NASA: New study: A warming world will further intensify extreme precipitation events

April 4, 2013 According to a newly-published NOAA-led study in Geophysical Research Letters, as the globe warms from rising atmospheric concentrations of greenhouse gases, more moisture in a warmer atmosphere will make the most extreme precipitation events more intense.

The study, conducted by a team of researchers from the North Carolina State University’s Cooperative Institute for Climate and Satellites-North Carolina (CICS-NC), NOAA’s National Climatic Data Center (NCDC), the Desert Research Institute, University of Wisconsin-Madison, and ERT, Inc., reports that the extra moisture due to a warmer atmosphere dominates all other factors and leads to notable increases in the most intense precipitation rates.

The study also shows a 20-30 percent expected increase in the maximum precipitation possible over large portions of the Northern Hemisphere by the end of the 21st century if greenhouse gases continue to rise at a high emissions rate.

“We have high confidence that the most extreme rainfalls will become even more intense, as it is virtually certain that the atmosphere will provide more water to fuel these events,” said Kenneth Kunkel, Ph.D., senior research professor at CICS-NC and lead author of the paper.

The paper looked at three factors that go into the maximum precipitation value possible in any given location: moisture in the atmosphere, upward motion of air in the atmosphere, and horizontal winds. The team examined climate model data to understand how a continued course of high greenhouse gas emissions would influence the potential maximum precipitation. While greenhouse gas increases did not substantially change the maximum upward motion of the atmosphere or horizontal winds, the models did show a 20-30 percent increase in maximum moisture in the atmosphere, which led to a corresponding increase in the maximum precipitation value.

The findings of this report could inform “design values,” or precipitation amounts, used by water resource managers, insurance and building sectors in modeling the risk due to catastrophic precipitation amounts. Engineers use design values to determine the design of water impoundments and runoff control structures, such as dams, culverts, and detention ponds.

“Our next challenge is to translate this research into local and regional new design values that can be used for identifying risks and mitigating potential disasters. Findings of this study, and others like it, could lead to new information for engineers and developers that will save lives and major infrastructure investments,” said Thomas R. Karl, L.H.D., director of NOAA’s NCDC in Asheville, N.C., and co-author on the paper.

The study, Probable Maximum Precipitation (PMP) and Climate Change, can be viewed online. More

 

 

Climate change "new normal," lessons from Sandy: U.N. chief

(Reuters) - Extreme weather sparked by climate change is "the new normal" and Superstorm Sandy that ravaged the U.S. Northeast is a lesson the world must pursue more environmentally friendly policies, U.N. Secretary-General Ban Ki-moon said on Friday.

The United Nations headquarters closed for three days when former hurricane Sandy slammed the Northeast on October 29 as a rare hybrid superstorm, killing at least 121 people, swamping seaside towns and leaving millions without power.

"We all know the difficulties in attributing any single storm to climate change. But we also know this: extreme weather due to climate change is the new normal," Ban told the 193-member U.N. General Assembly.

"This may be an uncomfortable truth, but it is one we ignore at our peril. The world's best scientists have been sounding the alarm for many years," he said. "There can be no looking away, no persisting with business as usual ... This should be one of the main lessons of Hurricane Sandy."

New York City Mayor Michael Bloomberg endorsed President Barack Obama for a second term after Sandy struck, citing Obama's record on climate change and saying he believed the Democrat would adopt more policies to curb greenhouse gases in a second term. Obama won re-election on Tuesday.

The head of U.N. security, Gregory Starr, said last week that U.N. headquarters sustained severe damage when Sandy produced heavy flooding in basement levels of the world body's Manhattan complex along the East River. �� Flood damage forced the relocation of a U.N. Security Council meeting on Somalia last week from its normal chambers to a temporary building inside the U.N. campus.

U.N. delegations sharply criticized the United Nations' management on Monday for an almost "total breakdown in communications" with the world body's member states after superstorm Sandy struck.

"Our global services were provided without interruption," said Ban. "However, it is clear that in focusing so much on operations and infrastructure, we fell short when it came to communications." More

 

The world is closer to a food crisis than most people realise

Unless we move quickly to adopt new population, energy, and water policies, the goal of eradicating hunger will remain just that.

Food riots in Algeria in 2008. Photograph: Fayez Nureldine/AFP/Getty Images

In the early spring this year, US farmers were on their way to planting some 96m acres in corn, the most in 75 years. A warm early spring got the crop off to a great start. Analysts were predicting the largest corn harvest on record.

The United States is the leading producer and exporter of corn, the world's feedgrain. At home, corn accounts for four-fifths of the US grain harvest. Internationally, the US corn crop exceeds China's rice and wheat harvests combined. Among the big three grains – corn, wheat, and rice – corn is now the leader, with production well above that of wheat and nearly double that of rice.

The corn plant is as sensitive as it is productive. Thirsty and fast-growing, it is vulnerable to both extreme heat and drought. At elevated temperatures, the corn plant, which is normally so productive, goes into thermal shock.

Time is running out. The world may be much closer to an unmanageable food shortage – replete with soaring food prices, spreading food unrest, and ultimately political instability– than most people realise.

As spring turned into summer, the thermometer began to rise across the corn belt. In St Louis, Missouri, in the southern corn belt, the temperature in late June and early July climbed to 100F or higher 10 days in a row. For the past several weeks, the corn belt has been blanketed with dehydrating heat.

Weekly drought maps published by the University of Nebraska show the drought-stricken area spreading across more and more of the country until, by mid-July, it engulfed virtually the entire corn belt. Soil moisture readings in the corn belt are now among the lowest ever recorded.

While temperature, rainfall, and drought serve as indirect indicators of crop growing conditions, each week the US Department of Agriculture releases a report on the actual state of the corn crop. This year the early reports were promising. On 21 May, 77% of the US corn crop was rated as good to excellent. The following week the share of the crop in this category dropped to 72%. Over the next eight weeks, it dropped to 26%, one of the lowest ratings on record. The other 74% is rated very poor to fair. And the crop is still deteriorating.

Over a span of weeks, we have seen how the more extreme weather events that come with climate change can affect food security. Since the beginning of June, corn prices have increased by nearly one half, reaching an all-time high on 19 July. More

 

Erratic Weather Across Globe Fueling Impending Food Crisis

In addition to the ongoing drought in the United States, experts warn that the potential for a worldwide food crisis is heightened by extreme and erratic weather across the globe.

A report in The Guardian cites recent flooding in Russia, an encroaching drought in South America, and heavy rains in the UK and says all contribute to a worldwide arithmetic that adds up to an agricultural nightmare.

The report says that deteriorating conditions are leading more and more analysts to draw parallels to events that led up to the 2008 global food crisis "when high food prices sparked a wave of riots in 30 countries across the world, from Haiti to Bangladesh."

Nick Higgins, a commodity analyst at Rabobank, is quoted as saying: "Food riots are a real risk at this point. Wheat prices aren't up at the level they got to in 2008 but they are still very high and that will have an effect on those who are least able to pay higher prices for food."

And Ruth Kelly, Oxfam's food policy advise, says that popular fury in less developed nations stems from the fact that people in poorer nation's spend a much larger percentage of their income on food than those in wealthier nations.

Kelly told The Guardian problems will be compounded by the previous two food price spikes in 2008 and 2011:

"People are already in debt from previous spikes and suffering the consequences. When the first food crisis hit people were forced to sell off their assets, their cattle and jewellery, and take on debt to make ends meet. After multiple crises, people run out of savings and that can be quite disastrous."

Raj Patel, expert on the global food system and author of the book Stuffed and Starved: Markets, Power and the Hidden Battle for the World’s Food System Writing, recently wrote on his website, "Changing the food system couldn’t be more urgent. All signs point to that conclusion, whether you consider the droughts, floods and fires caused by climate change, the rise in global food prices, or that the health effects of our current food system is predicted to shorten children’s lives."

"Better, and smarter ways of growing food, and feeding the world are needed, now," Patel said. More

 

Global Warming Is Happening Now

The science does not lie.

Warming and the Water Cycle: More than Just a Faster Wetter Wet and Drier Dry

One of the most serious consequences of global warming is its predicted impact on the water cycle. A new study, described below, presents evidence that the global water cycle is changing even faster than predicted. A further concern is that future rainfall patterns may be extremely variable in both space and time.

Since the 1950s, parts of the world's ocean became saltier (red) and parts became fresher (blue) as the global water cycle intensified. The color scale refers to the observed change in salinity. The numbers on the scale correspond approximately to grams of salt per kilogram of seawater.

As the atmosphere warms, its capacity to hold water vapor increases. This is quantified by the Clausius-Clapeyron relationship, which explains that the atmosphere will hold about about 7% more moisture for every degree Celsius of warming. That means more evaporation in areas that are already dry and increased precipitation in regions that already receive high rainfall. Thus we can expect increasing droughts in dry areas and more floods in regions now prone to flooding.

In the 27 April 2012 issue of SCIENCE, Paul Durack of the Lawrence Livermore National Laboratory in California and coworkers explored a historical database of the saltiness of the surface ocean waters, or salinity, and found evidence that the global water cycle has intensified over the past half-century. The observed shifts in ocean salinity are consistent with the Clausius-Clapeyron relationship and with the observed warming of the surface ocean by about 0.5°C.

Noting difficulties in obtaining accurate estimates of rainfall over land, Durack and coworkers used ocean salinity as a natural rain gauge. Just as the long-term average evaporation and precipitation leave their imprint on land in terms of characteristic landscapes, they are recorded in the ocean by the saltiness of surface waters. The saltiest ocean waters are found in the subtropics, where the dry descending air of the Hadley cell causes evaporation to exceed precipitation. By contrast, surface waters at high latitudes tend to be less salty as precipitation is greater than evaporation. This pattern has existed for much of Earth’s history. More