-covered, it's exposed, it can evaporate almost all year, whereas it used to be locked up for a few months. That makes a huge difference in how much water can leave that lake in the course of a year.

Weber: Are those lakes ever going to get back to normal?

Huttner: Great question. If our climate keeps evolving like it has in the Midwest and Upper Midwest, the long-term stressors are going to reduce lake levels. We've got as much as perhaps a foot less snowfall overall projected for the Midwest and Minnesota by the year 2050 or 2070 and that means less runoff as well. As we see these climate changes, one of the regional effects is pressure on the Great Lakes.

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