美國野生動物基金會（National Wildlife Federation）氣候科學家史都（Amanda Staudt）表示，「儘管不能將單一氣候事變歸因於全球暖化，但必須要了解，暖化的氣候一直以來確實醞釀出，助長各種氣候事變發生的環境。」
「針對美國陸軍工兵部(U.S Army Corps of Engineers)帶領的機關所用的最新研究，其中假設自然環境從過去至今未曾改變。」
Climate change will bring an increase in severe storms like the ones responsible for the devastating floods plaguing the U.S. Midwest, experts warned Tuesday. But current government flood forecasts and insurance programs do not consider the effects of global warming, leaving Midwest residents with an incomplete assessment of their flood risks.
"Although no single weather event can be attributed to global warming, it's critical to understand that a warming climate is supplying the very conditions that fuel these kinds of weather events," said Amanda Staudt, a climate scientist with the National Wildlife Federation, NWF.
The frequency of torrential rainstorms in the Midwest has jumped 20 percent since the late 1960s, Staudt said, and large storms that historically would only be seen once every 20 years are projected to happen as often as every five years.
"Global warming is making tragedies like these more frequent and more intense," Staudt told reporters in a telephone briefing. "As climate continues to warm and we have even more moisture in the air, the trend toward increasingly intense weather events will continue."
U.S. officials say the Midwest has seen two 100-year floods in the last 35 years as well as two 500-year floods - one in 1993 and this latest disaster.
Those numbers don't make sense and illustrate the government's flawed flood forecasting, said Nicholas Pinter, a geologist and flood researcher at Southern Illinois University.
"These are not random events," he said. "We are getting a systematic pattern of floods larger and more frequent than estimated by those calculations."
Relying on historical records, flow rates and river elevation, government agencies have consistently underestimated the flooding risks, Pinter said.
The latest study used by agencies, led by the U.S. Army Corps of Engineers, "assumed no natural changes" to the region over time, he said.
It ignored evidence of an increased risk from global warming and failed to consider significant land use changes, new levee construction and modifications to rivers in order to ease navigation, Pinter told reporters.
The Corps' study did include potential flood reduction benefits from dams throughout the Midwest, thereby further underestimating flood risks, Pinter explained.
The faulty estimates, used to set standards for the national flood insurance program, have contributed to the devastation, said David Conrad, a senior resource specialist with the National Wildlife Federation.